Abstract
In this study, with a view to improve the mechanical properties, the influence of the change in the micro-structure, crystal phase and mechanical properties were evaluated, by changing the amount of one of the sintering additives, Al2O3 and the HIP sintering conditions, from the viewpoint of the micro-structure consisting of α-Si3N4, β-Si3N4 and glassy grain boundary phase. The experimental results showed that 1) the combination of the sintering additives makes a various sorts of crystals and glassy phase formed which promotes the densification, 2) the addition of Al2O3 was effective in the densification, further, 3) as for the HIP sintering condition, N2 gas pressure higher than 60MPa greatly influences the transformation from α-Si3N4 to β-Si3N4 with densification.
Finally, Si3N4 ceramics consist of both α-Si3N4 and β-Si3N4 crystal phase has been applied for various industrial wear parts, for example, cutting tool, crasher parts, bonding tool for FPD and semiconductor with heating, etc. In these applications, it was recognized that this materials shows the excellent performance comparing with conventional materials.
