低温微晶玻璃结合剂结构和性能的研究

Study on the structure and properties of low-temperature glass-ceramic bond

采用石英、无水碳酸钠、无水碳酸钾、无水碳酸钙、氟化钙作为基础原料,在此基础上分别添加5%、8%、11%、14%H3BO3(质量分数)做为外加成分。高温熔炼成玻璃,淬冷后球磨成玻璃粉,通过烧结法制备了用于cBN砂轮的微晶玻璃结合剂。通过XRD、SEM分析,结果表明:在720℃晶化2 h后,在CaF2晶体的基础上析出了硅碱钙石晶体和富含氟的硅碱钙石。晶体为随机取向,尺寸为2.5μm以内互锁的板条状晶体,由于晶体各向异性,该微晶玻璃有很高的抗弯强度和断裂韧性,能提高砂轮强度。其中硼酸含量为11%时,经850℃烧结的微晶玻璃结合剂的强度最大,可以用于cBN砂轮做为结合剂。

Using quartz,anhydrous sodium carbonate,anhydrous potash,anhydrous calcium carbonate and calcium fluoride as basic materials,and 5%,8%,11%,14% of H3BO3（mass fraction） as the addition agents,the mixture of the above was fired,then cooled,and ball milled to produce a fritted glass.Glass-ceramic bond for cBN grinding wheels was prepared with the fritted glass by solid-state sintering.The composition and microstructure of samples were characterized by X-ray diffraction（XRD） and scanning electron microscope（SEM）.The results showed that canasite and frankamenite were grown based on CaF2 crystal after heat-treated at the temperature of 720 ℃ for 2 h.The precipitated crystals were random oriented,interlocked and lathy,sized within 2.5 μm.The glass-ceramics had high bending strength and fracture toughness attributed to crystal anisotropy,and it could improve the strength of grinding wheel.The bending stength of samples with 11% H3BO3 sintered at 850 ℃ achieved maximum value.The glass-ceramics may be used as bond for cBN grinding wheel.