共查询到17条相似文献,搜索用时 156 毫秒
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渗硼过程中,随着硼浓度的增加,渗硼层的组织由内向外依次为芯部基体、过渡层和硼化物层.如碳钢的低温硼氮共渗层呈梳齿状,表层由FeB、Fe2B双相组成,内层为Fe2B单相.合金钢低温硼氮共渗层的针状变得平坦,渗层的相组成较为复杂,Cr12钢低温硼氮共渗表层由Fe2B、FeB、Fe4N组成,内层相由FeB、Fe2B、Fe3 (C,B)、(Fe,Cr)2B、Fe4N、Fe3C等组成,过渡区形成Fe3 (C,B)、Fe4N相及Cr的碳化物,有效地强化了对硼化物层的支撑作用.渗硼层具有良好的耐磨性、耐腐蚀性. 相似文献
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本文研究了T10钢盐浴法铌铬共渗(Nb-Cr共渗)的盐浴、渗层组织结构和性能。试验表明:Nb-Cr共渗层组织致密,与基体结合牢固,其组成相主要是NbC和(Cr,Fe)7C3,渗层具有优良的综合性能。 相似文献
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本文研究了T10钢盐浴法铌铬共渗(Nb-Cr共渗)的盐浴、渗层组织结构和性能。试验表明:Nb-Cr共渗层组织致密,与基体结合牢固,其组成相主要是NbC和(Cr,Fe)7C3,渗层具有优良的综合性能。 相似文献
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预氮化对碳素工具钢560℃双辉等离子渗铬的影响 总被引:1,自引:0,他引:1
为了降低双辉等离子渗铬的工艺温度,提高低温渗铬速度,对T10钢表面在550℃进行不同时间的离子预氮化处理,再进行560℃×4h低温双辉等离子渗铬,对渗层的组织与硬度进行了研究.结果表明:各种条件下渗铬后,表面均形成铬的沉积层 扩散层,沉积层厚度4~5μm,组织致密,与基体结合良好;扩散层铬含量与显微硬度随预氮化时间的增加而增加,且均呈梯度分布;未经预氮化处理试样的扩散层深20μm左右,表面物相为铁、铁-铬固溶体、铬碳化物(Cr7C3,Cr23C6),表面显微硬度约700HV;预氮化后试样的扩散层深25~30μm,表面物相主要为铬、铁-铬固溶体、铬碳化物(Cr7C3,Cr23C6)、铬氮化物(CrN),显微硬度达915~1250HV,较未预氮化的试样提高45%以上. 相似文献
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《机械工人(冷加工)》1976,(8)
盐浴渗金属按使用的盐浴可分为两类:一类是卤化盐为基的;另一类是以硼砂为基的盐浴渗金属法。前者要求在保护气氛中进行,实际生产中很少应用。后者是近几年才出现的一种新的化学热处理方法。它又可以分为电解法和非电解法两种。采用这两种方法可以渗入的元素有:铬(Cr)、钒(V)、 相似文献
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通过对T10等五处钢种在硼砂与中性盐的混合盐浴中,进行稀土渗铬,考察了加入稀土之后,盐浴渗铬的效果、工艺规律以及渗层的组织和性能。 相似文献
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镍-铬系涂层对锅炉管材高温持久强度的影响 总被引:2,自引:0,他引:2
对等离子喷涂NiCr—Cr3C2/Ni45Cr涂层的过热器管材12Cr2MowVTiB(钢研102)在现场运行3万h后取样,与无涂层锅炉管材及未运行过的原始锅炉管材进行了高温持久强度对比试验。结果表明:涂层锅炉管持久强度性能明显优于无涂层保护炉管,据此进一步分析讨论了燃煤烟气的热腐蚀对钢研102管材持久强度的影响及涂层防护机制。 相似文献
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应用电子探针、扫描电子显微镜和能谱仪等观察并分析了新型12%Cr铁素体耐热钢在650℃、120MPa蠕变后的组织和氧化层。结果表明:试验钢蠕变过程经历了3个阶段,在3 980h发生断裂;蠕变后,试验钢中的原板条马氏体组织消失,大量的M23C6粒子沿原奥氏体晶界长大并粗化,并在蠕变后期形成了Fe2(W,Mo)金属间化合物;在蠕变过程中试验钢表面形成了三层结构的氧化层,即以铬、锰和硅元素为主靠近基体的内层氧化物,以铁元素为主的中间层氧化物和以铬、锰和硅元素为主的最外层氧化物。 相似文献
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铁素体不锈钢激光熔覆层组织和性能研究 总被引:1,自引:0,他引:1
采用无碳合金粉末和低碳合金粉末对铁素体不锈钢进行激光表面熔覆处理,借助光学显微镜(Optical microscope,OM)、扫描电子显微镜(Scanning electron microscopy,SEM)、能谱分析仪(Energy dispersive spectrometry,EDS)、X射线衍射仪(X-ray diffractometry,XRD)、显微硬度仪、摩擦磨损试验仪、电化学工作站对熔覆层显微组织、化学成分、硬度、耐磨性和耐蚀性进行评价。结果表明,两种激光熔覆层均无裂纹、气孔等宏观缺陷,显微组织主要由等轴晶、包状晶、树枝晶和枝间共晶组成。无碳熔覆层与低碳熔覆层均含有α-Fe、Fe-Cr合金相、Cr单质相以及Cr_(9.1)Si_(0.9)、Fe_(9.7)Mo_(0.3)、Fe_(10.8)Ni、Fe_(19)Mn等金属间化合物。此外,低碳熔覆层还产生了间隙化合物Cr_7C_3以及马氏体相C_(0.055)Fe_(1.945)。低碳熔覆层硬度为750 HV0.5,显著高于母材硬度250 HV0.5;无碳熔覆层硬度为650 HV0.5,其热影响区发生软化。激光熔覆层相对于母材具有更为稳定的摩擦特性以及优异的耐磨性和耐蚀性,其中低碳熔覆层耐磨性和耐蚀性均优于无碳熔覆层。 相似文献
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Both plasma chromizing and carburization following plasma chromizing (duplex treatment) for Ti–Al–Nb alloy were performed,
respectively, and the microstructure, dynamic ultra-microhardness, and elastic modulus of the alloying layer were determined.
Using silicon nitride (Si3N4) balls as the counterface materials, dry sliding friction tests on the substrate, the chromized layer, and the duplex-treated
layer were completed by ball-on-disk tribometer at room temperature. The results indicated that the duplex-treated layer was
