Study the thermal shock resistance of Ni-WC composite nanostructure coating sprayed by thermal spray technique with different thickness

Abstract

In this study, a coating with a thickness of 200-300μm is applied to a nickel-based alloy using a thermal spray process. The top layer consisted of a tungsten carbide-reinforced nickel-based composite (WC), while the bond layer is made of a nickel-based superalloy. The Taguchi method, combined with the analysis of variance (ANOVA) used to determine the optimal coating conditions, which are achieved by selecting the following parameters: spray distance = 150 mm, transverse speed = 300 mm/min, and powder feeding rate = 30 g/min. This combination resulted in a low-porosity, high- adhesion nanostructure coating layer. The performance of the coating is evaluated through microhardness tests with a load of 9.8 N and thermal cycling tests. Samples are heated to 1100 °C in a furnace for 30 minutes, then rapidly cooled to room temperature with water. Additionally, results are analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Findings indicated that the use of Ni-WC increased the hardness of coated samples by a factor of four compared to uncoated samples. Moreover, during the thermal cycling test, the thickness of the harmful thermal growth oxide (TGO) layer decreased by 51% as the coating thickness increased from 200μm to 300μm.