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。     

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。     

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。     

奥氏体不锈钢镀纯铁、氟化处理后低温气体渗碳层的硬度和耐蚀性能

奥氏体不锈钢硬度低,使用寿命短,表面附着的钝化膜妨碍了其低温渗碳。采用电镀纯铁和氟化法对其表面进行处理,去除表面钝化膜后,500℃气体渗碳。结果表明:氟化处理比电镀纯铁去除钝化膜的效果好,2种前处理后低温气体渗碳层表面硬度均有明显提高,可满足构件硬度为600～800 HV的需求;渗碳层厚度均匀,耐蚀性略有提高。     

表面纳米化对316L不锈钢性能的影响

对316L不锈钢进行表面机械研磨处理(SMAT),研究表面组织变化对其硬度和在0.5 mol/LNaCl介质中腐蚀性能的影响.结果表明:通过SMAT可以在316L不锈钢表面制备出纳米结构层,随着处理时间的增加,表面纳米晶组织逐渐由单一的奥氏体相过渡到奥氏体与马氏体两相共存;表面纳米化和马氏体相变能够明显地提高316L不锈钢的表层硬度,使表面粗糙度略有下降;表面机械研磨处理降低了316L不锈钢在0.5mol/L NaCl腐蚀介质中的耐蚀性能.因为316L不锈钢表面纳米晶组织容易钝化,形成的钝化膜不稳定,提高了溶解速度.     

不锈钢离子渗碳后表面亮化处理方法对渗层形貌和性能的影响

奥氏体不锈钢离子渗碳后,表面覆盖了一层结合牢固、致密的黑色薄膜,不仅影响表面美观度,还影响了耐腐蚀性能.为了恢复不锈钢原有的颜色和提高渗碳不锈钢表面的耐腐蚀性,对其分别进行了机械法和电化学法亮化处理,并对亮化处理后不锈钢表面硬化层的表面形貌、组织结构、硬度及耐腐蚀性能做了比较.结果表明,与机械法相比,电化学亮化处理虽使不锈钢表面硬化层的厚度和硬度略有减小,但表面的耐腐蚀性能却有较大幅度的提高,用电化学法对渗碳不锈钢表面进行亮化处理是一种比较理想的处理方法.     

不锈钢低温盐浴表面氮化技术发展与现状

不锈钢具有良好的耐蚀性、韧性和可加工性,但其硬度低、耐磨性差,严重制约了其在有磨损腐蚀要求环境体系中的应用.为了提高不锈钢的抗磨损性能,通过低温活性盐浴表面处理技术提高其耐磨性的同时不降低其耐蚀性,使得其在具有磨损的腐蚀介质环境中能够提高其抗磨损性能而不被腐蚀,可延长其使用寿命.本文系统地介绍了低温活性盐浴表面氮化处理技术的发展、原理及应用和处理后表面氮化层的特点、组织和表面性能.低温活性盐浴表面处理后,表层活性N原子扩散在奥氏体间隙中形成过饱和固溶体的S-相,产生特殊的位错-应力FCC结构,使得奥氏体晶格发生严重变形,不但提高了其腐蚀性,同时大大提高了其硬度,使得不锈钢硬度能够达到1 000 HV0.1,其抗磨损性能亦得到了显著提高.     

碳含量对AISI304奥氏体不锈钢离子碳氮共渗性能的影响

对AISI304奥氏体不锈钢进行了不同C2H2含量下的离子碳氮共渗,利用金相显微镜、辉光放电光谱仪、x射线衍射仪和显微硬度计测试了经碳氮共渗处理后试样改性层的截面形貌、渗层成分、相组成和力学性能.结果表明低温下离子碳氮共渗可以同时获得性能好的γc相和γn相,且最大含量分别出现在不同深度;气氛中C2H2含量为3%时,渗层厚度最大,表面显微硬度最大.     

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。     

奥氏体不锈钢渗氮&物理气相沉积复合改性层的组织及性能

通过辉光离子渗扩技术对316L奥氏体不锈钢进行了不同温度下的离子渗氮处理,之后采用物理气相沉积技术在渗氮层外表面制备一层CrN涂层,检测不同温度下离子渗氮+物理气相沉积复合涂层的结合力、硬度、耐磨性和耐蚀性,并对其显微组织和物相进行了观测与分析.结果表明:奥氏体不锈钢不同温度渗氮+物理气相沉积复合改性层的组织随渗氮温度的升高从S相(内层)+CrN涂层(外层)转变为不同程度硬质相析出层(内层)+CrN涂层(外层),不同类型的渗氮层与CrN涂层均有良好的结合力;不论是S相层还是硬质相析出层,经过PVD处理后均能在一定程度上提高渗层的表面硬度、耐磨性和耐蚀性,其中耐蚀性随着渗氮温度的升高逐渐变差,硬度和耐磨性随渗氮温度的升高而逐渐提升.     

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.     

超级铁素体不锈钢表面超疏水结构的制备及其耐腐蚀性能

将多巴胺的自发聚合反应与低表面能物质ODA和PFDT结合,在超级铁素体不锈钢表面制备了均匀致密的超疏水薄膜.用水雾凝聚实验、扫描电子显微镜(SEM)和X射线能谱分析(EDS)等手段表征了涂层修饰前后的润湿性、表面形貌以及化学结构,并使用三电极体系电化学工作站测试了超级铁素体不锈钢表面修饰前后涂层的阻抗谱和极化曲线.结果...     

