金属注射成形Ti-6Al-4V烧结坯的力学性能与烧结时间关系

研究了在1260℃烧结时,烧结时间对Ti-6Al-4V烧结坯力学性能的影响.结果表明平均晶粒尺寸为45 μm的氢化-脱氢粉末样品在1 260C烧结3 h～6 h,其相对密度为95.6%～96.7%、拉伸强度648 MPa～686 MPa、屈服强度526 MPa～615 MPa,但延伸率仅小于4%.90%气雾化(晶粒尺寸为32.5 μm)和10%氢化-脱氢混合粉末样品在1 260℃烧结2 h～6 h,其相对密度大于95%、拉伸强度800 MPa～848 MPa、屈服强度712 MPa～762 MPa、延伸率7.4%～9.5%.混合粉末样品的力学性能几乎达到美国ASTM粉末冶金的标准.     

SHS-离心熔覆W-C-Fe金属陶瓷涂层的组织与耐磨性研究

以Fe2O3,WO3,Al,C为反应原料,采用SHS-离心法制备W-C-Fe内衬复合钢管。利用X射线衍射(XRD)、扫描电镜(SEM)分析了涂层的组织,用显微硬度仪测量内衬层硬度,并通过磨粒磨损试验测量了该涂层的耐磨性。结果表明,涂层组织包括主相Fe3W3C及少量的WC,W2C,Fe3C,Fe。涂层组织呈梯度分布,靠近基体处晶粒细小,远离基体处晶粒呈粗大树枝状。涂层硬度为13.5±1.6GPa。涂层的主要磨损机制为显微切削。涂层的相对耐磨性是淬火45#钢的16倍以上。     

A comparative study of hard turned and cylindrically ground white layers

Compared with grinding, hard turning is competitive in many cases, with substantial benefits. However, hard turning applications are not preferred, due to the existence of the process-induced white layer on the component surface, which is often assumed to be detrimental to component life. Nevertheless, white layer properties have not been well understood or clearly defined, especially the properties of the white layer induced in hard turning as against grinding. A clear understanding of white layer properties will provide a solid physics basis for product performance analysis and useful data for process selection. In this study, benchmark hard turning and cylindrical grinding experiments were conducted to generate thick white layers for reliable measurement. It was found that the properties of white and dark layers by hard turning and grinding are fundamentally different in four aspects: surface structure characteristics, microhardness, microstructures, and chemical composition. A white layer is not untempered martensite in terms of retained austenite. Additionally, a thick white layer can be produced in grinding under certain conditions.     

碘化钛的电子束熔炼提纯效果分析

通过对碘化钛电子束熔炼提纯效果分析，提出合理、经济的高纯钛制取工艺路线。     

SELECTION OF THE PROCESS PARAMETERS FOR BATH AUTOGENOUS SMELTING OF COPPER

The process parameters for bath autogenous smelting of copper were selected based on dynamic analysis of the experimental data and calculation of the mathematical model. Selecting the slag composition of SiO_2/Fe=0.80 and CaO％=16. desulphur ratio less than 80 wt.-％ in system. and the copper content of matte less than 60 wt.-％, it is able to limit Fe_3O_4 formation and obtain a high desulphurization. The critical oxygen content of the blast increased with decrease of the sulphur content of the concentrate and increase of copper contents of the matte. If the copper contents of the concentrate are respectively of 30 and 35 wt.-％, the critical oxygen contents of the blast will be 48 and 69 wt.-％ respectively. The smelling rate increases linearly with the blast intensity. When the sulphur content of the concentrate is 30 wt.-％, the oxygen content of the blast 70 vol.-％ and the copper content of the matte 60 wt.-％, a blast intensityy of 700 Nm~3/m~2·h results in a smeling rate of 48.81 t/m~2·d.     

高频窄脉冲电化学光整加工工艺特性研究

阐述了高频窄脉冲电化学光整加工原理;比较了其与脉冲电化学加工的区别与联系;通过实验,研究及分析了电流密度、加工间隙、工件材料、加工时间及脉冲参数等因素对加工后表面质量的影响.实验结果表明:在合适的工艺参数情况下,高频窄脉冲电化学光整工艺可大幅度提高加工效率,获得镜面级的表面质量,并能降低加工成本.     

少量添加稀土元素Nd和Er对挤压态Mg-6.0Zn-0.5Mn镁合金干摩擦磨损性能的影响

利用扫描电子显微镜、能谱仪、透射电镜、硬度计、3D轮廓仪和UMT-3型摩擦磨损试验机研究了复合添加微量Nd和Er元素对Mg-6.0Zn-0.5Mn干摩擦磨损性能的影响。结果表明，添加微量Nd和Er元素后，晶界处种类和数量更多的金属间化合物会阻碍晶界的迁移和滑移，基体中动态析出的β_1^"相密度增大且平均长度减小，更多的动态析出相以及弥散分布的金属间化合物提高了使基体的硬度，降低了磨损量。Mg-6.0Zn-0.5Mn合金在5N低载荷下的磨损机制以磨粒磨损为主，并伴有氧化磨损；当载荷增大至20N，磨粒磨损明显减弱，氧化磨损程度增大。复合添加微量Nd和Er后，Mg-6.0Zn-0.5Mn-0.6Nd-0.3Er合金在低载荷下（5N）的磨损机制以磨粒磨损为主，伴有氧化磨损和黏附磨损；由于耐磨性提高，当载荷增大至20N，磨损机制仍以磨粒磨损为主，黏附磨损程度有所减弱，并伴有氧化磨损。     

基于摆动油缸的电液力矩伺服控制系统设计

船舶减摇水舱试验台架是研究和设计减摇水舱的重要试验设备，能否准确的模拟船舶在海浪中的运动是设计试验台架的关键，本文设计了用于驱动船舶减摇水舱试验台架的电液力矩伺服控制系统，在伺服系统中用摆动油缸代替液压马达，建立了摆动油缸的数学模型，仿真结果表明系统符合设计要求。     

高铬铸铁筛板研究

对高铬铸铁合金化和热处理工艺的研究结果表明，选用Ｃｒ／Ｃ比为７左右的Ｃｒ２０型高铬铸铁，在添加适量的Ｍｏ、Ｃｕ、Ｍｎ，并经合适的热处理后，可获得在马氏体基体上分布着较为均匀的Ｍ７Ｃ３型碳化物，使材料达到良好的强韧性配合，耐磨性明显提高，使用寿命明显高于原用筛板，达到与进口筛板相当的寿命，具有明显的经济效益。     

高速切削机床主轴轴承的研究与发展

基于高速切削中高速机床主轴用轴承的运动机理，本文着重从润滑、密封、预紧等方面阐述了滚动轴承的研究与发展，并明确了其与工程应用的关系。