AISI 420F不锈钢表面等离子渗Zr层组织及性能研究

采用等离子合金化技术,在含一定碳量的AISI 420F马氏体不锈钢表面制备Zr/Zr C合金层。研究了等离子渗Zr合金化温度和时间对Zr/Zr C合金层组织、相结构、渗层厚度以及硬度和摩擦磨损性能的影响。利用扫描电镜和光导放电光谱分析仪分析Zr/Zr C合金层表面和截面的形貌及成分分布,用X射线衍射表征渗层的物相组成。结果表明:AISI 420F不锈钢渗Zr后,得到组织连续且致密的渗Zr合金层,合金层由表面富Zr层/富Zr C层/Fe-Cr-Zr-C扩散层组成。在900~1000℃合金化范围内,形成的Zr合金层厚度随渗Zr温度的升高由17μm增加至23μm。在950℃渗Zr时,合金层和富Zr C层厚度随着渗Zr时间的延长分别呈直线和抛物线规律增加;渗Zr后试样的硬度最大值为865HV0.025,与基体(269HV0.025)相比有显著提高;摩擦磨损检测表明,与基材相比,AISI 420F不锈钢经渗Zr处理后,划痕宽度由540降低至360μm,摩擦系数由0.8明显降低为0.4左右,耐磨性得到改善。     

混凝土桥梁金属配件粉末渗锌防腐蚀层研究

实验室小型共渗炉内制备的试样与工业化渗层试样在结构和性能方面不同。为更合理地评价工业化渗层质量,通过工业随炉共渗制备渗锌小尺寸试样,分析了渗锌防腐蚀层的厚度、微观结构、元素分布、硬度,并测试其耐盐雾性能。结果表明:渗锌后工件表面结构可分为Zn-Fe合金层和含Zn过渡层,Zn-Fe合金层在表层,Zn含量较高,是防腐蚀防锈的主要结构层; Zn-Fe合金层与铁基体的界面过渡层厚度约20μm,Zn-Fe合金层与基体结合紧密;渗锌温度高、保温时间长有助于提高工件表面渗层厚度,随炉渗锌小尺寸试样增重法测得的渗层厚度最小,较适用于监控每炉工件共渗质量;合金层硬度高于基体,硬度向基体方向逐步降低,合金层和离界面60μm处的硬度均高于基体30 HV以上,可提高工件表面的耐磕碰性能;常用渗锌温度(420℃)热处理对工件表面硬度无影响,渗锌工件表面硬度增加主要在于表面形成了合金层;随着渗锌层厚度增加,渗层样品耐盐雾性能逐渐提高,渗层厚度宜≥60μm。     

Q235钢表面双层辉光离子强化层摩擦磨损性能

在真空容器中,设置提供含有欲渗合金元素Mo,Cr的供给源和被渗Q235钢试样,利用双层辉光离子渗金属技术,在试样表面进行Mo-Cr共渗,之后经渗碳、淬火及回火复合处理形成强化层.Mo-Cr共渗层厚度在100μm以上,表面Mo含量可达20%(质量分数,下同),Cr含量达到10%.复合处理后表面硬度达到1300HV0.025.M-200磨损试验机磨损实验表明,摩擦因数平均在0.1左右,平均相对耐磨性是GCr15钢经渗碳、淬火及回火后的2.25倍.     

不锈钢表面TiO2改性层在NaCl溶液中的腐蚀行为研究

利用双层辉光离子渗金属技术,在不锈钢表面形成渗Ti层,渗金属温度为950℃,然后将渗钛试样置于GSL-1600X真空管式高温炉进行热氧化,形成金红石型TiO2改性层,氧化温度为750℃.利用电化学腐蚀系统对改性层及基体在0.5mol/的NaCl溶液中进行电化学对比实验.实验结果表明,不锈钢表面形成了致密、均匀的TiO2改性层,改性层由沉积层和扩散层组成,厚度约6μm.Ti-O改性层明显提高了不锈钢在0.5mol/的NaCl溶液中的耐蚀性.     

0Cr18Ni10Ti不锈钢热浸镀铝及高温扩散后的高温氧化行为

为提高0Cr18Ni10Ti不锈钢的抗高温氧化能力,采用熔剂法在0Cr18Ni10Ti不锈钢表面制备热浸镀铝层,并经950℃、2 h高温扩散。采用SEM、EDS对热浸镀铝高温扩散试样及不锈钢试样900℃氧化不同时间的表面、截面进行了形貌观察及成分分析。结果表明:镀铝高温扩散试样的氧化动力学曲线较平缓且氧化增重较小;0Cr18Ni10Ti不锈钢经900℃、100 h氧化后表面主要由Fe2O3组成,氧沿晶界向内扩散产生内氧化;镀铝高温扩散试样900℃氧化期间,表面主要由Al2O3氧化膜组成,有效地阻止了合金元素与氧的互扩散,Ni元素在Fe Al层与Al固溶层富集阻碍了Fe Al合金层Al向基体扩散,使镀铝高温扩散试样Fe Al合金层经900℃、100 h氧化后Al元素贫化量较少。镀铝高温扩散试样900℃、100 h下的抗氧化性能优于0Cr18Ni10Ti不锈钢。     

