Numerical modelling of the laser surface processing of magnesia partially stabilized zirconia by the means of three-dimensional transient finite element analysis

Abstract

A numerical technique has been employed to use the ABAQUS finite element analysis (FEA) package in order to simulate the CO 2 laser surface processing of a magnesia partially stabilized zirconia (MgO-PSZ) bioinert ceramic. The transient FEA takes into account the heat radiation, heat convection and phase change during the laser processing. The heat source has been modelled as a stepwise moving laser source with small steps in the scanning direction to approximate continuous movement. It further extends and validates numerical methods by comparing experimental data of surface temperature for laser surface processing of the MgO-PSZ to the solution from the FEA model. Experiments involving CO 2 laser surface melting of the MgO-PSZ were also carried out using various laser process parameters, and the measured melt width and depth of laser-treated tracks were used to evaluate the validity of the models. In order to prevent the crack formation in the laser processing, pre- and post-heating were proposed by using the scanning of laser beam with the lower power before and after laser processing with high power to lower the thermal gradient.

Mathematical modelling of the fibre laser surface processing of a zirconia engineering ceramic by means of three-dimensional finite-element analysis

“…Experimental measurement of the processing temperatures during the laser surface treatment is rather difficult with hard, brittle engineering ceramics and often requires a lengthy and time-consuming preparation for drilling holes, positioning, and mounting the temperature sensors or thermocouples. However, this method is ideal for measuring the temperature changes in the bulk; it is not suitable for measuring the surface temperatures so pyrometers or contactless devices are also employed, as demonstrated by Zhang and Modest [10], Hao and Lawrence [11], and Ignatiev et al [12]. Ignatiev et al also stated that such measuring techniques are helpful to detect the material's phase transformation.…”

“…However, this method is ideal for measuring the temperature changes in the bulk; it is not suitable for measuring the surface temperatures so pyrometers or contactless devices are also employed, as demonstrated by Zhang and Modest [10], Hao and Lawrence [11],…”

Fracture toughness modification by using a fibre laser surface treatment of a silicon nitride engineering ceramic

“…Other work by Hoe and Lawrence [19] within biomedical sector also involved improvement of cell adhesion through a CO 2 laser surface treatment. Hoe and Lawrence [20] in another investigation used a finite element model (FEM) and compare it to an experimental model to simulate the CO 2 laser surface treatment of the MgO-PSZ. Their finding revealed accuracy between the two models studied as well as the occurrence of phase changes within the ceramic during the laser beam interaction.…”

“…Moreover, the fibre laser was selected because of its shorter wavelength radiation in comparison to the conventional lasers previously used for ceramic processing [14][15][16][17][18][19][20][21][22][23][24][25][26]. It would be interesting to investigate further the effect of short wavelength on the surface properties of a Si 3 N 4 engineering ceramic.…”

Evaluation of fracture toughness of ZrO2 and Si3N4 engineering ceramics following CO2 and fibre laser surface treatment

“…Hae and Lawrence [12] also investigated the improvement of cell adhesion through a CO 2 laser surface treatment. Hae and Lawrence [13] in another investigation used a finite element model (FEM) and compared it to an experimental model to simulate the CO 2 laser surface treatment of the MgO-PSZ. Several other studies discussed the use of industrial lasers to modify the surface of engineering, structural and refractory type ceramics [14 -19].…”