The Research On Class-Ceramic Applied As CBN Grinding Wheels Binder

The development, fabrication and application of glass-ceramic and grinding wheels were systematically reviewed. According to the requirement of CBN grinding wheels and phase diagram, fluosilicate glass-ceramic was chosen as the subject investigated. A glass-ceramic was prepared by sintering glass powder formed by chemical pure agent and Na2SiF6 as nucleation agent. The major crystalline phase was fluorophlogopite. The phase of glass-ceramic was analyzed by XRD, and its microstructures were observed by SEM.The experiment results showed that Na2SiF6 could effectively prompt crystallization of glass ceramic. As Na2SiF6 content increasing, the crystallizing ability of glass increased. The content of fluorophlogopite also increased and the crystal size became smaller if the addition of Na2SiF6 was lower than 7%. MgO could be substituted by ZnO. As the ratio of ZnO/MgO increased from 2/10 to 8/4, the melting temperature of glass dropped from 1050C to 900C and the flexural strength also improved.Heating conditions had great influence on glass ceramics. To reduce pore ratio and improve flexural strength, two steps sintering treatment, liquid sintering phase and crystallizing phase, was adopted in this research. In this research, the optical crystallization parameters were liquid sintering at 900 C for 1h and crystallizing at 750 C for 2h. At these conditions, the glass-ceramics were formed, of which the size of crystal could be controled to 2um, microstructure was hexagonal platelet and major crystalline was fluorophlogopite.According to the trigonometric coordinate of grinding particles, binding agent and pore, the processing parameters were chosen to prepare "8 " model. The tensile strength test of " 8 " model showed that the tensile strength of grinding wheels formed by glass-ceramic was 135% higher than common binding agent. It indicated the bright future of using glass-ceramic as CBN grinding wheels. The results of tensile stress test were analyzed by using the theory of Maximum Stress and Average Stress. The highest application speed of the CBN grinding wheels was calculated out to be 100m/s, 66.6% higher than common binder.