铌硅化物基超高温合金表面包埋渗Al改性硅化物涂层的组织结构

分别采用两步包埋渗法和包埋共渗法在铌硅化物基合金表面制备了Al改性硅化物抗氧化涂层.两步包埋渗法是先在合金表面包埋渗Si制备(Nb,X)Si2(X表示Ti,Cr和Hf元素)涂层,然后再将渗Si试样于800～1000℃包埋渗Al.结果表明:当渗Al温度达到860℃时渗入(Nb,X)Si2层中的Al可形成(Nb,Ti)3Si5Al2相;当渗Al温度达到900℃时渗入的Al还可穿过(Nb,X)Si2层在渗Si层与基体之间形成(Nb,Ti)(Al,Si)3层.经1150℃/20h Si-Al包埋共渗后在合金表面形成的涂层具有多层复合结构:外层主要由(Nb,Ti)3Si5Al2和(Nb,Ti)(Al,Si)3组成;中间层上部为(Nb,X)Si2,下部为低硅化物(Nb,X)5Si3;内层由基体相(Nb,Ti)Al3和柱状晶(Cr,Al)2(Nb,Ti)组成.     

Cr12MoV钢盐浴渗钒后的组织及耐蚀性能

目前,对Cr12Mo V盐浴渗钒层的耐蚀性鲜有研究。采用自配的混合盐对Cr12Mo V钢在不同温度和时间进行盐浴渗钒处理。通过表面显微硬度测试、金相显微和SEM形貌观察、EDS和XRD分析表征了Cr12Mo V渗层性能与组织结构,选定了较佳渗钒的温度(1 000℃)和时间(6 h),对最优工艺渗件在3.5%Na Cl溶液中进行了电化学测试,以检验渗层的耐蚀性。结果表明:Cr12Mo V钢渗钒后形成了致密的渗层,表面硬度从渗钒前的713HV3 N提高到1 800~2 700 HV3 N;渗层厚度分别与渗钒温度和保温时间成正比关系;最优工艺渗钒后的耐蚀性比渗钒前提高了36%。     

T10钢低温双辉等离子表面渗镀铬硬化的研究

采用双辉等离子渗铬技术,首先在560℃对T10钢进行不同时间的渗铬,再对已渗铬试样进行4h离子氮化,研究了该工艺对渗镀铬层硬化效果的影响.结果表明:双辉渗铬后的渗层由厚3～5μm的沉积层+扩散层组成,沉积层组织致密并与基体结合良好,基体组织和晶粒度与渗铬前基本一致;沉积层铬浓度达45%(质量分数)以上,内有20～25μm的扩散层,铬浓度向内呈梯度分布;表面物相均由Fe,Fe-Cr,Cr7C3,Cr23C6等组成;渗层表面显微硬度达650~850HV,向内逐步降低,呈梯度分布.沉积层厚度、渗层深度、渗层的铬浓度及显微硬度等均随渗铬时间的增加而增加.渗层经离子氮化后的组织与氮化前的组织无明显变化,但表面物相为Fe-Cr,Cr7C3,Cr23C6,CrN,Fe4N,表面显微硬度提高到1000~1350HV,较未氮化前提高约60%以上.     

熔盐电解法和固体粉末法在纯镍表面渗硼的对比研究

本工作分别采用熔盐电解法和固体粉末法对纯镍表面进行渗硼处理,以提高镍的表面硬度。熔盐电解法以硼砂(Na₂O₄B₇·10H₂O)作硼源,碳酸钠(Na₂CO₃)作支持电解质,电流密度为750 A/m²;固体粉末法采用碳化硼(B₄C)和氟硼酸钾(KBF₄)作为渗硼剂。利用扫描电镜(SEM)和能谱仪(EDS)分析渗硼试样的断面形貌和元素含量,利用X射线衍射仪(XRD)分析试样的物相。结果表明：采用熔盐电解法和固体粉末法在纯镍表面渗硼,均得到由Ni₂B和Ni₃B组成的渗层;熔盐电解法在电解温度为950℃、电解时间为4 h时渗层厚度约为184.35μm,渗层表面硬度值为1 755HK;固体粉末法在渗硼温度为950℃、渗硼时间为10 h时所得渗层厚度约为176.35μm,渗层的表面硬度值是1 526HK;镍经过渗硼后其表面硬度值有明显的增加,渗层厚度越大,表面硬...     

