氟化钇对粉煤灰基堇青石陶瓷合成及性能的影响

Influence of YF 3 on Synthesis and Performance of Fly Ash-Based Cordierite Ceramics

本文以粉煤灰、滑石、氧化铝和氧化镁为原料,加入质量分数为0%、0.5%和1.0%的氟化钇,通过高温烧结制备了粉煤灰基堇青石陶瓷样品,研究了氟化钇掺量对样品的物相组成、显微结构及主要性能的影响。结果表明,氟化钇的引入可降低堇青石的生成温度,提高堇青石的物相转化率,显著改善材料的力学性能,同时对热学性能亦有一定积极影响。当氟化钇添加量为0.5%时,样品的综合性能最优。当烧结温度为1300℃时,XRD未见明显杂质峰,样品的体积密度为2.15 g/cm^(3),开孔孔隙率为7.49%,吸水率为3.49%,压缩强度为252.27 MPa,经5次热震试验后压缩强度仍然高至204.65 MPa,比热容为0.770~0.931 J/(g·℃)(25~150℃),热膨胀系数为2.54×10^(-6)℃^(-1)(100~800℃)。与不含添加剂的样品相比,添加0.5%氟化钇样品的体积密度增加了5.2%,开孔孔隙率降低了58.6%,吸水率降低了60.6%,而压缩强度增加了4.6倍,比热容增强而热膨胀系数降低。在粉煤灰基堇青石陶瓷的烧结过程中,氟化钇的引入可使其在较低的温度下形成液相,提高元素迁移率,促进晶粒发育完全且具有细化晶粒的明显效果。氟化钇作为一种有效的烧结助剂,微量的添加即可显著改善粉煤灰基堇青石陶瓷的综合性能。本工作拓宽了高效烧结助剂选择范围,可为高质量陶瓷材料的高温烧结提供一定参考。

Fly ash-based cordierite ceramics samples were prepared with fly ash,talc,alumina and magnesium oxide,by adding yttrium fluoride(YF_(3))with mass fraction of 0%,0.5% and 1.0%,respectively.The effect of YF_(3) on phase composition,microstructure and physical properties of samples were studied.The results show that the introduction of YF_(3) reduces formation temperature of cordierite,improves phase conversion rate of cordierite,significantly increases the mechanical properties and has a moderate positive effect on thermal properties of samples.When the YF_(3) content is 0.5%,the performance of sample is the best.For the sample with 0.5%YF_(3) content,when the sintering temperature is 1300℃,no obvious peak corresponding to any impurity is found in XRD patterns,the bulk density of sample is 2.15 g·cm^(-3),the open porosity is 7.49%,the water absorption is 3.49% and the compressive strength is 252.27 MPa.After 5 times heat shock experiments,the compressive strength is still high to 204.65 MPa.The heat capacity is 0.770~0.931 J/(g·℃)(25~150℃),and thermal expansion coefficient is 2.54×10^(-6)℃^(-1)(100~800℃).The bulk density of sample with 0.5%YF_(3) content increases by 5.2%,open porosity decreases by 58.6%,water absorption decreases by 60.6%,compressive strength increases by 4.6 times,heat capacity increases and the thermal expansion coefficient decreases,compared with the sample without additives.In the sintering process of fly ash-based cordierite ceramics,the introduction of YF_(3) can form a liquid phase at a lower temperature,improve the mobility of elements,and promote the development of grains and fine grain size.As an effective sintering additive,YF_(3) significantly improves the comprehensive properties of fly ash-based cordierite ceramics with a small content.This work broadens the additives range for high quality ceramic materials,which provides reference for excellent materials sintered at high temperature.