In many industries, the protection of components against wear and corrosion is very important, especially in harsh environments. For this, special coatings are developed and applied onto the components in order to extend their lifetime. One specific type of coatings is called cermet coating, and it combines hard ceramic particles, like tungsten carbides, with a metal binder. These coatings are sprayed onto metal surfaces through thermal spraying methods. This thesis aims to study thin coatings, made of tungsten carbide and an iron-based binder, sprayed through high velocity air fuel (HVAF), and to understand the effect of the powder feed rate and the carrier gas on the coating’s quality and performances. More specifically, the aim of the thesis is to study the influence of the powder feed rate and the carrier gas on the microstructure, mechanical properties, wear resistance, and corrosion resistance of WC-FeCrNiMo flash coatings.

In order to achieve this, three coatings were made under different parameters of spraying process. The microstructure was studied through a scanning electron microscope (SEM), and the software ImageJ was to get measurements of thickness and porosity. The hardness was tested through Vickers hardness testing, on the cross-sectional area of the coating. The wear was tested through a Ball-on-Disc test, getting both the friction coefficient and the wear rate. The corrosion resistance was studied through electrochemical testing in a saltwater solution.

The results showed that all three coatings were thin and dense, with very low porosity. The hardness varied through the coatings, with the highest for the coating made with air, and with a low powder feed rate. The friction coefficient varied between the coatings, and the coating with the lowest coefficient was also the one with the highest wear rate. The corrosion behavior was similar between the three coatings, all of them showing a good passivation plateau.

In conclusion, this study showed that the best HVAF spraying parameters for WC-FeCrNiMo, was a lower powder feed rate, with the use of air as carrier gas. However, further studies should be conducted, specifically with a broader amount of sample, in order to better understand the effect of these variables, and to find the best spraying parameter for WC-FeCrNiMo.