The present study demonstrates the fabrication of a CIGS/CdS heterojunction with enhanced photoelectrochemical performance using low-cost non-vacuum methods. A simplified economical pulse electrodeposition technique, with a two-electrode system in an additive-free electrolyte, has been used for the preparation of chalcopyrite Cu(In,Ga)Se<inf>2</inf> (CIGS) thin-films avoiding the selenization process and CdS subsequently chemical bath deposited onto these CIGS films. Photoelectrochemical (PEC) performance of bare CIGS and the CIGS/CdS heterojunction has been investigated in conventional Na<inf>2</inf>SO<inf>4</inf> electrolyte under chopped solar simulated light. The PEC analysis reveals nearly twenty-fold increase in the photoresponse of the CIGS/CdS heterojunction compared to bare CIGS films. The CIGS/CdS junction has also been tested in a PEC cell using a novel sulphide/sulphite electrolyte for the first time and found to yield further enhancement in photocurrent density with exceptional stability. Thus, apart from fabrication of an efficient CIGS/CdS heterojunction economically, the present study proposes use of a novel electrolyte yielding superior performance and showing potential for commercialization of CIGS devices and their use in photoelectrochemical cells.[Figure not available: see fulltext.] © 2015, The Korean Institute of Metals and Materials and Springer Science+Business Media Dordrecht.

Solar cells based on polycrystalline Cu(In,Ga)Se2 absorber layers have yielded the highest conversion efficiency among all the thin-film technologies. CIGS thin-films possess large optical absorption coefficient (≈105 cm-1) and a suitable bandgap of ≈ 1.20 eV for an ideal stoichiometry of CuIn0.7Ga0.3Se2. In the present study, Direct Current (DC) and Pulsed Current (PC) electrodeposition techniques are employed to obtain the near ideal stoichiometric CIGS thin-films on a Mo foil using a two electrode system at a constant potential. Deposited films are annealed at 550 °C under Ar atmosphere. Characterization of the annealed CIGS films is performed using SEM-energy dispersive X-ray spectroscopy, X-ray diffraction, Raman spectroscopy, and photoelectrochemistry to study the morphology, stoichiometry, phase constitution, and the photoelectrochemical response. PC deposition offered suitable manipulation of various parameters, which has helped in obtaining a better quality stoichiometric single phase chalcopyrite structured CIGS thin films with the elimination of unwanted secondary phases like Cu2-xSe. An improved photoelectrochemical performance, characteristic of a p-type semiconductor, is observed for the PC deposited CIGS films. © 2013 AIP Publishing LLC.

Copper indium diselenide (CuInSe2) films have been prepared by pulse electrodeposition technique on Molybdenum substrate followed by post-deposition annealing at 550°C. Optimization of pulse parameters by varying the pulse duration (duty cycle) in order to achieve high quality films has been reported. Appropriate manipulation of pulse parameters has resulted in a novel flake-like crystallite morphology and better control over the composition of individual elements. The CIS thin films were comprehensively characterized using SEM-EDS, FIB, XRD and UV-DRS to study their morphology, phase constitution, etc. and PEC (photoelectrochemistry) measurements were also carried out to ascertain the photoelectrochemical performance of the CIS absorber layer. The bandgap of the CIS films was determined to be 1.02 eV. The flake like crystallite morphology observed in CIS thin films under the optimized processing conditions was found to yield enhanced cathodic photoresponse under solar simulated light with a photocurrent density of 20 μA/cm2 (observed at a potential of -0.6 V vs. SCE). The films exhibited a photoresponse typical of a p-type semiconductor. © 2013 The Electrochemical Society.

A novel approach for the fabrication of compact stoichiometric copper indium gallium selenium (CIGS) thin-films is reported. It uses a solution of CuCl2, GaCl3 and H2SeO3, pH adjusted with HCl with LiCl as additive employing a high purity graphite plate anode and Mo sputtered glass cathode during a simplified sequential pulsed current electrodeposition which avoids impurities from the use of a reference electrode during deposition and a separate selenization step. A Cu-Ga-Se film is optimally deposited by optimizing the deposition voltage, followed by deposition of In from InCl3 solution, and then annealing of the Cu-Ga-Se/In thin-film in an Argon atmosphere at 550 °C. A single phase chalcopyrite CIGS forms with a compact morphology and well-controlled composition of individual elements. The flat-band potential and carrier density of CIGS thin-films are -0.15 V and 2.6 × 1016 cm-3, respectively, as determined by Mott-Schottky studies. The photoelectrochemical performance of CIGS films shows a photocurrent density of -0.8 mA cm-2 at -0.4 V vs. SCE, an eight fold increment compared to our previous reported value. This simplified preparation using pulse plating gives superior quality CIGS films which are promising for application in thin-film solar cells and photoelectrochemical cells. © 2014 Elsevier B.V. All rights reserved.

Cu(In,Ga)Se2 (CIGS) materials are one of the most promising solar cell technologies owing to their large absorption coefficient and tunable direct bandgap, and they have gained considerable commercial maturity. The study herein puts forward the preparation of nanostructured CIGS films containing branched nanorod architectures, which is reported for the first time. The process employs an economic pulse-reverse electrodeposition technique by utilizing the fundamentals of electro-reduction and oxidation to fabricate nanostructured CIGS and completely avoids conventional energy-intensive high-temperature annealing/selenization step. Comprehensive characterization of nanoarchitectured films reveals the stoichiometric composition and chalcopyrite structure with dominant (112) orientation. Nanostructured CIGS exhibits excellent photoactivity with a photocurrent density of 4.31 mA/cm2 at -0.13 V vs RHE in a liquid junction, which is highest for a bare CIGS film and is attributable to its inherent high interface area and better charge transport properties compared to planar films. The ability to produce such efficient nanostructures using an economic, scalable, sustainable, and eco-friendly approach can considerably reduce fabrication costs compared with existing high-temperature bulk material preparation methods. © 2018 American Chemical Society.

