Examination of temperature distribution and the thermal effects on Si₃N₄ engineering ceramics during fibre laser surface treatment

The thermal effects of fibre laser surface treatment on a Si₃N₄ engineering ceramic were studied using a computational finite element analysis (FEA). Temperature increases on the surface of the Si₃N₄ during fibre laser processing were measured using an infra-red thermometer; temperature distributions in the bulk were measured with specifically located thermocouples. A computational model by using FEA was then developed to model the flow and the distribution of the radiated heat resulting from the fibre laser treatment of the Si₃N₄ ceramic. By utilising data obtained from a TG-DSC analysis the FEA model predictions of the temperature distribution were used to map phase transformations and significant events occurring during the fibre laser surface treatment of the Si₃N₄. The TG-DSC analysis also indicated that the fibre laser surface treatment generally resulted in a phase transformation of the Si₃N₄ from α-phase to β-phase modification as elongated rod-like grains were found.