电沉积铁镍铬合金工艺参数对镀层铬含量的影响

给出了电沉积铁镍铬合金镀层的镀液配方和操作条件：着重研究了配合剂浓度，电流密度三价铬离子浓度，温度和酸度对镀层Ｃｒ含量的影响；通过优化工艺参数，得到了铬含量１５％￣４０％合金镀层。     

三价铬镀液电沉积装饰性铬-磷合金层的特性

为了进一步提高三价铬镀层的性能,在硫酸盐三价铬镀液中加入次磷酸钠,电沉积出了装饰性铬-磷合金层(磷含量为9%～16%).研究了磷含量对镀液和镀层性能的影响,对比了电沉积铬镀层、三价铬-磷合金镀层和六价铬镀层的耐蚀性能.结果表明:铬-磷合金镀层为非晶态结构,具有良好的外观和耐蚀性能,能够很好地满足防护装饰性要求.     

镀铬液中三价铬离子和铁离子含量对镀液、镀层性能的影响

在电镀铬电镀液中,三价铬适用范围为装饰铬电镀2～8 g/L,工业铬电镀1～5 g/L.由于工业铬电镀时,因为混入的不纯物常包含有铁质成分,因此管理者大多将三价铬及铁离子含量合计在5～10 g/L的范围.     

碳钢与不锈钢表面高浓度渗铬法

在氩气气氛下，应用固体渗铬填料法对碳钢、不锈钢作了表面高铬浓度的渗铬处理，探讨了渗铬温度、时间和渗铬组分对渗层表面铬含量、厚度，试样增重和物相组分影响，碳钢、不锈钢的表面渗铬浓度分别达８０－９４ｗｔ％和７０－８２ｗｔ％。     

黑铬镀层的红外辐射性能及镀液废水处理

镍钴镀层上沉积的黑铬镀层对可见光具有很高的辐射率,可用作光学器材,而其对红外光的辐射率目前未见报道.在硬铝合金基体表面依次电镀镍钴合金及黑铬,用红外辐射率测量仪测量了不同H-1添加剂和氟硅酸含量的镀液所得黑铬镀层的红外辐射率,通过高低温冲击试验定性检测了黑铬镀层与镍钴镀层的结合强度,并采用还原沉淀法对电镀废液进行了处理.结果表明:添加剂H-1含量为25 g/L时,黑铬镀层的红外辐射率最高;H-1含量为20 g/L和25 g/L时,黑铬镀层的红外辐射率均在氟化硅含量为0.16 mL/L时获得最大值;黑铬镀层与镍钴镀层结合牢固;电镀废液经2次处理后可达到国家排放标准.     

FeCuCrC粉末冶金材料性能研究

在烧结铁基材料FTG70Cu3 3 5的基础上 ,以铬铁合金粉的形式引入铬元素 ,制备了FeCuCrC材料。考察了铬元素含量及烧结温度对该材料力学性能、密度的影响 ,并探讨了其强化机理     

铬系白口铸铁的热塑性及其锻前加热新工艺研究

对不同铬含量白口铸铁的热塑性，铬对白口铸铁热塑性的影响规律以及铬影响白口铸铁热塑性的机理进行了探讨，通过试验提出了可明显提高铬系白口铸铁热塑性的锻前加热新工艺。     

锻造中铬合金白口铸铁组织和性能研究

利用锻造方法并结合锻后适当的热处理工艺可大幅度提高铬合金白口铸铁的冲击韧性．采用热望性镦粗试验方法,对不同碳含量中铬合金白口铸铁的热塑性、碳对中铬白口铸铁热塑性的影响规律进行了研究,分析了不同热处理工艺对其锻后组织和性能的影响,并提出了可明显提高锻造中铬合金白口铸铁抗冲击磨损性能的热处理工艺参数．研究表明：含碳量为1.85％-2．59％的中铬合金自口铸铁在850-1130℃的温度范围内,具有良好的塑性变形能力,且随碳含量的增加,中铬白口铸铁的热塑性下降,其主要原因是碳含量不同所引起的组织中共晶碳化物的数量的改变所致．     

铬对锰硅硼铸造耐磨钢组织和性能的影响

研究了铬对锰硅硼低合金耐磨钢组织及性能的影响,结果表明：加入铬合金化后,组织仍然以马氏体和贝氏体为主,存在少量残余奥氏体。随着铬含量增加,马氏体数量增加,贝氏体数量减少。加入铬对钢的硬度基本没有影响,但加入铬明显提高冲击韧性,比相同成分和热处理条件下不加铬钢的冲击韧性提高10J／cm^2左右;还对比了铬对常温及低温冲击韧性影响。     