mainly composed of Cr23C6, Cr2Nb, pure chromium, and carbon phases, while the chromized layer consisted of Al8Cr5 and Cr2Nb phases. The ultra-microhardness of the duplex-treated layer was higher than that of the chromized layer, whereas the elastic
modulus of the duplex-treated layer was lower than that of the chromized layer. The friction coefficient of the duplex-treated
layer was about three times lower than that of the chromized layer, while the wear rate was one order of magnitude lower than
that of the chromized layer. 相似文献
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《Wear》2004,256(1-2):66-72
Cavitation erosion tests of three Fe–Mn–Si–Cr shape memory alloys were carried out at speed 34 and 45 m/s using a rotating disc rig, and their cavitation damage has been investigated by comparison with a referring 13Cr–5Ni–Mo stainless steel used for hydraulic turbine vanes. The research results proved that the cavitation erosion of the Fe–Mn–Si–Cr shape memory alloys is a failure of low cycle fatigue and fracture propagates along grain boundaries. After 48 h cavitation erosion the cumulative mass losses of the studied alloys at speed 45 m/s are more than theirs at speed 34 m/s; however, the effect of velocity on cavitation damage of the Fe–Mn–Si–Cr alloys is much lower than that of 13Cr–5Ni–Mo stainless steel. The cumulative mass loss of the 13Cr–5Ni–Mo stainless steel are 26.3 mg at speed 45 m/s and 3.2 mg at speed 34 m/s, and the mass losses of the Fe–Mn–Si–Cr alloys are within the range of 3.6–7.3 mg at speed 45 m/s and 2.0–4.1 mg at speed 34 m/s. The surface elasticity of the Fe–Mn–Si–Cr shape memory alloys is better than that of the 13Cr–5Ni–Mo stainless steel, and the effect of surface elasticity on cavitation damage increases with velocity. The excellent surface elasticity of the cavitation-induced hexagonal closed-packed (h.c.p.) martensite plays a key role in contribution of phase transformation to the cavitation erosion resistance of the Fe–Mn–Si–Cr shape memory alloys. The cavitation damage of the studied alloys at speed 45 m/s mainly depends on their surface elasticity, and the variation of 48 h cumulative mass loss (Δm) as a function of the elastic depth (he) can be expressed as Δm=2.695+[1371.94/(4(he−46.83)2+12.751)] with a correlation factor of 0.99345. 相似文献
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An intermittent sliding test was used in order to study the formation and build-up of tribofilms during intermittent sliding of PVD coated HSS against case hardening steel (20NiCrMo2). Two cutting tool coatings were tested, TiN and AlCrN, and the influence of sliding speed was evaluated. With moderate speed, two tribofilms were formed separately, one consisting of Mn, Si, Al and O on an intermediate layer of Fe and one consisting of Fe, Mn, Cr and O on an intermediate layer of Cr and Mn. At low sliding speeds an uneven transfer of steel occured while high sliding speeds resulted in thermal softening of the substrate leading to coating failure. AlCrN provided better substrate protection at high speeds than TiN did. 相似文献