Development of the Combined Technology of Modification of the Surface of Titanium Implants by Laser Radiation with Subsequent Plasma Spraying of Biocompatible Coatings

Metallurgist - We propose a combined technology for the modification of the surfaces of titanium implants by laser radiation followed by the plasma spraying of biocompatible coatings. We performed...     

NOM Accumulation at NF Membrane Surface: Impact of Chemistry and Shear

The effects of solution chemistry, surface shear, and composition of natural organic matter (NOM) were investigated for their impact on accumulation of foulant material at the surface of charged polymeric nanofiltration membranes. The source of NOM was the Suwannee River. A bench-scale, batch recycle system was used with 20 hollow fiber, nanofiltration membranes. Membrane flux decline and foulant accumulation increased at low pH and high ionic strength as a result of neutralization of charge, electric double layer compression, and the apparent shift in conformation of charged NOM macromolecules. The rate of NOM accumulation decreased with operating time, suggestive of an eventual steady state between adsorption and desorption. The effect of NOM composition on membrane fouling could not be discerned by a standard technique to isolate hydrophobic and hydrophilic NOM fractions, quite possibly because of the fractionation methodology's failure to recover a small but important fouling fraction or because of NOM interactions that are lost when individual fractions are separately tested. However, a greater percentage of the hydrophilic than hydrophobic fraction permeated the membrane, in agreement with prior observations by others. Increasing the cross flow velocity from 85 to 255 cm∕s reduced the extent of flux decline, presumably due to hydrodynamic disruption of cake layer formation.     

分子自组装技术及其在表面改性中的应用

介绍了分子自组装技术的基本概念、原理、特点以及合成方法,阐述了自组装技术在摩擦学和腐蚀学上的应用,总结了自组装技术的一些局限性,并对未来进行了展望.     

Understanding the Corrosion and Remedial Measures to Control the Deterioration of Reinforcement Steel Bars by Modification in Their Chemistry and Application of Surface Coatings

Corrosion of reinforcement bars embedded in structures near coastal areas is a serious problem and has been attributed to many premature distresses of structures. The passivity imparted by the alkalinity of the cement to reinforcement steel surface becomes ineffective when chloride concentration at the steel surface exceeds a critical threshold value. Under such a situation, the total loss of the steel thickness per unit area is negligibly small in comparison to penetration rate at certain susceptible part of the reinforcement bars. As a result of increase in stress intensity factor at the tip of localized pits formed on the surface of rebars, the tensile strength of the concrete structures which is mainly imparted by the steel reinforcement bars, is adversely affected and results in collapse of structures. Many techniques have been developed to control the corrosion problems associated with rebars. These include use of corrosion resistant alloys, corrosion inhibitors, cathodic protection and use of organic/metallic coatings on surface of steel bars. Amongst these techniques, the applications of surface coatings appear an effective and economical method to control corrosion of steel rebars. However, the efficacy and mechanism of their protective action are still matter of controversy and subject matter of studies all over the world. The present work is in continuation of our earlier studies published in different scientific journals where the above aspects had been addressed. This paper incorporates experimental results and literature review in understanding the corrosion and remedial measures to control the deterioration of reinforcement steel bars by modification in their chemistry and application of surface coatings. A brief historical background is given on development of reinforcement concrete structures. Various types of reinforcement bars used in construction industries and their merits and demerits are described. It has been established by the experimental proofs that the current scenario of protecting steel rebars used in chloride contaminated concrete, is not at all satisfactory. Amongst the protective coatings, metallic coated rebars appear to be more effective than organic based coatings. Causes and mechanism of deterioration of coated and bare steel rebars are discussed by providing experimental evidences.     

纳米Eu2O3的表面修饰及其在PP中的分散性研究

以钛酸酯偶联剂在无水乙醇中对纳米氧化铕进行表面修饰,分别测定了处理好的样品的粒径及分布、在二氧六环中的沉降稳定性以及在聚丙烯中的分散性。结果表明,表面修饰有利于纳米氧化铕在聚丙烯中的分散,其中以10%钛酸酯处理的效果最佳;处理后样品的红外光谱表明,纳米氧化铕与偶联剂发生了化学键合作用,他们之间并不是简单的物理包覆。     

MLCC内电极用超细镍粉表面改性研究

利用还原法对超细镍粉进行表面改性，形成Ni—BO体系，从而提高镍粉的抗氧化性能。文章着重研究了NaBH4的用量、反应温度、PH值对超细镍粉抗氧化性的影响。最终确定了最佳条件。利用热重分析法DTA—TGA对镍粉的抗氧化性进行检测。研究表明，改性后镍粉的抗氧化性得到明显的改善。     

医用钛合金及其表面改性技术的研究现状

介绍了新型医用钛合金的研究开发现状，分析了医用钛合金存在的主要问题，即耐磨性、耐腐蚀性和生物活性有待进一步提高。阐述了表面改性对提高钛合金的耐磨性能、耐腐蚀性能和生物活性的作用。指出应当重视钛合金表面生物活性陶瓷涂层的稳定性问题。认为通过研究开发综合性能更优的新型医用钛合金，寻求更为理想的表面改性工艺以及运用复合涂层制备技术，有望逐步解决钛合金在临床应用中存在的问题。     

中厚板表面微裂纹成因及影响因素研究

对重钢连铸板坯轧制中厚板出现的表面微裂纹进行取样,经低倍检验发现,微裂纹有3种类型;与之对应的连铸板坯酸洗后发现,微裂纹也有3种类型,采用镀层结晶器铜板前以网状裂纹为主,尔后以横裂纹为主;对裂纹量最多的网状裂纹进行高倍和能谱检验,发现网状裂纹主要是铜裂纹.分析产生裂纹炉次的对应工艺,找出其主要影响因素是结晶器铜板、结晶器保护渣、二次冷却制度、钢中的w(N)等,针对性地采取预防措施,使中厚板表面微裂纹大幅度减少.     

