CaO-B2O3玻璃助烧的零膨胀系数β-锂霞石陶瓷的制备及性能研究

采用固相反应法制备CaO-B₂O₃玻璃（简称“CB”玻璃）助烧的零膨胀系数β-锂霞石陶瓷。通过差示扫描量热(DSC)、X射线衍射(XRD)、扫描电子显微镜(SEM)手段分别对CB玻璃的热学特性和助烧后的β-锂霞石陶瓷样品的物相与显微形貌进行表征。结果表明, CB玻璃具有良好的助烧效果, 可以显著降低β-锂霞石陶瓷的烧结温度(从1300℃降至1150℃), 并大幅提高陶瓷的相对密度(从93.3%提高到97.4%)。加入CB玻璃助烧剂, β-锂霞石陶瓷致密性显著提高, 内部无微裂纹存在。加入4wt%和6wt% CB玻璃的β-锂霞石陶瓷在室温~200℃范围内具有零膨胀系数, 分别为0.02×10^-6/K和0.4×10^-6/K。然而, 加入8wt% CB玻璃的β-锂霞石陶瓷样品中产生了具有高正膨胀系数的新物相LiAlO₂, 使样品的热膨胀系数提高至3.46×10^-6/K。

Preparation and Property of β-eucryptite Ceramics Possessing Zero Coefficient of Thermal Expansion with CaO-B2O3 Glass as Sintering Aid

β-eucryptite ceramics with zero coefficient of thermal expansion (CTE) were prepared via solid state reaction method, adding CaO-B₂O₃ glass (CB glass) as sintering aid. The thermal property of CB glass and the crystalline phase, micro-structure of β-eucryptite ceramic samples were investigated by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. The results indicate that CB glass is a good sintering aid. It significantly decreased the sintering temperature of β-eucryptite ceramics (from 1300℃ to 1150℃) and increased the relative bulk density (from 93.3% to 97.5%). No micro-cracks were found in β-eucryptite ceramics aided with CB glass. β-eucryptite ceramics added with 4wt%, 6wt% CB glass possessed zero CTE of 0.02×10^-6/K and 0.4×10^-6/K ranging from room temperature to 200℃, respectively. However, a new phase LiAlO₂ with extremely high positive CTE appears in the β-eucryptite ceramics added with 8wt% CB glass which leads to a positive CTE of 3.46×10^-6/K.