土壤中铬的危害及分析方法的改进

目前随着工业废水的排放肆意排放对突然造成的严重污染,土壤中铬的含量越来越高,因此土壤中铬含量的实验室检测越来越引起人们的重视。测定土壤中的铬含量通常采用高锰酸钾氧化法,但是此法分析时间长、操作步骤繁琐、工作量大、仪器磨损严重。针对上述问题,对原高锰酸钾氧化法中的样品处理、离心等步骤进行了改进,克服了原法的一些缺点,缩短了分析时间,大大提高了分析效率,并保持了原法分析的精确度。     

低温与真空条件下1Cr18Ni9Ti钢的疲劳行为

分别在室温大气、室温真空及低温真空几种环境条件下,对1Cr18Ni9Ti钢进行对称载荷拉-压疲劳试验,利用TEM观察疲劳断口附近的显微组织,研究了环境因素对疲劳性能的影响,并对影响的原因进行了分析和讨论.研究表明:1Cr18Ni9Ti钢在低温真空条件下疲劳性能显著提高;疲劳断口附近出现大量板条马氏体;真空与低温显著提高1Cr18Ni9Ti钢疲劳性能的原因与真空对裂纹表面的净化效应,以及低温促进疲劳裂纹前沿形成板条马氏体有关.     

A new way to produce Al + Cr coating on Ti alloy by vacuum fusing method and its oxidation resistance

An Al + Cr coating successfully produced by the vacuum fusing method was proposed for improving the oxidation resistance of Ti–6Al–4V alloy specimens. Unlike powder pack cementation, this technique was much more effective and cheap without the need for long time diffusion, and the Al concentration and the thickness of vacuum fusing coating layer could be controlled by adjusting powder mixing ratio and adding the immersed times, respectively. Compared with the specimen with an Cr-modified aluminide coating, the oxidation resistance of the specimens with vacuum fused Al + Cr coating was about two times than that of the specimens with Cr-modified aluminide coating. During oxidation, Cr additions suppressed metastable θ-alumina formation. It is only one phase -alumina scale that developed on the vacuum fused Al + Cr coating surface, while a single metastable θ-alumina scale formed on the Cr-modified aluminide coating surface.     

真空分级淬火对8Cr4Mo4V钢组织和性能的影响

在真空条件下对航空轴承用8Cr4Mo4V钢进行不同温度的分级淬火并采用扫描电镜观察其微观组织、用XRD谱进行相分析并测试洛氏硬度、冲击性能和旋转弯曲疲劳性能,研究了真空分级淬火对其微观组织和力学性能的影响。结果表明,真空分级淬火后的8Cr4Mo4V钢其微观组织由下贝氏体、马氏体/残余奥氏体和碳化物组成;随着分级淬火温度的提高,淬火和回火态钢中析出碳化物的数量增加,残余奥氏体的含量降低。分级淬火温度为580℃时淬火态钢中贝氏体的含量最高(达到13.87%),残余奥氏体的含量为28.59%。回火后析出碳化物的含量和洛氏硬度均为所有分级温度中的最大值,分别为4.37%和62.38HRC。真空分级淬火能提高8Cr4Mo4V钢的综合力学性能。与未分级真空淬火相比,进行580℃×10 min真空分级淬火的8Cr4Mo4V钢的冲击韧性提高了23.3%,旋转弯曲疲劳极限提高了110 MPa。     

用镍基薄带钎料真空熔结Cr3C2-NiCr涂层的组织和性能

提出了一种采用薄带钎料进行真空熔结的新方法，用BNi-2薄带钎料粘贴在Cr3C2-NiCr预置层表面进行了真空熔结处理，对涂层的组织和微动磨损性能进行了研究。结果表明，真空熔结涂层组织致密，涂层与基体、涂层内部硬质相与粘结相之间可形成良好的冶金结合。涂层主要由Cr3C2，Cr7C3，Cr23C6，Ni的硼化物、Cr的硼化物等硬质相和镍基固溶体韧性相组成。基于致密的组织、良好的结合和硬质相强化，真空熔结Cr3C2-NiCr涂层的抗微动磨损性能明显优于等离子喷涂Cr3C2-NiCr涂层和1Crl8Ni9Ti不锈钢。     

Effect of oxidation on the creep behaviour of copper–chromium in situ composite

The creep deformation and fracture behaviours of a Cu–Cr in situ composite were investigated in air and in vacuum over a temperature range of 400–650 °C to study the effect of environment. The similarities of the activation energy and the stress exponent in air and in vacuum strongly suggest that the oxygen and/or the oxide have no direct effect on the deformation mechanism of Cu–Cr in situ composite. The higher creep rate of the composite in air than in vacuum is due to the gradual decrease of the cross-sectional area of the matrix due to increasing thickness of the oxide layer. The mechanism of damage was found to be similar for all the creep tests performed.     

