自动化机械用高碳钢在纳米锑颗粒添加作用下的摩擦学性能

通过在液压油中添加纳米锑颗粒,对机械用高碳钢在不同摩擦条件下的摩擦学性能进行了研究。结果表明,纯液压油润滑过程中的摩擦主要为磨粒磨损和粘着磨损。纳米锑颗粒通过在摩擦表面形成表面润滑膜,有效减小了表面犁沟效应和粘着磨损,从而起到抗磨减摩作用。     

ZA27锌合金的摩擦磨损特性及磨损机制

采用摩擦磨损试验机研究了油润滑、不同载荷条件下ZA27锌合金的摩擦磨损特性,并与ZCuAl10Fe3铝青铜和ZCuSn6Zn6Pb3锡青铜进行了比较。利用扫描电子显微镜对合金的磨损表面形貌进行了观察。结果表明：3种合金的磨损量均随着载荷的增加而逐渐增加,不同载荷下ZA27合金的摩擦因数及磨损量均低于两种铜合金;随着载荷的增加,3种合金的磨损机制均从磨粒磨损转变为粘着磨损;在较高载荷(550 MPa)下两种铜合金发生了较严重的粘着磨损,而ZA27合金只有轻微粘着磨损,表现出更好的耐磨性能。     

三维连续镍-铝(骨架)增强铝基复合材料的磨损行为

采用真空吸铸和真空热处理技术制备了三维连续镍-铝(骨架)增强铝基复合材料,研究了其在干摩擦条件下的磨损行为.结果表明,复合材料的耐磨性能远优于基体合金.主要是由于硬的Ni2 Al3金属间化合物(骨架)裸露在磨损表面,成为微凸体,起承载作用,抑制或延迟了基体从轻微磨损向严重磨损的转变时间.同时将载荷分散至各个方向,抑制了磨损面基体合金因塑性变形产生的流失.基体合金的磨损机制为严重粘着磨损,复合材料的磨损为以磨粒磨损为主和轻微的粘着磨损.     

石墨增强聚酰亚胺在海水中的摩擦学性能

目的为石墨增强聚酰亚胺复合材料在海水环境下的摩擦学应用提供实验依据。方法利用SST-ST销/盘摩擦试验机,研究了质量分数为15%石墨增强聚酰亚胺复合材料与17-4PH不锈钢组成的摩擦副在海水介质中的摩擦学性能,并与干摩擦和纯水润滑条件下的摩擦学性能进行比较。结果聚酰亚胺复合材料在干摩擦下的摩擦系数和磨损体积最大,分别为0.134、1.930 mm~3。干摩擦条件下,聚酰亚胺复合材料的磨损表面存在较深的犁沟,在犁沟周围出现了材料塑性流动及粘着剥落现象,对偶件表面有聚酰亚胺复合材料转移。磨损机理主要表现为磨粒磨损、材料塑性变形以及粘着和剥落。在纯水润滑下,聚酰亚胺复合材料表面存在较多材料粘着撕裂现象,同时存在宽浅不一的犁沟,磨损机理主要为粘着磨损和磨粒磨损。在海水润滑下,复合材料的摩擦系数和磨损体积最小,分别为0.086、1.235 mm~3,材料磨损表面十分光滑,只有沿运动方向存在少量轻微犁沟,磨损机理主要表现为磨粒磨损。结论石墨增强聚酰亚胺复合材料在海水中的摩擦学性能优于干摩擦和纯水环境下的摩擦学性能。     

二种锌铝合金和一种铝青铜在重载和润滑条件下摩擦磨损特性的研究

试验对比了锌铝合金ＨＤＺＡ、ＺＡ－Ｓｉ和铝青铜ＺＣｕＡｌ１０Ｆｅ３在重载及四种润滑剂润滑条件下的摩擦磨损特性。研究结果表明，ＨＤＺＡ合金和ＺＡ－Ｓｉ合金在润滑脂润滑条件下的摩擦磨损性能明显优于机油润滑；而ＺＣｕＡｌ１０Ｆｅ３合金在常用润滑脂润滑条件下的摩擦磨损性能远不及这二种锌铝合金。油润滑时，磨损机制是犁削、辗压和粘着；脂润滑时，磨损机制主要是辗压，基本上无粘着。油和脂的润滑特性，影响合金的摩擦磨损特性     

