低温等离子体氮化压力对304不锈钢摩擦性能的影响

采用低温等离子体氮化技术,对304奥氏体不锈钢进行表面氮化处理。运用XRD、SEM、金相技术和显微硬度计等分析手段对氮化层的物相组成及表面硬度进行分析及测量;利用球-盘摩擦实验在干摩擦条件下对氮化层的摩擦磨损性能进行测试并分析磨损机理。结果表明:304奥氏体不锈钢经低温等离子体氮化处理后,形成单一高氮面心立方相γN,显微硬度及耐磨损性能均明显提高,摩擦系数减小;氮化压力为10 Pa时,渗氮层具有最高的表面显微硬度850HV0.025及较好的耐摩擦磨损性能。     

奥氏体不锈钢低温气体渗碳后的组织性能

采用自主研发的低温气体渗碳炉对AISI316和AISI304奥氏体不锈钢进行低温气体渗碳处理,在不损害原有耐蚀性的基础上,增加其表面强度,提高其耐磨性。运用金相、硬度和XRD表征奥氏体不锈钢的渗碳层的组织,采用电化学工作站检测其耐蚀性能,采用摩擦磨损试验检测其耐磨性。结果表明,470℃低温气体渗碳处理的AISI316和AISI304奥氏体不锈钢,表层硬度从250HV0.25 N增加到800~1 000 HV0.25 N,有效硬化层都达到36μm以上,耐磨性提高2~3倍,耐蚀性能基本不变。     

脉冲偏压对低温氮化不锈钢表面结构及摩擦学性能的影响

采用低温等离子体辅助氮化奥氏体不锈钢316L,能够在不破坏其抗腐蚀性能的同时有效提高不锈钢表面的摩擦学性能,研究了不同脉冲偏压下氮化层的结构和摩擦学性能(硬度、摩擦系数和耐磨性)。采用X射线衍射仪研究了脉冲偏压对氮化层相结构的影响;采用光学显微镜和扫描电镜分别观察了氮化层表面和横截面的形貌,并利用能量色散谱测量了氮化层中氮含量及其分布;基于纳米压痕和摩擦磨损结果,研究了脉冲偏压对氮化层摩擦学性能的影响。结果表明:低温氮化后,不锈钢表面形成一层无氮化物析出的单一过饱和固溶体相——扩展奥氏体γN,晶格常数随偏压的增加由0.359增至0.395nm。当脉冲偏压为-300 V时,氮化层厚度达9.45μm,表面硬度达21.0 GPa,摩擦系数降低至0.09,耐磨性能获得显著提高。     

奥氏体不锈钢离子渗碳后的腐蚀行为

为了提高奥氏体不锈钢零件的使用寿命,利用低温离子渗碳技术对AISI 316L奥氏体不锈钢进行了表面渗碳处理.用X射线衍射仪和光学显微镜分析了渗碳层的微观组织结构,用显微硬度计测试了渗碳层的硬度分布,通过电化学极化曲线测试技术和化学腐蚀试验研究了离子渗碳AISI 316L不锈钢的腐蚀行为.渗碳层为单相碳过饱和奥氏体固溶体,由此明显提高了AISI 316L不锈钢的抗腐蚀性能,渗碳层硬度梯度平缓,表面显微硬度高达900 HV.结果表明,奥氏体不锈钢低温离子渗碳处理不仅提高了其表面硬度,而且提高了不锈钢表面的耐腐蚀性能,从而提高了其使用寿命.     

低温离子渗氮提高2Cr13不锈钢的冲蚀磨损与冲刷腐蚀抗力

采用喷射式固体粒子冲蚀磨损实验机和浆体冲刷腐蚀装置对比研究了350℃低温离子渗氮和550℃常规高温离子渗氮对2Cr13不锈钢冲蚀磨损和冲刷腐蚀行为的影响规律,通过组织结构分析、硬度测试和电化学交流阻抗分析探讨了低温渗氮改善2Cr13不锈钢抗冲蚀磨损和抗冲刷腐蚀性能的机制。结果表明：低温和常规高温离子渗氮均可提高2Cr13不锈钢在小角度固体颗粒干冲蚀条件下的冲蚀磨损抗力,但是,350℃低温渗氮处理表现出比550℃高温离子渗氮层更好的抗冲蚀磨损性能。在含10%石英砂的中性和酸性5%NaCl水溶液中,350℃低温渗氮处理使2Cr13不锈钢冲刷腐蚀速率分别降低96.7%和87.4%;然而,550℃常规离子渗氮却导致2Cr13不锈钢冲刷腐蚀速率分别提高4.13倍和0.49倍。350℃渗氮层由-εFe3N和N过饱和固溶体αN相组成,其化学稳定性好,硬度高,因而表现出良好的耐腐蚀、抗冲刷磨损与抗冲刷腐蚀性能。550℃渗氮处理时,αN相分解成了α相和CrN化合物,造成基材贫Cr,耐腐蚀性能下降,同时表面硬度低于350℃低温渗氮层,其抗冲蚀磨损性能不及350℃低温渗氮处理,冲刷腐蚀抗力则低于2Cr13不锈钢基材。     

