有机钼对低黏度润滑油摩擦学性能的影响

目的 制备一种非活性油溶性有机钼添加剂(SPFMo)以为满足汽油发动机润滑油低黏度化发展的需求。方法 将SPFMo添加到0W–20润滑油中,利用SRV摩擦磨损试验机详细分析了在不同温度、载荷条件下,自研减摩剂SPFMo、商用减摩剂Molyvan855和商用抗磨剂MOM201在0W–20中摩擦学性能的影响,并采用3D激光共聚焦显微镜和扫描电子显微镜对摩擦副表面进行分析。结果 SPFMo具有良好的减摩抗磨性能,并有效降低润滑油0W–20的摩擦因数及磨损率。摩擦过程中钼元素会发生富集,并发生摩擦化学反应生成包含硫–钼–氧的复合减摩片层,实现减摩抗磨功能。SPFMo添加到0W–20中可以发挥良好摩擦学性能的使用温度区间和载荷区间分别为80~180 ℃和150~250 N(1 559~1 848 MPa)。0W–20+1% SPFMo与润滑油0W–20相比,在130 ℃、200 N下,摩擦因数降低13.28%,磨损率降低37.91%;在130 ℃、250 N下,摩擦因数降低18.05%,磨损率降低57.68%。0W–20+1% SPFMo润滑油的摩擦因数随温度的升高先减小后增大,随载荷的增大而减小;磨损率随温度的升高先减小后增大,随载荷的增大而减小。结论 低黏度润滑油中添加SPFMo可有效增强其摩擦学性能。     

有机钼为润滑油抗磨减摩添加剂的摩擦学性能研究

用四球摩擦磨损试验机考察了两种油溶性有机钼(二硫代磷酸氧钼、二硫代磷酸钼)抗磨减摩添加剂在液体石蜡基础油中的摩擦学性能,采用扫描电子显微镜对边界润滑状态下形成的磨斑形貌和表面膜的元素组成进行了分析。试验结果表明:两种有机钼添加剂均具有优异的抗磨减摩性能和极好的承载能力。其中二硫代磷酸钼添加剂使基础油的抗磨性能提高53 %,减摩性能提高40 %,极压承载能力提高一倍多。SEM分析显示钢球表面的磨痕和犁沟较浅,且有含硫和钼的沉积物生成。由此推断出有机钼添加剂在摩擦副表面形成吸附膜,部分吸附膜通过摩擦化学反应生成了具有抗磨减摩作用的MoS2和FeS膜,从而起到了改善摩擦磨损性能的作用。     

纳米锑颗粒粒径对润滑油摩擦性能的影响

采用硅烷偶联剂KH-570作为表面分散剂,利用机械球磨法制备了不同粒径的纳米锑颗粒,将其分散到900SN基础油中,在CFT-1型材料性能测试仪上进行往复式摩擦实验,考察其作为润滑油添加剂的摩擦学性能。采用SEM和EDS分析了45钢钢盘磨损表面的形貌和化学成分。结果表明:纳米锑颗粒以微观填充与黏着的机制对磨损表面起到修复作用。随着纳米锑颗粒粒径的减小和摩擦载荷的增大,试验润滑油的减摩、抗磨效果越明显。其中,含粒径为40 nm的锑颗粒润滑油在高载荷下表现出优异的减摩与抗磨性能。     

