TiAl基合金的离子表面Nb-C复合渗研究

利用双层辉光离子渗金属技术对TiAl基合金进行离子Nb-C复合渗处理,通过研究源极电压与工件电压对渗层显微组织及其厚度的影响,确定合理的工艺参数.试验结果表明,源极电压和阴极电压电位差为250 V,TiAl基合金经过Nb-C复合渗后可在表面形成紧密较厚的Nb-C合金层,其表面硬度达HV1 150.     

等离子渗Mo提高TiAl基合金高温氧化性能的研究

研究了等离子渗Mo处理对Ti-46.5Al-1.0V-2.5Cr(原子分数)合金抗高温氧化性能的影响.结果表明,等离子渗Mo处理能显著提高TiAl基合金的抗高温氧化能力,归因于TiAl基合金经等离子渗Mo处理后在表面形成成分含Ti-Al-Mo的致密合金层,该致密合金层具有良好的抗高温氧化性能.     

H13钢表面不含白亮层的渗氮层制备及其耐磨性能

采用等离子氮化技术对H13钢进行离子氮化,通过改变渗氮气压和温度得到不同成分和厚度的渗氮层,用光学显微镜和X射线衍射仪分析了渗层的组织及物相组成,借助球-盘磨损试验机对渗层在大气环境下与Al_2O_3球对磨时的摩擦学性能进行了研究。结果表明:渗层主要由ε-Fe_(2-3)N、γ′-Fe_4N和少量α-Fe、Fe_2O_3、Fe_3O_4相构成;渗氮温度为510℃时没有形成明显的渗层,渗氮温度为570℃、气压为200,300 Pa和渗氮温度为540℃、气压为100 Pa时渗层只有扩散层,而在其他条件下渗层由白亮层和扩散层组成;氮化后表面硬度为1100～1200 HV,较基体增加1倍左右;在温度为570℃、气压200 Pa制备渗层的摩擦因数比基体大幅度降低,磨痕宽度变窄,比磨损率明显降低,耐磨性明显改善。     

曲轴离子渗氮工艺的改进

离子渗氮的温度可根据零件的材质、技术要求（包括：渗氮层硬度和深度、心部硬度、允许的变形量等）综合考虑进行选择。生产上常用的渗氮温度范围为450～650℃。对结构钢而言，渗氮温度低能得到较高的渗层硬度，保持较高的心部硬度，减小变形，但渗层较浅；若渗氮温度高，则心部强度降低，变形增大。保温时间的长短取决于零件的材料、渗氮层深度和渗氮温度。     

压缩变形对渗硅钛铝基合金抗氧化性能的影响

研究了渗硅处理后的钛铝基合金分别在高温和室温压缩变形后的抗高温循环氧化性能。试验结果表明，由Al2O3基层（厚约1μm，其中分布少量硅化物）和Ti5Si3基层（厚约7μm，其中分布少量Al2O3）构成的复合渗硅层，可有效保护TiAl基体的高温氧化，其优异的抗高温氧化性能在高温压缩变形约1％后不受影响，即使较大的变形仍能保持良好的抗高温氧化性能。说明渗硅钛铝基合金具有非常好的耐应力应变和高温氧化交互作用的性能。     

离子渗氮技术的进展

离子渗氮技术自发明以来，以其渗速快、热效率高、渗层质量高、综合力学性能好受到广泛关注。离子渗氮不仅能实现可控氮化和局部硬化，不生成脆性相，且渗层致密，有更高的耐磨性、耐蚀性和抗疲劳性能，生产周期短，工件变形小，因而在工业生产上得到广泛的应用。近几年来，热处理工作者从不同角度研究离子渗氮的原理、工艺和设备，推动了离子渗氮技术的发展。本文将简单介绍一下近几年离子渗技术的进展，以期对同行有所帮助。     

34CrNi3MoA钢气体渗氮工艺研究

文中介绍了一种采用加入稀土催渗剂的方法对34Cr N3Mo Ai钢进行气体渗氮的工艺方法。通过试验对比研究了常规气体渗氮和稀土催渗渗氮动力学曲线、温度对层深和硬度的影响,结果表明:稀土催渗剂的加入可以有效提高渗氮层表面的硬度和渗氮速度。     