国外文摘

化学热处理8906001 提高燃油泵柱塞副的耐磨性和耐腐蚀性——等,1988,№5～8。(俄文) 油泵柱塞副使用寿命短,主要是因磨粒磨损和腐蚀。造成磨粒磨损的石英硬度为HV 1130,而工件表面硬度H V800～950。提高表面硬度就能提高耐磨性。研究了用铬钛复合渗提高零件的耐磨性和耐蚀性,表明,铬钛复合渗能有效地提高氮化零件的耐磨和耐蚀性。因为在渗层形成了硬度为H1650的氮化铬(Cr_2N),同时有较高的耐腐蚀性。使用过的氮化处理25 X5MA钢件,经铬钛复合渗后     

氮化处理金属陶瓷刀具的磨损形态和机理

利用真空烧结工艺和表面氮化处理工艺，制备了纳米复合Ti（C，N）基金属陶瓷可转位刀片和功能梯度Ti（C，N）基金属陶瓷可转位刀片，详细研究了氮化处理对自制金属陶瓷刀具磨损形态和机理的影响,结果表明：自制刀片氮化处理前后的磨损形态有较大不同，显示了氮化处理后，刀片表面硬度的提高和表面层合金元素的变化，使得刀片的磨损机理和切削性能发生较大变化。氮化处理刀片切削正火态45^#钢、铸铁和奥氏体不锈钢时表现出较优的耐磨性。     

AISI316奥氏体不锈钢低温渗碳层的组织及耐蚀性

为了提高奥氏体不锈钢的表面硬度并保持其良好的耐蚀性,采用自主开发的低温渗碳工艺对AISI316奥氏体不锈钢进行渗碳处理。运用金相显微镜和显微硬度计表征了渗碳强化层组织,通过电化学试验检测了渗碳强化层的耐蚀性。结果表明:渗碳温度越高,渗碳强化层表面硬度越高,耐蚀性越差;经过470℃低温渗碳处理的AISI316奥氏体不锈钢表面硬度从原来的300 HV0.25 N增加到800～1 000 HV0.25 N,有效硬化层达36.1μm,而其耐蚀性保持不变。     

TA2钛合金真空脉冲气体氮化层的性能

为了进一步提高钛合金表面改性层的质量,采用真空脉冲气体氮化法在不同温度下对工业纯钛TA2进行氮化处理。利用金相显微镜、扫描电镜、X射线衍射仪、硬度仪、摩擦磨损试验及极化曲线分析了氮化层的组织结构、耐磨性能、耐腐蚀性能和表面硬度梯度等,研究了氮化温度对氮化层性能的影响。结果表明:TA2钛合金经过不同温度氮化处理后,其表面主要形成Ti N_(0.3)相;氮化层厚度和表面硬度都随温度的升高而增加,当温度升高到900℃时,氮化层厚度达60μm,表面硬度达750 HV,耐磨性及耐蚀性较基材大幅提高,磨损速率由基材的0.277 8 mg/(h·cm~2)减小至0.000 4 mg/(h·cm~2),腐蚀速率降低了2个数量级;800~900℃温度范围内,氮化温度对氮化层的耐腐蚀性能影响不大,但是温度的升高使得表面组织变得粗大,同时脆性有所增加。     

离子能流密度对AISI304不锈钢氮化层摩擦性能的影响

采用低温等离子体氮化技术,对AISI304不锈钢进行表面氮化处理。考察了离子能流密度对不锈钢氮化层性能的影响。运用X射线衍射、扫描电镜和显微硬度计等分析手段对氮化层的物相组成及表面硬度进行分析及测量;利用球-盘摩擦实验在干摩擦条件下对氮化层的摩擦磨损性能进行测试。结果表明:AISI304不锈钢经低温等离子体氮化处理后,形成单一高氮面心立方相γN。在氮化处理过程中,离子能流密度受工作压力及基片负偏压影响较大。离子能流密度变化能显著影响不锈钢氮化层的摩擦性能,随着离子能流密度的增加,氮化层显微硬度增大,摩擦系数减小,耐磨损性能上升。     

Modifying the properties of AISI 316L steel by glow discharge assisted low-temperature nitriding and oxynitriding

Apart from titanium, its alloys and CoCrMo alloys, austenitic steels are widely used in medical applications. In order to improve the frictional wear resistance of these steels, they are subjected to various surface treatments such that the good corrosion resistance of the steels is preserved.The paper analyzes the structure and phase composition of AISI 316L steel after subjecting it to low-temperature nitriding and oxynitriding under glow discharge conditions. The treatments produced diffusion-type surface layers composed of nitrogen-expanded austenite (known as the phase S, i.e. supersaturated solution of nitrogen in austenite) with a thin surface layer of chromium nitride (CrN) zone (after nitriding) or chromium oxide (Cr₂O₃) zone (after oxynitriding). It has been shown that the treatments substantially increase the hardness and frictional wear resistance of the steel without degrading its good corrosion resistance (examined in the Ringer physiological solution at a temperature of 37 °C).     

