Bulk growth of Hg0.8Cd0.2Te single crystals by a combined CVT-seeding technique

The growth of high quality Hg_0.8Cd_0.2Te bulk single crystals by CVT, combined with an in-situ seeding technique, is reported here for the first time. For this purpose, a temperature difference of 590° → 540° C with a gradient of 40°-50° C/cm at the solid-vapor interface, and about 0.1 atm of HgI₂ as a transport agent, were employed. The bulk crystals have the expected stoichiometry and compositional homogeneity. Etch pit densities of 10⁴-10⁵ cm⁻² on the (111) face and hitherto unreported etch pits on the (100) face were observed in this work. Possible origins of the sub-grain structure are discussed.     

Synergistic inhibition between o-phenanthroline and chloride ion for steel corrosion in sulphuric acid

The corrosion inhibition of cold rolled steel in 0.5 M sulphuric acid in the presence of o-phenanthroline and sodium chloride (NaCl) has been investigated by using weight loss and electrochemical techniques. The experimental data suggest that the inhibition efficiency increases with increasing NaCl concentration in the presence of 0.0002 M o-phenanthroline, but decreases with increasing temperature. A synergistic effect is observed when o-phenanthroline and chloride ions are used together to prevent cold rolled steel corrosion in 0.5 M sulphuric acid. The polarization curves showed that the complex of o-phenanthroline and NaCl acts as a mixed type inhibitor. The experimental results suggested that the presence of chloride ions in the solution stabilized the adsorption of o-phenanthroline molecules on the metal surface and improved the inhibition efficiency of o-phenanthroline. The adsorption of the complex accords with the Langmuir adsorption isotherm. Some thermodynamic parameters such as adsorption heat, adsorption entropy and adsorption free energy have been calculated by employing thermodynamic equations. Kinetic parameters such as apparent activation energy and pre-exponential factor have been calculated and discussed.     

The effect of neutral red on the corrosion inhibition of cold rolled steel in 1.0 M hydrochloric acid

The corrosion inhibition of neutral red on the corrosion of cold rolled steel in 1.0 M hydrochloric acid (HCl) was studied using weight loss method and potentiodynamic polarization method. Results obtained revealed that neutral red is an effective inhibitor. It was found that the adsorption of neutral red could prevent steel from weight loss and the adsorption accorded with the Langmuir adsorption isotherm. Potentiodynamic polarization studies showed that neutral red mainly acted as a mixed-type inhibitor for steel in 1.0 M hydrochloric acid. Thermodynamic parameters such as adsorption heat, adsorption entropy and adsorption free energy were obtained from experimental data of the temperature studies of the inhibition process at four temperatures ranging from 30 to 45 °C. The most suitable range of inhibitor concentration was discussed. The kinetic data such as apparent activation energies and pre-exponential factors at different concentrations of the inhibitor were calculated, the effect of the apparent activation energies and pre-exponential factors on the corrosion rates of cold rolled steel was discussed. The inhibitive action was satisfactorily explained by using both thermodynamic and kinetic models. Synergism between chloride ion and neutral red was proposed. The results obtained from weight loss and potentiodynamic polarization were in good agreement.     

预变形对Ni-Mn-Ga合金马氏体相变的影响

研究了形变对Ni-Mn-Ga合金马氏体相变及其组织形态的影响，并应用马氏体相变热力学和动力学探讨了适当塑性变形后马氏体相变滞后得以大幅度提高的微观本质。结果表明，随着应变量的增加，马氏体相变温度几乎保持不变，而其逆相变温度则迅速升高，塑性应变导致储存在界面处的弹性应变能的释放是塑性变形提高合金相变滞后的主导因素。     

