太阳能热发电用锂辉石低膨胀陶瓷的制备及其低膨胀机理研究

Preparation and Mechanism of Low Expansion Beta-Spodumene Ceramics for Solar Power Generation

为拓展低膨胀陶瓷在太阳能热发电领域的应用,本文以澳州锂辉石、星子高岭土和山东石英为原料,通过半干压成型,无压烧成制备了锂辉石低膨胀陶瓷,对其相组成、微观结构、热稳定性和低膨胀机理进行了探讨。研究表明,经1330℃烧成的L2样品(锂辉石70wt%,高岭土20wt%,石英10wt%)的热稳定性最佳,其热膨胀系数为1.13×10-6℃-(10-900℃),抗折强度为53.02 MPa,经30次热震后(1000℃-室温,气冷),L2样品的抗折强度为56.17MPa(强度增加率为5.94%)。相组成和微观结构分析表明,L2样品的相组成为β-锂辉石(Li2O.Al2O.34SiO2)、莫来石(3Al2O.32SiO2)和少量的鳞石英(SiO2)。30次热震后,针棒状莫来石发育更为完全。β-锂辉石固溶游离态SiO2,使样品的热膨胀系数较低,莫来石和磷石英也使样品的抗热震性能得到改善,二者共同作用,赋予样品较好的高温热稳定性,使其满足太阳能热发电的使用要求。

In order to expand the application of low expansion ceramics in solar thermal power generation, Australia spodumene, Xingzi kaolin and Shandong quartz were used as the raw materials in this experiment. The low expansion spodumene ceramics was prepared by using semi-dry pressing and pressureless sintering. The phase composition, microstructure, thermal stability and low expansion mechanism were analyzed. The results indicated that Formula L2 （spodumene 70 wt%, kaolin 20 wt%, and quartz 10 wt%） fired at 1330℃ had the best performance. The coefficient of thermal expansion and bending strength were 1.13×10-6℃-1 （0-900℃） and 53.02 MPa respectively. After 30 thermal shock cycles （1000℃-RT, air cooling）, the bend strength of L2 samples was 56.17 MPa （the increasing rate was 5.94 %）. The analysis showed that β- spodumene, mullite and tridymite were the phases identified in L2 samples. After 30 thermal shock cycles, needle-shaped mullite developed more completely. The solid solution of free SiO2 by β-spodumene could reduce the coefficient of thermal expansion. Mullite and tridymite could improve the thermal shock resistance of L2 samples. Both of these actions provided the good thermal stability of the samples, and satisfied the requirements for solar power generation.