齿轮渗氮

一、前言众所周知,渗氮具有许多的优点,然而渗氮层的脆性却阻碍着渗氮齿轮的推广应用。传统的可控渗氮方法虽然可以有效地降低渗层脆性,但有效硬化层深度浅,以致在齿轮中应用也受到限制。本文作者们先后开发了分段可控渗氮和动态可控渗氮两种新技术,既能降低渗层脆性,又能保持良好的渗层硬度分布,是很有价值的齿轮热处理方法。     

提高3Cr2MoWVNiRe钢热冲头寿命途径

本文研究了常规渗硼处理与硼氮复合渗不同处理对3Cr2MoWVNiRe电渣钢制热冲头寿命的影响。硼氮复合渗层既有渗硼层的高硬度、高红硬性、高耐磨性、比单渗硼低的脆性，又有良好的强硬化过渡层对渗层的支撑能力，充分发挥渗硼和渗氮各自优势，弥补各自不足，使用寿命比单一渗硼提高4－6倍，技术经济效益显著。     

双相钢离子渗氮工艺研究

介绍了00Cr22NiSMo3N双相（A＋F）钢制活塞的离子渗氮工艺，旨在解决活塞的表面硬度、深度、脆性等技术要求，来提高其耐磨性。通过研究发现，采用N2＋H2气氛比NH3气氛渗氮时渗层均匀，并且抗拉脆性小；并找到了N2＋H2最佳配比的离子氮化工艺。     

热等静压氮化硅 (HIP- Si3N4)试件制备及性能测试

热等静压氮化硅(Hot Isostatic Pressure），一种新型工程陶瓷，作为耐高温、抗腐蚀复合材料摩擦副的一方，这里从配料、湿磨与湿筛、干馏与粒化、成型与脱脂、氮化、热静等压烧结等工序介绍了它的制备，并用BET，XPS方法对产品的物化及机械性能进行试验分析。     

煤柴油加氢装置热高分系统腐蚀机理与失效分析

以某石化企业煤柴油加氢装置换热器腐蚀失效为研究对象,采用PENG-ROB物性方法构建腐蚀失效预测模型,通过分析系统内铵盐结晶温度、腐蚀介质含量、液态水含量等分布规律,明确了该系统内主要是以NH 4Cl结晶沉积堵塞为主的失效模式。此外,研究结果表明,该系统内无NH 4HS结晶风险,管、壳程NH 4Cl结晶温度分别为164~170℃,161~171℃,温度段位置位于E104换热器尾端出口以后的低温区。由液态水含量可知,该温度下换热器无充足液态水溶解NH 4Cl,极易发生NH 4Cl堵塞、穿孔、泄漏等问题。结合对E104内部温度分布预测以及现场垢物化验,得知热高分系统内存在NH 4Cl结晶沉积问题,其位于管束出口端向内3.94 m区域,与模拟分析结果相吻合,验证了预测方法的准确性。该研究成果可为加氢反应流出物换热系统的抗腐蚀优化设计提供理论支撑。     

W18Cr4V钢钛催渗盐浴氮碳共渗工艺研究

试验研究了钛催渗对W18Cr4V钢盐浴氮碳共渗的影响,分别就盐浴处理温度和时间等工艺参数对试样表面性能影响进行了研究。试验结果表明,钛催渗剂的多少对提高共渗层表面硬度具有显著作用,钛催渗可显著缩短盐浴处理时间,有效提高渗层厚度和硬度,能得到质量良好的渗层。     

Effect of Plasma Nitriding Environment and Time on Plain Fatigue and Fretting Fatigue Behavior of Ti–6Al–4V

Plasma nitriding was performed on Ti–6Al–4V fatigue test samples at 520°C in two environments (nitrogen and nitrogen–hydrogen mixture in a ratio of 3:1) for two time periods (4 and 18 h). Plain fatigue and fretting fatigue tests were conducted on unnitrided and plasma nitrided samples. Plasma nitriding degraded lives under both plain fatigue and fretting fatigue loadings. The samples nitrided in nitrogen exhibited superior lives compared with the samples nitrided in the nitrogen–hydrogen mixture, possibly due to the relatively higher hardness (and presumably lower toughness) of the nitrided layer of the samples nitrided in the nitrogen–hydrogen mixture environment. For those samples nitrided in the nitrogen–hydrogen mixture, those nitrided for 18 h exhibited superior lives compared with those nitrided for 4 h. This trend was observed for samples nitrided in nitrogen gas at lower stress levels only; the converse was true at higher stress levels of 550 MPa and 700 MPa under plain fatigue loading. However, under fretting fatigue loading, the plasma nitriding time did not influence the lives significantly.     

