双层铸件铸造工艺的试验与应用

采用分隔砂芯，可在一个铸型内制作两层铸件，明显提高了生产率。计算机模拟表明，这种工艺方法还可以降低铸件冷却速度。通过调整隔件用的砂芯厚度，可以将铸件原来很小的补缩通道扩宽，使冒口真正发挥补缩作用，解决了缩松问题。     

ICT技术测试炭/炭复合材料内部密度分布

利用工业计算机辅助层析成像技术(ICT)对不同尺寸的炭/炭复合材料进行了断层摄像试验,发现该技术能真实地反映材料内部的实际密实情况.利用ICT图像给出的相关数据,经过一系列计算,得出材料内部各处的密度值,该方法比传统的排水法所得的结果精确,而且无需从制品中取样,节省了材料和时间.ICT技术有望用于其它复合材料的密度测试.     

拉深筋对板厚减薄量的影响

利用数值模拟的方法,着重研究了板料通过半圆形拉深筋和矩形拉深筋时板厚的变化规律和特点,分析了板料通过拉深筋时影响板厚减薄的主要因素,为探索板料通过拉深筋后的后续可成形性提供理论基础。研究结果表明,板料通过拉深筋时的弯曲变形是导致板厚减薄的根本原因,同时减薄量还受到板内张力及变形程度的影响。并指出累积等效应变不适于用来评价板料通过拉深筋后的变形程度。     

液压机用液压缸的计算机辅助设计

针对液压机用液压缸，在AutoCAD R14平台上开发了一套以专家系统、结构优化、参数化绘图技术为支撑的计算机辅助设计软件YYGCAD2．0。其专家系统YYGES的知识和数据来源于液压机领域专家的经验，基于规则推理，具有庞大的数据库和良好的人机接口。参数化绘图模块是在Visual C 6．0环境下用Object ARX语言开发的应用程序，运行速度快，利用MFC(微软基础类库)开发的用户界面，具有Windows风格。操作简单，易于推广。用户在输入液压缸的主要技术参数后，可以借助专家系统直接设计出液压缸的成套施工图纸，也可以通过优化设计得到结构最优并符合技术要求的设计图纸。该软件可以在Windows95／98／NT系统的微机上运行，具有较高的设计效率和设计水平。     

铸钢表面耐热复合涂层的制备

采用铸造反应合成技术制备出TiC/Ni3Al表面复合涂层材料,研究了涂层的物相、组织和界面形态,测试了涂层的硬度和耐磨性。结果表明：Ti-C-3Ni-Al体系反应完全,产物为TiC和Ni3Al。表面复合涂层中直径为1～3μm的TiC颗粒呈球形镶嵌在Ni3Al基体上,随着TiC含量的提高,颗粒尺寸略有长大、分布更均匀、涂层更致密,且涂层与钢基体界面为良好的冶金结合,随TiC含量的变化而界面呈现出不同的形貌,在TiC含量〈45%时,涂层为一整体,从涂层到界面处Ni、Al、Ti、Fe元素呈梯度变化;在TiC含量≥45%时,涂层出现了分层现象。随着涂层中TiC含量的增高,材料的硬度和耐磨性提高,表面复合涂层的硬度和耐磨性均明显高于钢基体。     

Ti(CN)涂层的宏观应力与破坏方式SCIEI

用Nb-752薄长条做衬底材料,按C_2H_2/N_2分别为3/2和2/3两种气体流量比获得Ti(CN)_(3/2)和Ti(CN)_(2/3)两种涂层,由单面镀膜样品弯曲的曲率半径计算出涂层的宏观残余应力约为2—3GPa,其中热应力占10—20％,涂层与基材界面处应力状态分析表明,界面存在一剪切残留应力并计算大小为0.1—0.2GPa。此外,采用应力圆法分析涂层受力状态,讨论了涂层受外载作用下的破坏方式。     

Determination of isothermal section of Fe-Ti-Zr ternary system at 1173 K

Phase relations in the Fe-Ti-Zr ternary system at 1173 K were investigated by means of diffusion-triple approach together with electron probe microanalysis（EPMA） technique. A series of tie lines and tie-triangles were determined and the isothermal section at 1 173 K was established, which consists of four three-phase fields： β（Ti, Zr）＋FeZr2＋FeTi, FeZr2＋FeTi＋Fe2Zr, FeTi ＋Fe2Zr ＋Fe2Ti and Fe2Zr ＋Fe2Ti ＋Fe. The results show that the largest solubility of Ti in Fe2Zr is about 11.3 %（mole fraction） and the solid solubility of Ti in FeZr2 is about 26.9%, the solid solubility of Zr in Fe2Ti is about 8.1% and the solid solubility of Zr in FeTi is 7.2%. The binary compound FeZr2 is nearly a linear compound. No ternary compound is found.     

Determination of phase equilibria in the Ni-Ta-Zr system at 1223 K

The phase equilibrium relations of the ternary Ni-Ta-Zr system at 1223 K were investigated by means of diffusion triple and electron probe microanalysis (EPMA) techniques. Two ternary compounds were found and a series of tie lines and tie triangles have been determined. The maximum solubility of Ta in NiZr2 is about 13.5% (atom fraction). The corresponding tentative isothermal section at this temperature was constructed based on current experimental information.     

某直升机主减撑杆疲劳试验断裂分析

某直升机主减撑杆在进行疲劳试验时,未达到疲劳周次发生断裂,通过对断裂主减撑杆进行断口检查、金相组织观察以及构件之间配合状况分析,找出主减撑杆提早断裂的原因是微动磨损疲劳断裂.     

Analysis of the abnormal resistance in AlGaN/GaN heterostructure＇s ohmic contact tests

Ti/Al/Ti/Au and Ti/Al/Ni/Au ohmic contacts were fabricated on AlGaN/GaN heterostructure under different temperatures of rapid thermal processing （RTP）. Since abnormal resistance values were observed during the contact resistance testing,the surface morphology and contact borders of the samples were analyzed to determine the physical mechanism. Such abnormal phenomenon is found to originate from cracking of the AlGaN layer during RTP,flowing of Ti/Al metallic liquid along the crevices,and continuous reaction of the metallic liquid with AlGaN/GaN. Such processes result in abnormal conduction channels. The possible mechanism of the crevice formation was discussed,and the possible solutions to avoid the crevices were proposed.