堇青石-莫来石复相储热陶瓷与PCM相容性研究

Compatibility between cordierite-mullite ceramics and PCMs

以煅烧铝矾土、滑石及石英为原料,采用挤出成型,制备堇青石-莫来石复相蜂窝陶瓷,用这种显热储热陶瓷(简称基体)封装PCM制备潜热/显热复合储热材料。设计F系列封装剂配方组成,选择PCM为Al Si20、Na2SO4,制得PCM/蜂窝陶瓷复合储热材料,热震循环(200~900℃)30次,每次循环在900℃保温12 h。利用XRD、SEM、TG-DSC等分析相组成、微观结构、封装剂与基体结合性、基体与PCM相容性、复合储热材料的相变温度及相变焓。结果表明,经1440℃烧成的蜂窝陶瓷,Wa、Pa、D及a轴抗压强度分别为2.38%、6.32%、2.65 g/cm^3,25.77 MPa;XRD显示相组成为堇青石、莫来石及少量镁铝尖晶石;30次热震后,Wa、Pa略有升高,D及σa略有降低。封装剂剪切强度测定结果表明,封装剂F2与基体结合强度最大,达2.53 MPa,SEM显示F2与基体结合良好。热震循环30次后,基体断面SEM图表明,PCM无渗漏。TG-DSC结果表明,经30次热循环后,Al Si20/蜂窝陶瓷复合储热材料的相变范围为571.7~583.5℃,峰值为578.3℃,峰值温度偏移不超过0.7%。复合储热材料具有优良的储热性能。

Cordierite-mullite composite ceramics were synthesised with calcined bauxite, talc and quartz as raw materials, and shaped to honeycomb configuration. A series of sealing agents（F series） were designed and tested for sealing Al Si20 and Na_2SO_4（phase change materials, PCM） within the ceramic honeycomb for heat storage applications. Thermal shock cycles between 200 and 900 ℃were performed for 30 times on the composite material（samples held at 900 ℃ for 12 h in each cycle）. XRD, SEM, TG-DSC were used to study phase composition, microstructures and the thermal properties. The results show that Wa, Pa, D and σa of honeycomb ceramic after fired at 1440 ℃ are 2.38%, 6.32%, 2.65 g·cm^-3 and 25.77 MPa the phase compositions are cordierite, Mullite and a small amount of magnesium aluminum spinel. After 30 times thermal shock tests, the Wa and Pa increase slightly whereas D and σa decrease slightly. One of the sealing agents, F2, gives the highest shearing strength at about 2.53 MPa, which is also validated by SEM analyses. The SEM analyses also show that, after 30 times thermal shock tests, the PCMs have a good compatibility with the ceramic substrate with no leakage. TG-DSC studies also show that the phase change temperature of Al Si20/honeycomb energy storage composite material ranges from 571.7 ℃ to 583.5 ℃ with a peak temperature of 578.3 ℃.