两种NiAl基合金在酸腐蚀工况下的磨损特性

研究了Ni Al-2.5Ta-7.5Cr-x(0,1)B合金在5%H2SO4溶液中的腐蚀磨损特性,结果表明:在酸腐蚀工况下Ni Al-2.5Ta-7.5Cr-1B合金的耐蚀性能优于Ni Al-2.5Ta-7.5Cr合金,易钝化成膜,静置腐蚀速率为0.007 mg/(cm2·h1),钝化电流密度为0.299(m A·cm-2),自然腐蚀电位为-0.213 V,表现出良好的耐酸腐蚀性能及稳定性。物质膜完整地覆盖在Ni Al-2.5Ta-7.5Cr-1B合金的磨损表面,抑制了腐蚀对磨损的加速作用,Ni Al-2.5Ta-7.5Cr-1B合金比Ni Al-2.5Ta-7.5Cr合金的腐蚀磨损率减小了2-8倍。Ni Al-7.5Cr-2.5Ta-1B合金的磨蚀,受控于腐蚀磨损和完整的物质膜的保护作用。Ni Al-2.5Ta-7.5Cr合金的磨蚀机制,受控于腐蚀磨损和磨粒磨损。     

海洋环境下钛及钛合金的腐蚀磨损研究进展

钛和钛合金作为钝化金属合金广泛用于海洋工程领域,具有优异的耐腐蚀性。腐蚀磨损是近年来摩擦学领域的研究热点之一,是影响钝化金属结构材料在腐蚀环境下应用的重要因素之一。围绕腐蚀磨损研究,对近年来国内外关于钛及钛合金在海水环境下的腐蚀磨损行为及机理研究进行了整理综述,并对未来钛合金主要研究发展方向进行了展望。     

铜在甲胺-铁氰化钾化学机械抛光液中的腐蚀与钝化

用电化学测试技术研究了腐蚀介质和成膜剂浓度对铜表面的腐蚀与钝化成膜的影响,分析了钝化膜的成分,探讨了钝化膜在抛光压力和转速作用下的磨损与表面再钝化的行为,测量了铜在化学机械抛光过程中的极化曲线。结果表明铜在甲胺溶液介质铁氰化钾抛光液中易钝化,钝化膜的主要成分为Cu4[Fe(CN)6],有少量Cu20存在。钝化膜的磨损特性随成分浓度不同而不同。钝化膜的磨损难易程度与钝化膜的本身特性、抛光压力及转速有关。抛光过程中因钝化膜被磨损,腐蚀加快,腐蚀电流密度大幅增加。配方0．1％甲胺溶液 0．5％K3Fe(CN)6 5％Al2O3可行。     

HAc-KOH-KClO3抛光液中铜的钝化与磨损研究

用电化学测试技术研究了铜在Hac-KOH-KClO3化学机械抛光液中的腐蚀与钝化,分析了钝化膜的成分,研究了成膜的伏安曲线特征,考察了化学机械抛光过程中铜腐蚀电位随时间变化的轨迹、钝化膜的磨损与再钝化以及铜的极化曲线.结果表明,铜在Hac-KOH-KClO3化学机械抛光液中钝化膜主要由Cu2O和CuCl组成,CuCl的存在改善了铜的抛光特性.钝化膜的成膜过程符合Müller钝化成膜模型.氯酸钾的存在不仅加快了化学机械抛光过程中的钝化成膜速率和磨损除膜速率,而且降低了抛光磨损的压力和转速,大幅提高了抛光中的腐蚀电流密度,加快了铜的腐蚀.     

铌基泥纹膜片材料抗蚀性研究

用称重法，电化学方法以及做成元件实用考核等办法，研究了铌基波纹膜片材料（Nb-1-5Mo-1-3Zr-≤4Ti）抗蚀性能。试验结果如下：在100－126℃浓醋酸、次氯酸钠、海水以及干或湿氯气中，浸泡1－2年后，该合金试片表面仍光亮，未发现任何腐蚀斑点，根据试验前后重量变化，计算出的腐蚀速率很低（10^-4-10^-5mm／年）。该合金波纹膜片装入差压变送器中，在上述介质中使用2年后，波纹膜片仍光亮，未出现任何受腐蚀的痕迹，而且，变送器的精度始终保持优于0．5级，电化学实验证明，该合金在含Cl^-离子介质中具有很高的钝性，钝态区宽度≥2V，产生产点蚀的临界电位＞1．7V；该合金自然浸泡在含Cl^-离子介质中可自发地形成钝化膜，而且当钝化膜被磨损后能迅速自行修复。     