Fabrication of Cu(In,Ga)Se 2 (CIGS) absorber layers containing two-dimensional nano-flake structures using a single stage pulse electrodeposition technique is reported for the first time, wherein CuCl 2 , InCl 3 , GaCl 3 and H 2 SeO 3 are used as precursors in a pH 3 buffer. The method employs tri-sodium citrate as complexing agent. The phenomenon of intrinsic electrochemical dissolution associated with pulse electrodeposition technique is efficiently utilized to obtain CIGS nano-flakes. The presence of tri-sodium citrate and the relaxation time during pulse electrodeposition play crucial role in achieving control over composition and morphology of CIGS films thereby aiding in the formation of nano-flakes. Evolution of nano-flake structures is systematically investigated with the increase in deposition time during pulse electrodeposition. Elemental analysis reveals the stoichiometric composition of nano-flake films while the formation of chalcopyrite phase-pure CIGS is confirmed by XRD and Raman analyses. The bandgap of CIGS nano-flakes is inferred to be about 1.21 eV from Tauc's plot. Mott-Schottky studies unveil the p-type conductivity of the CIGS with a flat-band potential and carrier density values of −0.15 V and 5.2 × 10 16 cm −3 , respectively. Photoelectrochemical characterization of CIGS films affirms their photoactivity and the photoresponse is almost 20 times compared to the traditional planar CIGS films. Nanostructured CIGS films fabricated by low-cost pulse electrodeposition method reduce materials consumption while promising excellent photoresponse and are suitable for photovoltaic and photoelectrochemical applications. © 2019 International Solar Energy Society

Hydroturbine steels, such as 13Cr-4Ni martensitic steels, are generally subjected to heavy-erosive wear and loss of efficiency due to solid particulate entrainment in the water. Surface-modified steels have proven to give better performance in terms of erosive wear resistance. In the present study, an attempt is made to investigate the effect of angle of impingement and particle size on slurry-jet erosion behavior of pulsed plasma nitrided and laser hardened 13Cr-4Ni steels. Laser hardening process has shown good performance at all angles of impingement due to martensitic transformation of retained austenite. Plastic deformation mode of material removal was also an evident feature of all laser-hardened surface damage locations. However, pulsed-plasma nitrided steels have exhibited chip formation and micro-cutting mode of erosive wear. Erosion with 150-300 mu m size was twice compared to 150 mu m size slurry particulates.

This study investigates the high-temperature wear behavior of laser-cladded (LC) cobalt-based Stellite 6 alloy coatings and compares the wear resistance of the cladding layer to the grey cast iron (GCI) substrate material at three different elevated temperatures: 150 °C, 250 °C, and 350 °C. Wear mechanisms at elevated temperatures were analyzed using SEM-EDS and Raman Spectroscopy to understand the material removal processes and degradation for the discs and counterpart composite friction material pins, respectively. The results indicated a significant improvement in wear resistance for cobalt-based alloy cladding at high temperatures. Wear rates were reduced by 5.0 %, 43.0 %, and 16.0 % at 150 °C, 250 °C, and 350 °C, respectively. The LC - brake pin tribo-pair exhibited a continuous increase in friction coefficients (CoF) with an increase in testing temperatures. The wear mechanism for laser-cladded discs exhibited a combination of abrasive and adhesive wear, with abrasive wear prevailing at 150 °C and increased adhesive wear at 250 °C and 350 °C. However, at 350 °C, decomposition of phenolic resin and the adhesive wear mechanism, led to brake pin failure. For GCI discs oxidative wear was identified as the predominant wear mechanism. The improved knowledge of wear mechanisms on LC Stellite 6 against composite brake pins, is set to enhance surface modification of GCI for brake disc applications. © 2024 Elsevier Ltd and Techna Group S.r.l.

This study investigates the high-temperature wear behavior of laser-cladded (LC) cobalt-based Stellite 6 alloy coatings and compares the wear resistance of the cladding layer to the grey cast iron (GCI) substrate material at three different elevated temperatures: 150 °C, 250 °C, and 350 °C. Wear mechanisms at elevated temperatures were analyzed using SEM-EDS and Raman Spectroscopy to understand the material removal processes and degradation for the discs and counterpart composite friction material pins, respectively. The results indicated a significant improvement in wear resistance for cobalt-based alloy cladding at high temperatures. Wear rates were reduced by 5.0 %, 43.0 %, and 16.0 % at 150 °C, 250 °C, and 350 °C, respectively. The LC - brake pin tribo-pair exhibited a continuous increase in friction coefficients (CoF) with an increase in testing temperatures. The wear mechanism for laser-cladded discs exhibited a combination of abrasive and adhesive wear, with abrasive wear prevailing at 150 °C and increased adhesive wear at 250 °C and 350 °C. However, at 350 °C, decomposition of phenolic resin and the adhesive wear mechanism, led to brake pin failure. For GCI discs oxidative wear was identified as the predominant wear mechanism. The improved knowledge of wear mechanisms on LC Stellite 6 against composite brake pins, is set to enhance surface modification of GCI for brake disc applications. © 2024 Elsevier Ltd and Techna Group S.r.l.

Liquid feedstock plasma spraying (LFPS) involves deposition of ultrafine droplets of suspensions or solution precursors (typically ranging from nano- to submicron size) and permits production of coatings with unique microstructures that are promising for advanced thermal barrier coating (TBC) applications. This paper reviews the recent progress arising from efforts devoted to development of high-performance TBCs using the LFPS approach. Advancements in both suspension plasma spraying and solution precursor plasma spraying, which constitute the two main variants of LFPS, are presented. Results illustrating the different types of the microstructures that can be realized in LFPS through appropriate process parameter control, model-assisted assessment of influence of coating defects on thermo-mechanical properties and the complex interplay between pore coarsening, sintering and crystallite growth in governing thermal conductivity are summarized. The enhancement in functional performances/lifetime possible in LFPS TBCs with multilayered architectures and by incorporating new pyrochlore chemistries such as gadolinium zirconate, besides the conventional single 8 wt.% yttria-stabilized zirconia insulating ceramic layer, is specifically highlighted.

Spinel Li4Ti5O12 (LTO) is a promising anode material for solid state thin film batteries (SSTB) due to its almost-zero volume change and promising Li-ion mobility. However, preparing LTO anodes for SSTB demands tedious vacuum-based processing steps that are not cost effective. In this context, the present study embarks on evaluating the versatile suspension plasma spraying (SPS) approach to fabricate LTO coatings without using any binder. The microstructure and stoichiometry of the fabricated LTO coatings developed through the SPS route reveals retention of ∼76 wt.% of the spinel LTO from the starting feedstock, with minor amounts of rutile and anatase TiO2. The SPS experiments yielded varying thickness build up rates of the LTO coatings depending on the processing parameters adopted. The electrochemical data of the produced LTO based electrode tested in a half-cell through galvanostatic cycling show reversible lithiation and delithiation at expected potential, thereby validating the promise of the SPS technique for potential fabrication of SSTB components once fully optimized.

