聚四氟乙烯-玻璃纤维复合材料在海水润滑下的摩擦特性（英文）

利用球盘摩擦磨损实验机对按照不同比例共混的聚四氟乙烯-玻璃纤维复合材料在海水中的摩擦特性进行了测试,并且在试验后利用扫描电镜(SEM)分析实验材料磨损表面。结果显示:玻璃纤维的添加使得聚四氟乙烯基体的减摩耐磨性能得到大幅度提升。按20%的比例(质量)添加了玻璃纤维的聚四氟乙烯在海水润滑下比其他比例的具有更低的摩擦系数和磨损率。对于20%的进一步研究发现摩擦系数和磨损率随着负载的增加而增加,并随着摩擦表面的相对运动速度的增加而减小。     

新型镶嵌式自润滑轴承材料的摩擦磨损性能研究

制备以聚四氟乙烯(PTFE)、石墨、铅粉、玻璃纤维(GF)掺和成自润滑剂的铜基镶嵌式自润滑轴承材料样品,采用立式万能摩擦磨损试验机,在干摩擦条件下考察其摩擦磨损性能,并用三维视频显微镜对摩擦表面进行形貌观察和分析.结果表明,在PTFE中掺入不同配比石墨、铅粉、GF形成的自润滑剂,可不同程度地降低铜基自润滑轴承材料样品摩擦系数和磨损率,且GF的加入还能大幅度降低摩擦配副的磨损率.其中镶嵌有40%PTFE+20%石墨+20%铅粉+20%GF自润滑剂的铜基自润滑轴承材料样品具有较佳的综合摩擦磨损性能.     

晶须CaCO3和PTFE填充聚醚醚酮复合材料的摩擦学性能

用MM200磨损试验机和45钢环配副,研究不同含量碳酸钙(CaCO3)晶须和10%的聚四氟乙烯(PTFE)共同填充聚醚醚酮(PEEK)复合材料的摩擦磨损性能,用扫描电镜观察磨损表面形貌并分析磨损机理。结果表明,随着复合材料中晶须含量增加,摩擦系数持续降低,最低可降到纯PEEK的1/2;复合材料的磨损率随晶须含量的增加先大幅度减小后又缓慢回升,当晶须含量为15%-20%时,磨损率降至3.3×10-7mm3/Nm,仅为纯PEEK的3.6%,20?CO3/10%PTFE/PEEK综合摩擦学性价比较好。CaCO3晶须增强PEEK减少了复合材料在摩擦过程中摩擦副表面粘着和剥层,阻止基体树脂的热塑性变形,同时PTFE的优先粘着转移使得复合材料在对偶件表面形成连续、均匀的转移膜,两者协同有效降低摩擦系数和磨损率,提高材料的摩擦学性能。     

离子氮化高速钢沉积掺钨类金刚石薄膜的摩擦磨损性能研究

目的 探究湿度和加载载荷对氮化高速钢基体上沉积掺钨类金刚石薄膜的摩擦磨损性能的影响.方法 通过非平衡磁控溅射技术在氮化处理后的高速钢基体上制备了掺钨类金刚石(W-DLC)薄膜.利用纳米压痕仪和划痕实验检测了薄膜的硬度和结合力,通过摩擦磨损实验检测了不同湿度(30％和60％)和不同载荷(10、20、30、40 N)条件下薄膜的摩擦系数和磨损率,利用扫描电子显微镜对摩擦磨损后的形貌与成分进行了观察与分析,并利用拉曼光谱对磨屑的结构进行了分析.结果 在湿度为30％和60％的条件下,薄膜的摩擦系数均随着摩擦载荷的增加呈现先增加后降低的规律,且在载荷为30N取得最小值;磨损率均随着载荷的增大而增加,且湿度为60％条件下薄膜的磨损率大于湿度为30％条件下的磨损率.磨屑产物的拉曼光谱结果显示,摩擦过程导致薄膜发生石墨化转变,而载荷和湿度对磨屑结构的影响不大.结论 高速钢基体进行离子氮化后,可以明显提高掺钨类金刚石薄膜的硬度和结合力.     

