Influence of high-voltage argon ion bombardment on the adhesion and friction properties of GLC coatings and its application in friction and noise reduction for heavy-load gears

Abstract

In this study, polished and shot-peened carburized substrates, pretreated with high-voltage argon ion bombardment (2800 V), were then coated using the physical vapor deposition method at bias voltages of −40 V, −60 V, and − 80 V. The microstructure and mechanical properties of the coating were analyzed. The results showed the adhesion strength of polished substrates initially increases with increasing bias voltage and then decreases, the coating prepared at a bias voltage of −60 V exhibited superior wear resistance and the best performance, with adhesion strengths of 93.4 N for polished substrate and 65.7 N for shot-peened substrate. However, when high-voltage argon ion bombardment was removed, the adhesion strength significantly declined. The interface analysis between the substrate and the Cr interlayer revealed that the absence of argon ion bombardment resulted in an amorphous layer formed at the interface, which weakened the adhesion between the substrate and the Cr layer. In contrast, after argon ion bombardment, the amorphous Cr layer disappeared, and a semi-coherent interface was formed between the substrate and the Cr interlayer, resulting in enhanced adhesion. Additionally, the argon ion bombardment activated the substrate surface, increasing the nucleation rate, thickness, and growth uniformity of the Cr layer, thereby providing a robust foundation for subsequent coating growth. As a result, the coating exhibited fewer internal defects and superior comprehensive performance. The optimal coating was applied to the gears in a heavily loaded 14-speed gearbox, and the results showed that coating could effectively help to reduce noise, improve transmission efficiency, prevent pitting, thereby extending gear lifespan.