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

Welding or brazing of metals to ceramics often leads to failures under aggressive conditions due to abrupt changes in physical, chemical, and thermal properties at the metal-ceramic interface. Metal-ceramic Functional Graded Materials (FGMs) replace the strict interface with a gradual transition of composition and properties, which protects the material from failures. The powder-blown Laser-Directed Energy Deposition (DED-LB) is one of the widely known Additive Manufacturing (AM) processes that offer unique features like developing FGMs and multi-material structures. Various studies have been conducted to process metalceramic FGMs using the DED-LB process but significant differences in thermal properties, varying laser-material interactions, and the possibility of formation of complex reaction products make the processing of metal-ceramic FGMs challenging. This study aims to understand the effect of laser power on a ceramic substrate, and its interaction with a metal powder introduced in the melt pool. A single track of nickel-based superalloy Alloy 718 powder was deposited on an Alumina substrate with different laser powers. The deposition was performed with and without substrate pre-heat to understand the effect of pre-treatment on deposition. Metallographic analysis was performed to reveal the microstructure of the resolidified metal mixed ceramic region

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.

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.

With the development of human-cyber-physical-production systems in intelligent manufacturing, cyber-supported production based on artificial intelligence is becoming an increasingly powerful means of controlling machines and collaborating with human users. Semi-autonomous systems with a medium degree of automation enable human-centered, flexible, and sustainable production, for instance, in hybrid decision-making. Especially in applications that do not meet the requirements for full automation and when humans are to be involved in their role as qualified decision-makers, teaming-capable systems are desirable and offer considerable advantages. This paper outlines the transdisciplinary concept of human–machine teaming and the role of human cognition in engineering tasks with multi-criteria decision-making. An illustrative real-life example from thermal spray technology is used to show how explainable artificial intelligence models offer targeted, hybrid cyber decision support. This new approach based on fuzzy pattern classifiers combines expert knowledge- and data-based modeling and enables a transparent interpretation of the results by the human user, as shown here using the example of test data from atmospheric plasma spraying. The method outlined can potentially be used to provide hybrid decision support for a variety of manufacturing processes and form the basis for advanced automation or teaming of humans and cyber-physical-production systems. 

The astonishing safety and capacity characteristics of solid-state-batteries are encouraging researchers and companies to work on the manufacturing, development, and characterization of battery materials. In the present work, the effects of laser beam interaction with a liquid feedstock plasma-sprayed ceramic solid-state-battery (SSB) material coating were studied. Lithium Titanium Oxide (LTO) in the form of an aqueous suspension consisting of submicron powder particles was plasma-sprayed for the first time using a high-power axial III plasma torch on an aluminum substrate. The plasma-sprayed LTO coating suspension was subsequently post-processed using a fiber laser. The energy input of the laser beam on the surface of the deposited layer was the main variable. By varying the laser power and laser processing speed, the energy input values were varied, with values of 3.8 J/mm2, 9.6 J/mm2, 765.9 J/mm2, and 1914.6 J/mm2, and their effects on some key characteristics such as laser-processed zone dimensions and chemical composition were investigated. The results indicated that changing the laser beam parameter values has appreciable effects on the geometry, surface morphology, and elemental distribution of laser-processed zones; for instance, the highest energy inputs were 33% and 152%, respectively, higher than the lowest energy input.

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 work represents a preliminary study of atmospheric plasma-sprayed (APS) YttriaStabilized Zirconia (YSZ)-based thermal barrier coatings (TBCs) deposited on forged and additivemanufactured (AM) HAYNES®282® (H282) superalloy substrates. The effect of different feedstockmorphologies and spray gun designs with radial and axial injection on APS-deposited YSZ layercharacteristics such as microstructure, porosity content, roughness, etc., has been investigated. Theperformance of TBCs in terms of thermal cycling fatigue (TCF) lifetime and erosion behaviour werealso comprehensively investigated. In view of the high surface roughness of as-built AM surfacescompared to forged substrates, two different types of NiCoCrAlY bond coats were examined: oneinvolved high-velocity air fuel (HVAF) spraying of a finer powder, and the other involved APSdeposition of a coarser feedstock. Despite the process and feedstock differences, the above two routesyielded comparable bond coat surface roughness on both types of substrates. Variation in porositylevel in the APS topcoat was observed when deposited using different YSZ feedstock powdersemploying axial or radial injection. However, the resultant TBCs on AM-derived substrates wereobserved to possess similar microstructures and functional properties as TBCs deposited on reference(forged) substrates for any given YSZ deposition process and feedstock.