新型渣浆泵用材料的腐蚀性能研究

针对渣浆泵用耐磨蚀材料在服役过程中由于腐蚀严重导致使用寿命缩短的问题,研发了一种新型耐磨蚀材料(A合金)。采用金相显微镜、X射线衍射仪、全浸腐蚀、扫描电镜、极化曲线、阻抗谱、X射线光电子能谱对材料在模拟服役环境腐蚀液中的腐蚀速率、腐蚀特征、电化学特性以及钝化膜组成进行了分析。将A合金与SUS316L不锈钢、KMTBCr26高铬铸铁进行对比分析,结果表明:A合金的显微组织是由高铬的奥氏体基体以及高硬度的M_(23)C_6型碳化物组成,这种碳化物类型使得材料具有优异的耐腐蚀性能。在室温条件下腐蚀192 h,A合金、SUS316L、KMTBCr26的腐蚀速率分别为0. 019 7 mm/y、0. 322 mm/y、26. 039 6 mm/y。A合金表面出现少量点蚀坑,而SUS316L和KMTBCr26材料表面发生局部腐蚀甚至全面腐蚀。A合金基体在析出碳化物后Cr含量没有出现贫化,降低了相与基体之间的腐蚀电位差;材料中富含的Cu元素使得表面钝化膜的稳定性提高。在电化学腐蚀过程中,A合金的自腐蚀电位最高、腐蚀电流密度最小、阻抗谱容抗弧半径最大、腐蚀倾向最小、表面形成的钝化膜稳定性最强,钝化膜的组成为Fe_2O_3、Cr_2O_3以及部分Cu氧化物。     

电沉积Ni-P非晶合金的冲蚀-腐蚀磨损行为

采用MSH型腐蚀磨损实验机,通过改变水砂两相流的冲击速度、含砂量和固相粒径等环境因素,研究了电沉积Ni-P非晶合金的冲蚀-腐蚀磨损行为。结果表明,电沉积Ni-P非晶合金的冲蚀失重率和冲蚀-腐蚀失重率均随着冲击速度、含砂量和固相粒径的增加而增大。与AISI 304不锈钢相比,电沉积Ni-P非晶合金冲蚀失重率和总失重率较高,但腐蚀失重率较低,也表现出了良好的抗冲蚀-腐蚀磨损性能。棒状Ni-P非晶合金镀层的冲蚀-腐蚀磨损,正面以砂粒挤压锻打造成的唇片和断裂为主,侧面以切削和犁削为主。     

离子束动态混合形成非晶膜及其特性研究

同时用离子溅射及高能离子轰击相结合的离予束动态混合技术,直接在轴承钢GCr15衬底土制备富Ta表面合金。适当控制沉积温度及原子·离子到达比,可形成一定组分的非晶合金膜。分别用TEM、EDAX与XPS观察膜的结构与其所含主要成分。在NaCl、H_2SO_4溶液中检验了膜的抗局部腐蚀和均匀腐蚀能力。通过硬度测试、摩擦、磨损试验考查了膜的机械性能。实验表明,用此工艺形成的GCrl5-Ta非晶合金膜,具有优良的化学性质和物理性质。在盐溶液中的自腐蚀电位、点蚀电位和保护电位均明显上升,在酸溶液中的极化电流密度降低2～3个数量级,钝化区大大扩大。     

电沉积镍合金的冲蚀-腐蚀磨损研究

采用MSH型腐蚀磨损试验机研究了电沉积纯Ni、Ni-P非晶合金、Ni-W-P非晶合金的冲蚀-腐蚀磨损行为,并结合电化学测量系统研究了上述材料冲蚀与腐蚀之间相互促进机理。结合XRD分析了冲蚀前后电沉积镍合金的相变行为。结果表明：冲蚀-腐蚀磨损试验前后,电沉积镍合金镀层的硬度都增加;Ni-P非晶合金受到冲击后,镀层明显的发生了由非晶向微晶的转变;镍合金在含盐砂浆中的腐蚀性能随着工况的不同而不同,试样在含盐砂浆中的冲击速度由0增加到3.14ms-1时,三种材料的腐蚀速率都减小,之后随着冲击速度的增大,试样腐蚀速度增加;镍及镍合金材料的冲蚀-腐蚀磨损失重都以冲蚀失重为主,试验条件下冲蚀与腐蚀的交互作用最高能使材料的冲蚀-腐蚀磨损失重增加42%。     

