一种复合催渗剂用于氮碳共渗的研究

采用一种由氯化铵、海绵钛、稀土和固态铬酸盐组成的复合催渗剂,对Cr12、3Cr2W8V和35CrMo钢进行了氮碳共渗.测定了渗层的硬度、深度、组织和相结构,并与采用纯稀土催渗剂的效果作了比较.试验结果表明,复合催渗剂对氮碳共渗有明显的催渗效果,并优于纯稀土催渗剂.     

不锈钢加铁稀土离子硫氮碳共渗工艺的研究

对1Cr18Ni12Mo2Ti奥氏体不锈钢在稀土催渗条件下进行了加与未加辅助铁板的离子硫氮共渗对比试验.试验表明:稀土具有很强的催渗作用.在与辅助铁板的共同作用下,可使奥氏体不锈钢的氮化温度降低60℃,减小了零件的变形;在相同的共渗温度条件下,可使氮化层深度比离子硫氮碳共渗增加30%以上,比未加辅助铁板的稀土离子硫氮碳增加10%.且稀土元素可渗入钢表层,细化渗层组织,促进氮碳化合物弥散细小析出,提高渗层硬度.     

硫碳氮共渗及稀土的作用

在渗剂中不加稀土和加入不同量稀土的条件下，对３Ｃｒ２Ｗ８Ｖ钢进行了硫碳氮共渗试验。用金相法和显微硬度法测定了硫碳氮共渗动力学曲线。利用二次离子质谱仪和Ｘ射线光电子能谱仪，对稀土在试样表面分布与存在状态进行了研究。结果表明，适量稀土对硫碳氮共渗具有明显的催渗作用；稀土能渗入钢中，渗入试样表面的稀土以氧化物和固溶态的形式存在；稀土通过促进碳氮硫原子在表面的吸附及破坏表面氮化层，清洁界面，加速硫碳氮共渗     

稀土在离子氮碳共渗中的应用

采用光学显微镜、显微硬度计、Ｘ射线衍射仪和俄歇能谱仪等手段研究了稀土及稀土加入量、共渗时间对渗层厚度、硬度及渗层组成的影响。研究结果表明，稀土对离子氮碳共渗过程有明显的催渗作用，尤其是一些难渗氮的奥氏体不锈钢。在给定条件下，稀土的催渗效果有一最佳含量。稀土对渗层相组成也有影响。     

稀土时离子硫氮碳共渗的影响

研究了稀土浓度、保温时间对渗层深度和性能的影响，探讨了稀土元素对离子硫氮碳共修的催渗机理。试验结果表明，在渗剂中加入一定量的稀土对离子硫氮碳共渗具有明显的催渗作用，可使渗层深度提高约２５％，硫化物层牢固，表面硬度增高且渗层硬度梯度平缓，耐磨性提高５０％以上。     

稀土对离子硫氮碳共渗的影响

研究了稀土浓度，保温时间对渗层深度和性能的影响，探讨了稀土元素对离子硫氮碳共渗的催渗机理，试验结果表明，在渗剂中加入一定量的稀土对离子硫氮碳共渗具有明显的催渗作用，可使渗层深度提高约２５％，硫化物层牢固，表面硬度增高且渗层硬度梯度平缓，耐磨性提高５０％以上。     

稀土对42CrMo钢等离子体氮碳共渗组织及性能的影响

在渗剂中添加稀土,在42CrMo钢表面进行了等离子体氮碳共渗试验,并对渗层的组织形貌、显微硬度及接触疲劳强度进行了测试和分析,研究了稀土对等离子体氮碳共渗层的影响.结果表明,稀土在短时间内的催渗效果优于长时间,本次试验以低于8 h的效果最为明显;稀土有细化晶粒,使渗层组织结合得更加致密的效果,还可提高次表层的显微硬度和接触疲劳强度.     

