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40Cr钢富氮层快速离子渗氮技术的探索 总被引:1,自引:0,他引:1
用活性屏离子渗氮(ASPN)技术对40Cr钢进行快速离子渗氮技术的研究.本项研究是利用氮在奥氏体与铁素体中分别具有不同的溶解度和扩散速度的特性,采用了在共析温度以上短时间溶氮和在共析温度以下长时间扩散渗氮的两种不同的渗氮机制,进行交替渗氮处理.试验结果表明,采用这种新的渗氮工艺不仅可以显著提高渗氮处理中氮在钢中的内扩散速度,而且渗氮层具有较高的硬度.这种快速渗氮工艺可以用"吸收-扩散"渗氮模型进行解释. 相似文献
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5活性屏离子的渗氮技术
[22-26]钢铁工件渗氮的典型处理温度为450~590℃,一般工件处于铁素体或铁素体+渗碳体状态。依靠辉光放电的离子渗氮技术自上世纪70年代以来已获得愈来愈广泛的应用,但气体渗氮和盐浴渗氮(硫碳氮共渗)仍占65%的比例。离子渗氮过程中工件的打弧和空心阴极效应以致损坏处理工件表面是必须予以克服的。5.1离子渗氮过程中氮传递的本质T.Bell等1987年综述了这个问题,Ederihofer和Keller等认为由于离子轰击使工件表面溅射出来的原子和气氛中的活性氮原子结合沉积,后来, 相似文献
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渗氮处理通常指在低于钢的临界点Ac1,基体不发生相变的前提下,将活性氮原子渗入钢的表层,形成氮化物层的化学热处理工艺。氮化物具有高的硬度、热稳定性和弥散度。因而渗氮件能获得高的表面硬度、耐磨性、疲劳强度、抗咬合性、抗回火软化能力以及抗大气和过热蒸汽的腐蚀能力,并降低缺口敏感性。如38CrMoAl钢渗氮后表面硬度可达1100~1200HV(68~72HRC),光滑试样抗疲劳强度提高20%~40%,缺口试样抗疲劳强度提高1~2倍,高硬度可在500℃下长期保持或在600℃短期保持。当前渗氮新工艺和新设备不断涌现,离子渗氮、真空渗氮、催化渗氮以及复合渗氮等已应用生产。 相似文献
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为提高40Cr钢的抗磨及耐蚀性能,用304不锈钢冲孔板制成的活性屏对40Cr钢进行离子渗氮(ASPN)处理,研究了活性屏与工件的距离对渗层组织结构和性能的影响,并与普通直流离子渗氮(DCPN)进行了比较。用光学显微镜(OM)、X射线衍射仪(XRD)、辉光放电光谱仪(GDOES)、显微硬度计、往复摩擦磨损试验机和电化学工作站对渗层组织、相成分、硬度、耐磨及耐腐蚀性能进行分析。结果表明:经不锈钢活性屏离子渗氮处理后,试样表面得到了致密均匀的渗氮层,渗层主要由ε-Fe2-3N、γ′-Fe4N和CrN相组成,且随着试样与活性屏距离从10mm、20mm增加到30mm,对应的渗层厚度从6μm、4.7μm减小到3.5μm。经氮化处理后,40Cr钢的耐磨性和耐腐蚀性都有显著的提高,ASPN处理后试样的耐腐蚀性较DCPN有明显的提高。 相似文献
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随着改革的不断深入 ,国外各大公司纷纷在华投资 ,有些原来在其国内生产的配套件也开始相应在华寻求合作伙伴。不锈钢筛网便是日本某株式会社在华寻求合作伙伴的一种要求较高的易耗品。在国外 ,此类产品的焊接生产已实现了自动化 ,生产效率高 ,焊接质量好。而在国内目前的情况下 ,还不可能实现自动化。因此 ,摸索一套利用现有的焊接设备、进行切实可行的焊接工艺是很有意义的。1 基本情况不锈钢筛网是不锈钢丝网与不锈钢薄板焊接而成的类似筛子的产品 ,其产品结构见图 1。主要由两部分图 1 产品结构构成 ,即不锈钢丝网和不锈钢薄板。不锈… 相似文献
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《International Heat Treatment & Surface Engineering》2013,7(1):34-38
AbstractThe rapid development and the uptake of plasma nitriding technology into industrial surface engineering have slowed down in recent years. This is attributed to some of the inherent shortcomings of conventional dc plasma technology, for example, difficulties in maintaining a uniform chamber temperature, instability of the plasma and potential surface damage to parts caused by arcing. Efforts in overcoming these problems have led to the development of active screen plasma nitriding (ASPN) technology. This review demonstrates that with all its technological and environmental advantages, ASPN can be used to treat low alloy steels, tool steels, stainless steels and other steels which can conventionally be nitrided with dc plasma technology. In addition, ASPN can be used to treat non-conducting materials such as oxidised steels and polymeric materials which are not suitable for a dc plasma nitriding system. In the longer term, environmental friendly and technologically advanced plasma nitriding will outperform conventional salt bath and gaseous methods. Active screen plasma nitriding is a novel way of possibly achieving the full potential of plasma technology for thermochemical surface engineering. 相似文献
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《International Heat Treatment & Surface Engineering》2013,7(1):19-23
AbstractActive screen plasma nitriding (ASPN) is commonly used when regular surface hardening is necessary. The ASPN technique produces a more homogeneous surface coating than direct current plasma nitriding (DCPN) due to different process principles. The term active screen in plasma nitriding refers to a cathodic cage with a defined geometry. The purpose of this work was to study the differences between ASPN using a hemispherical cathodic cage and ASPN using a normal cylindrical cathodic cage. Following some trials using similar parameters, the tests were carried out with three conditions: with DCPN, with a cylindrical cathodic cage in ASPN and with a hemispherical cathodic cage in ASPN. X-ray diffraction and scanning electron microscopy analysis together with energy dispersive spectroscopy were applied to characterise the nitrided layers. The nitrided layers are not the same for each of the conditions used. The ASPN with a hemispherical cathodic cage produced a layer of almost Fe3N alone, while the other processes gave significant amounts of Fe4N in the nitrided layer. Scanning electron microscopy analysis showed different surface morphology for each condition. 相似文献
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Complicated motion of particles on vibration screen surface 总被引:2,自引:0,他引:2
lINTRODUCTIONToday,them0tiontheoryofparticlesonscreensurfaceisanimp0rtantresearchdirectionofscreeningtechn0logyandtheory['~8].Bymeansofstudyingmotionregularityofparticles,wecanobtaintheoptimumkineticparametersfortheindustrialscreeningandraiseitsefficien-cy.Thematerialbeingscreenedhasvariableshapeandsize,withdifferentsurfacemoistureandclaymineralscontents.Themotionofparti-clesisaffectedbydisplacement,velocity,accel-erationofscreensurfaceandfrictionamongpar-ticles.S0theparticles'motiononscr… 相似文献
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