Influence of plasma nitriding on fretting wear behaviour of Ti–6Al–4V

Plasma nitriding was performed on Ti–6Al–4V samples at 520 °C in two environments (pure nitrogen and a mixture of nitrogen and hydrogen in the ratio of 3:1) for two different time periods (4 and 18 h). Fretting wear tests were conducted on unnitrided and nitrided samples for 50,000 cycles using alumina ball counterbody. Plasma nitriding reduced the tangential force coefficient of Ti–6Al–4V. The samples nitrided for 4 h exhibited higher hardness and lower tangential force coefficient compared to the specimens nitrided for 18 h. The samples nitrided in nitrogen–hydrogen mixture environment exhibited higher hardness and lower tangential force coefficient compared to the specimens nitrided in pure nitrogen. The samples plasma nitrided in nitrogen–hydrogen mixture for 4 h exhibited the highest hardness and the lowest tangential force coefficient. The wear volume and specific wear rate of the plasma nitrided samples were lower than those of the unnitrided samples. A consistent trend was not observed regarding which nitriding condition would result in lower wear volume and specific wear rate at different loads.     

Characteristics of fatigue crack initiation and fatigue strength of nitrided lCr-lMo-0.25V turbine rotor steels

To investigate the effect of nitriding layer on both fatigue crack initiation and fatigue life, turbine rotor steel (lCr-IMo-0.25V steel) specimens were nitrided by the nitemper method and then put to a rotary bending fatigue test at room and elevated temperatures. In nitriding, temperature and time were controlled to obtain a different nitrided thickness. Microstructure analysis, micro-Vickers hardness test, and scanning electron microscope observation were carried out for evaluating experiments. In results, the fatigue cracks of nitrided specimens were initiated at inclusion near the interface between nitrided layer and substrate, which showed fish-eye type appearance in fractograph. The fatigue life of nitrided specimens at every temperature was prolonged compared to that of the non-nitrided. However, there was not observable improvement in fatigue characteristics with the increase of a nitrided thickness.     

离子硫氮复合渗42CrMo钢的耐磨性和抗咬合性研究

研究了离子硫氮复合渗对42CrMo钢的耐磨性和抗咬合性的影响。数据表明，与42CrMo钢调质态和单一离子渗氮工艺状态相比，该钢经离子硫氮复合渗处理后可明显提高钢的耐磨性和抗咬合性。通过对渗层的组织结构分析，探讨了硫氮复合渗层对提高42CrMo钢的耐磨性和抗咬合性的作用机理。     

NaClO-NH4Cl法生产MoO3工艺的研究

研究了用 Na Cl O浸取低品位钼精矿及用 NH4 Cl从浸取液中沉淀钼的工艺条件。钼的总回收率不低于 94% ,产品 Mo O3 中的钼含量不低于 57%。     

A comparative study on the tribological behaviors of nitrided and sulfur-nitrided 35CrMo steel lubricated in PAO base oil with MoDTC additive

A nitrided layer on 35CrMo steel was prepared by the ion nitriding process, and then a sulfur-nitrided layer was obtained by low temperature ion sulfuration. The results showed that both the nitrided and sulfur-nitrided surfaces improved the wear resistance efficiently under PAO lubrication, and exhibited the best wear resistance and friction-reducing property under PAO with 0.75% MoDTC lubrication. Compared with the plain and nitrided surfaces, the sulfur-nitrided surface exhibited the best synergistic effect with MoDTC displaying the lowest friction coefficient and wear volume. The mechanism of the best effect was due to MoS₂ and FeS formed on the sulfur-nitrided surface.     

A comparative study on the tribological behaviors of nitrided and sulfur-nitrided 35CrMo steel lubricated in PAO base oil with MoDTC additive

A nitrided layer on 35CrMo steel was prepared by the ion nitriding process, and then a sulfur-nitrided layer was obtained by low temperature ion sulfuration. The results showed that both the nitrided and sulfur-nitrided surfaces improved the wear resistance efficiently under PAO lubrication, and exhibited the best wear resistance and friction-reducing property under PAO with 0.75% MoDTC lubrication. Compared with the plain and nitrided surfaces, the sulfur-nitrided surface exhibited the best synergistic effect with MoDTC displaying the lowest friction coefficient and wear volume. The mechanism of the best effect was due to MoS₂ and FeS formed on the sulfur-nitrided surface.