Study Of Dental Machinable Ceramic

Following the advancement of CAD/CAM (computer aided design/computer aided manufacturing) technic and pursuing for esthetics to many people, the machinable dental ceramic is more and more popular in the dental sufferers. At present, The color of machinable feldspathetic porcelain that has been applying to clinic is the most similar to nature teeth. It can show the vitality of nature teeth. But feldspathetic porcelain is too brittle and fracture toughness is very low. So it fails in clinic for often. The aim of the paper is to improve fracture toughness value of feldspathic porcelain by making use of the special sintering mechanism of spark plasma sintering (SPS) and to study other performances of feldspathic porcelain. Besides, machinable ZrO2 material is also researched prepared by SPS technique.The effect of crystal content and grain size of feldspathic porcelain on fracture toughness was discussed in the paper. When crystal content is under of 10wt%, The KIC value of feldspathic porcelain is ascending obviously with the increase of crystal content. But the KIC value does not improve any more and keeping the value of 1.50-1.64 MPa·m1/2, although the crystal content maintains increasing. According to the analytic result of X-Ray Diffraction, The crystal is microcline (KAlSi3O8). The crystal in feldspathic porcelain prepared by SPS is left from the crystal of power after sintering. As a result, the heating rate and sintering temperature play an important part in the crystal content and grain size. The sintering temperature of feldspathic porcelain is between 1100℃and 1160℃when the particle size is between 2μm and 9μm. Besides, the proper heating rate should be controlled between 150℃/min and 200℃/min. Otherwise, particle size is another important factor which influences crystal. Both The crystal content and grain size tend to lessen with the minishing of particle size. It can gain the best combining point when the particle size is controlled between 2μm and 7μm and the fracture toughness value can reach maximum value(1.64 MPa·m1/2).The problem that feldspathic porcelain samples are apt to darken after sintering in SPS can be solved effectively by adding HA to feldspathic porcelain, which can not...