高铬自熔合金喷焊涂层磨损特性研究

采用喷焊技术在低碳钢表面获得几种合金涂层。对涂层的形貌、组织、硬质相等进行了分析。利用扫描电镜、X射线衍射仪、显微硬度计和摩擦磨损实验机等对喷焊熔覆层显微组织、化学成分、相结构、显微硬度和摩擦磨损性能进行了研究。与国外耐磨材料在相同的磨损条件下进行磨损对比试验。结果表明，制备的合金涂层具有较高的硬度，达到HRC58，其相对耐磨性提高了1．18－4．71倍。     

变质与热处理对Al-Si-Fe/Al-20Si复合材料组织和磨损性能的影响

以还原Fe粉和Al-20Si为反应物,采用熔体反应法原位反应生成Al-Si-Fe/Al-20Si复合材料,通过Mn、Sr、Y对复合材料进行变质处理,并对样品进行T6处理。研究了复合材料的显微组织及室温干滑动摩擦磨损性能。结果表明,变质后复合材料的耐磨性明显高于基体,热处理后所有样品的耐磨性均高于铸态,其中热处理前采用Sr变质的复合材料耐磨性最好,热处理后经过Y变质的复合材料耐磨性最好。分析可知复合材料的耐磨性主要受富铁相和硅相粒子形貌和大小的影响,富铁相和热处理后高强度的基体会促进摩擦转移膜的形成,提高耐磨性。     

含稀土氧化物的WC-TiC-TaC-Co/CuZnNi复合耐磨堆焊材料

以WC-TiC-TaC—Co硬质合金、CuZnNi及氧化物La2O3为原料，研制出一种具有高耐磨性和良好抗冲击性能的堆焊材料，利用SEM、TEM、摩擦磨损试验分析了堆焊材料的组织及耐磨性，探讨了稀土氧化物对堆焊材料组织性能的影响．研究结果表明：硬质合金与Cu基合金通过元素扩散形成连接界面；堆焊层耐磨性随硬质合金含量的增加而增加，随载荷的增加而降低；加入La2O3后，基体组织细化，硬质合金与基体的界面上形成微晶过渡区，改善了界面结合强度，堆焊层耐磨性得到提高。     

基体硬度对材质耐磨性的影响—Al—Si合金和Si相锌基复合…

对两种硅相复合的材质耐磨性进行了研究，指出在复合相相同，摩擦工况一致的情况下，基体硬度对材质的磨损性能影响很大，基体硬度大，耐磨性能好，磨损方式都是疲劳磨损。     

高强高导铜合金的研究概述EI

高强高导铜合金是一类很有应用潜力的功能材料，近年来研究和开发应用高强高导铜基合金取得了显著成效。本文叙述了开发和研究高强高导铜合金的基本原理及制备方法，并对国内外高强高导铜合金的研究和开发应用现状进行了综述，同时，阐述了高强高导铜合金的发展方向及应用前景。     

控温铸型连铸Cu-Ni-Si合金的加工工艺与组织性能的关系及其机理

采用控温铸型连铸(temperature controlled mold continuous casting,TCMCC)技术制备C70250铜合金带坯,对带坯进行冷轧及不同温度和时间的时效处理,研究加工工艺与微观组织、力学性能及导电性能的关系,并揭示其机理。结果表明:TCMCC制备的C70250铜合金带坯具有粗大的柱状晶组织,横向晶界较少,经变形量97.5%的冷轧后形成了沿轧向的纤维条带状组织。当时效温度为450℃、时效时间为60min时,合金的抗拉强度为758MPa、导电率为54.5%IACS;与传统制备工艺相比,抗拉强度提高了5.3%,导电率提高了36.3%,实现了强度和导电率的同步提升。该条件下合金保留了纤维条带状组织并均匀析出了大量尺寸为6~10nm的Ni2Si相,通过加工硬化和Orowan强化共同作用提高了合金的强度;且溶质原子得到充分析出,横向晶界较少,显著提高了C70250铜合金的导电性能。     

微量Zr对Cu-Ag合金力学性能的影响

采用真空熔炼的方法制备了一种新型的高强高导兼顾的铜合金材料Cu-Ag-Zr合金。利用显微硬度测试、金相和透射电镜分析等方法，研究了微量zr对Cu．Ag合金力学性能的影响．结果表明，微量Zr的加入，能显著提高Cu-Ag合金的显微硬度和再结晶温度，使Cu-Ag合金的再结晶软化温度提高200℃以上，Cu-Ag-Zr合金经550℃退火2h后，其显微硬度仍保持为128Hv，能够满足高强高导铜合金高温性能的要求；微量Zr对Cu-Ag合金的强化主要通过使该合金中形成细小、弥散分布的析出相来实现的。     

