镁质黏土对碳化硅-堇青石复相陶瓷结构及性能影响

Effect of magnesia clay on structure and properties of SiC-Mg 2Al 4Si 5O 18 composite ceramics

采用烧结法制备碳化硅-堇青石复相陶瓷。利用TG-DTA分析仪确定原料组成的热行为和反应机理,XRD确定晶相组成,SEM观察形貌结构,PCY高温卧式膨胀仪测定热膨胀系数。结果表明,800℃制备的添加镁质黏土复相陶瓷的抗折强度从0.84 MPa提高到1.91 MPa,表明加入镁质黏土能够提高复相陶瓷在烧制过程中的强度;在1300℃烧结温度下,添加镁质黏土试样的抗折强度从37.25 MPa提高到40.61 MPa,气孔率从19%降低到16%,体积密度从1.63 g/cm^(3)提高到1.64 g/cm^(3),热膨胀系数从2.958×10^(-6)℃^(-1)降低到2.789×10^(-6)℃^(-1),表明添加镁质黏土对复相陶瓷性能有所改善,堇青石结晶度更高,致密度更好。

The sintering method was used to prepare SiC-Mg_(2)Al_(4)Si_(5)O_(18)composite ceramics.TG-DTA analyzer was used to determine the thermal behavior of raw materials and reaction mechanism,XRD to determine the crystal phase composition,SEM to observe the morphology and structure,and the PCY high temperature horizontal dilatometer to determine the thermal expansion coefficient.The results showed that the flexural strength of the magnesia clay composite ceramics increased from 0.84 to 1.91 MPa prepared at 800℃,indicating that the addition of magnesia clay could increase the strength of the composite ceramic during the firing process.At a sintering temperature of 1300℃,the flexural strength of the sample with magnesia clay increased from 37.25 to 40.61 MPa,the porosity decreased from 19%to 16%,the bulk density increased from 1.63 to 1.64 g/cm^(3),and the thermal expansion coefficient decreased from 2.958×10^(-6)to 2.789×10^(-6)℃^(-1).The results showed that adding magnesia clay could improve the performance of composite ceramics,and the cordierite crystallinity was higher and the density was better.