Investigations on composition and morphology of electrochemical conversion layer/titanium dioxide deposit on stainless steel

In this study, the formation and characterization of conversion coatings modified by a sol-gel TiO₂ deposit were investigated as a way to develop a new photocatalyst for water and air depollution. The conversion coating, characterised by strong interfacial adhesion, high roughness and high surface area facilitates the sol-gel deposition of titania and enhances its adhesion to the substrate. The conversion treatment is carried out in an acid solution. Observation by Scanning Electron Microscopy (SEM) reveals a rough surface with pores and cavities. According to SIMS measurements, the thickness of the initial conversion layer is evaluated at about 1.5 μm. On this pre-functionalised support, the titanium dioxide was deposited by the sol-gel method. The roughness measurements coupled with SIMS analysis allowed a precise evaluation of the surface state of the final layers. The coating consists of two layers: a TiO₂ outer layer and an inner layer containing iron chromium oxides. Characterization by X-ray diffraction (XRD) showed the existence of the TiO₂ anatase structure as the main compound.     

微型点焊时电极表面熔敷TiC涂层对电极失效的影响

研究了表面处理对微型点焊镀镍钢板和镍板时电极失效的影响.结果表明:微型点焊镀镍钢板和镍板时电极的失效主要是电极头部的塑性变形以及电极和镀镍板之间局部焊接的断裂发生在电极表面而导致的电极磨损;表面涂敷TiC的CuCrZr电极的寿命(1 200点)是CuCrZr电极寿命(600点)的两倍,表面处理能提高电极寿命的主要原因是表面涂敷的TiC颗粒能阻碍电极和镀镍板之间的局部焊接,以及减小电极表面的塑性变形.     

40CrNi2Si2MoVA钢制零件磁痕显示分析

本文采用磁粉、X射线、CT和超声等无损检测和金相分析等方法对40CrNi2Si2MoVA钢制零件的磁痕显示进行了系统分析.研究认为,40CrNi2Si2MoVA钢制零件的磁痕显示为显微成分沿变形方向偏析导致的马氏体转变点Ms差异所致.显微成分偏析是钢锭结晶过程中不可避免的,但可通过优化熔炼工艺参数降低显微偏析的程度.本文还分析了四种磁痕显示的类型及其判别方法.     

苯骈三氮唑对碳钢在溴化锂溶液中的缓蚀作用

用静态挂片法研究了苯骈三氮唑(BTA)对碳钢在溴化锂溶液中缓蚀作用，并通过极化曲线探讨其缓蚀作用的机理，用扫描电镜观察形成的表面膜形态，用红外光谱探讨表面膜的组成。实验表明苯骈三氮唑对碳钢在溴化锂溶液中有一定的缓蚀作用，其中添加0．020mol／L苯骈三氮唑和0．20mol／L氢氧化锂显著抑制溴化锂溶液对碳钢的腐蚀，分析可能是在碳钢表面形成一层Fe-BTA吸附膜，对阳极反应和阴极反应起一定阻滞作用。     

汽车轮毂钢板的真空退火

采用ＲＪＺ型微机控制组合式真空多用炉对小汽车１６Ｍｎ钢轮毂钢板进行真空退火，介绍了退火工艺参数的制定及实际生产应用效果。     

力学因素对Welten60管线钢应力腐蚀开裂行为的影响

采用慢应变速率实验,低频小振幅加载实验,研究了力学因素的变化对Welten 60钢在80℃的0.5mol/L Na_2CO_3和1mol/L NaHCO_3溶液介质中的应力腐蚀开裂(SCC)行为的影响。实验结果表明:Welten 60钢在该溶液中为沿晶型的SCC;用小锥度拉伸试样获得的应力腐蚀开裂门槛值σ_(th)与应变速率ε和加载频率f有关,σ_(th)随ε和f的减小而降低;用板状单边缺口试样测得的SCC裂纹扩展速率(平台期)da/dt约为3.5×10~(-6)mm/s,应力腐蚀开裂临界应力强度因子K_(ISCC)约为32MPam~(1/2)。     

无缝钢管和电焊钢管的使用领域

详细介绍了无缝钢管和电焊钢管在机械、汽车、建筑、锅炉、石油天然气输送管线及石油钻采等方面的使用情况。     

DM7新型工具钢的组织与性能

研究了ＤＭ７新型工具钢的组织与性能。结果表明，ＤＭ７钢的退火组织为球状珠光体，淬火温度以９００～９５０℃为宜，淬火组织为马氏体＋残留奥氏体＋碳化物，碳化物类型有Ｆｅ３Ｃ，Ｍ２３Ｃ６，Ｍ６Ｃ及ＶＣ，回火温度不应高于３００℃，ＤＭ７钢比６ＣｒＷ２Ｓｉ钢硬度高２ＨＲＣ，屈服强度高２０％，耐磨性高６０％。     

铜-不锈钢复合材料在HSO3-和/或Cl-介质中的腐蚀行为

采用选择腐蚀技术，提取了铜一不锈钢复合材料中的纤维相，并测定了纤维相电极电位。通过循环加速腐蚀试验和电化学测试方法，研究了3种铜一不锈钢复合材料和纯铜在HSO^3-和／或Cl^-介质中的腐蚀行为。同时研究了腐蚀对材料的力学性能、导电性能和显微组织的影响。结果表明，Cu-10wt％SS原位(微观)复合材料在HSO3^-和／或Cl-介质中具有一定的耐蚀性。HSO3^-对铜-不锈钢复合材料腐蚀的影响显著。     

Hydrogen embrittlement susceptibility and permeability of two ultra-high strength steels

Slow displacement rate tensile tests were carried out in a saturated H₂S solution to investigate the effect of hydrogen embrittlement on notched tensile strength (NTS) and fracture characteristics of two ultra-high strength steels (PH 13-8 Mo stainless steel and T-200 maraging steel). Hydrogen permeation properties were determined by an electrochemical permeation method. The results of permeation tests indicated that over-aged specimens showed a lower diffusivity/hydrogen flux and higher solubility than those solution-annealed. The great increase in reverted austenite (irreversible hydrogen traps) together with numerous precipitates at the expense of dislocations (reversible) in the over-aged specimen led to such a change in permeability. Ordinary tensile tests indicated that four tested specimens had roughly the same yield strength level. Hence, the hydrogen embrittlement susceptibility of the material could be related to their permeation properties. The uniform distribution of strong hydrogen traps in over-aged specimens instead of weak traps in the solution-annealed impeded the hydrogen transport toward the strained region, thus, the resistance to sulfide stress corrosion cracking was improved in over-aged specimens.