Diamond-reinforced metal matrix composites (DMMC) have great potential for wear-resistance applications due to the superior hardness imparted by diamond. Atmospheric plasma spraying involving axial injection of suitable feedstock is a convenient pathway to fabricate DMMC coatings for tribological applications. In this paper, thick DMMC coatings were deposited by plasma spraying Ni–P clad diamond particles under varying spray conditions. It was found that the phase characteristics of DMMC coatings as well as extent of diamond retention and fragmentation were significantly influenced by spray conditions such as, stand-off distance (SOD) and carrier gas flow rate (CGFR). Mechanical characterization (by micro-indentation) on all DMMC coatings developed in this work showed that coatings sprayed with longer SOD and higher CGFR has relatively higher hardness than other two coatings. However, on nanoindentation, the diamond hardness was found overestimated due to effect of diamond roughness on fragmentation. Ball-on-disc wear testing showed excellent tribological properties in all cases, with enhanced wear performance being noted when more diamond is retained in the coating. © 2024

High velocity air fuel (HVAF) spraying is an emergent thermal spray process, which is used in this work to realize high-performance large area tribological coatings of nickel-phosphorus cladded cubic-boron nitride (c-BN) particles. To the best of authors’ knowledge, this is the first time that HVAF has been utilized for developing Ni–P coatings reinforced with c-BN (NBN). The importance of appropriate processing was highlighted by utilizing two different nozzle configurations, for which microstructure, phase analysis and hardness results demonstrates considerable differences. Furthermore, the coatings were subjected to sliding wear tests to assess their friction and wear characteristics. Post-wear SEM analysis reveals the associated wear mechanisms. Effect of annealing on tribological performance of NBN coatings was also examined, and it is shown that optimal processing can preclude the need for post-treatment. Results ensuing from this work lay the foundation for new generation of HVAF-sprayed wear resistant metal/c-BN composite coatings for diverse applications. © 2022 The Author(s)

Metallic coatings of Al2CoCrFeNi high entropy alloy (HEA) were deposited using the suspension high velocity air fuel spray (SHVAF) process, towards exploring its viability as a bond coat in thermal barrier coatings. The relatively high Al content promoted a BCC + B2 phase-dominated coating structure, leading to enhanced mechanical properties. The oxidized microstructure exhibited a protective Al2O3 layer with characteristics comparable to conventional bond coat alloys. 

Thermal spray high-entropy alloy (HEA) coatings have demonstrated potential for improving the wear resistance of conventional materials used in extreme engineering environments. In the present work, an equiatomic AlCoCrFeNi HEA coating was manufactured using the high velocity air fuel (HVAF) process. The phase and microstructural transformations in gas-atomized (GA) powder during HVAF spraying were analyzed using SEM, EDS and EBSD techniques. The tribological properties of this HEA coating sliding against an Al2O3 ball at both room temperature (RT) and 600 °C were also evaluated. The GA powder was composed of Body Centred Cubic (BCC) + ordered BCC (B2) phases, which transformed to BCC + B2 + minor Face Centred Cubic (FCC) phases during the HVAF coating process, validating the thermodynamic phase prediction projected by the Scheil simulation for non-equilibrium processing conditions. The rapid solidification and high velocity impact-assisted deformation of GA powder resulted in significant grain refinement in the HVAF coating, which ultimately improved the mechanical properties at both micro and nanoscale levels. The wear resistance of the HEA coating at RT was severely impacted by the relatively brittle BCC/B2 phase structure, leading to susceptibility to abrasive wear and surface fatigue. The wear resistance at 600 °C was slightly lower at RT due to the formation of a brittle oxide layer on the worn surface, which induced surface fatigue and aggravated mass loss of the coating.

This study explores the possibility of tailoring the fusion zone in conduction mode laser welding using a deformable mirror for beam shaping of multi-kilowatt continuous wave laser sources. Three power density distributions were shaped and used in bead on plate welding of Ti64 plates in conduction mode at three travel speeds. The effect on melt pool free surface geometry, cross section, microstructure and hardness profiles was measured and studied. It is shown that the geometry of the melt pool can be modified using a deformable mirror. A narrower and longer melt pool or a wider, shorter and shallower one were indeed obtained forming Gaussian-elliptical power density distributions oriented along and transverse to the travel direction, respectively. The latter distribution could be a favourable option for laser beam additive manufacturing as it could improve process efficiency while reducing remelting of the previous layer. This system has also a promising potential for adaptive process control since it could change fundamentally the beam shape at a rate faster than 10 ms. 

Tribaloy T400 (CoCrMoSi) caters to heavy-duty industrial tribological demands, but exhibits low fracture toughness with compromised resistance to crack propagation owing to the disparity in % Laves phases. In response to this limitation, hybrid suspension-powder plasma-sprayed novel Cr3C2 (d50 of 3.8 ÎŒm)/TiC (d50 of 2.2 ÎŒm) reinforced T400 (average powder size of 10–45 ÎŒm) coatings are deposited on grit-blasted SSAB Domex®350 LA steel. Continuous, adherent and co-existing lamellar T400-carbide coatings of 100 ÎŒm thickness were revealed in microstructure analysis. Intermetallic CoMoSi/Co3Mo2Si Laves and eutectic Co7Mo6/Co2Mo7 phases in T400 in addition to Cr3C2/TiC characteristic phases are confirmed via X-ray diffraction study. T400-Cr3C2 and T400-TiC have exhibited enhancement in elastic modulus (E) by 39%, and 36%, Vickers hardness (Hv) by 68%, and 82.5%; which consequently elucidates the augmentation in plasticity index (re) by 15.7% and 26.7%, and the drop in maximum displacement amplitude (hmax) by 14.9% and 19.8%, respectively, in T400-Cr3C2 and T400-TiC with reference to T400 (E of 135.2 GPa, Hv of 6.3 GPa, re = 0.318, and hmax = 1947 nm). A subsequent surmised fretting Hertzian contact diameter in T400-Cr3C2 ( 95.43 ÎŒm)/T400-TiC ( 96.1 ÎŒm) evaluated against T400 ( 106.9 ÎŒm) from optical profilometry indicates an improved damage tolerance. A contact area-based wear model, proposed herein to assess wear on a rough surface, further justifies the wear characteristics. Furthermore, synergistic L929 cell viability is recorded in T400-Cr3C2 (by 46%) and T400-TiC (by 30%) when compared with the control (+ve) disk. To conclude, suspension-powder plasma-sprayed T400-Cr3C2/T400-TiC composite coatings allude potential application in wear-resistant articulating surfaces by eliciting significantly enhanced micro-hardness through refined microstructure retention, improved fretting wear resistance by forming protective tribofilm, and augmented cellular response. © 2020 Elsevier B.V.

