玻璃组成对CaO-Al2O3-SiO2系玻璃烧结、晶化和性能的影响

采用烧结法制备以钙长石为主晶相的微晶玻璃.采用差热分析(DTA)、X射线衍射(XRD)、扫描电镜(SEM)和性能测试研究玻璃组成对玻璃的烧结、晶化特性和性能的影响.结果表明:随着CaO含量的增加,玻璃转变温度和析晶放热峰温度逐渐降低,而且析晶放热峰变得尖锐;增加氧化钙降低玻璃的析晶活化能,有利于玻璃的析晶;随着SiO2量的增加,玻璃转变温度和析晶放热峰温度移向高温,使玻璃的析晶困难;玻璃样品的烧结温度随CaO含量的增加而降低, 但过多的CaO促进硅酸钙的析出,增加样品的介电常数和热膨胀系数;增加SiO2能够降低微晶玻璃样品的热膨胀系数,改善其介电性能;所制备的微晶玻璃具有相对密度高(≥98.3%),介电常数适中(6.9～7.5),介电损耗低(≤0.1%),热膨胀系数低(3.8×10-6～4.5×10-6 /℃),烧结温度(900～1 000 ℃)低,及介电常数温度稳定性低(66×10-6～113×10-6 /℃).

Effect of composition on sintering, crystallization behavior and properties of CaO-Al2O3-SiO2 system glass

Glass-ceramics with main crystalline phases of anorthite were prepared by sintering method. The effect of glass composition on sintering and crystallization behavior as well as properties of the glasses were investigated by using differential thermal analysis (DTA), X-ray diffraction(XRD), scanning electron microscopy (SEM) and property measurements. The results show that the increase of CaO content decreases the glass transition temperature (T_g) and the crystallization peak temperature (T_p) of anorthite-based glasses and makes the crystallization exothermic peak sharp. The crystallization activation energy of the glasses decreases and the glass crystallization improves with the increase of CaO content. The glass transition temperature (T_g) and the crystallization peak temperature (T_p) shift to high temperature and the glass crystallization becomes hard with the increase of SiO_2 content. The sintering temperature of the glass samples reduces with the increase of CaO contents. Whereas, overfull CaO content will improve the precipitation of Ca_2SiO_4 phases and enhance the dielectric constant and the thermal expansion coefficient of samples. On the other hand, the increase of SiO_2 content can lead to the thermal expansion coefficient to decrease and the dielectric properties of glass-ceramics improve. The prepared glass-ceramics exhibit high relative density (≥98.3%), moderate dielectric constant (6.9-7.5), low dielectric loss (≤0.1%), low thermal expansion coefficient (3.8×10~(-6)-4.5×10~(-6) /℃), low sintering temperature (900-1000 ℃) and low temperature coefficient of dielectric content (66×10~(-6)-113×10~(-6) /℃), as well, which can be applicable in the electronic packaging field.