离子渗氮对耐磨性的影响

对四种离子渗氮工艺条件下的３８ＣｒＭｏＡｌ新渗氮钢进行了磨损试验研究。通过Ｘ射线衍射表面相结构分析以及测量表明硬度，截面硬度梯度，化合物层厚度和渗氮层深度等试验结果表明，离子渗氮前的原始组织对３０Ｃｒ２ＭｏＶ钢耐磨性影响较小，而对３８ＣｒＭｏＡｌ钢的耐磨性影响较大。离子渗氮工艺条件对这两种钢耐磨性具有一最佳值。     

等离子原位合成Fe-Cr-V-C堆焊合金的耐磨性

采用等离子堆焊技术制备了不同Cr含量的Fe-Cr-V-C堆焊合金,借助扫描电镜和X射线衍射等分析手段研究了碳化物形貌及合金物相组成。同时研究了Cr含量对合金硬度和耐磨性的影响,并探讨了磨损机理。结果表明:堆焊合金组织由马氏体、铁素体、奥氏体、M7C3及VC组成。合金中随着Cr含量的提高,由于硬质相M7C3和VC的数量及形态变化不大,而具有高硬度的针状马氏体基体组织的减少使得合金的耐磨性先降低,当达到一定值后继续增加Cr含量,M7C3的数量逐渐增多,因而耐磨性随后增大;当Cr含量达到27.2%(质量分数)时,大量高硬度六边形M7C3复合物(约HV1200)结合一定量VC(约HV1600)颗粒构成坚实的耐磨骨架,使得合金具有最佳的耐磨性。     

锻造对RE-WC-钢复合材料组织与耐磨性的影响

为了研究锻造对电冶重熔稀土-WC-钢复合材料耐磨性的影响,对电冶重熔稀土-WC-钢复合材料锻造后经适当热处理,利用MM-200磨损试验机测试合金锻造前后和锻后不同热处理工艺下的摩擦磨损特性和力学性能,利用光学显微分析技术、SEM技术分析了磨损前后合金组织、摩擦面形貌及其磨损机理.结果表明:锻造使RE-WC-钢基合金冲击韧性明显提高,硬质相桥接减少,摩擦表面硬质相剥落减小,合金的耐磨性明显提高;锻后1150℃加热淬火、150℃×2 h回火后合金耐磨性最好.     

硼对铜合金组织和性能的影响

研究了加硼铜合金的组织以及力学、腐蚀、腐蚀磨损和冲蚀性能。结果表明：硼能明显细化铜合金的组织，提高其强度、硬度，改善其耐蚀、耐腐蚀磨损及耐冲蚀能力；并确定硼在铜合金中的最佳含量范围。     

Developing aluminium–zinc-based a new alloy for tribological applications

In order to develop aluminium–zinc-based a new alloy for tribological applications, six binary Al–Zn and seven ternary Al–25Zn–(1–5)Cu were prepared by permanent mould casting. Their microstructure and mechanical properties were investigated. Dry sliding friction and wear properties of the ternary alloys were investigated using a pin-on-disc machine. Surface and subsurface regions of the wear samples were studied with scanning electron microscopy (SEM). The highest hardness and tensile strength were obtained with the Al–25Zn alloy among the binary ones. The microstructure of this alloy consisted of aluminium-rich α and eutectoid α + η phases. Addition of copper to this alloy resulted in the formation of θ (CuAl₂) phase. The hardness of the ternary alloys increased with increasing copper content. The highest tensile and compressive strengths and wear resistance and the lowest friction coefficient were obtained from the ternary Al–25Zn–3Cu alloy. The dimensional change measured on ageing (stabilization) of this alloy was found to be much lower than that obtained from the copper containing zinc-based alloys. Microstructural changes were observed below the surface of the wear samples of the Al–25Zn–3Cu alloy. These changes were related to the heavy deformation of the surface material due to normal and frictional forces, and smearing and oxidation of wear material. Adhesion was found to be the main wear mechanism for the alloys tested.     