氮合金化堆焊硬面合金的耐腐蚀性能研究

在马氏体不锈钢中加入氮合金,并通过铌、钒、钛固氮形成氮合金化堆焊硬面合金,进行了电化学腐蚀和化学侵蚀实验,研究了硬面合金的耐腐蚀性能。结果表明:堆焊硬面合金的氮合金化,抑制了铬的碳化物的析出,有效增强了钝化膜的稳定性,使硬面合金的自腐蚀电位从-345mV提高到-264mV,增强了堆焊硬面合金抗电化学腐蚀性能;氮合金化堆焊硬面合金均匀细小的组织形态,使得在FeCl3溶液中发生点蚀的蚀坑小且分散,提高了硬面合金的耐腐蚀性能。     

The properties of a wrought biomedical cobalt-chromium alloy

Two wrought biomedical cobalt-chromium alloys have been developed, and their mechanical properties and corrosion resistance determined by means of tensile and hardness tests and by electrochemical potential-time curves for isolated specimens in a 6.0 wt% NaCl solution at room temperature. In comparison with a current dental alloy, SC-H, and the basic type 18-8 austenitic stainless steel, it is shown that alloy II (chemical composition in wt%:0.11 C, 22.07 Cr, 15.20 Ni, 3.75 Mo, 9.30 W, balance Co) has superior properties. The alloy has a high strength together with a good ductility which permits adequate workability. Also, both cobalt-chromium alloys show a passive behaviour in 6.0 wt% NaCl solution, whereas the basic type 18-8 austenitic stainless steel shows a fluctuating potential and is thus susceptible to pitting, making it unsuitable for surgical implants.     

微观组织对0Cr17Ni4Cu4Nb马氏体不锈钢的耐点腐蚀性能的影响

采用化学浸泡法和模拟闭塞电池方法研究了固溶+时效和固溶+调整+时效处理的0Cr17Ni4Cu4Nb马氏体不锈钢的耐点腐蚀性能,并与18-8型奥氏体不锈钢(316L)耐点蚀性能进行了对比。结果表明,0Cr17Ni4Cu4Nb马氏体不锈钢组织内富Cu析出相促进了点蚀坑萌生,而点蚀坑发展则与组织形貌有关。固溶+调整+时效处理的0Cr17Ni4Cu4Nb马氏体不锈钢因组织内析出富Cu相多而大,其萌生的点蚀坑密度较高,但由于马氏体板条较细,其点蚀坑尺寸和深度较小;固溶+时效处理的0Cr17Ni4Cu4Nb马氏体不锈钢因组织内析出富Cu相少而小,萌生的点蚀坑密度较低,但粗大的板条马氏体组织导致点蚀坑尺寸和深度较大。与18-8型奥氏体不锈钢耐点蚀性能对比表明,通过对0Cr17Ni4Cu4Nb马氏体不锈钢进行合理的热处理,其耐点蚀性能可与18-8型奥氏体不锈钢相当。     

Super austenitic stainless steels — a promising replacement for the currently used type 316L stainless steel as the construction material for flue-gas desulphurization plant

Potentiodynamic anodic cyclic polarization experiments on type 316L stainless steel and 6Mo super austenitic stainless steels were carried out in simulated flue-gas desulphurization (FGD) environment in order to assess the localized corrosion resistance. The pitting corrosion resistance was higher in the case of the super austenitic stainless steel containing 6Mo and a higher amount of nitrogen. The pit-protection potential of these alloys was more noble than the corrosion potential, indicating the higher repassivation tendency of actively growing pits in these alloys. The accelerated leaching study conducted for the above alloys showed that the super austenitic stainless steels have a little tendency for leaching of metal ions such as iron, chromium and nickel at different impressed potentials. This may be due to surface segregation of nitrogen as CrN, which would, in turn, enrich a chromium and molybdenum mixed oxide film and thus impedes the release of metal ions. The present study indicates that the 6Mo super austenitics can be adopted as a promising replacement for the currently used type 316L stainless steel as the construction material for FGD plants.     

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.     

Effects of copper content on the machinability and corrosion resistance of martensitic stainless steel

The effects of copper addition on the machinability and corrosion resistance of martensitic stainless steel 4Cr16Mo are presented in the article. The results showed that the machinability of stainless steel 4Cr16Mo was obviously improved by adding Cu. When the content of copper in the stainless steel was 1.4%, the machinability of stainless steel was optimal. With the increase in the content of copper, the corrosion resistance of stainless steel 4Cr16Mo was improved. From the observation of the electron backscattered diffraction (EBSD) and high resolution electron microscopy (HREM), it can be seen that Cu-rich phases were dispersed in the stainless steel, and determined to be about 10 nm.     

