Tribological behaviour of multi-shape photochemical textured surfaces

The purpose of this paper is to investigate the effect of multi-shape photochemical textured (PCT) steel surfaces on tribological performance. The textured surface with specific arrangement was fabricated by photochemical texturing, a common technique implemented in the microelectronic mechanical systems (MEMS) industry. It involves photolithography and chemical etching processes. The multi-shape studied were circle with line (CL) and circle with wavy (CW). Fabricated samples' surfaces were characterized by using a 3D optical profiler to check the produced texture's dimension. The effect of six different etching times on the texture's dimension was observed. Then, only two sizes of both multi-shape textures were considered for tribological characterization. It was conducted by using ball-on-disk tribo-tester under lubricated conditions. The results obtained are compared with the reference untextured (UT) surface. From the results, it is found that appropriate size and shape of texture could lead to good friction reduction and anti-wear behaviour. The smaller size, size A, of CL multi-shape presented a lower friction coefficient compared to size B. However, different size of CW multi-shape has no effect on the friction behaviour. This is believed due to higher area density of CW compared to CL resulting in detrimental effect on friction for both CW's size. Additionally, CL(size A) textured surface shows improved tribological behaviour compared to UT surface as lower friction coefficient and better wear resistance is obtained. This is maybe due to effective lubricating layer formation, good debris trapping effect and lower contact stress of the CL(size A) textured surface. These beneficial effects were achieved under lubricating condition through an increase in applied load.