马氏体不锈钢低温等离子体稀土氮碳共渗研究

将17-4PH马氏体不锈钢在430℃进行了有无稀土添加的等离子体氮碳共渗处理,其利用OM、XRD、显微硬度计和摩擦磨损试验机研究了共渗动力学、渗层组织结构、硬度以及摩擦磨损行为.结果表明,添加稀土使共渗层组织更加致密,渗层增厚;添加稀土不改变渗层的表面相结构组成,即主要由含氮碳膨胀马氏体(α 'N)、γ '-Fe4N和CrN相组成;添加稀土可使氮碳共渗层厚度增加46％以上,渗层显微硬度可提高100 HV0.1左右,同时明显提高耐磨性能.     

45钢淬火与氮碳共渗复合处理工艺

对45铜进行了淬火与氯碳共渗复合处理工艺试验和传统的氮碳共渗处理,分析了经两种工艺处理后45铜的显微组织及显微硬度。结果表明,45铜经淬火与氮碳共渗复合处理可获得更深的渗层及更好的渗层硬度分布,从而进一步提高了零件的耐磨、耐蚀性及疲劳强度、     

SKD11钢的离子氮碳共渗工艺及其稀土催渗研究

为了探究SKD11钢的优化氮碳共渗工艺,对SKD11钢在530℃不同共渗时间、不同炉内气压、NH3/CO2不同气氛比值情况下的离子氮碳共渗进行了研究.运用XRD、SEM、显微硬度、摩擦磨损试验,对材料的显微组织、显微硬度和耐磨性进行了分析.试验结果表明:对于冷作模具钢SKD11,时间为10 h、NH3/CO2为10∶1、炉内气压为500～700 Pa时,氮碳共渗效果相对最好.另外,在上述优化工艺基础上,随着稀土La的加入,渗层变厚且渗层与基体结合更致密,表层到心部的硬度梯度更小,氮碳共渗效果更好.     

17-4PH钢脉冲等离子体稀土氮碳共渗研究

基于XRD、OM、STM、TEM分析与显微硬度和磨损测试研究了17-4PH钢在500℃有无稀土添加时脉冲等离子体氮碳共渗动力学、渗层的组织结构和性能。结果表明,添加稀土不改变共渗层的表面相结构,但提高了渗层中γ-Fe4N相的比例,使表面氮浓度提高7％,渗层深度最大可增加55％,表层显微硬度提高100～200HV;无稀土添加共渗层在抛光研磨过程中发生了粘着磨损;此外,在渗层中观察到了位错、层错等晶体缺陷。     

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.     

碳氮共渗-深层稀土硼碳氮共渗复合处理

探讨了碳氮共渗与深层稀土硼碳氮共渗复合处理工艺.结果表明:复合处理在工艺上是可行的;复合处理试样的截面组织由表层稀土硼碳氮共渗层、中间碳氮共渗层及内部基体组织三部分组成;相当于在高硬度表层与较软基体中间插入一层中等硬度的过渡层,减小了硬度梯度,有效避免工件在工作过程中高硬度表层的剥落.     

碳氮共渗-深层稀土硼碳氮共渗复合处理在20Cr钢耐火砖模具中的应用

在20Cr钢耐火砖模具表面进行了碳氮共渗-深层稀土硼碳氮共渗复合处理的生产试验研究.结果表明,复合处理硬化层的硬度梯度较平缓,稀土硼碳氮共渗层、碳氮共渗层以及基体形成了冶金结合,使模具寿命提高了80%以上.     

17-4PH钢等离子体稀土氮碳共渗层的组织结构和性能

利用OM、XRD、扫描电镜(SEM)、能谱仪(EDS)、显微硬度计和摩擦磨损试验机研究了17-4PH马氏体沉淀硬化不锈钢在500 ℃脉冲等离子体稀土氮碳共渗层的组织结构和性能.结果表明,稀土添加使共渗层致密;共渗层主要由α'、ε-Fe3N、γ'-Fe4N及CrN组成;添加稀土或减小氮氢比,渗层中ε-Fe3N相的比例降低.表面形貌SEM观察和EDS成分分析结果表明,共渗表面主要由弥散分布的(Fe,Cr)xNy化合物颗粒、颗粒团和颗粒团簇,以及少量"柱状"生长的γ'-Fe4N相组成;当氮氢比为1:6时,稀土氮碳共渗层表面硬度可达1580 HV0.1.随磨损时间延长,稀土添加较无稀土添加的共渗层摩擦系数变化较小.     

钢表面获得单相ε化合物层的二段氮碳共渗工艺

在井式气体渗氮炉中,采用氨气加二氧化碳和氨气加甲醇两段法对碳钢和合金钢进行了氮碳共渗,通过控制共渗温度和氮势等主要工艺参数,使氮碳共渗表层化合物层获得单相ε组织,并探讨了温度对不同材料共渗层组织、渗层深度及显微硬度的影响.结果表明:在570 ℃和615 ℃下氮碳共渗都可在表层获得单相ε组织,并随温度的升高,渗层深度和显微硬度都明显提高,能满足不同材料多种零件的使用要求.     