This study investigated the feasibility of depositing graphene nanoplatelet (GNP)-reinforced yttria-stabilized zirconia (YSZ) composite coatings. The coatings were deposited from an ethanol-based mixed YSZ and GNP suspension using suspension plasma spraying (SPS). Raman spectroscopy confirmed the presence of GNPs in the YSZ matrix, and scanning electron microscopy (SEM) analysis revealed a desired columnar microstructure with GNPs distributed predominantly in the inter-columnar spacing of the YSZ matrix. The as-deposited YSZ-GNP coatings were subjected to different isothermal treatments—400, 500, and 600 °C for 8 h—to study the thermal stability of the GNPs in the composite coatings. Raman analysis showed the retention of GNPs in specimens exposed to temperatures up to 500 °C, although the defect concentration in the graphitic structure increased with increasing temperature. Only a marginal effect on the mechanical properties (i.e., hardness and fracture toughness) was observed for the isothermally treated coatings. 

Abstract Suspension based plasma sprayed coatings can yield superior microstructural and tribological properties compared to conventional powder based plasma sprayed coatings. This study investigates a new hybrid method, using simultaneous spraying from powder and suspension, to produce composite coatings using alumina and yttria stabilised zirconia (YSZ), with potentially excellent wear and thermal properties. Dry sliding wear showed the alumina suspension-YSZ suspension coating yielded half the specific wear rate of the alumina powder-YSZ suspension, explained by preferential gamma alumina formation and increased porosity in the latter. Both YSZ-containing samples showed superior toughness and wear rate than simple alumina powder and suspension coatings.

This study explored the impact of microstructure and residual stresses on the fracture behavior of as-deposited thermal barrier coatings (TBCs). Two distinct air plasma sprayed TBCs, Coating A (conventional lamellar porous) and Coating B (dense vertically cracked), were investigated. Coating A involved coarser but less dense powders as feedstock and a lower substrate temperature during deposition. Further, Coating A had (Formula presented.) times higher randomly oriented porosities, finer grains, lower hardness, and elastic stiffness. Strikingly, however, the fracture strength was higher for the porous as-deposited Coating A. The answer to this apparent contradiction emerged from the intergranular residual stresses. These were measured using both X-ray diffraction and high-resolution-electron backscattered diffraction. Coating B, deposited at a higher substrate temperature, had clear growth selection of (Formula presented.) oriented grains. These also had more out-of-plane normal and shear residual stresses. The growth selection induced residual stresses appeared responsible for the decohesion of Coating B from the substrate and, correspondingly, lower fracture strength. © 2024 The American Ceramic Society.

High-entropy alloys (HEAs) represent a relatively new group of multicomponent alloys that have shown great potential for applications requiring tribological and oxidation resistant properties. Consequently, thermally sprayed coatings of different HEA chemistries have received increasing research attention. In this paper, atomized equimolar CrFeCoNi and AlCrFeCoNi feedstocks were used for high velocity air-fuel spraying (HVAF) to produce overlay coatings using two different nozzle configurations. The microstructure, phase constitution and hardness of the coatings were analyzed along with the primary aim of testing the coatings for their oxidation behavior. The performance of the two HEA chemistries was compared with two commercial MCrAlY coatings that are well-established bond coat materials for thermal barrier coatings (TBCs). An investigation was conducted to test the coatings’ performance as bond coats by applying suspension plasma sprayed yttria-stabilized zirconia top coats and evaluating the thermal cycling behavior of the TBCs. The AlCrFeCoNi-coating was found to demonstrate a lower oxidation rate than the CrFeCoNi-coating. However, the AlCrFeCoNi-coating was found to form more rapid oxide scales compared with the commercial bond coat material that also contained reactive elements. © 2022, The Author(s).

Ti-6Al-4V is a widely used titanium alloy in aviation and bio/chemical applications for its attractive mechanical and corrosion resistance properties. The use of Ti-6Al-4V as a coating for repair purposes through thermal spray techniques provides a unique productivity opportunity. A repair coating must be dense to provide the required in-service functionalities, such as resistance to wear. The High Velocity Air Fuel (HVAF) thermal spray technique deposits dense coatings with reduced concern for oxide inclusions. This work presents an investigation of the microstructure, dry sliding, and solid particle erosive wear performance of four different coatings engineered through the configuration of the nozzle of an HVAF spray gun, based on the length of the nozzle and the size of the nozzle exit. A long nozzle length and wide nozzle exit mean increased inflight dwell time and reduced average inflight temperature for the sprayed particles, respectively—a reversed configuration means the opposite. The tested coatings showed a porosity of less than 2%. The sliding and erosion wear performance of the densest of the coatings compares to that of the bulk material tested under the same conditions. Electron microscopy was used to investigate the driving mechanisms for the performance of the respective coatings. The implications of the results are discussed for the potential adoption of HVAF-sprayed coatings in metal component repair.

Light alloys are being increasingly investigated as alternatives to ferrous-based engineering components, based on weight considerations. However, in-service applications of such light alloy components often require a surface modification step to enhance their wear and corrosion responses for improved functionality. Thermally sprayed cermet coatings offer an enhanced resistance to wear and corrosion. This work investigates WC-CoCr coatings deposited using two different feedstocks comprising fine and coarse powder size distributions on aluminum alloy and steel substrates using high-velocity air-fuel (HVAF) and high-velocity oxy-fuel (HVOF) spray techniques. The WC-CoCr coatings were HVAF sprayed at various parameters to investigate the relationship between the processing conditions, microstructure, and performance. Microindentation, dry sliding wear, dry sand abrasion, cavitation erosion, and corrosion tests were conducted to assess the performance of the coatings. Despite the qualitative similarities in the microstructures of the coatings, the measured microindentation hardness values were observed to vary, and coatings deposited with higher particle impact velocities showed the highest microhardness between 1400 and 1600 HV0.3. For the three categories of wear investigated, the HVAF coatings showed better resistance than the HVOF coating investigated in this study. The estimated average specific wear rate (SWR) due to sliding wear of the HVOF coating was 16.7 ± 4.0 × 10−8 mm3/Nm compared to that of the most resistant HVAF coating, which exhibited a SWR of 1.7 ± 0.6 × 10−8 mm3/Nm. The cumulative mass loss rate due to the abrasive wear on the HVOF coating reached 1.11 mg/min compared to 0.76 mg/min of the most abrasion-resistant HVAF coating. All coatings showed similar corrosion resistances under the investigated conditions. The combination of wear and corrosion performance of the respective coatings could provide insight into the coating selection for intended applications.  

