硫化菜籽油润滑添加剂对钢-镁摩擦副摩擦学性能的影响(英文)

在菜籽油(RO)分子中引入硫,合成一种改性菜籽油润滑添加剂(SRO)。结果表明:以菜籽油为基础油的硫化菜籽油润滑添加剂对钢-镁摩擦副具有优良的抗磨减摩性能;镁合金的摩擦因数和磨损体积随着SRO添加量的增加而减小;与菜籽油润滑的镁块表面相比,用含SRO菜籽油润滑的镁块表面摩擦划痕较轻微。SRO对钢-镁摩擦副具有优良抗磨减摩作用的机理是由于添加剂和菜籽油分子在摩擦表面吸附并与镁合金发生了摩擦化学反应而生成了一层复杂的边界润滑膜。     

陶瓷润滑油添加剂对钢-钢接触疲劳及磨损性能的影响

研究了一种以羟基硅酸铝为主的陶瓷润滑油添加剂对钢-钢接触疲劳及磨损性能的影响。利用球-棒疲劳试验机进行试验,证明该陶瓷添加剂提高了摩擦副接触疲劳寿命L10 1．3倍,改善了钢的磨损性能。通过扫描电镜分析,发现在点蚀坑内和点蚀坑的边缘存在微裂纹被覆盖的现象;纳米压痕测试结果表明,接触表面已经形成了一层白亮色物质,并具有极高的硬度。它们可以解释陶瓷添加剂提高接触疲劳寿命及改善磨损性能的原因。     

陶瓷润滑油添加剂对钢/钢摩擦副摩擦学性能的影响

研究了金属陶瓷润滑油添加剂在球（销）盘磨损试验机上对钢/钢摩擦副摩擦学性能的影响及其作用机理,采用扫描电镜,原子力显微镜,纳米压痕仪,X光衍射仪等仪器对摩擦表面形成的金属陶瓷修复层进行了分析.结果表明,该添加剂对钢/钢摩擦副具有很好的抗磨作用,试验中反复出现的负磨损现象体现了其显著的动态自修复功能;在钢/钢摩擦副表面形成的金属陶瓷修复层,粗糙度可低至十几个纳米,硬度高达16GPa,对改善摩擦学性能发挥了重要作用;但XRD广角衍射和小角掠射的分析都只发现基体α-Fe相,没有发现其它新相.陶瓷润滑油添加剂代表当前添加剂领域中一种最新发展趋势,其作用机理有待进一步深入系统的研究.     

纳米SiC微粒作为润滑油添加剂对钢/钢摩擦副磨损机制转变影响的研究

本文采用经过表面修饰的纳米SiC微粒作为润滑油添加剂,在M200磨损试验机上进行磨损试验,通过磨损表面的显微分析和能谱分析,研究载荷为400~1300 N、滑动速率为0.42~0.84 m/s范围内,纳米SiC微粒对油润滑条件下钢/钢摩擦副磨损机制转变的影响,并建立磨损机制图。结果表明：低速低载荷条件下,纳米SiC微粒的添加破坏润滑油膜的连续性,造成磨损量增加;高速高载荷条件下,纳米SiC微粒通过隔离摩擦副,变宏观滑动磨损为微观滚动磨损,并抑制黏着磨损的产生,提高了润滑油在恶劣环境下的润滑能力,降低了磨损量。     

疏水性硼酸镧纳米棒的制备及其在菜籽油中的摩擦磨损性能(英文)

采用水热法合成油酸修饰的硼酸镧纳米棒(OA/La BO3·H2O),利用X射线衍射和扫描电镜等测试技术对其微观结构进行表征,并在四球摩擦试验机上考察其在菜籽油中的摩擦磨损性能。结果表明,所制备的OA/La BO3·H2O为直径约50 nm、长达500 nm的疏水性纳米棒。OA/La BO3·H2O能显著提高菜籽油的抗磨减摩性能;当OA/La BO3·H2O的添加量为1%(质量分数)时,菜籽油的抗磨减摩性能最佳。     