12Cr13马氏体不锈钢B/C化学热处理的研究

研究了固体硼碳共渗及复合渗技术工艺参数对12Cr13马氏体不锈钢的组织和性能的影响。共渗方面对12Cr13钢进行不同硼碳比例的固体硼碳共渗热处理;复合渗方面对12Cr13马氏体不锈钢先进行固体渗碳,然后再进行渗硼处理,得出最优的复合渗参数。对最优参数下的共渗及复合渗12Cr13马氏体不锈钢试样进行显微硬度、XRD物相结构、电化学下耐腐蚀和摩擦磨损性能检测分析。结果表明：共渗温度950℃、共渗6 h条件下,硼碳共渗最优渗剂硼碳比为6∶4;化学渗6 h条件下,硼碳复合渗最优参数为950℃渗碳,950℃渗硼;硼碳共渗和复合渗试件经过最终热处理(淬火+低温回火)后,表层组织硬度最高可达1 507.3 HV_{0.98 N},心部硬度为420.6 HV_{0.98 N},最优参数下硼碳共渗及复合渗渗层厚度分别为976μm和1 125μm;电化学测试表明硼碳共渗和硼碳复合渗处理后材料的耐蚀性有所提高,共渗腐蚀电位为-0.578 V,复合渗为-0.582 V。磨损试验显示硼碳共渗和硼碳复合渗后经化学热处理可以显著提高12Cr13马氏体不锈钢的耐磨性能。     

双辉等离子涂层对机械曲轴耐磨耐蚀性能的影响

采用双辉等离子技术在机械曲轴表面制备了SiC/Ta复合涂层,研究了合成温度对复合涂层显微形貌、物相组成、耐磨和耐腐蚀性能的影响.结果 表明,当合成温度从750上升至900℃时,复合涂层表面形貌由花纹状逐渐演变成细小颗粒团簇状,截面形貌中可见不同合成温度下复合涂层厚度和内部质量存在一定差异,不同合成温度的复合涂层中都出现...     

深冷处理对碳钢表面Mo-Cr合金层摩擦性能的影响

介绍了一种在Q235钢表面进行等离子合金化及热处理工艺,获得表面高性能强化层的技术方法.通过该技术方法的处理,使Q235钢表面含有Mo,Cr,C合金元素,成分达到或接近冶金高速钢.该工艺技术的基本原理是在真空容器中,利用辉光放电的溅射现象,首先在Q235钢表面渗入合金元素Mo,Cr,表面含量分别达到12%(质量分数,下同)和4%左右,随后进行超饱和渗碳,使表面含碳量达到2.0%以上,合金化层成分接近钼系高速钢.合金层中的碳化物细小、均匀、弥散,无粗大的共晶莱氏体组织.Q235钢表面合金化后分别采用淬火 低温回火,淬火 2h深冷处理 低温回火两种工艺.结果发现,经深冷处理的试样表面硬度达到1600HV,明显高于未经过深冷处理试样的表面硬度.摩擦磨损实验表明,经深冷处理试样的滑动摩擦系数较未经深冷处理试样的要小,经深冷处理试样的耐磨性是未经深冷处理的1.6倍.     

Microstructure and Properties of Low Temperature Composite Chromized Layer on H13 Tool Steel

Low temperature composite chromizing is a process composed of a plain ion-carbonitriding or ion-nitriding at 550～580℃, followed by a low-temperature chromizing in a salt-bath of 590℃. The microstructure and properties of the low temperature composite chromized layer on H13 tool steel were investigated using metallography,X-ray diffraction, microanalysis, hardness and wear tests. It was found that this low temperature process was thermodynamically and kinetically possible, and the composite chromized layer on H13 steel, with a thickness of 3～6μm,consisted of three sub-layers (bands), viz. the outer Cr-rich one, the intermediate (black) one, and the inner, original white layer. After chromizing, the former diffusion layer was thickened. The results of X-ray diffraction showed that the composite chromized layer contained such nitrides and carbides of chromium as CrN, Cr2N, (Cr, Fe)23C6, and (Cr, Fe)7C3, as well as plain α-(Fe, Cr). A high surface microhardness of 1450～1550 HV0.025, which is much higher than that obtained by the conventional ion carbonitriding and ion nitriding, was obtained. In addition, an excellent wear resistance was gained on the composite chromized layer.     

