Effect of Al₂O₃ Addition on the Surface Roughness, Adhesion Strength, and Microstructure of Flame-Sprayed Cu–Al–Ni–Fe Alloy Coatings

Abstract

This study aims to synthesize (Cu-Al-Ni-Fe) alloy composite coatings reinforced with alumina (Al2O3) particles at weight fractions of 0 wt%, 3 wt %, and 6 wt%, deposited on AISI 304L stainless steel substrates using the flame thermal spraying technique. The coatings were evaluated by measuring surface roughness and adhesion strength, alongside microstructural and elemental characterization via Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray Spectroscopy (EDS). The SEM results revealed that the surface roughness of the samples increased from 5 to 8 µm and the adhesion strength increased from 22±0.655 Mpa to 26±0.818 Mpa As the Al2O3 content was increased, SEM micrographs showed reduced porosity and microcracks and improved homogeneity of the microstructure. Energy-Dispersive X-ray Spectroscopy (EDS) the presence of the main constituents of alloy (Cu,Al,Ni,Fe) and elements associated with the Al2O3 reinforcement. The incorporation of Al2O3 particles significantly contribute to the structural and mechanical properties of developed composite coatings as a whole