氧化石墨烯和二烷基二硫代磷酸锌添加剂对基础油PAO10摩擦学性能的影响

目的 探究氧化石墨烯(GO)和二烷基二硫代磷酸锌(ZDDP)添加剂的摩擦学性能以及协同作用机理。方法 选用GO和ZDDP作添加剂,利用纳米粒度分析仪、傅里叶变换红外光谱仪(FTIR)和原子力显微镜(AFM)分别对GO的粒径、表面官能团和层数进行表征。在四球摩擦试验机上对GO的摩擦磨损性能进行初步研究,并考察了ZDDP添加剂以及ZDDP和GO混合添加剂对基础油摩擦磨损性能的影响。利用金相显微镜、扫描电子显微镜(SEM)和能谱仪对钢球磨斑直径、磨斑形貌和磨斑表面的元素进行分析。利用球–盘点接触光干涉油膜厚度测量试验台,研究了GO和ZDDP在乏油条件下对基础油成膜特性的影响。结果 GO表现出了良好的减摩抗磨性能,在0.03%时减摩抗磨效果最佳,与基础油相比,摩擦因数降低了31.9%,磨斑直径减小了约20.1%;当ZDDP质量分数为2.5%时,油样的摩擦因数约为0.067,磨斑直径约为407 μm,与PAO10纯基础油相比,分别降低了约18.5%和41.86%;当ZDDP和GO的质量分数分别为2.5%和0.01%时,油样的减摩性能得到了有效提高,摩擦因数约为0.056,与仅添加ZDDP的油样相比,摩擦因数降低了约16.7%;当卷吸速度为90 mm/s和180 mm/s时,单独添加ZDDP或添加ZDDP和GO均可有效减缓接触区内的乏油状态,提高基础油的中心膜厚。结论 GO添加剂具有优异的减摩抗磨性能。GO和ZDDP作为复配添加剂有效地减缓了摩擦对偶间的摩擦磨损,表现出了较好的协同作用。在乏油条件下,在PAO10基础油中添加GO、ZDDP以及ZDDP和GO复配添加剂时,均可不同程度地减缓接触区内的乏油状况。     

含纳米CeO2，Cu混合物添加剂润滑油摩擦学性能研究

本文中将纳米二氧化铈与铜粒子混合物应用于润滑油添加剂，使润滑油具有优良的减摩、抗磨性能。纳米二氧化铈与铜粒子用适当的表面活性剂进行表面改性处理，经表面改性的纳米粒子在润滑油中具有良好的分散、稳定性。采用透射电镜（TEM）观察与测量纳米二氧化铈、铜粒子的形貌和平均直径。应用四球摩擦磨损试验机测定添加纳米二氧化铈、铜粒子的润滑油的极压性能（PB）、磨痕直径（WSD）和摩擦因数（μ）等。研究结果表明，最佳的纳米二氧化铈、铜粒子的总添加量为0．6％左右、纳米二氧化铈、铜粒子的质量分数之比为1：1，该润滑油具有最佳的的减摩、抗磨作用。文中还探讨了纳米二氧化铈、铜粒子混合物具有优良摩擦学性能的机理。     

白云母 / CeO2 复合粉体的制备及其摩擦学性能研究

目的研究白云母/CeO2复合粉体在500SN基础油中的抗磨减摩性能和抗磨减摩机理。方法以白云母、硝酸铈、草酸为原料,通过球磨固相法制备不同配比的白云母/CeO2复合粉体,用油酸改性,采用XRD,SEM等对粉体的结构特征和表面形貌进行表征,并通过四球磨损实验考察不同油样的摩擦学性能。结果添加了白云母/CeO2和单一白云母的润滑油,摩擦学性能均比无添加的基础油优越。其中,添加了白云母/10%CeO2复合粉体的润滑油抗磨减摩性能最好,摩擦系数比基础油降低了10.7%,磨斑直径比基础油减少了24.4%。结论白云母/CeO2复合粉体有较好的抗磨减摩能力,对磨损表面有修复作用,合理配比的白云母/CeO2能有效提高基础油的抗磨减摩性能。     