In the present study, an attempt was made to improve the corrosion resistance and microhardness of a cast magnesium-aluminium-zinc alloy by laser surface melting. A 400 W pulsed Nd:YAG laser was used to melt and rapidly quench the surface of the cast AZ91C alloy to improve the corrosion resistance. This was evaluated using potentiodynamic polarisation and EIS studies. The microstructure of the melt pool was examined using optical microscopy and scanning electron microscopy (SEM) along with energy dispersive spectroscopy (EDS), X-ray diffraction studies (XRD) and X-ray fluorescence (XRF). The work revealed that laser melting improves the corrosion resistance of as cast AZ91C alloy because of its fine microstructure and extensive solubility of aluminium in eutectic (β phase). The microhardness of the laser surface melted layer was also increased from 74 HV to 99-124 HV. © 2006 Institute of Materials, Minerals and Mining.

AZ91C cast magnesium alloy is an excellent candidate for automotive industries due to its low density. However, AZ91C alloy is not considered as suitable alloy for mechanical applications due to its low wear resistance property. In this present study, surface melting techniques were adopted to improve the wear resistance of AZ91C alloy. Gas tungsten arc with pulsing mode and pulsed laser surface melting techniques were carried out. The wear properties were evaluated from the pin-on-disc wear testing. The hardness values of the surface melted layers increased as compared with alloy in cast condition. The wear results showed that the surface melting processes has improved the wear resistance as compared with as cast. The improvement in wear resistance may be attributed due to grain refinement imparted by surface melting techniques. The wear rates of the alloy depend on hardness of alloy. The wear surface and wear debris were analyzed with optical microscopy, SEM along with EDS analysis and XRD studies for determining the mode of wear and wear mechanism. The worn surface analysis of surface melted samples were very smooth and granular peeling was hardly observed as compared to the generation of loose debris in the case of as cast alloy.

Cold gas dynamic spraying (CGDS), a relatively new thermal spraying technique has drawn a lot of attention due to its inherent capability to deposit a wide range of materials at relatively low-operating temperatures. A De Laval nozzle, used to accelerate the powder particles, is the key component of the coating equipment. Knowledge concerning the nozzle design and effect of process parameters is essential to understand the coating process and to enable selection of appropriate parameters for enhanced coating properties. The present work employs a one-dimensional isentropic gas flow model in conjunction with a particle acceleration model to calculate particle velocities. A laser illumination-based optical diagnostic system is used for validation studies to determine the particle velocity at the nozzle exit for a wide range of process and feedstock parameters such as stagnation temperature, stagnation pressure, powder feed rate, particle size and density. The relative influence of process and feedstock parameters on particle velocity is presented in this work. © ASM International 2008.

The idea of adding material only where needed to manufacturesolid metallic high-performing components is intriguing andone of the main reasons for the great interest in additivemanufacturing (AM) around the world. Especially whensustainability comes into play, as in recent times more thanever, AM technology is most appropriate since it enables almostfull material utilization with minimal waste. From an economicstandpoint, this becomes particularly advantageous for moreexpensive materials such as superalloys and titanium alloys.However, the route of going from a CAD drawing of a part to anadditively manufactured final component that is qualified and inserial production involves numerous challenges. The intentionof this book is to shed light on and explain some of theassociated challenges beginning with the importance of thestarting material and how it is manufactured, i.e., wire orpowder, continuing into description of the conventional andPederson, R., Andersson, J., & Joshi, S. (2023). Additive manufacturing of high-performance metallic materials. Elsevier.Created from vast-ebooks on 2024-01-08 16:09:20. Copyright © 2023. Elsevier. All rights reserved.most commonly used AM processes, followed by postbuildtreatments and nondestructive evaluations, to eventuallyproduce the final part with mechanical performance consistentwith the application requirements. In the end, selected realindustry examples of AM parts for actual applications will bepresented

This paper discusses multi-scale characterization of physical vapour deposited multilayer nitride coatings using a combination of electron microscopy and modulus mapping. Multilayer coatings with a triple layer structure based on TiAlN and nanocomposite nitrides with a nano-multilayered architecture were deposited by Cathodic arc deposition and detailed microstructural studies were carried out employing Energy Dispersive Spectroscopy, Electron Backscattered Diffraction, Focused Ion Beam and Cross sectional Transmission Electron Microscopy in order to identify the different phases and to study microstructural features of the various layers formed as a result of the deposition process. Modulus mapping was also performed to study the effect of varying composition on the moduli of the nano-multilayers within the triple layer coating by using a Scanning Probe Microscopy based technique. To the best of our knowledge, this is the first attempt on modulus mapping of cathodic arc deposited nitride multilayer coatings. This work demonstrates the application of Scanning Probe Microscopy based modulus mapping and electron microscopy for the study of coating properties and their relation to composition and microstructure. © 2013 Elsevier Inc.

Monolithic TiAlN coatings with varying Al content in the range 0-65 at.% were deposited by cathodic arc evaporation. The variation in mechanical properties was studied by nanoindentation and scratch testing, and correlated with the phase constitution, grain size and residual stress. The hardness was found to be nearly stable up to Al content of 53% followed by a large drop at 65%. Depending on the stoichiometry, phase constitution and microstructure of the Ti1-xAlxN coatings, the mechanical property measurements were observed to reveal distinct trends at particular Al contents-ranging from a large scatter to clustering of data around specific values. Focused Ion Beam milling and Transmission Electron Microscopy studies showed a gradual change in microstructure, from large columnar grains in TiN to finer columns at intermediate Al content and near equiaxed, ultrafine grains with a nanocomposite structure in case of Ti0.35Al0.65N. Scratch studies revealed the deformation modes to vary with Al content, with the ductile failure modes at low Al content giving way to brittle failure at the highest Al content. Toughness studies showed a gradual increase in toughness with Al%, with the maximum seen at 53% and a moderate drop seen at 65%. The toughness shows a close dependence on the mechanical properties, phase constitution and microstructure. The study outlines the role of Al content on the microstructure of PVD TiAlN coatings and highlights the advantage of a cubic, nanocomposite structure for enhancing the toughness of these coatings. © 2014 Elsevier B.V. All rights reserved.

