Evaluation of oxy-acetylene flame angle effect on the erosion resistance of SiC/ZrB2-SiC/ZrB2 multilayer coatings fabricated by the shielding shrouded plasma spray technique

In the present study, the effect of oxy-acetylene flame angle on the erosion resistance of SiC/ZrB2-SiC/ZrB2 multilayer coatings with the gradient structure was investigated. To this aim, first, the SiC inner layer was applied by the reactive melt infiltration (RMI) technique; then ZrB2 and ZrB2-SiC layers with 10, 20 and 30%wt. SiC were applied on graphite by the plasma spraying technique. To prevent the oxidation of ZrB2 and SiC particles, the plasma spraying process was performed by a solid protective shield. To evaluate the performance of the coatings in erosive environments, the samples were exposed to oxy-acetylene flame at the angles of 30 degrees, 60 degrees and 90 degrees for 360 s; the destruction mechanism of SiC/ZrB2-SiC/ZrB2 multilayer coatings appeared to be controlled mechanically and chemically. The results of the erosion test showed that at the low flame angles of about 30 degrees, due to the shear forces of oxy-acetylene flame, mechanical erosion overcame the chemical one. With increasing the flame angle, due to raising the surface temperature, chemical erosion overcame the mechanical one; so, most chemical destruction occurred at the flame angle of 90 degrees. Also, the results of the erosion test showed that the total chemical and mechanical destruction at the angle of 60 degrees was greater than that in other angles. Also, among the coatings tested, SiC/ZrB2- 20% wt. SiC/ZrB2 coatings had the best erosion resistance; so, the weight changes under the oxy-acetylene flame at the angles of 30 degrees and 60 degrees, respectively, were about -0.038%. and -0.355%; meanwhile, at the angle of 90 degrees, it was about +4.3%.

Automated summary

This study investigates the effect of oxy-acetylene flame angle on the erosion resistance of SiC/ZrB2-SiC/ZrB2 multilayer coatings. The results show that the destruction mechanism of these coatings is controlled by both mechanical and chemical factors. Chemical erosion becomes dominant at higher flame angles, while mechanical erosion prevails at lower angles. The SiC/ZrB2-20% wt. SiC/ZrB2 coating exhibits the best erosion resistance among the coatings tested.