双辉离子TiAl基合金表面Cr-Si共渗及改善其耐磨性能的研究

利用辉光离子渗金属技术,在TiAl基合金表面实现Cr-Si共渗。用SEM、EDS、XRD分别研究了由1号(880℃,2h,13mm)和2号(900℃,4h,18mm)工艺参数制备的合金层形貌、化学成分和相结构。结果表明,1号渗层厚度超过10μm,由外向内依次为Ti5Si3层、Al8Cr5和α2-Ti3Al层、合金过渡层,且与基体呈冶金结合;与之相比,2号渗层厚度仅为5~7μm,表面为富Cr沉积层。摩擦磨损实验结果表明,1号和2号渗层室温耐磨性较基体分别提高7.3倍和4倍,高温(500℃)耐磨性提高26.5倍和17.3倍。     

45 钢表面激光合金化组织分析及硬度测试

目的为了提高45钢表面性能,采用CO2激光器对其表面进行合金化处理。方法利用带有能谱的扫描电子显微镜(SEM/EDS)、金相显微镜、X射线衍射仪、显微/维氏硬度计、扫描电镜等,对合金化层组织及性能进行了观察和分析。结果激光合金化层由合金化区、结合区和热影响区3部分组成,涂层与基体呈冶金结合;涂层主要含Cr3C2,Fe Ni3,Cr23C6,Fe3C相;激光合金化层的显微硬度达1032 HV,约为基体的3.5倍。结论 45钢经激光合金化处理,可改善其表面性能,显著提高其硬度。     

Effect of Hf additions on phase transformation,microstructural stability,and hardness of nanocrystalline 304L stainless steels synthesized by mechanical alloying

304L stainless steels with Hf additions were nanostructured by mechanical alloying (MA) and annealed at temperatures up to 1100 °C. The results showed that face-centered cubic (fcc) phase in 304L transformed to body-centered cubic (bcc) phase during MA. The in-situ studies revealed that bcc-to-fcc phase transformation completed after 105 min annealing at 900 °C for 304L, whereas Hf addition increased the required time and temperature for the complete transformation. The grain size of 304L stainless steel was ~10 nm after MA and remained ~167 and ~293 nm after annealing at 900 and 1100 °C, respectively, with Hf addition in comparison to 960 nm average grain size of base 304L stainless steel after annealing at 900 °C. The hardness of 304L increased from ~200 HV to 408 HV after MA and remained 329 HV after annealing at 1100 °C with Hf addition as opposed to 195 HV hardness of 304L.     

Pulsed plasma nitriding of large components and coupons of chrome plated SS316LN stainless steel

Pulsed plasma nitriding of electroplated Cr on stainless steel substrates is reported. The properties of the chromium nitride coatings on small coupons synthesised simultaneously with large-scale components have been investigated. The effect of temperature and duration of the nitriding process on the coating properties are discussed. A gradual variation in the hardness profile from a peak harness of about 950 HV at the surface to about 650 HV at 90 μm of case depth has been achieved. The chromium nitride coating was not brittle. The resistance of the coating to abrasive wear was higher than that for Cr. X-ray diffraction and energy dispersive X-ray analysis confirmed that the coating is composed of polycrystalline Cr₂N and Cr indicating that there was partial conversion of the electroplated Cr film to nitride.     

Microstructure and Properties of Laser Surface Alloying 304 Stainless Steel with Si

Silicon was added to the surface of 304 stain-less steel by laser melting the sprayed preplaced Sipowders.The optical microscopy,X-ray diffractionand EPMA were employed to investigate themicrostructure and chemical composition of thelaser surface alloyed layer.The hardness of the al-loyed layer was measured by microhardness testand wear resistance was evaluated by scratch test.Corrosion resistance of laser alloyed sample wasstudied in 1N H_2SO_4+0.1N NaCl and0.5N HCl+0.5N NaCl aqueous solutions.Amicrocrystalline intermetallic compound coatingwith smooth surface and good chemicalhomogeneity without porosity and crack is ob-tained.The hardness is about 720 HV.The wear re-sistance is 2 times better than that of the substrate.The corrosion resistance of the laser alloyed sampleis much better than that of 304 stainless steelsample.     

HP40Nb钢热浸镀Al-Si高温氧化行为及组织研究

为提高高温抗氧化性能,对HP40Nb钢进行了热浸镀Al-10%(质量分数)Si,并进行不同温度扩散处理,研究了不同扩散处理试样在1000℃条件下的高温氧化行为,通过SEM,EDS和XRD分析了经不同扩散处理后的渗层在高温氧化过程中的组织结构变化.结果表明:经800℃/4h扩散处理,渗层由内层(NiAl+ Cr3 Si)...     

Formation of alloying layers in a carbon steel by compression plasma flows

The main regularities and features of steel surface alloying by means of compression plasma flows treatment of coating/substrate systems are investigated in this work. Ti, Zr, Mo and Cr were used as alloying elements. The thickness of the alloyed layer is about 8-15 μm. The mixed layer contains iron solid solutions, nitrides and possesses mechanical properties improvement. The peculiarities of alloying elements distribution are discussed.