The characteristics of a Pd–Ni/Pd–Cu double coating on 316L stainless steel and the corrosion resistance in stirred boiling acetic and formic acids mixture

A Pd–Ni/Pd–Cu double coating was deposited on stainless steel surface by electroplating. The microstructure and corrosion resistance of the double coating in strong reducing corrosive media were studied. In boiling 90 wt% acetic acid +10 wt% formic acid mixture containing 0.005 mol L⁻¹ NaCl with 900 r min⁻¹ stir, the corrosion rate of the double coating coated 316L stainless steel is one order of magnitude lower than that of Pd–Cu coated samples. The double coating shows lower porosity, higher hardness and elasticity modulus as well as higher adhesive strength, which may explain the better corrosion resistance in the testing environments.     

低磁不锈钢表面处理工艺及防护涂层体系设计研究

研究了不同表面处理工艺对低磁不锈钢基材自身耐蚀性能及涂层附着性能的影响,通过电化学阻抗及耐阴极剥离性测试确定了适用于低磁不锈钢表面的防护涂层体系.研究结果表明,以棕刚玉为喷砂磨料对基材进行喷砂处理,不仅可以提高基材表面粗糙度,满足涂层高附着需求,同时可降低基材表面残留粒料对基材引起的电化学腐蚀.以环氧锌黄为底层的防护涂...     

沉积扩散法制备含银抗菌不锈钢工艺研究

采用沉积扩散法制备含银抗菌不锈钢层,通过抗菌试验、盐干湿循环腐蚀试验、SEM、XPS等检测手段,研究了沉积扩散工艺制备含银抗菌不锈钢的抗菌性能、耐蚀性能及银在不锈钢基体中的分布状态和价态.结果表明,基材表面化学镀银后经离子轰击抗菌处理(工艺参数:电压1.25 kV,电流3 A,气流量20～60 mL/min,时间4 h),所得含银抗菌不锈钢的杀菌率达到99%以上,耐蚀性能没有降低,银在基体中呈弥散状态分布,其价态为零价态.     

Dry sliding wear behavior and corrosion resistance of NiCrBSi coating deposited by activated combustion-high velocity air fuel spray process

NiCrBSi is a Ni-based superalloy widely used to obtain high wear and corrosion resistant coatings. This Ni-based alloy coating has been deposited onto 0Cr13Ni5Mo stainless steel using the AC-HVAF technique. The structure and morphologies of the Ni-based coatings were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive spectrometer (EDS). The wear resistance and corrosion resistance were studied. The tribological behaviors were evaluated using a HT-600 wear test rig. The wear resistance of the Ni-based coating was shown to be higher than that of the 0Cr13Ni5Mo stainless steel because Fe₃B, with high hardness, was distributed in the coating so the dispersion strengthening in the Ni-based coating was obvious and this increased the wear resistance of the Ni-based coating in a dry sliding wear test. Under the same conditions, the worn volume of 0Cr13Ni5Mo stainless steel was 4.1 times greater than that of the Ni-based coating. The wear mechanism is mainly fatigue wear. A series of the electrochemical tests was carried out in a 3.5 wt.% NaCl solution in order to examine the corrosion behavior. The mechanisms for corrosion resistance are discussed.     

Stellite 21 coatings on AISI 410 martensitic stainless steel by gas tungsten arc welding

Abstract

Degradation of AISI 410 martensitic stainless steel, a typical alloy for many applications such as steam turbine blade, could impair its efficiency and lifetime. To overcome this problem, critical surfaces could be modified by weld cladding via gas tungsten arc welding technique. In the present research, a comparative study of Stellite 21 weld overlays deposited in three different thicknesses, i.e. dilutions, at various preheat and post-weld heat treatment temperatures on the surface of AISI 410 martensitic stainless steel, has been made. The surface of coatings has been examined to reveal their microstructures, phase characterisation and mechanical properties using XRD, microhardness tester and metallographic techniques. The results showed that the deposition of Stellite 21 coating on AISI 410 martensitic stainless steel improved its corrosion resistance. Moreover, the volumetric dilution had a considerable effect on the hardness, microstructure and electrochemical corrosion behaviour of Stellite 21 weld overlays.     

Analysis on microstructure and characteristics of TiAlN/CrN nano-multilayer films deposited by cathodic arc deposition

In this study, TiAlN/CrN multilayer thin films were deposited on SUS 403 stainless steel by cathodic arc deposition. The effects of substrate orientation (substrate surface parallel/perpendicular to target surface) and rotation speed were investigated in detail. Microstructure of the coatings was analyzed by X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. Meanwhile, tribological and corrosion tests were performed. The experimental results showed that the as-deposited films exhibit a nano-scale multilayer structure consisting of TiAlN and CrN phases. The TiAlN/CrN multilayer films prepared by a parallel orientation and a rotation speed of 4 rpm not only possesses the best coating hardness and hardness/elastic modulus ratio, but also reveals superior abrasion resistance and corrosion resistance.     

渗锌碳钢在天然海水中的腐蚀行为

碳钢渗锌后耐蚀性提高.采用固体粉末包埋对20碳钢进行热扩散粉末渗锌,测试了渗锌层的硬度、形貌、成分及其在20,40,60℃天然海水中的电化学腐蚀行为.结果表明:碳钢渗锌层的硬度在313.7～347.5 HV,厚度在77.1～81.2μm,属于第4等级;渗锌层与碳钢基体结合紧密;随渗锌层厚度增加,Fe含量逐渐降低,Zn含...