β相锻造加工工艺中固溶温度对Ti6242合金保载疲劳性能的影响

对Ti6242钛合金进行不同固溶温度(960,980℃)下的β相锻造加工,研究了不同固溶温度下合金的显微组织和拉伸性能,以及高峰值应力下的低周疲劳与保载疲劳性能。结果表明:不同固溶温度下β相锻造后Ti6242合金组织相似,均由网篮组织、晶内α相片层组织和羽毛状α相集束组织组成,960℃固溶温度下羽毛状α相集束多于980℃固溶温度下。与960℃固溶温度下β相锻造后相比,980℃固溶温度下β相区锻造后合金的强度较高,断后伸长率略低,低周疲劳寿命明显较低,保载疲劳敏感系数较低;980℃固溶温度下合金的保载疲劳寿命约为960℃固溶温度下的1.3倍。不同固溶温度下β相锻造后低周疲劳断口的疲劳特征明显,均由疲劳裂纹源、疲劳裂纹扩展区和瞬时断裂区组成,而保载疲劳断口均由韧窝和疲劳条带组成,呈现出一种以蠕变断裂为主、疲劳断裂为辅的断裂模式。

可加工复相陶瓷材料的研究现状与发展

介绍可加工复相陶瓷的研究发展现状。着重介绍可加工BN系复相陶瓷的研究现状与发展。主要论述可加工BN系复相陶瓷的制备工艺过程及力学性能和可加工性能等。对可加工复相陶瓷材料的研究发展方向作分析和预测。

人孔座相贯曲面机加工艺研究

在机械零件的数控加工中,空间复杂曲面所占比例越来越大,加工质量要求不断提高,对数控加工工艺提出了更高的要求。人孔座相贯曲面只能使用数控镗床采用卧铣方式加工或数控龙门铣采用立铣方式加工。通过先进的CATIA软件CAM模块对这两种加工方式进行加工模拟,并通过对这两种加工方式装夹方法的对比,最终合理选择加工方式和机床、刀具,完成人孔座圆柱相贯曲面、J形坡口扫掠曲面的加工。

固相剪切碾磨加工回收利用废弃人工草坪

人工草坪综合性能较好,被大量应用于现代体育场中,但是废弃量急剧增加。废弃人工草坪由于组分的相容性较差,编织结构复杂,不易进行分离、分类及回收利用,造成了严重的环境污染和资源浪费,是亟待解决的关键问题。采用固相剪切碾磨加工技术回收利用废弃人工草坪(WAT),能将其在室温下进行超细粉碎和均匀分散,由粉体粒径及粒径分布控制相畴尺寸,利用熔融加工制备了高性能复合材料。采用激光粒度测试、扫描电子显微镜、高压毛细管流变仪及万能拉力机等测试方法研究了固相剪切碾磨加工技术对WAT粉碎效率、粉体形貌、加工流变性能、WAT复合材料相畴及力学性能的影响。结果表明,固相剪切碾磨加工技术制备的WAT超细粉体加工性能明显提高,表观黏度下降,平衡扭矩下降至4.8 N·m。WAT复合材料的相畴尺寸最小值为7.2μm,力学性能明显提高,拉伸强度可以达到16.3 MPa,拉伸模量可以达到312.7 MPa,断裂生长率提升至18%,为高质高效地回收利用WAT提供了新途径。

低温固相反应挤出PET/PC合金中的多重网络增韧结构

以聚对苯二甲酸乙二酯(PET)瓶片为主要原料,加入聚碳酸酯(PC)、热塑性弹性体及扩链剂,采用低温固相反应挤出制备了具有良好强度与韧性的新型合金.在加工过程中产生PET相和PC相互穿的网络结构的同时,反应性扩链剂在PET相中发生交联反应,形成了次级网络结构.由于这些网络结构的存在,使合金材料的力学性能得到明显提高,特别是缺口冲击性能有了明显的改善.