金属陶瓷润滑油添加剂对钢-钢摩擦副磨损行为的影响及其铁谱验证

研究了一种以羟基硅酸铝为主的金属陶瓷润滑油添加剂对钢铁摩擦副磨损行为的影响，并用铁谱分析进行了验证。研究结果表明本添加剂具有明显的减磨作用和良好的磨损修复功能。加入添加剂后铁谱分析中的磨损烈度指数和磨粒浓度均随磨损过程呈下降趋势，提示了修复功能的机理可能是磨粒重返磨损表面。实际发动机润滑油的铁谱分析与试验机的分析结果一致。     

Effect of laser surface melting on friction and wear behavior of AM50 magnesium alloy

In the present study, an attempt has been made to enhance tribological properties of AM50 magnesium alloy by laser surface melting (LSM) with a 2 kW continuous wave CO₂ laser. The microstructure of the laser surface melted zone consists of fine columnar dendrites growing epitaxially from the liquid-solid interface. Microhardness of the melted zone was improved to 55-75 HV as compared to 40 HV of the substrate. The friction and wear behavior of the laser surface melted layer were investigated using a ball-on-flat apparatus under dry sliding condition. It was found that the friction coefficient curve of the laser surface melted layer was similar to that of substrate. They showed a lower initial friction coefficient about 0.18 that after the running-in period increased up to about 0.38. Furthermore, compared with the AM50 substrate, the wear volume of the laser surface melted layer was decreased by 42%, the wear resistance of the laser surface melted layer was improved.     

基于摩擦挤压增材制造的单道多层6061铝合金组织特征与力学性能

成功实现了6061铝合金摩擦挤压增材制造(friction extrusion additive manufacturing, FEAM)工艺,对单道1层、2层及9层增材试样组织特征、界面连接机制及力学性能进行了分析讨论。结果表明:在主轴转速600r/min和移动速度300mm/min下可获得完全致密无内部缺陷的每层厚度和宽度分别约为4和32mm的6061单道1层、2层及9层增材试样。增材组织均匀完全由细小等轴晶组成,单道1层和单道9层平均晶粒尺寸分别为5.63±1.66μm和8.31±1.67μm,与填充棒料母材(24.21±5.3μm)比较晶粒明显细化。单道1层增材组织内部强化相β″几乎全部溶解而β′发生粗化,平均硬度为母材的64.7%。增材界面实现冶金连接且晶粒细化最显著,由于强化相β″及β′几乎全部溶解,其硬度降低为母材的56.9%,单道9层试样因多次热循环降低为母材的50.6%。单道9层增材试样具有优良的强韧匹配,沿增材层长度方向平均抗拉强度和断后伸长率分别为194.25MPa和34.6%,沿增材层垂直方向(Z方向)平均抗拉伸强度和断后伸长率分别为151.0 MPa和10.4...     

MAO电压对TC4合金氧化膜层摩擦磨损性能的影响

通过微弧氧化技术(Micro-arc oxidation, MAO)对TC4合金进行表面处理,探究了不同MAO电压对TC4合金氧化膜层摩擦磨损性能的影响。使用激光共聚焦显微镜、扫描电镜、X射线衍射仪、显微硬度计及高温真空摩擦磨损试验仪对膜层形貌、相成分、硬度以及摩擦学性能进行了测试。结果表明:随着MAO工作电压的升高,MAO-TC4合金表面膜层中锐钛矿型TiO₂和金红石型TiO₂的含量随之增加,其表面粗糙度、显微硬度以及平均摩擦因数亦随之增大,磨损率先降低后增大。当MAO工作电压为280 V时,磨损率最小,为2.8 mg/cm²,摩擦磨损性能最佳。     

退火工艺对增材制造TC18钛合金力学性能和组织的影响

采用显微组织观察和力学性能测试等方法研究了退火工艺参数对增材制造TC18钛合金力学性能和组织的影响。结果表明,增材制造TC18钛合金试块宏观形貌平整,表面没有裂纹等缺陷,表面呈均匀的银白色。试样经600 ℃退火保温2 h后的各项力学性能均满足GJB 2744A—2007指标要求,其规定塑性延伸强度为1036 MPa,抗拉强度为1084 MPa,断后伸长率为9.8%,断面收缩率为30%。增材制造TC18钛合金的组织为典型的柱状晶组织,粗大的β相柱状晶粒内为细长的针状α相及编织细密的α+β相板条组织;随着退火温度的升高,β相柱状晶内的针状α相逐渐粗化。     