PVD hard coatings, notably transition metal nitrides and carbides, are being increasingly used by industry for improving the life and machining speeds of cutting and forming tools. There has been an increasing trend towards use of complex coatings, based on ternary and even more complex multi-component systems, as well as in novel configurations such as multilayers, superlattices, nanolayers and graded coatings, to achieve superior properties in the tool as well as the finished product. The service properties of the coatings are known to be influenced by their microstructure, phase assembly and composition, apart from the orientation and stress states which can be suitably tailored for diverse applications. In the present study, a ternary coating based on Titanium Aluminum Nitride was deposited on high speed steel substrates by cathodic arc evaporation under varied bias voltage conditions. Asdeposited coatings were characterized by X-ray diffraction, Residual Stress Analysis, Scanning Electron Microscopy (SEM), EBSD and FIB. Mechanical and tribological characteristics of the coatings were evaluated by nanoindentation and nanoscratch testing, respectively. The variations in coating hardness and adhesion with the bias voltage were studied. The changes in coating microstructure as a consequence of variation in bias voltage were also examined. Results from the above investigations are presented to illustrate how a combination of electron microscopy with nanoindentation. © (2012) Trans Tech Publications, Switzerland.

In this work, CrAlN films with Al/Cr atomic ratios between 0.02 and 1.4 were deposited on tool inserts by AC magnetron sputtering at 5 kW for three different Ar/N-2 flow rates. The unique configuration of the inverted cylindrical magnetron sputtering (ICM-10) system enables the deposition of compositionally graded Cr-Al-N coatings under a single deposition condition. The effect of aluminum on the structural, mechanical and tribological properties of (CrAl)N coatings are reported and compared with ALCRONA and CrN coatings from Balzers. Mechanical properties have been evaluated by the microhardness indentation technique, and the hardness is 18 and 15 GPa for CrN and CrAlN films, respectively. The tribological tests have been performed using the pin-on-disc method at room temperature and 700 degrees C. The results indicate that the coefficient of friction at room temperature and 700 degrees C for all the deposited coatings, Balzers-ALCRONA and CrN fall between 0.4-0.6. The wear volume at high temperature (700 degrees C) decreases with increase in Al incorporation. Auger Electron Spectroscopy reveals that all films have about 10 at.% of oxygen. Atomic Force Microscopy showed that our films had roughness ranging from 80 to 150 nm. X-ray mapping on (Cr, Al)N coatings for different Ar/N-2 gas compositions showed transitions from cubic to hexagonal with decreasing nitrogen. (0 2007 Elsevier B.V. All rights reserved.

CrAlSiN nanocomposite thin films with varying film chemistry were developed on tungsten carbide (WC)specimens using cylindrical cathodic arc physical vapor deposition (c-CAPVD) technique. The physical, mechanical, and tribological properties of all the films were comprehensively investigated for arriving at the film chemistry leading to the best properties with respect to mechanical applications. The best tribo-mechanical properties were obtained in films with Cr/(AlþSi) ratio of 1.2. This coating with best properties was translated on to WC drill bits for machining tests. The Al and Si content has shown major influence on the adhesion strength and phase constitution of the films, with a considerable change in residual stress too. The superior properties achieved could be attributed to the formation of an ear-perfect nanocomposite structure, with the crystalline CrAlN phase surrounded by an amorphous Si3N4 phase. The tool life of the coated CrAlSiN tools was investigated during dry machining of EN 24material. In comparison to the tool life of an uncoated tool and a TiAlSiN-coated tool, the best CrAlSiN coatings synthesized in this study performed exceedingly well. The present study clearly demonstrates the advantages of CrAlSiN over other existing similar coatings for high-speed machining.

The present study compares the performance of microarc oxidation (MAO) and hard anodizing (HA) treated Al-Mg-Si alloy (AA6063) test samples under cyclic loading in uniaxial tension with a stress ratio of 0.1 (plain fatigue) and fretting fatigue loading. Fatigue test specimens were treated using MAO and HA techniques. MAO coated specimens were ground to reduce the surface roughness comparable with that in HA coated specimens. In that process the porous outer layer was removed. Characterization of coated and uncoated specimens was done with reference to the coating morphology, microhardness, surface roughness and residual stress. The specimens were tested under plain fatigue and fretting fatigue loading at ambient temperature. While the ground MAO coating exhibited relatively less amount of porosity, HA coating had through thickness cracks. MAO coating had compressive residual stress and it was very hard compared with HA coating. Both types of coated samples exhibited slightly higher friction force than that experienced by the uncoated specimens. Fretted region of the HA coated samples was rougher than that of the MAO coated specimens. Plain fatigue lives of both coated samples were inferior to those of the uncoated specimens. The inferior plain fatigue lives of MAO coated specimens compared with those of the substrate may be attributed to the tensile residual stresses supposedly present in the substrate leading to an early crack initiation in the substrate adjacent to the coating. As friction force of MAO coated samples was higher than that experienced by uncoated specimens, the fretting fatigue lives of MAO coated samples were slightly inferior to those of uncoated samples. As the anodized layer had preexisting through thickness cracks and strong adhesion with the substrate, cracks propagated from HA coating through the interface into the substrate easily. This may be the reason for the HA coated samples exhibiting inferior plain fatigue and fretting fatigue lives compared with MAO coated and uncoated samples. © 2007 Elsevier B.V. All rights reserved.

Detonation gun spray technique was employed to coat Al-Mg-Si alloy (AA 6063) specimens with Cu-Ni-In powder. Coated samples were characterized with reference to the microstructure, porosity, residual stresses, microhardness and surface roughness. Plain fatigue (without fretting) and fretting fatigue tests were carried out at room temperature on uncoated and coated specimens. The detonation gun spray process resulted in a dense coating of almost uniform deposition with low porosity (0.3%) and good adhesion between the substrate and the coating. Under plain fatigue loading 40 mu m thick coated samples exhibited superior lives compared with uncoated and 100 mu m thick coated specimens due to the presence of higher surface compressive residual stress in the former. Delamination-induced failure resulted in inferior lives of 100 mu m thick coated specimens. Under fretting fatigue deformation 40 mu m thick coated specimens exhibited superior lives compared with 100 mu m thick coated samples owing to higher compressive residual stress at the surface and better interfacial adhesion. At 120 MPa stress level 40 pm thick coated specimens exhibited superior fretting fatigue life compared with uncoated sample and at stress levels above 120 MPa the converse was true. This was attributed to interface cracking at higher stress levels. (c) 2006 Elsevier B.V. All rights reserved.

