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制备了SiO_2-B_2O_3-Al_2O_3-Li_2O系CBN磨具用微晶玻璃结合剂。采用X衍射分析、热膨胀系数测试、扫描电镜、抗弯强度测试等方法研究了烧结温度对CBN微晶玻璃结合剂相组成、显微形貌和CBN磨具样品力学性能的影响。结果表明:烧结温度高于690℃烧结时,结合剂会析出β-锂霞石(Li_xAl_xSi_(1-x)O_2)相;随烧结温度升高,β-锂霞石晶粒尺寸变大,膨胀系数减小,膨胀系数在740℃达到最小值4.21×10-6K-1;当温度超过740℃时,随温度升高β-锂霞石晶粒变小,含量降低,结合剂膨胀系数增大,烧结温度为840℃时,结合剂变为纯玻璃相。在740℃烧结,结合剂的抗弯强度达到最大值147.8 MPa;在790℃下烧结,CBN砂轮试样的抗弯强度达到最大值64.8 MPa。
The glass-ceramics binders for SiO_2-B_2O_3-Al_2O_3-Li_2O series CBN grinding tools were prepared. The influence of sintering temperature on the phase composition, micromorphology and mechanical properties of CBN sample was investigated by X-ray diffraction, thermal expansion coefficient test, scanning electron microscopy and flexural strength test. The results show that the β-eucryptite (Li_xAl_xSi_ (1-x) O_2) phase precipitates when the sintering temperature is higher than 690 ℃. With the increase of sintering temperature, the β-eucryptite crystallites become larger and more swollen When the temperature exceeds 740 ℃, the β-eucryptite grains become smaller and the content of the β-eucryptite decreases with increasing temperature, and the coefficient of expansion of the binder increases , The sintering temperature of 840 ℃, the binder into a pure glass phase. After sintering at 740 ℃, the flexural strength of the bond reached the maximum of 147.8 MPa. After sintering at 790 ℃, the bending strength of the CBN grinding wheel reached the maximum of 64.8 MPa.