Effect of nitrogen ion implantation dose on torsional fretting wear behavior of titanium and its alloy

Various doses of nitrogen ions were implanted into the surface of pure titanium, Ti6Al7Nb and Ti6Al4V, by plasma immersion ion implantation. Torsional fretting wear tests involving flat specimens of no-treated and treated titanium, as well as its alloys, against a ZrO₂ ball contact were performed on a torsional fretting wear test rig using a simulated physiological medium of serum solution. The treated surfaces were characterized, and the effect of implantation dose on torsional fretting behavior was discussed in detail. The results showed that the torsional fretting running and damage behavior of titanium and its alloys were strongly dependent on the dose of the implanted nitrogen ions and the angular displacement amplitude. The torsional fretting running boundary moved to smaller angular displacement amplitude, and the central light damage zone decreased, as the ion dose increased. The wear mechanisms of titanium and its alloys were oxidative wear, abrasive wear and delamination, with abrasive wear as the most common mechanism of the ion implantation layers.     

摩擦氧化层对TC4合金磨损行为和摩擦系数的影响

选取TC4合金与3种对偶件微动磨损的完全滑移区,研究摩擦氧化层的形成对TC4合金微动磨损行为和摩擦系数的影响.结果 表明:室温下摩擦系数曲线经历阶段性变化,磨损表面未形成摩擦氧化层,磨损率均较高.合金基体加热至260℃时,TC4/GCr 15微动摩擦系数曲线最早出现由动态稳定向直线稳定的过渡,最早发生轻微磨损转变和摩擦...     

Effect of Nd addition on microstructure and tensile properties of laser additive manufactured TC11 titanium alloy

Single-layer and multilayer laser additive manufacturing (LAM) for TC11 alloy with different Nd additions was conducted and the effect of Nd addition on microstructure and properties was studied. With the addition of Nd, the aspect ratio of melting pools of single-layer specimens increases and the columnar-to-equiaxed transition occurs. The original β grain size and α plate width of TC11?1.0Nd are significantly reduced compared with those of pure TC11 specimens. It is proposed that the evenly distributed fine Nd₂O₃ precipitates of about 1.51 μm are formed preferentially during rapid solidification of melting pool, and they serve as heterogeneous nucleation particles to refine the microstructure in the subsequent solidification and solid-state phase transformation. Due to the multiple effects of Nd on the microstructure, the ultimate tensile strength of TC11?1.0Nd increases, while the yield strength, ductility and microhardness decrease compared with those of pure TC11.     

EFFECT OF TOOL WEAR ON MICROSTRUCTURE, MECHANICAL PROPERTIES AND ACOUSTIC EMISSION OF FRICTION STIR WELDED 6061 Al ALLOY

Tool condition is one of the main concerns in friction stir welding （FSW）, because the geometrical condition of the tool pin including size and shape is strongly connected to the microstrueture and mechanical performance of the weld. Tool wear occurs during FSW, especially for welding metal matrix composites with large amounts of abrasive particles, and high melting point materials, which significantly expedite tool wear and deteriorate the mechanical performance of welds. Tools with different pin-wear levels are used to weld 6061 Al alloy, while acoustic emission （AE） sensing, metallographic sectioning, and tensile testing are employed to evaluate the weld quality in various tool wear conditions. Structural characterization shows that the tool wear interferes with the weld quality and accounts for the formation of voids in the nugget zone. Tensile test analysis of samples verifies that both the ultimate tensile strength and the yield strength are adversely affected by the formation of voids in the nugget due to the tool wear. The failure location during tensile test clearly depends on the state of the tool wear, which led to the analysis of the relationships between the structure of the nugget and tool wear. AE signatures recorded during welding reveal that the AE hits concentrate on the higher amplitudes with increasing tool wear. The results show that the AE sensing provides a potentially effective method for the on-line manitoring of tool wear.     