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     

Layer growth kinetics and wear resistance of martensitic precipitation hardening stainless steel plasma nitrocarburized at 460°C with rare earth addition

To study the effect of rare earth (RE) addition on low temperature plasma nitrocarburizing of martensitic precipitation hardening stainless steel, 17-4PH stainless steel was plasma nitrocarburized at 460 °C for different times with RE addition. The modified layers were tested by optical microscope, scanning electron microscope, X-ray diffraction, microhardness tester and pin-on-disc tribometer. The experimental results show that the layer depth of plasma RE nitrocarburized layer can be increased up to 56% compared with plasma nitrocarburizing without RE addition. Incorporation of RE element is beneficial to the formation of nitrogen and carbon expanded martensite (α′_N). The surface microhardness of plasma RE nitrocarburized layer can be increased to 1286 HV and higher up to 80 HV than that obtained from the conventional treated one. The friction coefficient of martensitic stainless steel can be dramatically decreased by low temperature plasma nitrocarburizing with RE addition, and the friction coefficient of the modified specimens decrease gradually with increasing process time in the present test condition.     

Martensitic stainless steel modified by plasma nitrocarburizing at conventional temperature with and without rare earths addition

17-4PH Martensitic stainless steel was plasma nitrocarburized at conventional temperature (560 °C) with and without rare earths (RE) addition. The surface treated layers were characterized by optical microscope, scanning electron microscope equipped with an energy dispersive X-ray analyzer, X-ray diffraction and microhardness test. The wear and corrosion behavior of the modified specimens was studied respectively using pin-on-disc tribometer and anodic polarization tests. The results show that rare earths atoms can diffuse into the surface of the stainless steel. The microstructures of all modified layers are characterized by a compound layer containing three distinct zones but without an evident diffusion zone. The phases on all modified surface layers are mainly of θ-Fe₃C and CrN. It is exciting that the hardness profile of the modified layer is decreased gradually, which is rarely found in plasma nitriding of the stainless steel. The friction coefficient of a specimen can be dramatically decreased by plasma RE nitrocarburizing, whereas the corrosion resistance is deteriorated. In contrast, the corrosion resistance of a plasma nitrocarburized specimen is enhanced but the friction coefficient is not improved as much as that of a plasma RE nitrocarburized one.     

纳米化3J33钢稀土氮碳共渗生成相第一性原理表征

通过稀土化学热处理和第一性原理计算方法研究了纳米化3J33钢在500℃脉冲等离子体稀土氮碳共渗4h时共渗层的相结构和硬度分布以及共渗相的性质.结果表明,共渗层由厚度约5μm的化合物层和90μm的扩散层组成;共渗相主要由γ′-Fe4N和含碳氮的α′-Fe相组成;与纳米化的3J33钢相比,渗层表面硬度提高约1倍,基体时效后硬度也有所提高.计算结果表明,在共渗过程中γ′-Fe4N相较α′-Fe相更容易形成,但α′-Fe相更加稳定;γ′-Fe4N相的硬度高于α′-Fe相的硬度的主要原因是γ′-Fe4N相的N-Fe键较α′-Fe相的C-Fe键更强;此外,γ′-Fe4N相的体模量与剪切模量的比值大于1.75,因此该相具有延性.     

45钢无毒盐浴氮碳共渗工艺研究

对45钢无毒盐浴氮碳共渗工艺进行了研究.结果表明,共渗的温度和时间对渗层深度、结构和显微硬度梯度的影响很大,存在一个合理的温度和时间范围.在该范围内调整共渗温度和时间,可以获得理想的渗层.     

低温离子氮碳共渗温度对AerMet100钢摩擦学性能的影响

研究了不同温度对AerMet100钢渗氮层和氮碳共渗层的显微组织、表面硬度、渗层截面硬度梯度以及耐磨性的影响,并考察了渗层的磨损机理.结果表明,氮碳共渗层相较于渗氮层表面生成的化合物更加细小,表面更加平整光滑;离子渗氮、离子氮碳共渗处理都可显著提高AerMet100钢的表面硬度;随着温度的增加,共渗层厚度也明显增加;氮...     

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。     

氮—碳共渗钢的应变疲劳研究

45碳钢氮—碳共渗表面强化后的应变疲劳试验结果表明:共渗处理与基体,在整个试验应变范围内,均为大应变幅下呈循环硬化,小应变幅下呈循环软化;但在一定应变幅下,其硬化和软化程度各不相同。另外,共渗处理疲劳寿命的降低是表面强化层造成整体材料的塑性损失的结果。同时对断口和内部位错组态进行了观察分析。     

Microstructure of electroplated hard chromium coatings after plasma nitrocarburizing

Plasma nitrocarburizing was carried out on the hard chromium coating deposited on SM45C mild carbon steel substrate by electroplating. After plasma nitrocarburizing at 720 °C for 20 h, a 6–7-μm-thick nitride layer consisting of CrN and Cr₂N was formed on the surface of Cr coating with the microhardness of about 950–1100 HV0.1. Due to the effect of annealing caused by plasma nitrocarburizing process at higher temperature and the Cr being a strong carbide-forming element, the carbon in steel substrate diffused outward into the Cr coating and reacted with Cr forming Cr carbide interface layer between the Cr electroplating and substrate. The nitrogen going into the microcracks and the volume increase accompanied by Cr nitride and carbide formation would cause the microcracks inherent to hard chromium plating disappear and improve its corrosion resistance. The microstructures of nitride and carbide layers were studied using X-ray diffraction and cross-sectional transmission electron microscopy.     

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。