A comparative study on the processing parameters during fibre and CO_2 laser surface treatments of silicon nitride engineering ceramic

摘要

This paper demonstrates a comparative study of a relatively novel fibre laser and a conventional CO_2 laser to surface-process silicon nitride (Si_3N_4) engineering ceramic. The objective of the research is to investigate the threshold of the novel fibre laser and compare it to the conventionally used CO_2 laser to process Si_3N_4 engineering ceramic and to produce a laser surface treatment free from major surface cracking without using any of the pre- or post heating techniques as this would increase the cost of the process and add more expense to the product when considering a bigger view point. The results showed that the fibre laser surface processing of the Si_3N_4 engineering ceramic differed to that of the CO_2 laser as the Gaussian beam modes, the beam quality factors, wavelength and the beam delivery systems were different between the two lasers. This consequently had a different effect on the surface of the Si_3N_4 engineering ceramic. The CO_2 laser wavelength when surface treating the Si_3N_4 engineering ceramic was being absorbed more than that of the fibre laser as higher power density and same traverse speed was used to reach the threshold for the Si_3N_4 engineering ceramic.