激光功率对5356铝合金激光诱导MIG电弧增材制造组织性能的影响

为了改善MIG电弧增材制造5356铝合金的组织及力学性能,将低功率激光与MIG电弧增材制造结合,采用低功率脉冲激光诱导MIG电弧增材制造技术进行了不同激光功率下5356铝合金单道多层墙体成形试验,分析了激光功率对沉积态5356铝合金组织、显微硬度及拉伸性能的影响.结果表明,低功率脉冲激光诱导MIG电弧增材制造成形试样整体冶金结合良好、无明显的未熔合现象.墙体的微观组织主要呈等轴晶状,与单MIG电弧堆积的墙体相比,等轴晶变得细小均匀,显微硬度提高,波动较小.加入激光可以减少Fe元素、Si元素含量和气孔数量,使墙体的力学性能提高,当激光功率为300 W时达到最大值,较单MIG电弧堆积墙体的抗拉强度提高了12.0%.     

Effect of the T6 heat treatment on corrosion behavior of additive manufactured and gravity cast AlSi10Mg alloy

This study investigates the corrosion behavior of AlSi10Mg alloy produced by additive manufacturing and gravity casting before and after T6 heat treatment. Electrochemical tests showed that the additive manufactured material in as‐produced condition exhibits high corrosion resistance, due to the very fine microstructure, while immersion test allowed to identify an exfoliation‐like corrosion phenomenon, which caused a significant mass loss. In this case, T6 heat treatment was beneficial for corrosion resistance since the related change in microstructure led to a less detrimental corrosion mechanism. Therefore, the T6 heat treatment resulted necessary to use additive manufactured AlSi10Mg components in aggressive chloride‐bearing environments.     

Effect of hybrid ratio on friction and wear behavior of AZ91D matrix nanocomposites under oil lubricated conditions

Friction and wear behavior of AZ91D and its nanocomposites reinforced by different contents of hybrid multi-walled CNTs and nano-SiC particulates under oil lubrication was investigated using a MRS-10P four-ball tribometer. Friction coefficients and wear rates were measured within a load range of 200–1000 N at a spindle rotary speed of 380 r/min. Worn surface morphologies, phase and element compositions were studied by scanning electron microscope (SEM), X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS), respectively. The mechanism of synergistic effect of CNTs and SiC nanoparticles was discussed. The results indicate that the AZ91D nanocomposites show better wear resistance properties and different wear mechanisms compared with AZ91D. The AZ91D nanocomposites reinforced with 0.5% CNTs and 0.5% nano-SiC have the best tribological capacity. The wear mechanisms for the Mg-based hybrid nanocomposites appear to be a mix-up of micro-ploughing, micro-cutting, slight adhesive wear and delamination.     

The effect of sliding speed and amount of loading on friction and wear behavior of Cu–0.65 wt.%Cr alloy

Friction and wear behavior of a peak aged Cu–0.65 wt.%Cr alloy was investigated. The friction and wear experiments were run under ambient conditions with a pin-on-disk tribometer. Experiments were performed using various applied normal loads and sliding velocities. The tribological behavior of the studied alloy was discussed in terms of friction coefficient, wear loss and wear mechanism.Friction coefficient and wear loss have shown large sensitivity to the applied normal load and the sliding velocity. At the sliding velocity of 0.3 m/s weight loss increased from 6.9 to 51 mg by increasing the normal load from 20 to 40 N. At higher sliding velocity minimum weight loss is achieved at 60 N normal load. So it can be seen that with increasing normal load wear rate decreases due to the formation of a continuous tribofilm which consists of Fe–Cu intermetallic. Varying of friction coefficients in different conditions of normal load and sliding velocity is correlated to the wear behavior.The analysis of worn surfaces by XRD and SEM showed that an increase in normal load and sliding velocity creates an intermetallic wear-induced layer, which modifies the wear behavior of the alloy. The XRD result indicates that new phase of Cu_9.9Fe_0.1 is generated on worn surfaces of the pin specimens during the wear tests. There is a significant correlation between the micrograph of worn surfaces and the wear rate of specimens.