搅拌摩擦孔道加工技术发展及应用展望

搅拌摩擦孔道加工技术(FSCP)是一种直接在铝合金材料上加工成形内部通道的固相加工专利技术,可用于结构减重及内部液体流道成形等。介绍了FSCP技术专利的技术进展及英国焊接研究所采用静轴肩FSC技术制备铝合金液冷流道的加工技术原理及应用问题,通过分析焊接过程及X射线断层扫描检测表明:搅拌工具形状及搅拌工具旋转速度、焊接前进速度、轴向力等工艺因素是影响液冷通道成形的关键工艺因素,搅拌摩擦加工过程中搅拌工具对金属的搅拌、挤压及塑化流动使回退侧金属的截面呈现参差不齐的界面形状。

凝析气藏地面轻烃回收及粗加工过程的模拟

轻烃回收指标预测已作为凝析气田开发方案经济评价的重要依据之一。在已知凝析气井流物组成条件下，建立了井口－常温高压分离－节流前浅冷－节流膨胀－透平机膨胀深冷分离－脱乙烷塔－脱丁烷塔产品的系统模拟计算模型，采用ＰＲ状态方程进行节流和精馏计算中的焓以及透平机膨胀中的滴的计算。在精馏计算中，采用了矩阵法求解精馏数学ＭＥＳＨ模型，自行开发了相应的计算程序，选用我国一凝析气藏实际数据在ＰＶＴ拟合后进行了实例计算。研究表明，此计算系统可靠，能满足气田开发中方案设计指标需要。

Morphology development of elongated α phases in hot working of large-scale titanium alloy plate

The role of subtransus hot working on microstructure morphology of TA15 titanium alloy plate with elongatedαphases was studied by quantitative metallography on different sections. The results show that the microstructure morphology is mainly affected by loading direction. When the sample is compressed along normal direction, microstructure on the section vertical to normal direction has equiaxed primaryαphase but microstructure on the section vertical to rolling direction has strip primaryαphase with long axis along tangential direction. When the sample is compressed along rolling direction, microstructure on the section vertical to normal direction has strip primaryαphase elongated along tangential direction but microstructure on the section vertical to rolling direction consists of strip and irregular broad-band primaryαphase. The strip primaryαphase aspect ratio is smaller at lower temperature due to the dynamic break-down ofαphase. The difference on primaryαphase aspect ratio between different sections decreases after compression along distinct directions in two loading passes, suggesting the improvement of equiaxity of primaryαphase.

Tuning mechanical properties for β(B2)-containing TiAl intermetallics

Based on the analyses of the microstructures and phase diagrams of the TiAl-based alloy, the relationship among the composition, structure and mechanical properties of the B2-containing y-TiAI alloys was reviewed. The refinement of microstructures and improvement of mechanical properties of TiA1 alloy through stabilization of the β/B2 phase were reviewed. The mechanism of the superplastic behavior of the B2-containing y-TiAI alloys was discussed. With a reasonable addition of β-stabilizer, metastable B2 phase can be maintained, which is favorable for fine-grained structure and better high-temperature deformation behaviors. The mechanical properties of the B2-containing TiAI alloy, including the deformability and elevated temperature properties, can also be improved with doping elements and subsequent hot-working processes. The above mentioned researches discuss a new way for developing TiAI alloys with comprehensive properties, including good deformability and creep resistance.

铝塑复合包装的应用及废弃物回收利用新技术

包装是商品使用、储存、运输的重要保障,不可或缺。塑料包装轻质、易加工、性价比高,增长极快,成为现代社会主要的包装材料,其中铝塑复合包装通过材料优势互补,可满足阻隔性、抗菌性、力学性能和印刷性能等多功能要求,应用广泛,但即用即弃,废弃物难分离难回收利用,无法降解,也难焚烧处理,污染环境,浪费资源,亟待治理。本文综述了铝塑复合包装结构性能和应用,以及废弃物回收利用难点,重点介绍了本团队采用自主创新的固相剪切碾磨加工装备和技术,实现废弃铝塑复合包装的室温超细粉碎和均匀分散,改善加工性和力学性能,制备可拆卸物流包装箱及导热导电功能制品的研究工作。

Deformation behavior and processing maps of Mg-Zn-Y alloy containing Ⅰ phase at elevated temperatures