Coating Multi-walled Carbon Nanotubes with Uniform Silica Shells:Independent of Surface Chemistry

A facile and general method was described to coat six types of multi-walled carbon nanotubes, functionalized by either noncovalent or covalent way, with smooth silica shells. 3-Aminopropyltriethoxysilane(APTES) and pH value play important roles in the coating process and the thickness of silica shell could be controlled by the added amount of silicon alkoxides. After the removal of multi-walled carbon nanotubes by calcination, the silica nanotubes were successfully prepared.     

油酸改性纳米ZrO2粉体及其机制研究

采用水热法制备了平均粒径小于10nm左右的氧化锫.用油酸对纳米ZrO2粉体进行了表面改性,研究了改性工艺条件中油酸添加量对亲油改性效果的影响.按质量百分比油酸:乙醇:水=l:2:2的比例配制改性剂,油酸添加量为ZrO2的lO%(摩尔分数)时,改性的ZrO2粉体在二甲苯中分散稳定性最佳.通过FT-IR分析表明,油酸与纳米ZrO2是以氢键和共价键两种形式结合,在无机纳米粒子表面形成单分子膜.     

碳纳米管表面辐照接枝改性及负载纳米铜的研究

采用硝酸(1∶1)对碳纳米管进行氧化纯化处理,然后采用~(60)Coγ射线辐照,引发丙烯酸单体在碳纳米管表面发生自由基加成、聚合反应,对碳纳米管表面进行表面改性,所得碳纳米管在水溶液中有良好的分散性。红外光谱证实C(=O)-H、C-OH等基团接枝到碳纳米管表面,表面改性前后的碳纳米管表面增强拉曼光谱(SERS)也存在显著差异。SEM研究结果表明,改性后的碳纳米管表面可以直接镀上连续、均匀的纳米铜颗粒,实现良好的异质连接。谢乐公式计算出铜晶粒平均大小为44.298nm。     

废铝液制备水合硅酸铝及其表面修饰

本研究以工业废铝液作为原料,通过反应合成、老化、洗涤、表面修饰等步骤,制备出水合硅酸铝,对差热、SEM等样品进行了化学分析,得出:修饰后样品粒子可达到纳米量级,各项指标均符合通用企业标准要求;加入Tween-80后,其以吸附形式附在硅酸铝颗粒表面,从而起到修饰作用;本体系中硅酸铝的生长过程分为四个阶段,分别受不同工艺条件的控制。     

板坯裂纹成因与对策

简述了太钢二炼钢厂碳钢连铸生产线生产的板坯出现的缺陷，分析了板坯的角横裂、表面纵裂的成因，提出了防止裂纹而采取的措施。     

废铝液制备水合硅酸铝及其表面修饰

本研究以工业废铝液作为原料，通过反应合成、老化、洗涤、表面修饰等步骤，制备出水合硅酸铝，对差热、SEM等样品进行了化学分析，得出：修饰后样品粒子可达到纳米量级，各项指标均符合通用企业标准要求；加入Tween-80后，其以吸附形式附在硅酸铝颗粒表面，从而起到修饰作用；本体系中硅酸铝的生长过程分为四个阶段，分别受不同工艺条件的控制。     

Microstructural Modification of Laser-Deposited High-Entropy CrFeCoNiMoWC Alloy by Friction Stir Processing: Nanograin Formation and Deformation Mechanism

Metallurgical and Materials Transactions A - Nanostructured CrFeCoNiMoWC high-entropy alloy layer was developed through laser-melting deposition and severe plastic deformation (SPD). The...     

Effect of RE Modification and Heat Treatment on Impact Fatigue Property of a Wear Resistant White Cast Iron

Withhigherhardnessandbetterwearresistance ,whitecastironscanbeusedaswearresistantpartsinmanyfields .Inpractice ,thewearresistantpartsareoftenrequiredtobesubjectedtogrindingofabrasivesandrepeatedimpactaction .Therefore ,fatiguecracksareliabletobegeneratedo…     

TLM钛合金表面白蛋白涂层的制备及抗凝血性研究

为提高医用钛合金Ti-3Zr-2Sn-3Mo-25Nb的抗凝血性能,首先通过溶胶-凝胶法在其表面制备一层TiO2薄膜,再将该TiO2薄膜活化处理,最后通过静电自组装法将牛血清白蛋白固定在TiO2薄膜表面形成抗凝血涂层。利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和接触角测试仪研究了该抗凝血涂层的相结构、表面微观形貌和亲水性特征,并通过动态凝血时间法和血小板黏附实验对比研究了白蛋白修饰前后Ti-3Zr-2Sn-3Mo-25Nb合金的抗凝血性能。结果表明,经白蛋白表面修饰处理后,Ti-3Zr-2Sn-3Mo-25Nb合金的抗凝血性能得到了明显的改善。     

尖晶石LiMn2O4表面改性的研究与新进展

LiMn2O4作为未来锂离子电池正极材料的基材，一直是人们研究的热点。但高温下与循环中容量衰减的问题，是制约它商品化的最重要因素。笔者详细阐述了近年来有关尖晶石LiMn2O4容量衰减机理和表面改性的研究与最新进展。     

Correction to: Structure Formation in the Zones of Joints Obtained by Explosion Welding with Subsequent Rolling of a Five-Layer Titanium-Steel Composite

Metallurgist - The fifth author’s name should read V. O. Kharlamov.