Size and pressure effects on solid transition temperatures of ZrO2

Transition temperatures between tetragonal and monoclinic polymorphs of ZrO₂ nanoparticles, thin films and nanostructured materials are calculated by considering energetic contributions of surface (interface) energy and surface stress on total Gibbs free energy. The transition temperatures drop as the size of the nanocrystals decreases, which is consistent with available results.     

Thermodynamic Analysis of Burning Resistivity of Ti-Cr-V-Mo Alloys

ＴｈｅｒｍｏｄｙｎａｍｉｃＡｎａｌｙｓｉｓｏｆＢｕｒｎｉｎｇＲｅｓｉｓｔｉｖｉｔｙｏｆＴｉＣｒＶＭｏＡｌｏｙｓ①ＬｉｕＹｕｑｉｎ，ＺｈｕａｎｇＷｅｉｄｏｎｇ，ＢａｉＫｅｗｕ，ＳｈｅｎＪｉａｎｙｕｎ②ａｎｄＺｈａｎｇＺｈｕ（刘玉芹）（庄卫东）（白...     

Some guidelines for thermodynamic optimisation of phase diagrams

Thermodynamic optimisation of phase diagrams is a procedure that requires considerable experience and skill. The purpose of this article is to furnish certain guidelines that might facilitate the work and improve the quality of the thermodynamic optimisation of phase diagrams using the Calphad method. Some particulars regarding experimental data, Gibbs energy models, constraints on model parameters, and performing the optimisation are discussed.     

硫化矿生物浸出过程的热力学

计算并绘制了主要金属硫化物氧化反应的Ｅ－ｐＨ图,并与细菌存活区对比,对主要金属硫化物的细菌浸出进行了热力学分析。     

Preparation of nickel-tungstate catalysts by a novel impregnation method

Nickel-tungstate/γ-alumina (NiW) catalysts were prepared by an incipient wetness impregnation method using citric acid as a complexing agent. Citric acid has been used by our research group in preparing cobalt-molybdate and nickel -molybdate catalysts. The extended X-ray absorption fine structure (EXAFS) data of the impregnating solutions indicated that citric acid contributes to the formation of polytungstate anions that are smaller than the dodecatungstate ions formed when conventional ammoniacal solutions are used. Sulfided NiW catalysts prepared by using citric acid showed higher hydrogenation activity and hydrogenation selectivity than NiW catalysts prepared using the conventional ammoniacal solutions.     

铬铁矿液相氧化的热力学分析

液相氧化法生产铬酸盐技术是对传统火法焙烧技术的突破．在600～900K温度范围内对液相氧化法处理铬铁矿的熔盐体系各反应趋势及物相组成的热力学进行了分析研究，对液相氧化法处理铬铁矿各体系的反应自由能变化（△G°R）与温度（T）关系的计算结果表明，铬铁矿中的（Mg,Fe）（CrO2）2在较低温度下与NaOH、O2具有较强的反应趋势，比传统的火法焙烧方法反应温度降低了873K，节约大量能源;铬铁矿中的杂质相在反应温度下进行一系列副反应，生成硅酸盐、铝硅酸盐等新相．     

Effect of cooling method on TiN precipitation behavior of high-titanium high-strength steel during solidification

Metallographic microscopy,scanning electron microscopy and TiN growth thermodynamic and kinetic equations were used to investigate the morphology,quantity,and size of TiN in the center of high-titanium high-strength steels under different solidification cooling rates.The results showed that TiN in the center of the experimental steels mainly existed in three forms:single,composite(Al2O3-TiN),and multi-particle aggregation.TiN began precipitating at around 1497 ℃(solidification fraction of 0.74).From the end of melting to solidification for 180 s,the cooling rates in the center of the experimental steels for furnace cooling,air cooling,refractory mold cooling,and cast iron mold cooling tended to stabilize at 0.17,0.93,1.65,and 2.15 ℃/s,respectively.The size of TiN in the center of the experimental steel cooled using furnace cooling was mainly concentrated in the 5-15 pm range.In contrast,the size of TiN in the center of the experimental steels cooled using air cooling,refractory mold cooling,and cast iron mold cooling were mainly concentrated in the 1-5 pm range.In addition,their density of TiN in the center of the experimental steels is signif-icantly higher than that of the furnace-cooled experimental steel.Thermodynamic and kinetic precipitation models of TiN established predicted the growth size of TiN in a high-titanium high-strength steel when the solidification cooling rates are not below 0.93 ℃/s.