A comparative study of WOKA-3903 and Tribaloy T-400 using high-velocity oxygen fuel (HVOF) sprayed coating
摘要
Wear resistance at elevated temperatures of Ti-6Al-4V is a great challenge for aerospace applications. This can be improved by depositing different kinds of wear and corrosion resistant coatings on Ti-6Al-4V by high-velocity oxy-fuel (HVOF) technique to deposit these coatings. Here, we report a comparison of WOKA-3903 and Tribaloy T-400 powders that were deposited by high-velocity oxy-fuel (HVOF) technique. Scanning electron microscopy (SEM) images of WOKA-3903 showed the presence of tungsten carbide (WC) in the cobalt and chromium matrix. Some WC agglomerates showed faceted morphology and formed a cobalt solid solution dendritic microstructure. While the SEM image of Tribaloy T-400 coating exhibited cobalt and chromium, another brittle intermetallic compound (Laves phase) was present in the coating, which constituted a solid solution of thicker lamellar Laves phase. X-ray diffraction peaks of WC and Laves phase were associated with both coatings, confirming the successful deposition. The micro Vickers hardness of WOKA-3903 coating was greater than twice that of the Tribaloy T-400 coating. Pin-on disc test by tribometer was used to analyze the wear behavior of both coatings under 30 N applied load with 130 rpm sliding speed for 300 s. The wear rate (1.8 × 10−2 mm3/Nm) of the WOKA-3903 coating due to the decomposition of WC and formation of the brittle phase of ditungsten carbide W2C was higher than the wear rate (4 × 10−3 mm3/Nm) of Tribaloy T-400. Despite this, the WOKA-3903 coating exhibited improved properties compared to those of the Tribaloy T-400.