铬鞣--一种可持续发展的工艺

从铬（Ⅲ）盐鞣革的优越性、铬（Ⅲ）对人类健康和环境的影响,以及与其它鞣法相比,铬鞣具有更为成熟的回收利用方法这几方面出发,论述了铬鞣是一种可持续的工艺,不可能被其它鞣法完全取代。     

利用铬渣制备铬酸铅的研究

利用铬盐生产中的含铬废渣制备出了铬酸铅,并副产浅绿色颜料.全部铬渣均转变为有用的产品,制备过程中无废渣排放.制备方法是对铬渣在95*!℃下用水浸取溶解可溶性铬盐,然后用15% NaOH溶液调pH值至13,再用双氧水将Cr(Ⅲ)氧化为Cr(Ⅵ),加入PbAc溶液,沉淀生成PbCrO4.确定了最佳工艺条件,详细讨论了各种因素对制备铬酸铅的影响.     

铬刚玉砖的性能与应用

以氧化铝 -氧化铬为主要原料生产的高性能铬刚玉砖 ,具有耐火度高、强度大、热震稳定性好、抗侵蚀能力强的特点 ,使用中耐冲刷 ,耐磨损 ,抗侵蚀 ,抗结构剥落 ,已在冶金、玻璃、炭黑、石油化工行业取得了良好的使用效果     

一种基于浏览器的CSRF攻击检测方法

互联网的安全形势日益严重,CSRF漏洞是最严重的Web漏洞之一,如何检测CSRF攻击成为业内热点.目前的CSRF检测技术主要通过验证字段例如Form表单字段、验证Same Origin等传统方式,但字段容易被攻击者更改,从而成功绕过CSRF检测.在验证字段的基础上,通过进一步分析网页内容,提出一种基于浏览器的CSRF检...     

国标中铝的测定方法改进研究

针对GB/T5009.182-2003《面制食品中铝的测定方法》中,铝的测定常因高氯酸残留而导致铬天青S显色不均,从而影响检测结果。文章通过实验研究、探索改进方法,旨在提高检测结果的准确性。方法:对铬天青显色剂的稳定性进行研究,以确定最佳显色时间;采用干法和湿法两种消解方法处理样品,通过氨水和盐酸调节pH值,以对硝基酚作为指示剂,使测定液酸度一致;比较干法和湿法两种方法的测定结果的准确度和精密度。结果:铬天青显色剂放置20 min左右反应完全且稳定,线性较好,R2=0.9974;干灰化法相对标准偏差(RSD)为3.3%,回收率为94.8%~103.2%;湿法相对标准偏差(RSD)为4.1%,回收率为92.7%~97.6%。两种方法检测结果无显著性差异(P>0.05)。结论:改进后的方法与GB/T5009.182-2003相比具有显色均匀,结果准确,精密度高,更易于操作等优点,可作为食品中铝的测定参考方法。     

Influence of different concentrations of Al2(SO4)3 and anionic polyelectrolytes on tannery wastewater flocculation

Tanning of hides and skins to convert them into leather can have a considerable environmental impact. Wastewatertreatment technology can successfully purify leather wastewater. The first part of this research investigated the influence of Al₂(SO₄)₃ concentration on the velocity of tannery wastewater settling. The wastewater sample was taken from two of the most polluted wastewater flows after liming and after chrome tanning. These wastewater flows were mixed together in a ratio of 1:1. The second part was carried out with the samples of wastewater mixed together with different concentrations of A1₂(SO₄)₃. The behaviour of settling was investigated after an addition of different concentrations of anionic polyelectrolytes in these samples. The pH, suspended solids mass, volume of sediment, γ(Na₂S), γ(Cr₂O₃), chemical oxygen demand, along with turbidity in the supernatant were determined in the obtained sludge. The results demonstrate the influence of A1₂(SO₄)₃ and anionic polyelectrolyte concentrations on the parameters studied and the improvement of environmental properties.     

Scouring erosion resistance of metallic materials used in slurry pump service

Low impact angle erosion resistance is a critical requirement of materials used in pumps, piping, valves, nozzles, cyclones and other components which transport and process most mineral slurries.The Coriolis method offers a suitable technique for assessing behavior under such scouring attack conditions. It is being used increasingly in support of the mining/mineral processing industry, to compare and discriminate between candidate materials and also assist in the development of new products and protection systems. The specific method used in the current study involves high velocity erosion with aqueous slurry containing 10 wt.% of AFS 50-70 silica test sand. This compares reasonably with the main, extremely abrasive solids constituent encountered in mining and processing oil sands deposits in northern Alberta, Canada. These are becoming a rapidly growing and critically important source of oil in North America.Abrasion resistant chrome white iron castings typically covered by the ASTM A532 standard, are used widely in slurry pump components particularly in oil sand operations. However, the development of proprietary cast hypereutectic chromium white irons with microstructures containing primary M₇C₃-type carbides, is providing the capability to significantly improve the wear performance of such parts. In certain applications where corrosion contributes significantly to overall attack, lower carbon and higher chromium-bearing variants are employed.A comparison of the Coriolis erosion behavior of a wide range of commercially available cast wear and corrosion resistant and high toughness alloys used in pump manufacture, has confirmed anticipated performance ranking and the superiority of the latest generation of hypereutectic chrome white irons. The ameliorative influence on scouring erosion behavior of high carbon content, hardness and carbide volume fraction and particularly of fine carbide size has been demonstrated. A correlation is drawn between test data and service performance.     

影响活塞环复合镀铬层网纹特性的因素研究

本文简要介绍了活塞环复合镀铬技术及其主要性能指标和网纹特性定义,重点分析了影响活塞环复合镀铬层网纹特性的因素,试验表明镀铬槽液成份特别是添加剂的种类和含量、镀液温度和特殊处理方法工艺等是影响网纹特性的最主要因素。     

Problems in laser repair-welding a surface-treated tool steel

A research work is described on the development of defects in laser repair welding of a surface-treated tool steel. Repair welding tests were carried out on plasma-nitrided and on chrome-plated type 1.2738 steel plates. Welding defects in the chrome-plated samples were mainly due to chrome and oxygen overalloying of the weld metal, leading to extensive hot cracking. Cracks of the surface chrome deposit in the HAZ due to welding stresses were also detected. In the nitrided samples, welding resulted in the copious formation of gas pores due to nitrogen release during weld metal solidification. A procedure for combined laser pre-treating and laser welding of the nitrided samples was thus presented. The procedure is aimed at minimising the negative effect of the laser beam on the structural integrity of the base and welded material. The results of the microstructural analyses revealed that a significant reduction in defects could be achieved by the proposed method in the nitrided samples.     

钢的稀土硼铬共渗层耐磨损性能的研究

通过对钢单渗硼层和稀土硼铬共渗层的硬度、脆性和磨损特性进行研究。结果表明，稀土硼铬共渗层在保留了单渗硼层高硬度的同时，明显降低了脆性(约为42．7％)，使共渗层的粘着磨损、疲劳磨损和磨粒磨损性能都得到较大的提高，有较强的实用性。