Modification of Ceramic Powders by Utilizing Organic-Inorganic Hybrid Interface

下面尝试了各种新型功能材料的制备及其性能的改进。采用癸二酸对金属氮化粉末进行表面化学改性，提高了金属氮化粉末的抗水稳定性，同时保持了金属氮化粉末的亲水性。用醋酸钇对己二酸改性粉末进行处理，可以通过离子交换使助烧结剂Y^<3+ b>离子在金属氮化物粉末表面高度分散。在1900℃无压烧结5h的条件下，通过选择较好的脱絮凝剂和烧结条件，获得了导热系数约为250 W m^<-1>K^<-1>的材料。采用1,12 -十二烷基二羧酸的Langmuir-Blodgett薄膜，在硅或玻璃衬底上制备了亚微米大小的致密单层球形氧化物颗粒，然后在衬底和陶瓷球的表面羟基与二羧酸的羧基之间发生脱水缩合反应。以锡酸钠为原料，利用n-十六烷基吡啶自组装法制备了高比表面积305 m^2g^<-1>的有序介孔SnO_2粉体，经磷酸处理，在600℃下煅烧5h。采用二乙基氧基二甲基硅烷对SnO_2粉体进行了表面化学改性，并对其气敏性能进行了评价。TEM观察发现，表面改性引入的SiO_2以晶界相的形式存在。SiO_2薄膜涂层限制了SnO_2颗粒之间的颈部生长，提高了势垒高度，改善了对H_2、CH_4和C_3H_8等易燃气体的传感性能。

Preparation of various new functional meterials and improvement of its properties were attempted as below.1.Chemical stability of metal nitride powders against water was improved by surface chemical modification with sebacic acid, while maintaining a hydrophilic surface. Treatment of the sebacic acid-modified powder with yttrium acetate resulted in strong immobilization of Y^<3+> ions, as a sintering aid, at a highly dispersive level on the metal nitride powder surface through ion exchange. By selecting slip compositions for better deflocculation and firing conditions, a thermal conductivity of ca.250 W m^<-1>K^<-1> was attained by the pressureless sintering of AIN at 1900℃ for 5h.2.Closely packed monolayer of spherical oxide perticles of sub-micron size was fabricated on a silicon or glass substrate by employing a Langmuir-Blodgett film of 1, 12-dodecanedicaboxylic acid, followed by dehydration-condensation reatcion between carboxyl groups of the dicarboxylic acid and the surface hydroxyl groups of both the substrate and the ceramic spheres.3.Ordered mesoporous SnO_2 powders with high thermal stability and a high surface area 305 m^2g^<-1> were prepared from sodium stannate by utilizing the self-assembly of n-cetylpyridinium chloride, followed by treatment with phosphoric acid and calcinations at 600℃ for 5h.4.SnO_2 powder was subjected to surface chemical modification with diethyoxydimethylsilane and the gas sensing properties were evaluated. The SiO_2 introduced by the surface modificaton was found to exist as a grain-boundary phase from TEM observation. The limitation of neck growth between SnO_2 particles by the SiO_2 thin film coating is anticipated to be responsible for increasing the potential barrier height and improving the sensing properties to inflammable gases such as H_2, CH_4 and C_3H_8.