Properties of phyllosilicate-based porous ceramics shaped by conventional tape casting and freeze tape casting

Silicate ceramics were shaped using tape casting (TC) and freeze tape casting (FTC) processes from three clays labeled HCR, KORS, and KCR. These clays exhibited mass content of 77% halloysite–10 Å, 29% kaolinite, and 98% kaolinite minerals, respectively. After casting the slurries, the dried tapes were sintered at 1200°C. The microstructure changes were characterized before and after sintering using scanning electron microscopy. The apparent porosity of TC samples was lower (36–47 vol.%) compared to values obtained with FTC samples (67–79 vol.%). The latter samples exhibited a highly textured porosity, with micron-sized pores aligned perpendicular to the tape surfaces. Upon sintering, the porosity of TC samples tended to decrease conversely to the case of FTC samples. Such behavior seemed related to the simultaneous effect of organic additives and ice templating. Consequently, the FTC samples showed a relatively low mechanical strength of 3–7 MPa and thermal conductivity of .14– .22 W m⁻¹ K⁻¹. After sintering, the mullite crystallization contributed to strengthen the bulk materials, helping to compensate for the detrimental effect of porosity on the stress to rupture and on thermal conductivity values.     

水基流延制备片式PTCR陶瓷的研究

采用sol-gel法制备纳米BaTiO3基PTCR粉体,并以其为原料,采用水基流延成型工艺制备片式PTCR。研究了在sol-gel法制备BaTiO3粉体中,施受主元素含量、陶瓷的烧成温度与PTC效应、晶粒尺寸的关系以及水基流延工艺中各种添加剂对浆料和膜片性能的影响。结果表明:以纳米BaTiO3粉体为原料、水基流延的片式PTCR坯片,在1240℃下就能半导化,所得陶瓷样品的升阻比高于104,温度系数大于13%℃–1,平均晶粒尺寸小于2μm。     

海量存储系统中磁带文件缓存管理

针对磁带库的数据访问特点,根据高能物理领域的实际需求,提出了分组协同缓存策略.这一策略以缓存模型为基础,结合本地缓存与协同缓存的优点,把缓冲区分成不同的组,不同组的缓冲区之间相互独立;同一组的缓冲区由网络上不同节点上的磁盘组成,这些磁盘之间相互协作.还对该缓存策略的目录管理、更新算法、一致性等问题进行了详细分析.实验说明,该策略能很好的满足高能物理领域的数据处理和海量存储需求.     

拉线放卷恒张力控制系统的研究

GD4350CH小包透明卷烟包装机生产中由于拉线放卷张力波动较大,易出现拉线褶皱现象.在对原系统进行分析与研究后,提出利用交流伺服技术改造放卷控制系统,在转速跟随过程中加入张力闭环调节,通过改变放卷速度使张力保持恒定。     

铝合金节能门窗配套件的甄选及应用

从国内市场上常见的几种断桥隔热铝合金门窗配套件入手,探讨了现阶段门窗系统的常见弊病,分析产生的原因并提出解决办法。     

The preparation of SiCP/Ag–Cu–Ti hybrid tapes and application in the joining of silicon carbide ceramics

Abstract

A novel method of tape casting to fabricate ceramic-particulate-reinforced composite filler alloy tapes with low organics (no more than 6?wt.%) was developed, with which SiC_P/Ag–Cu–Ti hybrid tapes were successfully prepared and used in joining of sintered silicon carbide ceramics. The stress rheometer, scanning electron microscopy and energy dispersive spectrometer were used to characterize the rheological properties of slurry and microstructure of green tapes and joints. The slurry for tape casting consists of dispersant, binder, solvent, a mixture of ceramics particulates and metal powders, and no plasticizer was added. Castor oil phosphate was proven the suitable dispersant for the slurry, and the content of dispersant, binder, solid loading was optimized as 3?wt.%, 2.6?wt.% and 26?vol.%, respectively. The fabricated hybrid tapes possess good ductility and uniform thickness. The SiC particulates were homogeneously distributed in the metal powders matrix in both sides of the green tapes, and the distribution was retained in the SiC/SiC joints.     

连续玻纤增强聚丙烯预浸带熔融浸渍过程纤维断裂研究

为提高连续玻纤增强聚丙烯预浸带（PP/GF）性能,采用熔融浸渍法制备连续玻璃纤维增强聚丙烯预浸带,研究了PP熔体浸渍连续GF束过程。基于Weibull分布函数建立了纤维断裂数学模型,预测预浸带生产过程中纤维断裂率并描述实验结果。结果表明,模型与实验数据吻合较好,能够为工业化生产提供指导;纤维束在浸渍模具中受到树脂熔体的作用,及纤维与设备之间的摩擦是影响纤维断裂的主要因素,适当提高浸渍模具温度,降低纤维束牵引速度,增大浸渍模具间隙能有效降低纤维断裂率,提高工艺稳定性。     

流延工艺对BSZT-0.02MgO陶瓷微结构和性能的影响

采用溶胶凝胶法制备BSZT陶瓷粉,将Mg O粉体以2%摩尔比固相法掺入BSZT陶瓷粉中,研究不同流延工艺对Ba0.3Sr0.7Zr0.18Ti0.82O3(BSZT)-0.02Mg O陶瓷微结构和电学性能的影响。研究结果表明,适当的烧结温度和优化的流延成型工艺能有效改善陶瓷的电学性能,提高击穿强度和储能密度,本实验击穿强度达到233.33 k V/cm,储能密度达到1.539×106Jm-3。     

装管密度对Bi-2223／Ag超导带材性能的影响

研究了不同装管密度对Bi-2223／Ag带材(19芯)性能的影响。结果表明：采用压棒装管工艺提高了带材芯丝的填充系统，有利于提高带材的工程电流密度；第一次热处理后带材表面的鼓泡明显比松装带材少，有利于提高电流沿长度方向上的均匀性，更适合制备长带。压棒装管带材与松装带材相比，宽展更大，最终热处理后芯丝致密，孔洞少，而且2223相含量高，最终带材的载流性能好于松装带材。     

1998年~1999年磁性功能材料研究和应用新进展

综述了１９９８年～１９９年间若干磁性功能材料研究和应用新进展。其内容包括：（１）磁传感器新材料;（２）六角晶系微波铁氧体材料;（３）大容量自旋阀磁存储器;（４）磁薄带和磁薄膜变压器;（５）大功率应用的铁氧体材料。