Uniaxial plain fatigue and fretting fatigue tests were carried out on detonation gun sprayed Cu-Ni-In coating on Al-Mg-Si alloy samples, The samples in three conditions were considered: uncoated, as- coated and ground after coating. Ground coated specimens exhibited superior plain fatigue and fretting fatigue lives compared with uncoated and as-coated specimens. The life enhancement has been discussed in terms of surface finish and residual compressive stresses at the surface. (C) 2008 Elsevier Ltd. All rights reserved.

The objective of this work was to investigate the performance of microarc oxide coatings of two different thicknesses (40 and 100 mu m) on Al-Mg-Si alloy samples under plain fatigue and fretting Fatigue loadings. Tensile residual stress present in the substrate of 40 mu m thick coated samples induced early crack initiation in the substrate and so their plain fatigue lives were shorter than those of untreated specimens. Presence of more pores and tensile surface residual stress in 100 mu m thick coated samples caused early crack initiation at the surface leading to their inferior plain fatigue lives compared with 40 mu m thick coated samples. While the differences between the lives of coated and uncoated specimens were significant under plain fatigue loading, this was not the case under fretting fatigue loading. This may be attributed to relatively higher surface hardness of coated specimens. The performance of 40 mu m thick coated samples was better than that of 100 mu m thick coated specimens under both plain fatigue and fretting fatigue loadings. (C) 2007 Elsevier Ltd. All rights reserved.

The influence of detonation gun sprayed alumina coating on Al-Mg-Si alloy (AA 6063) test samples subjected to cyclic loading with and without fretting was studied in the present work. Coated samples were grounded to have coatings of two different thickness values, 40 and 100 mu m. Both 40- and 100-mu m-thick coated specimens experienced almost the same but slightly higher friction force compared with uncoated samples. Under plain fatigue loading, 100 pm coated specimens exhibited inferior lives due to the presence of lower surface compressive residual stress compared with uncoated and 40-mu m-thick coated samples. Under fretting fatigue loading, uncoated specimens exhibited inferior lives compared with coated samples owing to the very low hardness of the uncoated specimens (80 against 1020 HV0.2). The reason for the superior fretting fatigue lives of 40-mu m-thick coated samples compared with 100-mu m-thick coated samples was the presence of relatively higher surface compressive residual stress in 40-pm-thick coated specimens. (c) 2007 Elsevier Ltd. All rights reserved.

Cu-Ni-In powder was coated on Ti-6Al-4V fatigue test samples using plasma spray and detonation gun (D-gun) spray processes. Coatings were characterized in terms of microstructure, porosity, microhardness, residual stresses and surface roughness. Uniaxial plain fatigue and fretting tests were carried out at room temperature on uncoated and coated specimens. D-gun sprayed coating was dense with lower porosity compared with the plasma sprayed coating. D-gun sprayed coating was harder than the plasma sprayed coating and substrate because of its higher density and cohesive strength. Surfaces were very rough in both the coatings. While D-gun sprayed coating surface had higher compressive residual stresses, plasma sprayed coating surface exhibited lower values of compressive residual stresses and even tensile residual stresses. The ill effect of surface roughness was overcome by the beneficial influence of higher compressive residual stresses on the surface and higher surface hardness and so the D-gun sprayed samples exhibited superior plain fatigue lives compared with uncoated specimens. Though the plasma sprayed samples had relatively lower hardness, higher surface roughness and almost similar values of residual stresses on the surface compared with the uncoated specimens, they exhibited longer plain fatigue lives. This may be attributed to the layered structure of the coating. Though D-gun sprayed samples experienced higher friction forces, they exhibited superior fretting fatigue lives due to the presence of higher compressive residual stresses, higher surface hardness and higher surface roughness compared with uncoated specimens. The very rough surface of plasma sprayed samples enhanced their fretting fatigue lives compared with the uncoated samples. Higher surface hardness and higher compressive residual stress of the D-gun sprayed specimens were responsible for their superior fretting fatigue lives compared with the plasma sprayed specimens. (c) 2007 Elsevier B.V. All rights reserved.

Cu-Ni-In coating was formulated on two substrate materials-Ti-alloy (Ti-6Al-4V) and Al-alloy (AA 6063) fatigue test specimens using detonation gun (D-gun) spray process. Coating on both substrates was dense with low porosity, high hardness, and high surface roughness. Relatively higher surface compressive residual stress was present at the coating on Ti-alloy specimens. In case of the coating on Al-alloy samples, tensile residual stress was also present in some places. Uniaxial plain fatigue and fretting fatigue experiments were conducted on uncoated and coated specimens. The detrimental effect of life reduction due to fretting was relatively larger in the Al-alloy compared to the Ti-alloy. While Cu-Ni-In coating was found to be beneficial on the Ti-alloy, it was deleterious on the Al-alloy substrate under both plain fatigue and fretting fatigue loading. The results were explained in terms of differences in the values of surface hardness, surface roughness, surface residual stress, and friction stress.

The physical and mechanical properties of yttria stabilized zirconia (YSZ) coatings deposited by the electron beam physical vapor deposition technique have been investigated by varying the key process variables such as vapor incidence angle and sample rotation speed. The tetragonal zirconia coatings formed under varying process conditions employed were found to have widely different surface and cross-sectional morphologies. The porosity, phase composition, planar orientation, hardness, adhesion, and surface residual stresses in the coated specimens were comprehensively evaluated to develop a correlation with the process variables. Under transverse scratch test conditions, the YSZ coatings exhibited two different crack formation modes, depending on the magnitude of residual stress. The influence of processing conditions on the coating deposition rate, column orientation angle, and adhesion strength has been established. Key relationships between porosity, hardness, and adhesion are also presented. (C) 2011 American Vacuum Society. [DOI: 10.1116/1.3563600]

