材料期刊网，材料期刊，材料类期刊，材料期刊投稿

Calcium treatment is nowadays a well-established method to improve steel castability and final properties e.g. machinability, toughness and surface quality. The effects of calcium are mainly based on its strong ability to form sulphides and oxides. The topic of the present paper concerns the basic mechanism and kinetics of the transformation process of alumina inclusions in steel when calcium introduced into the steel e.g. by wire feeding or powder injection. To clarify the mechanisms model experiments were performed by studying reactions between Al2O3 and CaO in a laboratory furnace as well as by performing Ca treatments in an 8 kg induction furnace for Al deoxidised melt. The phases formed during the reaction between Al2O3 and CaO were examined by SEM-EDS, and the proposed reaction sequence of Al2O3CA6CA2CACAx(liquid) was discussed based on the experimental observations. The kinetics of the reaction of calcium with alumina inclusions were simulated by immersing alumina plates in a Ca treated steel melt in the induction furnace. Results were compared with observations of real inclusion transformation. Based on the results a kinetic model was proposed.

关键词: Alumina inclusions , 夹杂 , 机理 , 钙处理 , 动力学

Removal Mechanism of Aqueous Lead by a Novel Eco-material: Carbonate Hydroxyapatite

Huanyan XU , Lei YANG , Peng WANG

材料科学技术（英文）

Kinetics and mechanisms on the removal of aqueous lead ion by carbonate hydroxyapatite (CHap) are investigated in the present work. Experimental results show that, in the whole pH range, the lead removal percentage increases with decreasing pH values and reaches a maximum at pH=2–3. Under some conditions, the lead residual concentration is below national integrated wastewater discharge standard, even drinking water standard. The removal behavior is a complicated non-homogeneous solid/liquid reaction, which can be described by two stages from kinetic point of view. At the earlier stage, reaction rate is so fast that its kinetic course is intricate, which requires further study. At the latter stage, the rate of reaction becomes slow and the process of reaction accords with one order reaction kinetic equation. Experimental results show that the relationship between reaction rate constant k1 and temperature T accords to Arrhenius Equation, and the activation energy of sorption (Ea) is 11.93 kJ/mol and frequency factor (A) is 2.51 s-1. X-ray diffraction (XRD), scanning electron microscopy with an energy dispersive X-ray fluoresence spectrometer (SEM-EDS) and toxicity characteristic leaching procedure (TCLP) test were conducted in this work. It is indicated that the main mechanism is dissolution-precipitation, accompanying with superficial sorption.

关键词: Carbonate hydroxyapatite , 铅离子 , 动力学 , 机理 , 溶解－沉淀

高酸度磷化液成膜机理探讨

张圣麟 , 李红玲 , 郑洪河 , 常照荣

表面技术 doi:10.3969/j.issn.1001-3660.2005.05.022

有关高酸度磷化液的成膜机理目前尚无定论,作者通过对高酸度磷化液进行反复的实验,主要从时间、温度、促进剂等因素对高酸度磷化液所形成的磷化膜的耐蚀性的影响进行了讨论,并在此基础上初步探讨了高酸度磷化液的成膜机理, 形成的磷化膜为非晶型的磷酸铁盐.

关键词: 磷化处理 , 高酸度处理 , 机理 , 促进剂 , 耐蚀性 , 磷化液 , 磷化膜 , 成膜

2种缓蚀剂对Q235B碳钢在乙醇胺CO2饱和溶液中的缓蚀效果及机理

沈世玉 , 辜敏 , 杜云贵

材料保护

以往少有采用循环伏安(CV)法研究碳钢在乙醇胺CO2饱和溶液中的腐蚀行为.采用Tafel极化曲线、循环伏安法(CV)研究了Q235B碳钢在含缓蚀剂(NaVO3和CuCO3)的CO2饱和乙醇胺(MEA)溶液中的电化学腐蚀行为.Tafel结果表明:NaVO3和CuCO3能抑制碳钢腐蚀,当浓度为500 mg/L时,两者的缓蚀率分别为61.3％和74.2％.CV曲线结果表明:在MEA-CO2溶液中,铁的阳极过程包括铁溶解为Fe2+和Fe3+2个过程.CuCO3和NaVO3的加入抑制了铁的溶解反应,其原因在于它们的加入导致溶液的pH值升高和CO32-浓度增大,生成了更多的FeCO3和Fe2O3钝化膜;此外CuCO3本身引入了CO32-,在相同浓度下CuCO3的缓蚀效果更优.

关键词: 缓蚀作用 , 机理 , 乙醇胺-CO2 , CuCO3 , NaVO3 , Tafel极化曲线 , 循环伏安曲线 , Q235B碳钢

Effect of Deposition Temperature on Dynamics and Mechanism of Deposition for Si-B-C Ceramic from BCla/SiCH3Cl3/H2 Precursor

材料科学技术（英文）

关键词: 沉积温度 , 化学成分 , 动力学 , 机理 , 陶瓷 , 沉积速率 , 形态学变化 , 微观结构

Co/Pd催化剂上CH4/CO2等温两步反应直接合成乙酸的热力学

章日光 , 黄伟 , 王宝俊

催化学报

采用量子化学密度泛函理论对CH4/CO2两步法合成乙酸反应中表面碳化物CHx (x=0～3)在Co和Pd模型表面上不同吸附活性位上的吸附能、空间构型和反应吉布斯自由能进行了系统性的比较研究. 计算结果表明, CH4/CO2两步反应在单一金属Co或Pd催化剂上在常压等温条件下不能有效进行,但在Co和Pd组成的双金属催化剂上,两步反应在常压等温下可以进行. 在Co和Pd双金属催化剂上,金属Co活化CH4生成金属碳化物CHxCo(x=0, 1)为热力学允许反应,其后CHx溢流到金属Pd上形成CHyPd (y=1～3)碳化物,最后CO2插入CHyPd生成乙酸,后两者在常压等温情况下也为热力学允许反应,并且在435 K以上可以与前者构成等温循环. 计算结果与实验结果吻合.

关键词: 表面碳物种 , 钯 , 热力学 , 机理 , 密度泛函理论 , 甲烷 , 二氧化碳 , 乙酸

离子镀玫瑰金镀层变色机理的研究

刘海华 , 王永宁 , 谢逸

电镀与涂饰

以0.80 μm厚的TiCN高硬质薄膜为底层,采用离子镀技术在316不锈钢片表面制备0.20 μm厚的玫瑰金镀层.对比了TiCN和玫瑰金镀层的颜色,并对玫瑰金镀层与TiCN底层之间的结合力、耐人工汗腐蚀性能、耐磨性能进行测试,以研究现今离子镀玫瑰金镀层的变色机理.结果表明,离子镀玫瑰金镀层具有良好的耐人工汗腐蚀性能,其变色并非由腐蚀引发.玫瑰金镀层变色的主要原因是其与TiCN底层之间的色差大,及其耐磨性较差,在使用过程中易磨损而变色.

关键词: 不锈钢 , 离子镀 , 玫瑰金 , 氮碳化钛 , 变色 , 腐蚀 , 磨损 , 机理