石墨含量对铜基材料摩擦磨损性能的影响

探讨了石墨含量对铜基材料摩擦磨损性能的影响和材料的摩擦磨损机理。结果表明：不含石墨时，材料的摩擦系数和磨损率均较大，磨损主要为粘着磨损；添加石墨后，材料的摩擦系数和磨损率均显著降低，且随石墨含量增加，摩擦系数逐渐降低，在一定石墨含量范围内（＜３．５％），磨损率也逐渐减小，这与材料的强度、硬度有关。材料的磨损以应变疲劳磨损为主。随载荷增加，摩擦系数和磨损率均增加。     

激光织构化青铜表面在油润滑条件下的摩擦特性

利用UTM-2摩擦磨损试验机进行试验,考察了在PAO4基础油润滑下,不同温度条件下织构(不同面密度-ρt,5%、10%、20%和排列方式-θ=0、30°、60°、90°)对青铜表面摩擦性能的影响。结果表明:在PAO4基础油润滑下,在60℃和100℃工况下,相对于原始表面,织构增大了摩擦系数和磨损率,而在25℃和150℃工况下,表面织构对摩擦磨损的影响不明显;随着温度的升高,原始表面和各类型织构表面的摩擦系数与磨损率都是呈现先升高再降低的趋势,No.3(ρt=20%,θ=0)和No.5(ρt=20%,θ=60°)试样有着较好的耐磨性能。     

EM42与GCr15干摩擦磨损性能的研究

在HT- 1000型高温摩擦磨损试验机上对M42高速钢的进行干滑动摩擦磨损试验.利用SEM观察并分析摩擦面磨损形貌及磨损机理.结果表明:M42高速钢在与GCr15钢配副干摩擦条件下,随着摩擦速度的增加,摩擦系数先降低后升高再降低;当摩擦热累积达到一定值后,摩擦表面产生严重塑性变形和化学变化,摩擦副表面起初产生氧化磨损、粘着磨损、磨粒磨损和犁沟磨损,形成转移润滑膜.此时摩擦系数较低,但磨损率相对又有所回升.     

石墨烯/高密度聚乙烯在水润滑条件下的摩擦学性能研究

目的 探究石墨烯/高密度聚乙烯高分子材料在水润滑条件下的摩擦学性能,提高高密度聚乙烯的自润滑和耐磨损性能.方法 采用石墨烯纳米片填充高密度聚乙烯材料,利用RTEC摩擦磨损试验机,开展新型复合材料在水润滑条件下的摩擦学性能研究.通过分析新型复合材料的典型机械性能、摩擦系数、磨损形貌以及摩擦副接触表面的元素成分及分布情况,揭示石墨烯/高密度聚乙烯在水润滑条件下的摩擦磨损机理.结果 新型复合材料的拉伸强度、撕裂强度和肖氏硬度均随着石墨烯纳米片含量的增加而先增高后降低,1.5％石墨烯纳米片改性高密度聚乙烯表现出最高的强度,分别为19.81 MPa、31.34 MPa和92.6HSA.新型复合材料的平均摩擦系数和体积行程磨损率总体随着石墨烯含量的增加而减小,1.5％石墨烯纳米片改性的高密度聚乙烯平均摩擦系数和体积行程磨损率比纯高密度聚乙烯分别降低了53.6％和73.9％.Si3N4陶瓷球与1.5％、0.6％石墨烯纳米片改性高密度聚乙烯进行3600 s对磨试验,其磨损区域的碳元素质量分数分别约为3.5％和0.3％,表明含量较高的石墨烯纳米片有利于在微观界面形成石墨烯润滑层,从而降低摩擦系数.结论 石墨烯纳米片显著影响高密度聚乙烯的自润滑性能和耐磨损性能,适量的石墨烯纳米片促进了高密度聚乙烯磨损界面石墨烯润滑层的形成,降低摩擦系数和磨损量.该研究可为设计低摩擦、耐磨损的水润滑轴承复合材料提供参考.     

EM42与TC4干摩擦磨损性能的研究

在MMW-1高温高速摩擦试验机上进行M42高速钢的高速干滑动摩擦磨损试验。利用SEM观察并分析磨损形貌及磨损机理。结果表明:M42高速钢在与TC4钛合金配副干摩擦条件下,随着摩擦速度的增加,摩擦因数和磨损率先降低后升高。当摩擦热累积达到一定值后,摩擦表面产生严重塑性变形甚至形成润滑薄膜。随着载荷的增加,摩擦表面起初产生犁沟磨损、磨粒磨损和粘着磨损,形成转移润滑膜,该膜厚度增加并被带走脱落;摩擦系数先降低然后升高,磨损率随着载荷的增加而逐渐上升。     

WCp/Fe-C再生复合材料的高速摩擦磨损性能研究

通过对废旧WCp/Fe-C复合材料辊环的重熔和离心铸造,获得了由外表面厚度达10～15 mm的再生复合材料层和芯部Fe-C基体材料组成的复合结构辊环.使用MMS-1G高速销盘摩擦试验机,研究了WCp/Fe-C再生复合材料层的摩擦磨损性能.试验结果表明:再生复合材料的磨损率在相同的摩擦速度下随着载荷的增加逐渐增大,而摩擦系数逐渐减小;在相同的载荷下,再生复合材料的摩擦系数随着摩擦速度的增大而减小,磨损率随着摩擦速度的增大而增加.与原复合材料相比,再生复合材料的耐磨性能略有降低,但远高于高速钢.     

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).     

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.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

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.