干旱区膜下滴灌农田土壤盐分非生育期淋洗和多年动态

膜下滴灌土壤盐分在生育期和非生育期的累积与淋洗,共同决定了土壤的盐碱化趋势,影响着当地农业的可持续发展。为分析长期膜下滴灌土壤盐分多年动态,于2008—2013年在中国西北干旱区的清华大学-库尔勒生态水文实验基地开展了棉田实验,采集和化验了15 000余个土壤样本,结合SHAW模型模拟,探讨了非生育期冬春灌方式的盐分淋洗效果;基于长期连续观测及理论分析,评估了区域盐碱化趋势。结果表明:冬灌和春灌的盐分淋洗作用明显,冬灌盐分淋洗深度大致为60 cm,效果优于春灌。若膜下滴灌条件下综合采用非生育期冬灌或春灌洗盐,在多年尺度上土壤根区盐分不会出现明显累积,土壤盐碱化趋势可以得到控制。     

Time evolution of coal structure during low temperature air oxidation

The time evolution of coal structure during low temperature oxidation was investigated by oxidizing coal samples in air at 120 °C for periods of up to 14 days. The structure of the oxidized coal samples was characterized by Fourier transform infrared spectroscopy (FTIR) and curve fitting analysis. The results show that carboxyl and ether groups are the main oxygen containing moieties in oxidized coal. Ethers are most abundant during the first 3 days of oxidation, thereafter carboxyl groups predominate. The content of carboxyl and ester functionality increases with oxidation time. The other oxygen containing groups vary in concentration over time. The amount of hydroxyl groups first decreases then increases and finally decrease again during the oxidation. The aliphatic structure and the degree of branching of the aliphatic chains is reduced as the oxidation proceeds. The proportion of aromatic structure increases with oxidation time. Obvious decomposition of aromatic rings occurs after about 9 days of oxidation. The aryl ester bands and the CH₃/CH₂ ratio both have a good linear relationship to oxidation time.     

Influence of stresses on martensitic transformation in ferromagnetic shape memory Ni_(50)Mn_(19)Fe_6Ga_(25) ribbons

~~Influence of stresses on martensitic transformation in ferromagnetic shape memory Ni_(50)Mn_(19)Fe_6Ga_(25) ribbons1. Ullakko, K., Huang, J. K., O'Handley, R. C. et al., Large magnetic-field-induced strains in Ni2MnGa single crystals, Appl. Phys. Lett., 1996, 69(13): 1966-1968. 2. James, R. D., Wuttig, M., Magnetostriciton of martensite, Philos. Mag., 1998, A 77: 1273-1275. 3. Wu, G. H., Yu, C. H., Meng, L. Q. et al., Giant magnetic-field-induced strains in H…     

Martensitic transformation and magnetic properties in ferromagnetic shape memory alloy Ni43Mn46Sn11−xSix

This study investigated the effects of Si addition and heat treatment on the martensitic transformation and magnetic properties of Ni₄₃Mn₄₆Sn_11?xSi_x (x = 1, 2, 3) alloys. The martensitic transformation temperatures were found to increase with increasing Si content in the alloy. A magnetic field-induced martensite-to-austenite transformation was found in Ni₄₃Mn₄₆Sn₁₀Si₁. Ageing of the Ni₄₃Mn₄₆Sn₁₀Si₁ alloy at 673 K resulted in the formation of a (Mn,Ni)–SiSn precipitate. The precipitate contains very low Sn content, causing the increase of the Sn content in the matrix phase and a decrease of martensitic transformation temperature. Ageing at 573 K is found to increase the Curie temperature and the saturation magnetization. This is attributed to the increase of atomic ordering of the matrix. Solution treatment of the aged samples at 1073 K was effective to restore the original transformation behaviour and magnetic properties.     

高线速度主轴密封材料HGW2082Mo的安装工艺及运行特点

为解决广州蓄能水电厂一期工程机组主轴密封易烧损的问题,经应力模态计算及材料性能研究,主轴密封材料最终选用了高分子材料HGW2082Mo。介绍了适合高分子材料HGW2082Mo特点的安装工艺和安装后的调试方法,并对其运行特点进行了研究,为新型主轴密封材料的研究提供参考。     

Van der Waals型立方状态方程的改进——Ⅱ体积平移及多参数方程

体积平移是改进ｖａｎｄｅｒＷａｌｓ型立方状态方程，使之能精确预测液相密度的一种有效方法。采用多参数方程能同时较准确地计算蒸气压和液相密度。本文介绍这两种方法近年来的主要进展。