Nickel and its alloys offer excellent chemical resistance and mechanical properties under elevated temperatures. This makes them suitable for high- and low-temperature applications. Microreactors, due to their microscale dimensions, pose challenges for conventional joining techniques. Diffusion bonding offers a promising approach to overcome these challenges, with bond strength influenced by temperature, time, contact pressure, and surface state. This study investigates how face-turning and diamond smoothing affect the surface state of pure nickel. Specimens are face-turned at cutting speeds from 50 m/min to 400 m/min, followed by diamond smoothing with forces of 100 N to 200 N. Surface properties are characterized, and the results indicate that increasing the cutting speed decreases surface roughness values, coarsens crystallites, and increases tensile residual stresses. Smoothing at all forces induces compressive residual stresses and minimizes the surface roughness values at 100 N and 150 N. The findings highlight the influences of turning and diamond smoothing on the surface state of pure nickel, providing a basis for selecting surface preparation parameters that are expected to enhance diffusion bonding performance. With this knowledge, the field of application of diffusion bonding can be improved by achieving the suitable surface state.
Ghorbanalipour et al. (Sun,) studied this question.