α－Al_2O_3与CaO－Al_2O_3－B_2O_3系玻璃复合材料的等速升温

NON-ISOTHERMAL SINTERING OF COMPOSITES α-Al_2O_3AND A GLASS IN CaO-Al_2O_3-SiO_2-B_2O_3 SYSTYEM

用ＤＴＡ、ＸＲＤ及压汞方法研究了α－Ａｌ２Ｏ３与ＣａＯ－Ａｌ２Ｏ３－ＳｉＯ２－Ｂ２Ｏ３系玻璃复合材料的等速升温烧结与相组成．实验表明：在７０－９００℃时烧结快速进行．９００℃后由于闭气孔大量生成使致密化速度减慢．钙长石是由玻璃析晶及α－Ａｌ２Ｏ３与玻璃在＞７００℃反应生成．

he non-isothermal sintering with a heating rate of 10℃ / min to the end temperatres of 700,800, 850, 900, 950 and 1000℃ was studied. The porosity, density and pore size distribution were determined by Archimedes principle and mercury porosimetry, respectively. The phase composition was determined by XRD. It was found that the samples densified rapily in the temperture range from 700 to 900℃. Raising the end tempearature above 900℃ gave little effect to the relative density because of the formation of closed pores and escaping of gas from glass at high temperature. The closed pores begin to form at about 850℃, and the aparant pores almost disappear at about 900℃. To delay the formation of closed pores may promote densification of the samples. The crystal phase are α-Al2O3 and anorthite which was obtained by reaction between α-Al2O3 and glass, as well the crystallization of glass.When the temperature is blow 700℃, anorthite is obtained by crystallization of the glass principally. With increasing the end temperature, the reaction between α-Al2O3 and glass become more and more important.