试论Si促使铁液凝固过程中石墨化的机理

Si促使铁液凝固过程中不断G化,奥氏体(A)共析分解为F+G的机理分析认为:铁碳合金凝固以稳定状态转化,是Si熔于铁液中的化学特性,不断促使铁液的C溶解度下降所形成G的速度>凝固时铁液C的变化速度的必然结果。铁液凝固的过冷度,随Si的提高,过冷度是减少的,是Si对铁碳合金物理性能产生的影响之一,与C的G化无关,不能与Si的化学特性混为一谈,也不能作为促进铸铁G化退火的依据。     

Densification and compressive strength ofin-situ processed Ti/TiB composites by powder metallurgy

In the present study, the densification of Ti/TiB composites, the growth behavior ofin-situ formed TiB reinforcement, the effects of processing variables — such as reactant powder (TiB₂, B₄C), sintering temperature and time — on the microstructures and the mechanical properties ofin-situ processed Ti/TiB composites have been investigated. Mixtures of TiB₂ or B₄C powder with pure titanium powder were compacted and presintered at 700°C for 1 hr followed by sintering at 900, 1000, 1100, 1200, and 1300°C, respectively, for 3hrs. Some specimens were sintered at 1000°C for various times in order to study the formation behavior of TiB reinforcementin-situ formed within the pure Ti matrix. TiB reinforcements were formed through different mechanisms, such as the formation of fine TiB and the formation of coarse TiB by Ostwald ripening or the coalescence of fine TiB. There was no crystallographic relationship between TiB reinforcement and the matrix. There were voids at the interface between the TiB reinforcement and the Ti matrix due to the preferential growth of coarse TiB without a particular crystallographic relationship with pure Ti matrix and the surface energy between the Ti matrix and TiB reinforcements. Therefore, the densification of Ti/TiB₂ compacts was hindered by the preferential growth of coarse TiB reinforcements. The mechanical properties ofin-situ processed composites were evaluated by measuring the compressive yield strength at ambient and high temperatures. The compressive yield strength of thein situ processed composites was higher than that of the Ti-6A1-4V alloy. It was also found that the compressive yield strength of the composite made from TiB₂ reactant powder was higher than that of the composite made from B₄C at the same volume fraction of reinforcement. A crack path examination suggested that the bonding nature of interface between matrix and reinforcement made from TiB₂ reactant powder was better than that made from B₄C.     

基于UGNX的五坐标数控编程后处理程序开发应用

针对UGNX平台下的五坐标数控铣削编程后处理程序开发,以PostBuilder为环境,详细介绍了其五坐标数控铣削机床的后处理程序开发的关键技术,包括PostBuilder后处理开发模式、五坐标机床运动学原理配置、TCL语言应用等方面,并以FIDIA KR214六坐标高速铣削加工中心的后处理开发为实例进行应用说明。     

基于USB总线的数据采集系统

介绍了一种USB数据采集系统的实现方法，该系统采用Philips公司的PDIUSBD12接口芯片。本文具体介绍了该数据采集系统的硬件、Firmware（固件）、基于Windows驱动程序模型（WDM）的设备驱动程序以及应用软件的设计。     

基于I2C总线技术的等离子喷焊系统的研究

阐述了基于I^2C总线技术的等离子喷焊过程控制系统的设计原理，介绍了软硬件及接口设计技术。实践表明，采用I^2C总线技术，不仅使系统的芯片大大减少，系统的灵活性增强，而且提高了系统的抗干扰能力。     

Ni粘结的Ti（C,N）金属陶瓷的横向断裂强度与断口的分形分析

以分维几何学为基础，建立了断口二次电子像的分维Ｂｒｏｗｎｉａｎ模型，提出了以图像处理系统为手段的断口形貌的分维测量方法，研究了Ｎｉ粘结的Ｔｉ（Ｃ，Ｎ）金属陶瓷在三点弯曲条件下，断裂表面的分形维数与横与断裂强度与显微组织之间的关系，建立了金属陶瓷的微观断裂的Ｆｒａｃｔａｌ模型，给出断口分形维数的计算表达式，实验结果表明，横向断裂强度的对数值ｌｇσｂｂ随分形维数ＤＦ增加呈单调上的直线关系；显微组织的对     

五机架轧制设定规范处理系统的开发与应用

介绍了开发的五机架轧制设定规范处理系统，通过对轧钢主控工的操作设定进行了收集、理论运算、分析评价、并建立“轧制规范数据库”，以便直接在线回收进行轧制预设定，同时可用于对新产品品种规格工艺设定方案的制定，或对已有试轧设定方案进行离线模拟，测试其可行性及优劣。     

高密度锂离子电池正极复合材料LiFePO4/C

以FeC2O4-2H2O、NH4H2PO4、Li2CO3和乙炔黑为原料,采用两步固相反应法制备了高密度LiFePO4/C正极复合材料.利用差热(DSC),热重(TGA)和X射线衍射(XRD)等分析手段具体探讨了第一步固相反应中可能存在的反应过程和中间产物.利用扫描电镜表征了复合材料LiFePO4/C中LiFePO4微粒形貌和接触状态.结果表明,乙炔黑的含量是影响LiFePO4微粒尺寸和微粒间接触界面的重要因素.在一次热处理的基础上,二次球磨和烧结有利于第二次固相反应过程中反应物质的接触和传质,较一步固相法提高了生成的LiFePO4的振实密度.当乙炔黑的含量(质量分数)为0.1%～1.5%时,两步固相法所制正极材料LiFePO4/C的振实密度可达到1.7 g/cm3,初次放电容量达到105 mA.h/g.     

4Cr5MoSiV1钢热轧辊的热处理工艺试验研究

从提高4Cr5MoSiV1钢热轧辊的辊面硬度的角度出发,对于4Cr5MoSiV1钢的热处理工艺进行试验研究,分析了4Cr5MoSiV1钢热处理工艺参数对其性能的影响,所得到的工艺使轧辊辊面硬度和机械性能得到改善,在生产过程中使用良好。