The tribocorrosion behavior of titanium-based alloys is of significant interest as bio-implant materials. Bare alloys may not offer enough resistance to tribocorrosion, so coatings could be used to improve their performance. An important biomedical alloy, Ti-13Nb-13Zr, and a newly developed β titanium alloy called "Gum metal" (Ti-23%Ni-0.7%Ta-2%Zr-1 %O<inf>2</inf>) were used as substrates in the current work. Both were coated with conventional and nano-ceramic materials of Al<inf>2</inf>O<inf>3</inf>-TiO<inf>2</inf>. Bilayered coatings of ZrO<inf>2</inf>+Al<inf>2</inf>O<inf>3</inf>-13%TiO<inf>2</inf> were also applied to the Ti-13Nb-13Zr using plasma spray. The coatings on Ti-13Nb-13Zr were applied using plasma spray, whereas that on the Gum metal was applied by a detonation gun (D-Gun). Surface morphology was characterized using a scanning electron microscope (SEM). Tribocorrosion experiments were performed in salt water using a linear reciprocating ball-on-plate tribometer with an aluminum ball as the slider. The nano particles are embedded in the fully melted splats and offered better crack propagation resistance. The high velocity of the D-Gun process resulted in a higher volume fraction of the embedded nano particles and produced substantial improvement in wear resistance relative to the air-plasma-sprayed coating. The conventional coating, with its higher porosity, exhibited a high corrosion rate compared to nano coating. The D-Gun coating, with its lower porosity, had a higher corrosion resistance than the plasma-sprayed coating, but bilayered plasma-sprayed coating showed even higher corrosion resistance, owing to its dense microstructure. Open-circuit potential measurements before and during tribocorrosion showed that the bilayered plasma-sprayed coating had better tribocorrosion resistance than the other coatings. Electrochemical impedance spectroscopy indicated stable impedance values for the bilayered plasma-sprayed coating before and after tribocorrosion. Copyright © 2013 by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959.

TiN and Ti–Al–Si–N nanocomposite coatings of the type nc-TiAlN/a-Si3N4 have been prepared by cathodic arc physical vapour deposition process using cylindrical cathodes on high speed steel substrates with different surface roughness values, where the roughness is induced by emery paper method and diamond hand polishing. Fracture toughness studies by indentation method have shown that TiN is tougher than Ti–Al–Si–N nanocomposite coatings. Scratch and pin on disc wear tests have been conducted on the specimens to study the adhesion and tribological behaviour of these coatings respectiely. The wear mode between two mating surfaces is complex, and the wear behaviour can be understood better by studying the progression of surface changes and wear debris. The adhesion pattern of harder nanocomposite coating on smooth substrate surfaces is different from that of tougher TiN coating. Wear volume of these coatings decreases with substrate roughness, but it is found more for nanocomposite than for TiN.

Cyclic nanoimpact tests were carried on nc-TiAlN/a-Si3N4 nanocomposite, TiN and multilayered TiN/nanocomposite (NC) coatings to evaluate their resistance to fracture under cyclic impact loads. Fracture behaviour of the coatings was ascertained from fracture probability obtained from time-depth curves and focus ion beam milling images of resulting indentation impressions. TiN coating mainly showed intercolumnar cracks while the other coatings showed other modes of cracking, that is, lateral, inclined, bending, edge cracks, during testing. The performance ranking of the coatings, TiN &gt; TiN/NC &gt; nc-TiAlN/a-Si3N4, is linked to their β0 value, representing relative indentation depth of the coating-substrate composite hardness system at which the fractional hardness improvement equal to 50% of the maximum is retained and also their corresponding microstructure. Apart from enabling prediction of fracture resistance of the coatings, these studies provide useful insights into design and selection of coating materials for targeted machining applications. © 2016 Institute of Materials, Minerals and Mining

The present work investigates effect of nitrogen pressure on composition and mechanical properties of superhard nc-TiAlN/a-Si3N4 nanocomposite coatings deposited by cathodic arc PVD process. As the nitrogen pressure increases, at.% ratio of (Al+Si)/Ti, initially, increases to a maximum and thereafter, it decreases while the nitrogen content follows the reverse trend. Hardness is influenced by chemical composition and crystallite size of TiAlN phase. Maximum average hardness of 37 GPa is achieved when at.% ratio of Al(+Si)/Ti or N/(Ti+Al+Si) approaches 1.0 and decrease in scratch adhesion strength is attributed to the defects caused by nitrogen deficiency.

This paper highlights the hot tensile and accelerated creep properties of a thermal barrier coated (TBC) AE 437A alloy used as a candidate blade material in aero engines. Acoustic emission technique has been utilised to characterise the ductile-brittle transition temperature of the bond coat. Results revealed that the DBTT (ductile to brittle transition temperature) of this bond coat is around 923 K, which is in close proximity to the value reported for NiCoCrAlY type of bond coat. Finite element technique used for analysing the equivalent stresses in the bond coat well within the elastic limit, revealed highest order of equivalent stress at 1073 K as the bond coat is ductile above 923 K. The lifetime of the TBC coated superai loy was superior to that of the bare substrate and that oxidation is likely the cause of the reduced life of the bare substrate as compared to the coated substrate while stress rupture or accelerated creep experiments are carried out in an oxidizing environment.. Delamination of the bond coat and that of the TBC at high stresses during accelerated creep was evident. During accelerated creep, the mode of fracture in the substrate at very high stresses was transgranular whereas that at low stresses was intergranular.

This paper highlights some of the results obtained while studying Ni20Co18Cr12.5Al0.6Y (NiCoCrAlY) type metallic bond-coat properties of a thermal-barrier coated (TBC), AE-437A Ni base superalloy mostly employed for manufacturing compressor and stationary stator blades in aero turbines. Experiments were mainly focused in the area of evaluation of microstructure, residual stress, shear strength, hardness and with special emphasis in establishing the ductile to brittle transition temperature (DBTT) of the bond coat by using acoustic emission technique during room temperature and high temperature tensile tests. Results reveal that the residual stress was tensile in nature in the TBC layer and compressive in the bond coat as well as in the substrate. The DBTT of this bond coat is around 650 °C, which is in close proximity to the value reported in literature for CoCrAlY type of bond coat. Finite element technique was used to analyze the equivalent stresses in the bond coat, the result of which revealed the highest order of equivalent stress 800 °C, as the bond coat is ductile above 650 °C. Shear strength of the bond coat is in close proximity with that of the bond strength reported in literature for CoCrAlY and Ni22Co17Cr12.5Al0.6Y types of bond coat. © 2009 Elsevier B.V. All rights reserved.