LAUSR

Abstract It is important to study the gradient wettability of a Si3N4 ceramic tool surface to improve the lubrication performance of cutting tools. A gradient microstructure was processed on the surface of Si3N4 ceramic using a femtosecond and a nanosecond laser. The effects of different laser fluences, scanning passes, and laser overlap rates on the surface roughness and the surface contact angle under two lasers were studied. The result shows that the surface roughness and surface contact angle processed by two lasers have a similar trend, however, the femtosecond laser requires lower energy. The surface roughness gradually increases with the increase of the laser fluence, the scanning passes, and the laser overlap rate. With the increase of the laser fluence and the scanning passes, the surface contact angle first increases and then decreases. However, with the increase of the laser overlap rate, the surface contact angle continues to decrease. By designing the surface roughness distribution reasonably, different gradient wettability surfaces can be obtained. The larger the gradient, the faster the droplet wetting speed. Through the friction test, the great effect and potential of gradient wettability surface on reducing the friction has been confirmed, which provides a new direction for the development of new ceramic tools.