摘要
以正硅酸乙酯、乙酸钡、乙酸钙为原料,通过液相混溶的方式将三者均匀混合获得预处理粉体,而后利用XRD与DTA-TG研究固相合成法过程中预处理粉体中各物质间的相互反应,同时利用XRD探究不同的升温速率、不同的煅烧工艺以及保温时间对合成高膨胀系数Ba1.55Ca0.45SiO4晶体的影响。结果表明,在固相反应的过程中,预处理粉体中的乙酸盐首先分解生成相对应的碳酸盐,同时可能形成相对应的BaCa(CO3)2固溶体;随着温度升高,低熔点的碳酸盐开始分解,当温度升高至1 063℃时,BaCO3与SiO2反应生成Ba2SiO4晶体,继续升温至1 144℃时,Ca^2+固溶进入Ba2SiO4晶体形成Ba1.55Ca0.45SiO4晶体;另外,将预处理粉体二次煅烧或压制成条状样品进行加热时,粉体中的BaCO3难以完全参与反应,而当粉体自然堆积、以1℃/min的升温速率加热至1 250℃保温5 h后可获得平均线性热膨胀系数为12.63×10^-6 K^-1的Ba1.55Ca0.45SiO4晶体。
Ethyl orthosilicate, barium acetate, and calcium acetate were used as raw materials, and the three were evenly mixed through a liquid phase miscible method;to obtain pretreatment powder, and then the interaction of various substances of the pretreatment powder in the solid phase synthesis process were studied by XRD and DTA-TG. At the same time, the effects of different heating rates, different calcination processes and holding time on the synthesis of high expansion coefficient Ba1.55Ca0.45SiO4 were explored by XRD. The results show that during the solid phase reaction, the acetate in the pretreated powder first decomposes to form the corresponding carbonate, and at the same time, the corresponding BaCa(CO3)2 solid solution may be formed. The melting point of carbonate begins to decompose. When the temperature rises to 1 063 ℃, BaCO3 reacts with SiO2 to form Ba2SiO4 crystals. When the temperature continues rise to 1 144 ℃, Ca^2+solid solution enters Ba2SiO4 crystals to form Ba1.55Ca0.45SiO4 crystals. In addition, when the pre-processed powder is calcined or pressed into a strip sample for heating, it is difficult for BaCO3 in the powder to fully participate in the reaction, and when the powder naturally accumulates, it is heated to 1 250 ℃ at a heating rate of 1 ℃/min after 5 h, Ba1.55Ca0.45SiO4 crystals with an average thermal expansion coefficient of 12.63×10^-6 K^-1 were obtained.
作者
徐利华
XU Lihua(Wuxi Vocational Institute of Art Technology,Yixing 214206,China;Jiangsu Ceramic Materials and Process Engineering Technology Research and Development Center,Yixing 214206,China)
出处
《人工晶体学报》
EI
CAS
北大核心
2020年第7期1286-1293,共8页
Journal of Synthetic Crystals
基金
江苏省陶瓷艺术传承创新产教融合平台建设项目(57201629)
江苏省高职院校高水平骨干专业建设项目。