Influence of nitriding on corrosion resistance of martensitic X17CrNi16‐2 stainless steel

Nitriding increases surface hardness and improves wear resistance of stainless steels. However, nitriding can sometimes reduce their corrosion resistance. In this paper, the influence of nitriding on the corrosion resistance of martensitic stainless steel was investigated. Plasma nitriding at 440 °C and 525 °C and salt bath nitrocarburizing were carried out on X17CrNi16‐2 stainless steel. Microhardness profiles of the obtained nitrided layers were examined. Phase composition analysis and quantitative depth profile analysis of the nitrided layers were preformed by X‐ray diffraction (XRD) and glow‐discharge optical emission spectrometry (GD‐OES), respectively. Corrosion behaviour was evaluated by immersion test in 1% HCl, salt spray test in 5% NaCl and electrochemical corrosion tests in 3.5% NaCl aqueous solution. Results show that salt bath nitrocarburizing, as well as plasma nitriding at low temperature, increased microhardness without significantly reducing corrosion resistance. Plasma nitriding at a higher temperature increased the corrosion tendency of the X17CrNi16‐2 steel.     

Corrosion resistance of the layers formed on the surface of plasma-nitrided AISI 304L steel

Austenitic stainless steels have good corrosion resistance, but their low hardness and low wear resistance limit their use whenever surface hardness is required. Nitriding treatments have been successfully applied to stainless steels to improve their mechanical and tribological properties; however, at temperatures above 723 K, gas or salt bath nitriding processes decrease the corrosion resistance due to the formation of CrN and other phases within the modified layer. Chromium compounds draw chromium and nitrogen from the adjacent regions, degrading the corrosion resistance. The plasma nitriding technique permits the use of treatment temperatures as low as 623 K without promoting degradation in the corrosion resistance of stainless steel. In this work, the pulsed glow discharge (PGD) technique was used for nitriding steel (AISI304L) in order to investigate the effect of the temperature of this treatment in the morphology and, as a consequence, in the anodic behavior of the formed layers, in solution with and without chloride ions. Four different temperatures were employed (623, 673, 723, and 773 K). The samples were characterized by optical microscopy (OM), scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), microhardness measurements, and electrochemical tests with potentiodynamic anodic polarization curves. The nitriding temperature alters the anodic behavior due to a displacement of the polarization curve towards higher currents, in a solution free of chloride ions. In a chloride solution, the nitriding temperature increases the pitting potential up to the oxygen evolution region.     

QPQ盐浴复合处理技术对3Cr2W8V钢组织和性能的影响

QPQ盐浴复合处理是一种新的金属盐浴表面强化改性技术,将QPQ技术应用干3Cr2W8V钢,利用OM、SEM、显微硬度计、X射线衍射仪、高温摩擦磨损试验机和电化学工作站分别对QPQ渗层的显微组织、化学成分、显微硬度,物相,耐磨性和耐蚀性进行了分析研究.结果表明,QPQ渗层表面平整,当盐浴氮碳共渗时间一定时,随着氮碳共渗盐...     

Surface hardness improvement of plasma-sprayed AISI 316L stainless steel coating by low-temperature plasma carburizing

Low-temperature carburizing below 773 K of austenite stainless steel can produce expanded austenite, known as S-phase, where surface hardness is improved while corrosion resistance is retained. Plasma-sprayed austenitic AISI 316L stainless steel coatings were carburized at low temperatures to enhance wear resistance. Because the sprayed AISI 316L coatings include oxide layers synthesized in the air during the plasma spraying process, the oxide layers may restrict carbon diffusion. We found that the carbon content of the sprayed AISI 316L coatings by low-temperature carburizing was less than that of the AISI 316L steel plates; however, there was little difference in the thickness of the carburized layers. The Vickers hardness of the carburized AISI 316L spray coating was above 1000 HV and the amount of specific wear by dry sliding wear was improved by two orders of magnitude. We conclude that low-temperature plasma carburizing enabling the sprayed coatings to enhance the wear resistance to the level of carburized AISI 316L stainless steel plates. As for corrosion resistance in a 3.5 mass% NaCl solution, the carburized AISI 316L spray coating was slightly inferior to the as-sprayed AISI 316L coating.     