The microstructure and mechanical properties of extruded Mg-Zn alloy containing Y element were investigated in temperature range of 300-450°C and strain rate range of 0.001-1 s-1 through hot compression tests.Processing maps were used to indicate optimum conditions and instability zones for hot deformation of alloys.For Mg-Zn and Mg-Zn-Y alloys,peak stress,temperature and strain rate were related by hyperbolic sine function,and activation energies were obtained to be 177 and 236 kJ/mol,respectively.Flow curves showed that the addition of Y element led to increase in peak stress and decrease in peak strain,and indicated that DRX started at lower strains in Mg-Zn-Y alloy than in Mg-Zn alloy.The stability domains of Mg-Zn-Y alloy were indicated in two domains as 1)300°C,0.001 s-1;350°C,0.01-0.1 s-1 and 400°C,0.01 s-1 and 2)450°C,0.01-0.1 s-1.Microstructural observations showed that DRX was the main restoration mechanism for alloys,and fully dynamic recrystallization of Mg-Zn-Y alloy was observed at 450°C.The instability domain in Mg-Zn-Y alloy was located significantly at high strain rates.In addition,the instability zone width of Mg-Zn and Mg-Zn-Y alloys increased with increasing strain,and cracks,twins and severe deformation were considered in these regions.

Kinetics of Formic Acid-autocatalyzed Preparation of Performic Acid in Aqueous Phase

Performic acid （PFA） is an oxidant used in chemical processing, synthesis and bleaching. The macro kinetic models of synthesis, hydrolysis and decomposition of PFA were investigated via formic acid-autocatalyzed reaction. It was found that the intrinsic activation energies of PFA synthesis and hydrolysis were 75.2 kJ·mol^-1 and 40.4 kJ·mol^-1 respectively. The observed activation energy of PFA decomposition was 95.4 kJ·mol^-1. The experi-mental results indicated that the decomposition of PFA was liable to occur even at the ambient temperature. Both the spontaneous decomposition and the radical-introduced decomposition contributed to the decomposition of PFA.

Fabrication of integrated resistors in printed circuit boards

In order to utilize integrated passive technology in printed circuit boards （PCBs）, manufacturing processing for integrated resistors by lamination method was investigated. Integrated resistors fabricated from Ohmega technologies in the experiment were 1 408 pieces per panel with four different patterns A, B, C and D and four resistance values of 25, 50, 75 and 100 fL Six panel per batch and four batches were performed totally. The testing was done for 960 pieces of integrated resistors randomly selected with the same size. The value distribution ranges and the relative standard deviation （RSD） show that the scatter degree of the resistance decreases with the resistor size increasing and/or with the resistance increasing. Patterns D with resistance of 75 and 100% for four patterns have the resistance value variances less than 10%. Patterns C and D with resistance of 100 Ω have the manufacturing tolerance less than 10%. The process capabilities are from about 0.6 to 1.6 for the designed testing patterns, which shows that the integrated resistors fabricated have the potential to be used in multilayer PCBs in the future.

Morphology transformation of primary strip α phase in hot working of two-phase titanium alloy

Microstructural development in hot working of TA15titanium alloy with primary stripαstructure was investigated withthe aim to globularizeαstrips.Results show that the mechanisms of morphology transformation are the same to the spheroidizationmechanisms of lamellar structure.Boundary splitting and termination migration are more important than coarsening due to the largesize of stripα.Theαstrips are stable in annealing due to the unfavorable geometrical orientation of intra-αboundaries,the largethickness of strip and the geometrical stability ofαparticles.Predeformation and low speed deformation accelerate globularization ofαstrips in the following ways:direct changing of particle shape,promotion of boundary splitting and termination migration byincreasing high angle grain boundaries and interfacial area,promotion of coarsening by forming dislocation structures.Largepredeformation combined with high temperature annealing is a feasible way to globularize stripα.