Bilayer Cr/Au contacts on n-GaN

Cr/Au (40/65 nm) metal layers have been deposited by thermal evaporation onto n-GaN epitaxial layers grown by metal-organic chemical-vapour deposition (MOCVD) on a sapphire substrate. The samples have been annealed at 400, 700 and 900 °C for 10 min in vacuum. Techniques of TEM, EDS, HRTEM, FESEM, XRD and I-V characteristics have been used to characterize the micro-, and nanostructure, morphology, composition and electrical properties of the contacts before and after annealing. A binary phase of Cr₃Ga₄ and Au₇Ga₂ were identified at the interface of the n-GaN/Cr/Au contacts after annealing in vacuum at 700 and 900 °C. Current-voltage characterizations showed that the as-deposited and annealed Cr/Au contacts are rectifying up to 600 °C. After heat treatment in vacuum at 700 °C and 900 °C the Cr/Au contacts were linear.     

Tribological mechanism and property of 9Cr18 friction pair at atmosphere and in vacuum

In this paper, the comparative tribological property of 9Cr18 friction pair used for aerospace components was investigated using a ball-on-disc tester in four different service conditions: in air, in vacuum, and with or without MoS₂-based film. The results indicate that the friction coefficients of the 9Cr18 couplings with MoS₂ solid lubrication or in vacuum are much lower than those in the conditions of dry friction or atmosphere, with relatively flat ground trace surfaces. While the friction coefficients of usual materials of friction pairs in vacuum are higher than those in atmosphere, it is shown in our study that the abnormal performance may be induced by the surface hardenability of dry friction transition and the lubrication effect of the MoS₂-based film. At the same time, the tribological mechanism of the pair is considered as well.     

耐特种气体腐蚀涡旋干泵的研制

采用化学镀、氟涂料和真空离子镀(PVD)技术对涡旋干泵实施防护涂层,对转子和定子采用化学镀镍磷和氟涂料封闭技术制备防护涂层;对曲柄轴和曲柄销采用PVD技术制备Cr/CrN多层复合防护镀层。通过腐蚀试验表明,防护涂层可以长时间抵抗高腐蚀性气体的腐蚀,能够有效地提高涡旋干泵的使用寿命。     

Tribomechanische und -chemische Vorgänge an dem Wälzlagerstahl 100 Cr 6

Tribological Processes of the Ball Bearing Steel 100 Cr 6 . Tribomechanical and tribochemical processes of the ball bearing steel 100 Cr 6 were investigated under the influence of ultra high vacuum and different gases by the pin/ring method. The conditions for adhesive wear indicated by prow formation were optimal in ultra high vacuum. Pressures of oxygen, nitrogen and air greater than 10^?6 Pa increase the lubrication by formation of thin films, measured by ellipsometry. Increasing nitrogen pressure produces a surface hardening, which can be observed by nitrided wear particles. The presence of pure oxygen creates permanently oxide films with a thickness of 10 nm. This causes abrasive wear.     

Graphene oxide effects on the properties of Al_2O_3-Cu/35W5Cr composite

Graphene oxide(GO) nanosheets were dispersed into premixed powders(Cu-0.4 wt% Al/35W5Cr) by wet grinding and vacuum freeze-drying process. The 0.3 wt% GO/Al_2O_3-Cu/35W5Cr and 0.5 wt%GO/Al_2O_3-Cu/35W5Cr composites, used for electrical contacts, were fabricated by vacuum hot-pressing sintering.The microstructure was analyzed by field emission scanning electron and transmission electron microscopy. In addition, the Raman spectroscopy and X-ray photoelectron spectroscopy were used to investigate the structural changes of GO before and after sintering. The arc erosion behavior was investigated by the JF04 C electrical contact testing apparatus. Consequently, the Al_2O_3 nanoparticles were evenly dispersed in the matrix, causing dislocation tangles. GO was converted to reduced graphene oxide after sintering. A group of carbon atoms combined with Cr forming Cr_3C_2 in situ during sintering, which enhanced the interface bonding. Compared with the Al_2O_3-Cu/35W5Cr composite, the tensile strength of the two contact materials containing 0.3 wt% GO and 0.5 wt% GO was increased by 45% and 34%, respectively. Finally, pips and craters were present on the anode and cathode surfaces, respectively.Tungsten has undergone re-sintering during arcing and formed needle-like structures. Compared with Al_2O_3-Cu/35W5Cr, the GO/Al_2O_3-Cu35W5Cr composites have better welding resistance. The final mass transfer direction of the two composites was from the cathode to anode.