脂润滑条件下滑动轴承合金耐磨性能的研究

采用MPX-2000型销-盘式摩擦磨损试验机对ZA30、ZCuSn6Zn6Pb3、ZCuAL10Fe3、ZCuSn10P1四种滑动轴承合金在2#通用锂基脂润滑条件下的耐磨性能进行了对比试验,并在扫描电子显微镜上观察了磨损表面形貌,及用X射线能谱仪分析了对磨副钢试件盘表面成分,探讨了磨损机理.结果表明,ZA30耐磨性能优于ZCuSn6Zn6Pb3、ZCuAL10Fe3、ZCuSn10P1;低载荷时,四种合金的磨损形式均为磨粒磨损;高载荷时,ZA30、ZCuAL10Fe3发生的是磨粒磨损,ZCuSn10P1的磨损形式是磨粒磨损及轻微粘着磨损,ZCuSn6Zn6Pb3发生的是剧烈粘着磨损.     

Mn对ZA43合金组织及磨损性能的影响

研究了Mn的添加量对ZA43合金组织、力学性能及油润滑条件下耐磨性能的影响.试验结果表明,添加适量的Mn元素能够细化合金组织,Mn加入量为0.55％时合金的综合力学性能最佳.高载荷(800 N)时,随着Mn含量的添加,磨损机制由磨粒磨损与粘着磨损的混合形式转化为单一的磨粒磨损.Mn在ZA43合金中主要形成富锰相且在晶界处呈弥散分布,提高了ZA43合金高温强度,同时可以作为硬质点分散剪切应力、阻碍微裂纹的扩展,从而提高合金的耐磨性能.     

重载对不同工艺Al-Si-Mg-Cu合金摩擦磨损性能的影响

研究了不同工艺Al-Si-Mg-Cu合金的组织、力学性能及其重载工况下的摩擦磨损性能。结果表明:微合金化、细化变质处理、热处理及其复合工艺对Al-Si-Mg-Cu合金的组织和力学性能具有显著影响。通过细晶强化、固溶强化、时效强化方式使合金的力学性能显著提升,其微观组织更均匀。重载工况对Al-Si-Mg-Cu合金的耐磨性提出更高的要求。对于复合工艺制备的高强度Al-Si-Mg-Cu合金,摩擦面表层Si相破碎以吸收部分重载压力产生的能量,受塑性流变应力作用均匀分布于摩擦面表层,间接提高合金的表面硬度,改善润滑条件,使摩擦面长时间处于磨粒磨损或轻微粘着磨损机制状态,有助于改善合金的摩擦磨损性能。     

不同组织状态的铜锌铝形状记忆合金滚动磨损性能

研究了在油润滑和酸性介质条件下不同相变温度时不同组织状态的铜锌铝形状记忆合金滚动磨损性能,采用电子扫描显微镜观察了磨损表面,分析了合金的磨损质量机制.结果表明:在油润滑条件下,不同组织状态合金的耐磨性有差异,室温下马氏体状态的合金比母相状态的合金耐磨,其磨损质量机制主要为磨粒磨损;在酸性介质下,不同组织状态的合金磨损性能相近,其磨损质量机制以腐蚀磨损和粘着磨损为主.     

三维连续镍网增强ZL109复合材料磨损机理研究

采用真空吸铸制备了三维连续镍网增强ZL109复合材料,利用M-200型摩擦磨损试验机对复合材料在干摩擦条件下的磨损行为及磨损机理进行了研究.结果表明,三维连续镍网与基体界面处生成了新相Al3Ni2；复合材料的耐磨性始终优于基体合金,且随着网络孔径的减小,复合材料的的耐磨性增强.在磨损过程中,ZL109为典型的粘着磨损,复合材料为粘着磨损和磨粒磨损同时起作用.     

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.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

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.     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

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.