Friction and wear properties of pitch／resin densified carbon—carbon composites used for airbrakes

By use of X-ray diffractometry and scanning electron microscope(SEM),the friction and wear results obtained from MM-1000 dynamometer tests of CVI pitch/resin C/C composites were analyzed.By investigating the factors that affected the friction and wear properties,such as matrix carbon,applcation environment,graphitization degree and brake pressure,etc,friction and wear mechanism of carbon materials were probed.The results indicate that pitch densified CVI initially treated composite is more graphitizable with its graphitization degree up 59 62%,and which results in uniform small debris easier to generate,more smooth friction curves with the coefficient of 0.3-0.4 and relatively higher wear and mass loss,compared with CVI/resin C/C composites.It was further proved by SEM observation that tribological behavior of C/C composite was system dependent.Factors determining the friction and wear properties such as the size of debris and its influence on friction and wear,brake pressure,graphization degree and debris bilm formation interacted and affected each other.The friction and wear mechanism of C/C composites under different high temperature treatments needs further research.     

基于LabWindows/CVI的结晶器液压振动在线监测控制

结合在线监测开发实例分析并介绍了LabW indows/CVI在测控领域的应用,详细阐述LabW indows/CVI环境下对结晶器振动油缸的油缸压力、位移等信号进行数据采集,并对关注的信号进行分析处理,达到监测控制的目的。同时利用ActiveX实现其与M atlab函数的调用,实现对信号的小波分析。     

数控系统加减速控制与程序段终点速度规划

加减速控制是CNC系统的关键技术之一。以前的加减速控制技术通常或单独采用前加减速控制，或单独采用后加减速控制。本文提出一种采用前加减速控制，同时结合运用后加减速控制算法原理的策略并且在加工前选择速度曲线模型，以提高数控系统的加工精度、实时性和通用性。同时本文进一步分析了在数控系统加工过程中，在程序段终点处存在速度无规则突跳的现象，讨论了该现象所带来的问题并提出了解决这些问题的办法。     

N490(DI)柴油机气缸盖消失模铸造生产工艺

通过一典型产品的消失模铸造生产工艺，系统地阐述了复杂型消失模铸造产品研发的一般性工作程序。借助CAD／CAM一体化技术手段，缩短了研发周期，稳定了产品质量，实现了复杂型消失模产品模具的国产化，丰富和发展了消失模铸造生产技术。     

面向并行工程的CAD/CAM系统及关键技术

本文提出了一种基于并行工程的CAD／CAM系统，阐述了该系统的主要功能模块及关键技术。     

Cr3Si／Crl3Ni5Si2金属间化合物合金组织与高温滑动磨损性能的研究

利用水冷铜模激光熔炼炉制得了由初生枝晶Cr3Si和枝晶间Cr3Si／Crl3Ni5Si2共晶组成的金属间化合物合金。利用OM，SEM，TEM，EDS和XRD分析了该金属间化合物的显微组织，在400℃，500℃和600℃条件下测试了其耐磨性能。结果表明，由于Cr3Si和Crl3NisSi2硬度高、原子键合力强、组织细小、均匀，在高温滑动磨损条件下具有优良的耐磨性能。     

不同Co含量Mm（NiCoMnAl）5贮氢合金的低温放电特性

用电化学方法研究了-40℃条件下Co含量对AB5型贮氢合金的放电容量、氢化物分解的稳定性及氢在贮氢合金中的扩散系数等的影响。结果表明：随Co含量的增大，晶胞体积增大，氢化物分解的焓变增大，低温放电容量减小。氢扩散是影响贮氢合金的低温放电性能的重要因素。     

高密度钨合金热静液挤压流动粘度的数值计算

采用粘性流体的运动微分方程分析工作介质在锥模中的挤压流动，通过分析工作介质的粘度对热静液挤压的影响，指出了合理的选择工作介质的成分使得粘度适宜，可以使热静液挤压力最小，而且能够避免挤压件缺陷的产生。挤压介质的粘度是关系到坯料变形流动的润滑性能及挤压变形流动性能的关键。在此基础上，给出了挤压介质的粘度的数学关系式，为热静液挤压工艺奠定重要的理论基础。     

Effect of temperature on mechanical behavior of AZ31 magnesium alloy

Strain rate sensitivity and tension/compression asymmetry of AZ31 magnesium alloy at different temperatures and strainrates were investigated.Both of mechanical behaviors are temperature dependent.Strain rate sensitivity increases with increasingtemperature.Thermally activated slip is the source of strain rate sensitivity.At the temperature below or near 373 K,strain ratesensitivity is very little.Tension/compression asymmetry in yielding decreases with increasing temperature.Twinning is the reasonof tension/compression asymmetry.At the temperature above or near 573 K,the material shows little tension/compressionasymmetry of the flow stress.     

浸渗工艺对SiC/Al复合材料残余气孔率的影响

采用无压浸渗法制备了SiC／Al复合材料，从浸渗动力学和工艺方法的角度探讨了浸渗保温时间和降温方式对复合材料的残余气孔率的影响。结果表明：随着保温时间的适当延长，能有效地降低复合材料的残余气孔率;连续降温优于分段降温，有利于降低SiC／Al复合材料的残余气孔率。