Optimization of abrasive water jet cutting of ductile materials

Full factorial design of experiments was developed in order to investigate the effects of jet pressure, abrasive mixing rate, cutting feed, and plate thickness upon three response variables, surface finish of cutting wear zone, percentage proportion of striation free area, and maximum width of cut. The set of sixteen experiments was performed on each of the following two ductile materials: AISI 4340 (high strength low alloy steel, hardened to 49HRc) and Aluminum 2219. Analysis of Variance (ANOVA) was performed on experimental data in order to determine the significance of effects of different parameters on the performance measures. It was found that cutting feed and thickness were highly influential parameters, while abrasive mixing rate is influential upon surface roughness only. Strong interaction was found between jet pressure and workpiece material. Multi-criteria numerical optimization was performed in order to simultaneously maximize/minimize different combinations of performance measures.     

Cr12MoV钢冷挤压模具的热处理工艺

通过对冷挤压凸模的工作特点及失效分析，提出改善模具材料中碳化物的分布的方式及合理的热处理工艺，这是提高该模具使用寿命的关键措施．     

关于住宅坡屋顶的思考

对近几年各城市住宅建设中出现的坡屋顶热进行了分析,认为住宅设计中采用坡屋顶有其客观必然性和现实意义;⑴美化住宅造型,改善城市景观形象;⑵提高住宅屋顶的防水性能,增强住宅商品的耐久性;⑶有较好的保温隔热能力,利于建筑节能;⑷带动新型建材产业的发展。对住宅设计中采用坡屋顶形式、改善住宅整体功能和美化城市形象、实现人居环境的可持续发展等提出4点建议和意见。     

2号高炉进风面积的调节

叙述了武钢2号高炉针对原燃料条件变化进行进风面积的调整及调整效果，并对其原因进行了分析。     

脱碳处理对Pt/WC复合材料催化性能的影响

采用溶胶-凝胶法,以钨酸钠为钨源、酚醛树脂为碳源合成碳化钨前驱体干凝胶,经原位碳化制备纳米碳化钨（WC）粉体,纳米WC粉体中的玻璃碳采用浓硝酸浸渍法脱除。在纳米WC粉料浆中以甲醛（HCHO）作为氯铂酸（H2PtCl6·6H2O）的还原剂,室温合成得到Pt/WC复合催化剂材料;以XRD、SEM、EDS等测试方法对样品的理化特性进行表征,并在酸性介质中采用循环伏安法测试材料的电化学催化活性。结果表明：相较于未经过脱碳处理的WC,经过浓硝酸脱碳处理后的Pt/WC电极催化材料的催化活性更好。经溶胶-凝胶法及原位碳化制备的纳米WC的颗粒径为20-80纳米,其本身具备较好的电催化活性。样品中残留的玻璃碳对WC具有包覆作用,会降低WC的电催化活性。采取浓硝酸脱碳的方式可有效脱除纳米WC粉体中的玻璃碳,发挥WC材料作为电极催化材料的电催化活性。     

Frequency-dependent dynamic effective properties of porous materials

The frequency-dependent dynamic effective properties (phase velocity, attenuation and elastic modulus) of porous materials are studied numerically. The coherent plane longitudinal and shear wave equations, which are obtained by averaging on the multiple scattering fields, are used to evaluate the frequency-dependent dynamic effective properties of a porous material. It is found that the prediction of the dynamic effective properties includes the size effects of voids which are not included in most prediction of the traditional static effective properties. The prediction of the dynamic effective elastic modulus at a relatively low frequency range is compared with that of the traditional static effective elastic modulus, and the dynamic effective elastic modulus is found to be very close to the Hashin-Shtrikman upper bound.     

正极材料LiNi1/3CO1/3Mn1/3O2包覆LiNi0.8Co0.15Al0.05O2的性能

以NiSO4·6H2O、CoSO4·7H2O、MnSO4·H2O、NH3·H2O及NaOH为原料,采用共沉淀方法在LiNi0.8 C00.15 Al0.05 (OH)2球形粒子表面包覆一层Ni1/3 Co1/3Mn1/3(OH)2三元材料前驱体,配锂后在750℃下、氧气气氛中焙烧12 h,合成复合层状材料Li[(Ni0.8 Co0.15Al0.05)0.97(Ni1/3Co1/3Mn1/3)0.03]O2.复合层状材料具有核壳结构,包覆壳层的厚度约为1μm.复合层状材料在2.8～4.3 V充放电,0.1C首次放电比容量为188.2 mAh/g;0.2 C循环100次的容量保持率为96.2％;在55℃下以0.2C循环100次,放电比容量保持在163.2 mAh/g.     

电弧作用下 AgMeO 触头材料的物理冶金过程分析

本文分析了ＡｇＭｅＯ触头材料电弧侵蚀机理,对电弧的热力作用下触头材料的各种响应从物理冶金本质角度进行全面研究,在此基础上对ＡｇＭｅＯ触头材料组元和组织的优化设计作了完整的分析讨论,提出优化设计判据,最后提出能充分表征触头材料电气使用性能的材料物理性能参数。     

不同介质环境条件下黏性土的分散性及其微观结构

采用碎块试验、双比重计试验、电动电位、扫描电镜等测试方法,对典型的分散性土和非分散性土在不同介质环境条件下的分散性及其微观结构特征进行了研究.研究表明,介质环境中的钠离子含量和pH值高低是决定土体是否产生分散的本质因素,两种因素缺一不可.如果土体中含有大量的钠离子,并且酸碱度呈强碱性,则土体具有分散性.通过掺加高价阳离子和酸性物质,降低土体中钠离子的相对含量和酸碱度,可对分散性土进行改良.在自然沉积条件下,分散性土的微观结构中含有较多的孔隙;而非分散性土比较密实,孔隙较少.     

一种新型超磁致压电混合精密位移机构的研究

为了研究大步距高精度精密位移机构,利用超磁致伸缩材料和压电陶瓷材料在驱动原理和使用方法上的相似性,提出一种超磁致伸缩材料与压电叠堆组成的混合驱动精密位移机构,介绍了机构运动原理及控制方式,制作了试验样机.测试表明,所研制的混合精密位移机构能实现双向可控运动,单步前进最大位移可达20μm,调节驱动电压可控制单步位移量,能满足大步距、高精度的驱动要求.