Conception of tooling adapted to thixoforging of high solid fraction hot-crack-sensitive aluminium alloys

Thixoforging is a type of semi-solid metal processing at high solid fraction (0.7<φs<1), which involves the processing of alloys in the semi-solid state.Tooling has to be adapted to this particular process to benefit shear thinning and thixotropic behaviour of such semi-solid material.Tooling parameters, such as the forming speed and tool temperature, have to be accurately controlled because of their influence on thermal exchanges between material flow and tool.These thermal exchanges influence the high-cracking tendency and the rheology of the semi-solid material during forming, which affects parts properties and therefore their quality.Extrusion tests show how thermal exchanges influence quality of thixoforged parts made of 7075 aluminium alloys at high solid fraction by modifying process parameters like forming speed, tool temperature and tool thermal protector.Thus an optimum in terms of thermal exchanges has to be found between surface quality and mechanical properties of the part.A direct application is the evaluation of surface quality of thixoforged thin wall parts made of 7075 aluminium alloy.

CAE-Based Robust Optimization for Deep-Drawing Process of Sheet Metal Forming Using Grey Relational Analysis Method

The theory of grey systems is a new technique for performing prediction, relational analysis and decision making in many areas. The grey relational analysis was used to optimize the deep-drawing process parameters with considerations of the multiple response （the wrinkle, crack and thinning variation）. The deep-drawing parame- ters, such as the blank holding force （Fhh）, the radii of punch and die （R1.R2）, the coefficients of friction （μ1,μ2,μ3） are considered. An orthogonal array is used for the experimental design. The multiple response values are ob- tained making use of finite element analysis （FEA）. Optimal process parameters are determined by the grey rela- tional grade obtained from the grey relational analysis for multi-performance characteristics （the wrinkle, crack and the thinning）. The analysis of variance （ANOVA） for the grey relational grade is implemented. The results show that the quality of stamped parts can be improved effectively through the new approach. The grey relational analysis can be applied in sheet metal forming.

机械专业教学实行“产教结合”的探索

作为具有产业化和商业特征的职业技术教育,如何适应市场经济的需要,搞好产教结合,培养德智体全面发展的技术人才,已成为一线教师必须作出回答的重大课题了。本文阐述了顺德陈村职业技术学校机械专业实行产教结合教学模式的方法与意义。

Kuhn＇s Notion of Theory Choice and the Dual-Process Theory of Cognition

In The Structure of Scientific Revolutions, Kuhn claimed that theory choice is a conversion experience and depends upon the personality or psychology of the individual scientist making the choice. Critics charged Kuhn with an irrational and a relativistic position concerning theory choice, arguing he advocated a subjective instead of an objective approach to how scientists choose one theory over another and thereby undercut epistemic accounts for the generation of scientific knowledge. In response to critics Kuhn insisted that his approach, although subjective, was still rational in that the criteria----vomposed of epistemic values--determining theory choice operate both objectively and subjectively. Recent work in cognitive neuropsychology, particularly in the dual-process theory of cognition, supports Kuhn＇s notion of theory choice. In this paper, I initially discuss Kuhn＇s approach to theory choice, along with criticism of it and his response to the criticism, followed by an examination of the dual-process theory of cognition. I then explore the application of dual-process theory to Kuhn＇s notion of theory choice, especially in terms of a historical case study from the biomedical sciences. I finally discuss briefly the implications of the dual-process theory for contemporary philosophy of science.

Retinal Prosthesis:A Potential Benefit for the Blind

Retinal degenerative diseases may induce the degeneration of outer retina and in turn,blindness.Nevertheless,due to the maintenance of inner retina,the coding and processing of visual neurons responses are still able to be executed naturally.Therefore,an effective retinal prosthesis device may be developed by mimicking the function of outer retina:transferring the visual light into artificial stimulus and delivering the stimulus to the retina aiming to evoke the neural responses.As two main developing directions for current retinal prosthesis,epiretinal(ER)and subretinal(SR)prosthesis are both undergoing experimental stage and possessing advantages and limitations.Further investigations in power supply,biocompatibility,etc.are still required.Additionally,suprachoroidal transretinal stimulation(STS)and neurotransmitter-induced stimulation as some other alternatives in retinal prosthesis are also considered as promising research directions,although they are not mature enough to be applied commercially,either.