Bearing Wear Resistance of Monotectoid Zn-Al Based Alloy (ZA-35)

Based on the fundamental investigations of ageing characteristics and microstructures, pedermance properties of monotectoid Zn-Al based alloy ZnAl35Cu3Si2 (in wt-%) named ZA-35 were studied. The test results showed the ZA-35 alloy displayed better bearing wear resistance than copper bronze and lower coefficient of thermal expansion than other Zn-Al alloys. These excellent performance properties have been verified by practical applications.     

The effect of titanium addition on the microstructure,mechanical and tribological properties of Ni3Si alloys prepared by powder metallurgy method

Ni₃Si alloy with different content of titanium was fabricated by powder metallurgy method. The microstructures, hardness and tribological properties of the alloys were investigation. The results showed that pure Ni₃Si alloy was composed of β₁‐Ni₃Si phase and γ‐Ni₃₁Si₁₂ phase, and Ni₃Ti phase formed with titanium addition. The hardness of the alloy decreased with the increasing titanium content. The friction coefficient of pure Ni₃Si alloy increased with the increasing load, while the friction coefficient of the alloy with titanium addition decreased. The wear rates of the alloys were all increased with increasing load, and the alloy with 5 % titanium addition had the best wear resistance properties. The wear mechanisms of the alloys were abrasive wear at low load, and the wear mechanisms changed to oxidative wear at high load.     

An investigation into the tribological performance of Physical Vapour Deposition (PVD) coatings on high thermal conductivity Cu-alloy substrates and the effect of an intermediate electroless Ni-P layer prior to PVD treatment

The use of high thermal conductivity copper alloys in plastic injection moulds provides the benefit of rapid moulding cycles through effective heat transfer. However, copper alloys are relatively soft and wear rapidly so manufacturers are now developing copper alloys with increased hardness and wear resistance. Their wear resistance can be further improved by the deposition of hard coatings such as electroplated chromium, electroless nickel and Physical Vapour Deposition (PVD) coatings. In this paper, the tribological performance of three proprietary high-strength Cu alloys (Ampcoloy® 940, Ampcoloy® 944 and Ampcoloy® 83) coated with PVD CrN and CrAlN coatings has been evaluated. A medium phosphorous content electroless Ni-P (ENi-P) plated layer was also deposited as a pre-treatment to PVD CrN and CrAlN coatings to increase the load support. The effect of this intermediate ENi-P layer was also evaluated. Surface roughness and instrumented hardness measurements were used to characterise all coated systems in both plated (i.e. with the intermediate ENi-P coating) and standard (i.e. unplated) conditions. Scratch tests were also performed to evaluate the effect of the ENi-P on PVD coating adhesion to Cu alloy substrates. The tribological behaviour of PVD-coated Cu alloy systems was evaluated by pin-on-disc wear tests and ball-on-plate impact tests. Results demonstrate that the ENi-P layer improves the load support for PVD coatings on Cu alloys, thereby improving their tribological performance. However, for PVD-coated Cu alloys in the standard condition, the Cu alloy substrate type plays an important role in the tribological performance of PVD coatings. For instance, PVD CrN coatings were more suited to a certain Cu alloy type whilst CrAlN to the other two types.     

钛合金干滑动摩擦行为与磨损机理研究进展

钛合金因具有高的比强度、比刚度,良好的耐蚀性和耐热性等优点,在航空航天、化工、能源等领域广泛应用,但钛合金存在表面硬度低、抗塑性剪切能力较差、不易加工硬化以及表面氧化物保护作用较差等缺陷,使其耐磨性较差,阻碍了其在耐磨损领域的发展。为了提高钛合金自身的耐磨性潜力和扩大其应用领域,本文主要概述了近年来国内外有关钛合金干滑动摩擦磨损领域的研究现状,讨论了影响钛合金摩擦磨损性能的主要因素以及在不同条件下的磨损机理,并对钛合金干滑动摩擦磨损行为的研究进行了展望。     

锌基-结晶硅、陶瓷粒子复合材料的组织与性能

本文研究了用流变铸造工艺制造的锌基-结晶硅,陶瓷粒子复合材料的组织、凝固特点、力学性能,热膨胀系数及摩擦磨损特性.研究发现,SiC粒子可作为高铝锌基合金的初生相的形核衬底,分布在晶内并可细化晶粒;硅粒子的分布与合金的结晶特性有关.而Al₂O₃粒子分布在晶界,对初生相有粗化趋势.也研究了粒子对锌基合金力学性能的影响,发现合金抗拉强度略有下降,硬度提高,粒子含量适当时延伸率及韧性提高.加入粒子后锌基合金热膨胀系数减小,耐磨性明显提高,从而使其能更好的满足模具,轴承材升的要求.     