Boronizing for erosion resistance

Boronizing is a diffusion process analogous to carburizing and nitriding. It is achieved by heating parts in a pack. One layer or two may be formed, depending on the boron potential of the pack. A single layer is generally better for wear resistance than a duplex layer. Other methods such as salt bath or gas phase boronizing are available.The layer is very hard and confers great resistance both to sliding wear and to abrasive wear. With mild steel, sliding wear can be reduced by up to three orders of magnitude. Boronizing prevents the transition to adhesive or severe wear.Sintered carbide wire-drawing dies wear by a mixture of corrosion and adhesion. The life of a die will depend on the material being drawn. In this respect, stainless steel is particularly difficult. Boronized dies can lead to a life increase of 10 times.In abrasive wear, boronizing is more cost effective than any other material for such items as agricultural machinery.Molten zinc is very corrosive to mild steel. In jobbing galvanizers' works boronized mild steel is cheaper and longer lasting than titanium for carrying ware into the zinc bath.Resistance to acids, in particular to hydrochloric acid, is increased by boronizing.     

Influence of the microstructure on the corrosion resistance of plasma‐nitrided austenitic stainless steel 304L and 316L

Austenitic stainless steels are widely used in medical and food industries because of their excellent corrosion resistance. However, they suffer from weak wear resistance due to their low hardness. To improve this, plasma nitriding processes have been successfully applied to austenitic stainless steels, thereby forming a thin and very hard diffusion layer, the so‐called S‐phase. In the present study, the austenitic stainless steels AISI 304L and AISI 316L with different microstructures and surface modifications were used to examine the influence of the steel microstructure on the plasma nitriding behavior and corrosion properties. In a first step, solution annealed steel plates were cold‐rolled with 38% deformation degree. Then, the samples were prepared with three kinds of mechanical surface treatments. The specimens were plasma nitrided for 360 min in a H₂–N₂ atmosphere at 420 °C. X‐ray diffraction measurements confirmed the presence of the S‐phase at the sample surface, austenite and body centered cubic (bcc)‐iron. The specimens were comprehensively characterized by means of optical microscopy, scanning electron microscopy, glow discharge optical emission spectroscopy, X‐ray diffraction, surface roughness and nano‐indentation measurements to provide the formulation of dependencies between microstructure and nitriding behavior. The corrosion behavior was examined by potentio‐dynamic polarization measurements in 0.05 M and 0.5 M sulfuric acid and by salt spray testing.     

长庆油田渗氮套管的耐腐蚀性能研究

针对长庆油田油井套管腐蚀问题,采用并评价了真空渗氮工艺.该工艺处理套管表面形成氮化层,在不降低原有机械性能的前提下提高了表面耐磨、抗蚀能力.经室内、现场试验发现,渗氮管在长庆油井腐蚀情况下的耐腐蚀性能优良.此外,还就渗氮层在不同弯曲、拉应力条件下的微观表面变化对使用性能的影响进行了研究,确定了渗氮套管下井条件.并于2003年首次在2口井得以应用.该工艺为低产低渗透油田的防腐蚀研究提供了新思路.     

软氮化和化学镀镍双重强化对45钢表面性能的影响

先对45钢表面分别进行化学镀和软氮化处理,然后进行软氮化后再化学镀镍磷试验.测量了3种方法强化后渗(镀)层的厚度、硬度和分别在150 N和100 N试验压力下渗(镀)层的耐磨性.结果表明,软氮化后再进行化学镀所得的渗(镀)层有较大的厚度、硬度和耐磨性,该复合强化方法是一种有效的表面强化方法,有较好的应用前景.     

表面激光织构化复合盐浴渗氮改性304钢的摩擦学特性

为了较大程度上提高304钢在各工业领域的应用,采用M-DPSS-50半导体激光打标机在304钢基体表面刻蚀出直径及间距分别为269,131μm的点坑状织构,之后采用盐浴渗氮炉对织构化表面进行渗氮处理。分别采用X射线衍射仪(XRD)、光学显微镜及显微硬度测试仪检测复合改性表面的化学成分、表面形貌及表面显微硬度;采用微机控制多功能摩擦磨损试验机测试复合改性表面的摩擦学性能。结果表明:织构化处理获取了规则的织构点坑表面,盐浴渗氮处理后表面的显微硬度达到574.27 HV1 N,大大高于304钢基体表面的222.58 HV1 N。渗氮光滑表面的抗磨减摩特性都显著优于304钢基体表面,而复合改性表面又都明显优于渗氮光滑表面,说明复合改性表面具有极为优异的抗磨减摩特性。