Microstructure and wear characteristics of spray formed and hot extruded Al–Si alloys

Abstract

The microstructural and wear properties of spray formed Al–6.5Si, Al–18Si and Al–18Si–5Fe–1.5Cu (wt-%) alloys have been investigated. The microstructure of the Al–6.5Si alloy exhibits the equiaxed grain morphology of the primary α-Al phase with eutectic Si at the grain boundaries. The size of the primary Si particulates in the Al–18Si alloy varied from 3 to 8 μm embedded in the eutectic matrix. Complex intermetallic phases such as β-Al₅ SiFe and δAl₄ Si₂ Fe are observed to co-exist with primary Si in the spray formed Al–18Si–5Fe–1.5Cu alloy system. The periphery of the preforms invariably showed pre-solidified particles with a large amount of interstitial pores. An extrusion ratio of 6 : 1 for these alloys led to drastic porosity reduction and extensive breaking of second phase particles. These microstructural features showed distinct variation in the wear behaviour and the coefficient of friction of the alloys. The Al–18Si–5Fe–1.5Cu alloy shows better wear resistance compared with the other two alloys, particularly at higher loads. The coefficient of friction shows a dependence upon the applied load. However, this becomes steady at higher loads. The wear behaviour of these alloys is discussed in light of the morphology of debris particles as well as that of the worn surfaces.     

A model of fatigue crack growth based on Dugdale model and damage accumulation

The modified Dugdale model given by Budiansky-Hutchinson and a Coffin-Manson type damage law are used to calculate the cumulative fatigue damage of material elements at the tip of a fatigue crack. From this analysis a fatigue crack growth equation is obtained which gives predicted crack growth rates in reasonable agreement with experimental data for two aluminium alloys 7075-T6 and 2024-T81, two titanium alloys Ti-8A1-1Mo-1V and Ti-6A1-6V and a PH13-8Mo stainless steel. Limitations of this new fatigue crack growth model are also discussed.     

脉冲真空弧源沉积类金刚石薄膜耐磨特性研究

本文利用脉冲真空弧源沉积技术在Cr17Ni14Cu4不锈钢和Si(100)基体上制备了类金刚石(DLC)薄膜,研究在不同基体偏压下,DLC薄膜的结构与性能.采用拉曼光谱和X射线光电子能谱(XPS)研究DLC薄膜的原子结合状态,利用CSEM销盘摩擦磨损试验机研究其耐磨性,利用HXD1000B显微硬度仪测试其显微硬度,并采用压痕法评价其结合力.研究结果表明:DLC薄膜与基体结合牢固.随着基体偏压的提高,DLC薄膜内sp3键含量增大,薄膜硬度提高.Cr17Ni14Cu4不锈钢表面沉积DLC薄膜后,耐磨性大幅度提高,本文探讨了DLC薄膜的耐磨机理.     

Effect of surface nanocrystallization on the tribological properties of 1Cr18Ni9Ti stainless steel

Surface nanocrystallization of 1Cr18Ni9Ti austenite stainless steel was conducted by the supersonic fine particles bombarding (SFPB) technique. The friction coefficients and wear losses in air and vacuum were tested to analyse the effect of surface nanocrystallization on the tribological properties of 1Cr18Ni9Ti steel. The results show that the microstructure of the surface layer was refined into nano-grains successfully by SFPB treatment; furthermore, strain-induced martensitic transformation occurred during the treatment. The tribological properties of SFPB treated samples enhanced greatly, The dominant wear mechanism of the original 1Cr18Ni9Ti stainless steel is abrasive wear and adhesive wear, while it transfers to the combined action of fatigue wear, abrasive wear and adhesive wear after surface nanocrystallization by SFPB.     

基于TiNi合金的超弹性对其相关磨损机制的FEM研究

本文在重点考虑TiNi合金高弹性变形量的前提下，采用等向强化模型，对不锈钢和超弹TiNi合金在法向接触载荷作用下的六种模型进行了有限元(FEM)分析。结果表明：在相同载荷条件下，超弹TiNi合金产生的von Mises弹性应变要高于不锈钢，但其von Mises应力和塑性应变却恰恰相反，在同一载荷下该合金发生塑性变形的区域要小于不锈钢；此外，超弹TiNi合金发生塑性变形要比不锈钢困难，所需的临界载荷值随其最大弹性变形量(屈服点处的应变值)的增加而增加。最后，基于本文的有限元计算结果对超弹TiNi合金的蘑粒磨损和疲劳磨损机制进行了讨论。