A small sample-size automated adiabatic calorimeter from 70 to 580 K——Molar heat capacities of α-Al_2O_3

An automatic adiabatic calorimeter for measuring heat capacities in the temperature range 70—580 K, equipped with a small sample cell of 7.4 cm~3 in the internal volume has been developed. In order to obtain a good adiabatic condition of the calorimeter at high temperature, the calorimeter was surrounded in sequence by two adiabatic shields, three radiation shields and an auxiliary temperature-controlled sheath. The main body of the cell made of copper and the lid made of brass are silver-soldered and the cell is sealed with a copper screw cap. A sealing gasket made of Pb-Sn alloy is put between the cap and the lid to ensure a high vacuum sealing of the cell in the whole experimental temperature range. All the leads are insulated and fixed with W30-11 varnish, thus a good electric insulation is obtained at high temperature. All the experimental data, including those for energy and temperature are collected and processed automatically with a personal computer using a predetermined program. To verify the     

大气中无机盐粒水解过程中的微液滴现象

采用改变相对湿度, 无机盐/金属组合, 测定微液滴体系的pH值和电位分布等方法研究了微液滴形成和生长的特征. 结果表明, 微液滴的形成与大气腐蚀密切相关. 微液滴只在特定的盐粒/金属体系中出现, 微液滴区域具有较高的pH值和较高的电位分布. 此外, 微液滴形成和生长需要两个前提条件：第一, 环境相对湿度应高于盐粒水解液滴液面的饱和蒸汽压；第二, 在水解液滴下的金属能被液滴腐蚀.     

70～580 K小样品全自动精密绝热量热装置的建立--α-Al2O3的摩尔热容

建立了样品池容积为 7.4cm3 ,可在 70～ 5 80K温区工作的小样品量自动绝热量热计 .量热计设置有两层绝热屏 ,三层辐射屏及辅助控温套 ,以保证高温下量热系统良好的绝热条件 .样品池主体用紫铜制作 ,带有装卸管的容器上盖用黄铜制作 ,紫铜压帽盖与装卸管用螺纹连接铅锡合金垫片密封 ,保证样品池在整个实验温区保持高真空密封不泄漏 .量热计所有导线采用W30 11有机硅耐高温漆绝缘和固定 ,使量热计电测系统在高温下具有良好的稳定性 .所有量热测试数据 ,包括电能和温度的测量 ,全部由计算机按预定程序自动采集和处理 .测量量热标准物质α Al2 O3 的摩尔热容 ,检验了所建量热装置的可靠性 .α Al2 O3 的摩尔热容实验值与舒平值的标准偏差为± 0 .2 8%,与美国标准局数据比较 ,相对偏差在± 0 .4%以内