Cu-Al-Mn-Ti形状记忆合金抗母相时效的研究

利用弯曲试验、X射线衍射、金相和扫描电镜及透射电镜观察等方法研究了CuAl24Mn3Ti2合金在不同母相时效处理条件下的抗母相时效能力。结果表明,对于同一种变形量,Cu-Al-Mn-Ti合金在母相时效时,形状记忆效应随不同时效保温温度呈现先下降后上升的规律性变化,其中400℃记忆效应最好,500℃最差;而形状记忆效应则随不同时效保温时间呈现不同程度的先上升后下降的规律性变化,400℃合金下降缓慢,500℃下降加快;Mn和Ti的加入细化了组织,并且形成了富Mn和富Ti相,强化了合金组织,提高了合金的记忆效应。     

金属型铸造高铬铸铁Cr20组织及性能的研究

研究了金属型铸造高铬铸铁Cr20的铸态组织和性能,以及主要合金元素对性能的影响。结果表明,用金属型铸造的高铬铸铁Cr20的铸态组织为奥氏体基体,共晶碳化物为孤立的块状分布,具有较高的硬度和一定的韧性,并且还可以降低合金元素Mo和Ni的加入量。对于不能通过常规热处理进行淬火硬化的高铬铸铁件,可用金属型铸造来满足在铸态下使用的要求。     

Effect of solid fraction on steel-mushy Cu-graphite pressing bonding

The pressing bonding of steel plate to QTi3.5-3.5graphite slurry was studied. The bonding conditions were 620℃ for preheating temperature of steel plate, 530℃ for preheating temperature of dies, 50 MPa for pressure and 2 min for pressing time. The relationship between the solid fraction of QTi3.5-3.5graphite slurry and the interracial mechanical property of bonding plate was obtained. The results show that when the solid fraction of QTi3.5-3.5graphite slurry is smaller than 45.8%, the interracial shear strength of bonding plate increases with the increasing of solid fraction. When the solid fraction is larger than 45.8%, the interracial shear strength decreases with the increasing of solid fraction. When the solid fraction is 45.8%, the largest interracial shear strength of bonding plate 127 MPa can be got, and the interface is made up of Fe-Cu solid solution.     

流动液体中夹杂物超声去除的影响因素

以高密度聚乙烯（HDPE）颗粒和水形成的悬浮液为研究体系。考察了有无超声波作用下。介质流量、夹杂物数量以及夹杂物的粒径对总去除率、上浮去除率、壁面粘附去除率的影响。实验结果表明，在短时间内（30s)超声波对流动液体中的夹杂物具有明显的去除效果。总去除率达93％。夹杂物的总去除率随着超声波输入电功率的增大而提高；超声波对较多数量或较大粒径的夹杂物去除效果更显著。超声波作用下流动液体中的夹杂物比静止液体中的更容易去除。超声波对流动液体中夹杂物去除效果的去除机理主要是通过气泡捕获夹杂物，超声空化效应产生直接包裹夹杂物的气泡以及通过夹杂物碰撞凝聚使夹杂物容易上浮实现去除。     

数控加工仿真系统的研究现状

介绍了数控仿真系统研究的状况,并对国内外的研究进行了比较,由此提出了数控仿真系统的发展趋势。     

New method for determination of the pose of the grinding wheel for thinning drill points

Traditionally, twist drills are reconditioned by thinning the web so the correct chisel edge length is restored. Recently, thinning has been included in the original design of drills so as to reduce torque and tool force. Because the International Standards Organization (ISO) has a system which can comprehensively model conventional twist drills but cannot model thinning specifications, this paper presents a system for precise mathematical modeling and CNC control of a 6-axis grinding workstation for drill thinning. The presented method determines the position and orientation of the grinding wheel based on the evaluated rake and clearance angles of ISO standards for 2-flute twist drills. The mathematical model and background are discussed. For verification and demonstration, two experimental drills are produced to the identical ISO standard except that one is thinned. The modeling herein is of value to industry and research if incorporated into computer software for drill design and manufacture. It is suitable for linear notch-type cutting with controlled variable rake angle along the secondary cutting edge for purposes of thinning, notching, dubbing and advanced drill research.     

冷塑变及时效处理对CuCrNi合金导电率的影响

研究了冷塑变及时效处理对CuCrNi合金导电率的影响。结果表明:形变能降低CuCrNi合金的导电率,而形变后再经适当的时效处理能提高合金的导电率,且在变形量为0％-70％时,变形量越大,该合金时效处理后的导电率越高,同时合金获得较高导电率的时效处理时间越短。当CuCrNi合金形变后再经500℃时效处理,可获得最高的导电率。     

电脉冲孕育处理对Al-Cu-Mn合金时效过程的影响

考察了不同电脉冲孕育处理参数对Al-Cu-Mn合金时效过程的影响，结果表明：电脉冲孕育处理加速了A1．5％Cu-0．8％Mn合金时效进程，缩短了时效时间，使合金最大显微硬度较未处理试样提高了13％～17％；但不同的电脉冲参数影响时效过程的程度不同，一定范围内，500V电压，30s处理时间，频率为3Hz的电脉冲参数在740℃处理时，合金时效后的显微硬度最高。     

高层建筑消防机器人的机构研究与分析

结合高层建筑火灾现场的特殊条件,介绍了高层建筑消防救灾机器人的整体运作机理以及各主要功能部件的机构组成和工作原理.该机器人可以实现在保持姿态不变的条件下,携带一定数量的救生物品和灭火工具快速运动到壁面目标位置进行破障救生和火情探测,并将探测结果及时传递给处于安全地区的控制系统,便于救灾人员及时采取相应的措施.     

学术自由研究述评

本文主要阐述了有关学术自由这一议题的研究意义、研究现状及其在学理上搭建一个比较合理的理论基础的可能性