EFFECT OF SOME ATMOSPHERIC PLASMA SPRAYING PARAMETERS ON TENSILE STRENGTH OF Cr3C2-NiCr COATING

Abstract

The quality and performance of thermal spray coatings are highly dependent on the coating-substrate adhesion and the internal cohesion of the coatings. Hence, it is essential to have an effective spray mode for the coatings. However, predicting and controlling the adhesion of the coating appears complicated, depending on the spraying process and other operating conditions such as type of base steel, surface roughness, type of coating powder, and percentage of compounds present in the coating powder… The chromium carbide coating powder group is highly rated for wear erosion, and high-temperature work (up to 900°C) but still retains good mechanical properties, so it is widely used in practice. In this study, the Cr3C2 - NiCr coating with 30%NiCr content was created on the surface of the E355 steel specimens using the atmosphere plasma spraying (APS) method. The experiments are carried out based on a Central Composite Design with 20 trials. The study uses analysis of variance (ANOVA) and a genetic algorithm to optimize and evaluate the influences of 3 spraying parameters on the internal cohesion of the coating (Tensile strength). The coating’s tensile strength was determined using a multi tester, the results revealed that all 3 input parameters had a significant impact on the tensile strength, specifically, the powder feed rate was the most influential, followed by stand-off distance, current intensity; at the same time, the optimal spray parameters were found, including Is = 582.3A, ms = 33.2g/min and Ls = 170.2mm with the calculated expected value of 121.5MPa. The experimental result for examining the optimal values of parameters was 118.7MPa, achieving 97.6% of the calculated value.