热压对云母微晶玻璃微观结构及显微硬度的影响

Effect of Hot-Pressing on Microstructure and Micro-hardness of Mica Glass-ceramics

形成晶体定向排列的微观结构可显著提高材料的力学强度。在温度950～1150℃下对云母微晶玻璃保温1h,同时施加20 MPa压力。采用差示量热扫描仪（DSC）、X-射线衍射（XRD）、电子扫描显微镜（SEM）及显微硬度仪分别对材料进行热效应分析、晶体组成分析、组织形貌观察和显微硬度测试。结果表明：随着热压温度的提高,云母晶体含量一直减少,莫来石晶体含量先增加后减少,玻璃相含量一直增加;材料的显微硬度也提高,且在不同压力方向上的硬度差值变大。在云母晶体定向排列的样品中,其平行于压力方向的显微硬度值为5.66 GPa,比垂直于压力方向上高0.46 GPa。晶体相互作用阻碍晶体定向排列,而在晶体具有足够偏转空间前提下,延长热压时间有利于形成晶体定向排列的微观结构。

The mechanical strength of glass-ceramics is obviously enhanced by forming oriented microstructures.The mica glass-ceramics were hot-pressed at 950-1150 ℃ for 1 h,and at the same time a pressure of 20 MPa was applied.The thermal effect,crystallization phases,morphology and microhardness were investigated by differential scanning calorimeter,X-ray diffraction,scanning electron microscopy and micro-hardness tester.The results show that the content of mica decreased and the glass phase increased with the increasing of the hot-pressing temperatures.However,the content of mullite increased firstly and then decreased.The micro-hardness is also increased and the gap between the different pressure directions become larger.In the oriented-crystallized glass ceramics,the micro-hardness value is up to 5.66 GPa in the direction of parellelling to pressure aixs,which is higher 0.46 GPa than that of being perpendicular to pressure aixs.It was also suggested that the interactions of crystals impede the forming of oriented microstructure.But,the hot-pressing time is favorable for the forming oriented microstructure in the case of having enough space for crystals＇ rotation.