SPRAYING PROCESS FOR Cr<sub>3</sub>C<sub>2</sub>-NiCr COATING

Abstract

In this paper, the theoretical research of Cr3C2-NiCr coating for zirconia substrate is discussed. To obtain this coating, one of the multi-efficiency methods high velocity oxygen-fuel thermal spraying (HVOF) was investigated. The coatings were processed by different thicknesses of zirconia substrate sample of 3–5 mm also with length of 20 mm and width of 30 mm, at spraying speed of 600–700 m/s. The temperature during HVOF spraying is about 3000 ºC and the cooling temperature is 27 ºC. Investigating the theoretical data of Cr3C2-NiCr coatings, the development and thermal stresses after HVOF treatment were determined using Stone's method and Brenner-Senderoff equations with a coating thickness not exceeding 0.6 mm for carbide coatings. According to the results of theoretical research, the deposition efficiency values were found by the method proposed by Kosaku Shinoda. According to the theoretical and mathematical calculations, the deposition efficiency for Cr3C2-NiCr coating with zirconia substrate is in the range of 59.5%–69.4%. Thus, it was found that the deposition efficiency for the coatings depends on the thickness of the substrate, the powder feed rate, and the mass of the applied material and consequently the number of spraying passes.