# Study on Laser Surface Texturing and Wettability Control of Silicon Nitride Ceramic

## TL;DR

This study explores how laser texturing affects the surface wettability of silicon nitride ceramic using rectangular patterns.

## Contribution

The research introduces rectangular laser texturing patterns for wettability control in silicon nitride ceramics.

## Key findings

- Higher scanning speed and fewer scans caused less surface damage and smaller groove dimensions.
- Oxygen content increased in grooves due to reactions during laser texturing in air.
- Laser texturing increased the contact angle, showing improved hydrophobicity with fewer scans.

## Abstract

Silicon nitride (Si3N4) ceramic is widely used in the production of structural components. The surface wettability is closely related to the service life of materials. Laser surface texturing is considered an effective method for controlling surface wettability by processing specific patterns. This research focused on the laser surface texturing of a Si3N4 ceramic, employing rectangular patterns instead of the typical dimple designs, as these had promising applications in heat transfer and hydrodynamic lubrication. The effects of scanning speed and number of scans on the change of the morphologies and dimensions of the grooves were investigated. The results indicated that the higher scanning speed and fewer number of scans resulted in less damage to the textured surface. As the scanning speed increased, the width and depth of the grooves decreased significantly first, and then fluctuated. Conversely, increasing the number of scans led to an increase in the width and depth of the grooves, eventually stabilizing. The analysis of the elemental composition of different areas on the textured surface presented a notable increase in oxygen content at the grooves, while Si and N levels decreased. It was mainly caused by the chemical reaction between Si3N4 ceramic and oxygen during laser surface texturing in an air environment. This study also assessed the wettability of the textured surface, finding that the contact angle of the water droplet was significantly affected by the groove dimensions. After laser surface texturing, the contact angle increased from 35.51 ± 0.33° to 57.52 ± 1.83°. Improved wettability was associated with smaller groove volume, indicating better hydrophilicity at lower scanning speed and enhanced hydrophobicity with a fewer number of scans.