TiN/BN与AlN/BN纳米混合添加剂的摩擦学性能研究

目的探究TiN/BN与AlN/BN两类纳米混合添加剂在油润滑中的摩擦学性能,分析纳米润滑油润滑机理。方法以油酸作为分散剂,提高纳米添加剂在基础油中的分散性能,利用MRS-10A型四球摩擦磨损实验机对不同混合比例、不同添加浓度的TiN/BN与AlN/BN纳米润滑油进行摩擦学性能测试,使用扫描电镜观察磨斑表面形貌,用EDS和XPS检测磨斑表面元素种类及相应化合价态。结果经油酸分散的混合纳米粒子的质量比为1︰1时,纳米润滑油表现出最好的抗磨减摩性能。其中TiN/BN纳米混合添加剂的质量分数为0.6%时,磨斑直径和摩擦系数较基础油分别降低34.97%和16.75%,最大无卡咬负荷提高65.96%;AlN/BN纳米混合添加剂的质量分数为0.2%时,磨斑直径和摩擦系数较基础油分别降低24.49%和11.76%,最大无卡咬负荷提高38.30%。磨斑表面磨痕沟槽深度、宽度减小,表面粗糙度明显降低。结论分散在油液中的AlN、BN、TiN纳米粒子进入摩擦副间发挥承载支撑作用,将滑动摩擦变为滑动-滚动混合摩擦,降低摩擦磨损。进入摩擦副间的AlN纳米粒子由于高表面能特性,沉淀吸附于摩擦表面凹坑处,修复磨损表面,TiN、BN纳米粒子与摩擦表面发生化学反应,生成由Fe-O、Ti-O、BO_x及TiN_xO_y等物质所构成的自修复膜,表现出较好的抗磨减摩及自修复性能。     

微纳米层状硅酸盐矿物润滑材料的摩擦学性能研究

对微纳米层状硅酸盐矿物粉的摩擦学性能进行了研究.将微纳米层状硅酸盐矿物质量比为0.5%分散在汽油机润滑油SJ10W/40中,利用摩擦磨损实验机考察其减摩抗磨及自修复性能,与润滑油SJ10W/40进行对比.采用扫描电子显微镜(SEM)分析试样磨痕表面的形貌和元素组成,并进行了EDS能谱分析.试验结果表明:与润滑油SJ10W/40相比,含层状硅酸盐矿物油样润滑的摩擦副,摩擦因数降低了71.6%.SEM分析表明磨痕处有着与基体材料不同的修复区域,该修复区域沉积着Si、Mg等元素.这些说明微纳米层状硅酸盐矿物润滑材料具有优良的减摩抗磨和自修复性能.     

钛基纳米润滑添加剂的减摩抗磨及自修复特性对比

针对恶劣工作环境会加剧机械设备摩擦副间的磨损而降低其服役寿命的问题,对比研究3种纳米添加剂TiO2、TiN和TiC在不同工况下的摩擦学性能及其自修复性能。根据SH-T0762-2005标准润滑油摩擦因数测定法,并利用MRS-10A型四球磨损试验机磨斑测量光镜、激光共聚焦显微镜和能量色散谱仪(EDS)对磨损表面进行表征,探讨其润滑抗磨及自修复机理。结果表明:钛基纳米添加剂的加入很好地改善了润滑油的抗磨减磨性能,并使其具有一定的自修复性能;当钛基纳米质量分数为0.5%时,其减摩抗磨性能达到最佳。3种纳米添加剂中,对润滑油减摩抗磨性能改善效果最好的是纳米TiO2,而自修复效果最好的则为纳米TiN。故纳米TiN和纳米TiO2作为润滑油添加剂,具有较好的减摩抗磨和自修复能力。     

磨粒对不同服役阶段润滑油的摩擦学性能影响

利用铁谱分析仪和扫描电镜对4个不同服役阶段润滑油中的磨粒含量(质量分数)、大小和形貌进行分析;用SRV摩擦磨损试验机对4个服役油样与新油进行摩擦学性能对比。结果表明:在不同服役阶段,磨粒的含量随着润滑油服役时间的增长而增大,粒径大小关系为异常磨损期磨合磨损期正常磨损期。与新油相比,4个油样的摩擦因数曲线有不同程度的波动,减摩性能下降明显,且减摩系数下降的幅度与所含磨粒粒径大小相关;磨粒使润滑油的抗磨性能下降,与新油的磨斑直径相比,4个油样的增幅分别达到20.0%、25.7%、45.7%、71.4%,且磨粒的粒径、含量与摩擦表面损伤程度成正相关,粒径主要影响磨痕宽度,含量主要影响磨痕密度。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.