Optimizing spray parameters of high velocity oxy-fuel for hardness of WC- 12Co coatings on A6061 aluminum alloy substrate

Abstract

This study optimizes HVOF spray parameters to improve the microhardness of WC-12Co coating on A6061 aluminum alloy by the Taguchi method. The studied spraying parameters were arranged according to the L9 orthogonal array, including powder feed rate (A), spray distance (B), and oxygen/propane ratio (C). The analysis results through micrographs, SEM images, and XRD analysis showed that the WC-12Co coating formed well on the A6061 alloy substrate. Temperature causes WC to partially transformations to W, W2C, Co4W2C and reduces the microhardness of the coating. Optimum spray parameters with A = 32 g/min; B = 0.3 m; C = 5 gives a hardness of 1586.6 HV. The influence of spray parameters was determined through analysis of variance with: A (45.97 %) > C (30.97 %) > B (18.94 %). Verifying optimal results with high reliability, coating hardness is higher than A6061 aluminum alloy, confirming coating with spray powder WC- 12Co is an effective solution to improve wear resistance of the A6061 aluminum alloy surface.