球墨铸铁稀土催渗氮碳共渗动力学及其应用

在常规氮碳共渗基础上加入不同量的自制稀土催渗剂，研究了稀土元素对球墨铸铁氮碳共渗动力学的影响及其催渗机理。用于柴油机球铁曲轴，与常规氮碳共渗相比，可提高渗速５５％，生产率３３％，并使渗层性能明显提高，产品质量稳定，具有显著的经济效益和社会效益。     

低温气体碳氮(氮碳)共渗复合催渗工艺

研究了在低温碳氮共渗过程中采用催渗剂进行复合催渗的新工艺。试验结果表明 ,该工艺在降低共渗温度、缩短共渗时间的同时 ,能获得更高的表面硬度、耐磨性、耐蚀性     

42CrMo钢离子氮碳共渗与激光复合处理及其耐磨性的研究

在相同的激光工艺参数条件下，对经调质，离子渗Ｎ、离子ＮＣ共渗和稀土催渗ＮＣ共渗的４２ＣｒＭｏ钢进行相变复合处理，试验结果表明，离子ＮＣ共渗和稀土催渗ＮＣ共渗渗速度快，渗层深度大，渗层和钢表面的碳浓度高，使Ｍｓ点降低，增加了复合处理的硬化层深度，提高了硬化层的硬度，硬化层组织不高于其它复合处理，在滑动磨粒磨损条件下，其耐磨性比其它复合处理的更好。     

利用缓蚀协同效应降低二氧化碳缓蚀剂使用浓度

用失重法及电化学方法研究了抑制碳钢ＣＯ２腐蚀的缓蚀剂的协同效应,得到了低浓度下具有高缓蚀率的复合缓蚀剂,较侍浓度配比时复合缓蚀缓蚀率大于二组分单独作用时慢率之和,优良的缓蚀协同效果归因于复配后对电极过程特别是阳极过程的强烈抑制作用。     

碳气氛中熔炼金属时控制碳污染研究

进行碳气氛中陶瓷坩埚、带喷涂涂层石墨坩埚熔炼纯铁、铀、轴铌合金工艺试验，结果表明，与不带盖熔炼比较，坩埚带盖熔炼可有效降低铸锭碳增量。     

碳钢在CO2饱和的氯化钠溶液中腐蚀及缓蚀研究

采用失重法，动电位扫描法，研究了碳钢在ＣＯ２饱和３％氯化钠溶液中的腐蚀行为和缓蚀剂ＨＡ，ＨＢ抑制碳奂在ＣＯ２饱和３％氯化钠溶液中的腐蚀及其缓蚀机理。     

挤压铸造制备Cf/ZL109复合材料及其组织观察

采用挤压铸造制备碳纤维增强ZL109复合材料．SEM观察预处理前后的碳纤维以及碳纤维顶制件的形貌．金相显激镜观察纤维在复合材料中的分布结果表明：预处理使碳纤维长径比满足制备合格预制件的要求，并有利于纤维在预制件中的均匀分散及预制件的成型；模压预制件纤维分布均匀．表面无团聚．碳纤维无氧化；挤压铸造制备的Cf／ZL109复合材料中纤维在基体中分市均匀，并具有方向性。     

Electrical properties and applications of carbon based nanocomposite materials: An overview

The allotropic forms of carbon (amorphous and polycrystalline graphite, carbon black, fullerenes, nanotubes, graphene) exhibit a large variety of charge transport properties which have been stimulating fundamental and applied research for the development of new devices based on micro and nano-sized electronic systems. Carbon based nanocomposites offer the possibility to improve the device performances and to develop novel multifunctional material systems by combining the properties of each individual phase. In this paper we review the electrical properties of carbon materials and some of the most exciting carbon based nanocomposites, as well as their potential technological applications. First, the electrical properties of amorphous and polycrystalline graphitic materials and those of their related nanocomposites materials are discussed. Second, an overview of the state-of-art on research and applications of carbon nanotube-based composites is presented. Third, we discuss briefly the emerging area of research related to graphene materials. Finally, the electrical properties and applications of conducting carbon black aggregates and carbon black/polymer composites are overviewed.     

