Coating of superalloys and titanium alloys with high velocity oxygen fuel thermal spray process

The High Velocity Oxy-Fuel (HVOF) thermal spray coating process is widely utilized to improve the wear resistance of components operating under high-temperature conditions, enhance oxidation and corrosion resistance, and thereby extend the service life of materials. To achieve this, surface coatings are applied using powder materials such as tungsten carbide-cobalt, which are capable of maintaining their properties at elevated temperatures. In this thesis, HVOF thermal spray coatings were applied using tungsten carbide-cobalt powders with varying characteristics onto nickel- and titanium-based alloys. The microstructural and mechanical properties of the coated samples were examined. The study primarily focused on materials commonly used in aircraft engine components within the aerospace industry. Following the coating process, various tests were conducted to evaluate the performance of the coatings, including hardness measurements, microstructural analysis, tensile and bending tests. Additionally, characterization techniques such as X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) were employed for detailed analysis. The results revealed that enhancements in the microstructure had a positive effect on the mechanical properties of the coatings. However, the presence of microstructural defects such as oxide secondary phases, voids, cracks, and unmelted particles was found to significantly reduce the coating's overall strength and performance.