Mechanical and tribological properties of zinc-aluminium metal-matrix composites

Recently, commercial Zn-Al foundry alloys such as ZA-27 have found increasing use for many applications and have competed effectively against copper, aluminium and iron-based foundry alloys. However, the elevated temperature (> 100°C) properties of zinc-aluminium alloys are unsatisfactory and restrict their use in some applications. One viable approach to improving the elevated temperature properties is to reinforce the zinc-aluminium alloys with alumina fibres. In this investigation, the mechanical properties of a Zn-Al alloy reinforced with alumina fibres were evaluated. Tensile, compression and impact properties were determined at 25, 100 and 150°C. Lubricated wear tests were also performed on the unreinforced alloy and composites. It was found that although fibre reinforcement did result in some improvement of tensile and compression properties at elevated temperatures, the composites had poor toughness and ductility. The presence of a brittle SiO₂ layer at the fibre/matrix interfaces resulted in fibre/matrix decohesion under tensile loading, impairing the performance of the reinforced materials. Some improvement in wear resistance was noted for the composite materials but fibre reinforcement did not yield significant improvement in fatigue resistance.     

Influence of T5 heat treatment on the microstructure and lubricated wear behavior of ternary ZnAl40Cu2 and quaternary ZnAl40Cu2Si2.5 alloys

A ternary ZnAl40Cu2 and a quaternary ZnAl40Cu2Si2.5 alloys were produced by permanent mold casting and subjected to T5 heat treatment at a temperature of 150 °C for 24 hours. The structural, mechanical and lubricated wear properties of these alloys were investigated in the as-cast and heat-treated conditions and the results were compared with those of SAE 65 (CuSn12) plain bearing bronze. Microstructure of the ternary alloy consisted of aluminum-rich α, eutectoid conversion product of α+η and ϵ phase located in the interdendritic channels. In addition to these phases, silicon particles were observed in the microstructure of the quaternary alloy. T5 heat treatment caused a considerable amount of reduction in the hardness, tensile strength and wear resistance of ZnAl40-based ternary and quaternary alloys, but improved their ductility and stability. These alloys in the as-cast and heat-treated conditions exhibited lower wear volume or higher wear resistance than SAE 65 bearing bronze. Among the experimental alloys, the optimum mechanical properties and wear performance were obtained from ZnAl40Cu2Si2.5 alloy in both as-cast and heat-treated conditions. Adhesion appeared to be the main wear mechanism for the ZnAl40-based alloys, but abrasion dominated the wear of SAE 65 bronze.     

Effect of Niobium on Microstructure and Properties of the CoCrFeNb_xNi High Entropy Alloys

A series of CoCrFeNb_xNi(x values in molar ratio, x = 0, 0.25, 0.45, 0.5, 0.75, 1.0 and 1.2) high entropy alloys(HEAs) was prepared to investigate the alloying effect of Nb on the microstructures and mechanical properties. The results indicate that the prepared CoCrFeNb_xNi(x 0) HEAs consist of a simple FCC solid solution phase and a Laves phase. The microstructures of the alloys change from an initial single-phase FCC solid solution structure(x = 0) to a hypoeutectic microstructure(x = 0.25), then to a full eutectic microstructure(x = 0.45) and finally to a hypereutectic microstructure(0.5 x 1.2). The compressive test results show that the Nb0.45(x = 0.45) alloy with a full eutectic microstructure possesses the highest compressive fracture strength of 2558 MPa and a fracture strain of 27.9%. The CoCrFeNi alloy exhibits an excellent compressive ductility, which can reach 50% height reduction without fracture. The Nb0.25 alloy with a hypoeutectic structure exhibits a larger plastic strain of 34.8%. With the increase of Nb content, increased hard/brittle Laves phase leads to a decrease of the plasticity and increases of the Vickers hardness and the wear resistance. The wear mass loss, width and depth of wear scar of the Nb1.2(x = 1.2) alloy with a hypereutectic structure are the lowest among all alloy systems, indicating that the wear resistance of the Nb1.2 alloy is the best one.