Technical note Effect of ceramic heat insulating paste on degree of sensitisation of AISI type 304 stainless steel

Abstract

Double-loop electrochemical potentiokinetic reactivation (DL-EPR) tests and oxalic acid etch tests were conducted to evaluate the effect of a ceramic heat insulating paste on the degree of sensitisation of AISI type 304 stainless steel. Steel strips in the as received condition, partially and totally protected with the ceramic heat insulating paste, were heat treated in a furnace at 700°C for intervals of 15, 30, and 60 min. Measurements of the ratios of the reactivation current to the anodic current indicated that the ceramic heat insulating paste effectively prevented sensitisation of the steel for the first 15 min at 700°C and reduced the degree of sensitisation for specimens heat treated for 30 and 60 min. Microstructural examination of specimens after DL-EPR tests and oxalic acid etch tests provided additional evidence for the effectiveness of the ceramic paste. The decreased degree of protection at 30 and 60 min was due to dehydration and subsequent cracking of the protective paste layer on the steel surfaces.     

SiC/MoSi2高温抗氧化涂层的制备及性能探究

采用磁控溅射法在C/C复合材料表面制备SiC/MoSi2抗氧化涂层,并利用SEM、XRD以及EDS等测试手段对涂层的组织结构、抗氧化性能以及抗氧化机制进行了研究。结果表明,所得涂层结构致密、厚度均匀可控,呈柱状晶。在1500℃静态氧化60min后,涂层试样表现出了较优异的抗氧化性能,氧化质量损失仅为3.2x10-2g/cm-2。导致C/C基体被氧化失重的主要原因是涂层中沿晶界产生的贯穿裂纹为氧气进入基体表面提供了通道。     

Effect of Sulphur and Manganese on Nucleation of Corrosion Pits in Iron

Abstract

A study has been made of the effect of sulphur and manganese concentrations in iron on its tendency to pitting in a buffered potassium chloride solution. As revealed by electron microprobe and microscopic examinations, (Mn, Fe)S_x inclusions are the main sources of pit nucleation. Corrosion most frequently starts within the boundary region between the inclusion and the passive metal. Electrochemical investigations have shown that the critical pitting potential of the alloys under investigation, irrespective of S content, is lower than the corresponding value for ultra-pure iron. Mn has a dual effect on fhe resistance of Fe to pitting: it slightly increases the critical pitting potential, but it forms the sulphide inclusions at which the pits nucleate.     

羟基羧酸盐对碳酸盐体系碳钢钝化性能的影响

研究了葡萄糖酸钠，酒石酸钠，柠檬酸钠三种羟基羧酸盐对碳酸盐体系碳钢的钝化行为的影响，结果表明：葡萄糖酸钠，酒石酸钠浓度大于某一值后，碳钢的致钝电流随其浓度增加而降低，钝化电位负移，促进碳钢的钝化；柠檬到钠在一定的浓度范围内同样地难促进碳钢的钝化，但继续增加其浓度，致钝电流及又重新增大，碳钢钝化性能下降，最后不能进入钝化状态。就羟基羧酸盐对碳钢阳极钝化行为的影响进行了讨论。     

Effect on marine immersion corrosion of carbon content of low alloy steels

This paper attempts to reconcile information from a number of different sources about the effect of small changes in carbon content on the immersion corrosion of specimens of normal commercial mild and low alloy steels. It does so through interpreting the data reported in the literature in terms of the recently proposed theoretically based phenomenological model for marine immersion corrosion. This model postulates different corrosion phases as corrosion progresses. When the experimental results are interpreted in terms of the model it is found that carbon content has minimal effect on the kinetically controlled corrosion phase. The next phase, when corrosion rate is controlled by oxygen diffusion, is also unaffected, in agreement with theoretical predictions. However, carbon content does affect the two anaerobic phases, with increased corrosion as the carbon content and the water temperature increase. The model allows apparently conflicting observations to be reconciled and shows that carbon content may be influential for longer-term corrosion and for corrosion in tropical waters.