La0．8Ca0．2CrO3钙钛矿复合氧化物的GNP法合成与表征

采用GNP（Glycine-Nitrate Process）法合成La0.8Ca0.2CrO3初级粉料，研究甘氨酸用量对产物的晶体结构和显微形貌的影响，并测试烧结体的相对密度和电导率。研究结果表明，甘氨酸与金属离子的摩尔比（G／M^n＋）控制在2．0～2．5时可得到颗粒尺寸细小、均匀（100nm～200nm）的单相钙钛矿粉体，烧结温度为1350℃时样品的相对密度达到91．0％，测试温度为800℃时样品的电导率达到30．5S.cm^-1。与常规固相法相比，GNP法制备的样品具有更好的烧结活性和导电性能。     

Pro/E工程剖视图与制图国标不相符合问题的解决方法

利用Pro/E三维模型与二维图形双向关联功能可以快速生成工程图,但由于在视图表达上有些方面不符合我国制图标准而影响其有效使用.本文针对Pro/E制作工程剖视图时所存在的与制图国标不相符合的问题,提出了解决这些问题的方法和技巧.     

硅黄铜铸件的渗漏缺陷分析

为了满足耐海水腐蚀、高导热率和承压能力要求,冷却器盖均采用硅黄铜制造。某厂在冷却器盖的生产过程中,铸件废品率高达60%,主要问题是铸件在水压测试中出现渗漏。分析了冷却器盖铸件的渗漏缺陷。结果表明:硅的加入量和浇注温度偏高,硅熔化不完全是导致此类铸件产生渗漏的主要原因。针对性地采取措施后,冷却器盖铸件的成品率大幅提高,达到了90%以上。     

复合合金化对AZ91镁合金铸态组织的影响

利用光学显微镜、扫描电镜和X射线衍射仪研究了0.5?、0.2?、0.2%Sr(质量分数,下同)复合合金化对AZ91合金铸态组织影响。结果表明,0.5?、0.2?、0.2%Sr复合加入可以显著细化合金的铸态组织,0.5?、0.2?、0.2%Sr同时加入,其细化效果优于0.5?和0.2?或0.5?和0.2%Sr的复合加入,并且在组织中出现针状或杆状的Al4Ce新相。     

有机锡化合物引发D,L-丙交酯的开环聚合

D,L-丙交酯在有机锡化合物四苯基锡(Ph4Sn)、三正丁基醋酸锡(Bu3SnOAc)、辛酸亚锡(SnOct2)等催化剂引发下开环聚合,得到高分子量的聚D,L-乳酸,讨论了聚合单体D,L-丙交酯纯度、聚合温度、聚合时间、聚合体系真空度以及引发剂有机锡催化剂与聚合单体D,L-丙交酯的比例对聚D,L-乳酸合成的影响,通过红外光谱和核磁共振光谱对聚D,L-乳酸的结构进行了表征。实验结果表明,D,L-丙交酯开环聚合反应的较佳工艺路线是:D,L-丙交酯重结晶5次,聚合温度140℃,聚合时间24 h,聚合体系真空度13.3~133.3 Pa,引发剂有机锡催化剂与单体D,L-丙交酯比例0.2‰~0.5‰,此时聚D,L-乳酸的粘均分子量最高,分别达到32.46×104,33.43×104和41.36×104。     

添加剂对合成堇青石的影响

本文研究了锆英砂、碳酸钡、硅线石、氟化钙四种添加剂及其含量对合成堇青石晶相组成的影响。结果表明:四种添加剂的加入均提高了堇青石的含量,且加入量都有一最佳值,分别为锆英砂2wt%、碳酸钡3wt%、硅线石2wt%、氟化钙2wt%。     

多孔碳酸钙陶瓷--人造珊瑚的研究

天然珊瑚有三维贯通的多孔网络结构，它的主要成分碳酸钙(CaC03)在人体环境可降解。模拟珊瑚的组成与结构，研制新型的组织工程支架材料有着良好的应用前景。本文探索了多孔碳酸钙陶瓷的制备方法，并通过盐析法制备了一种多孔的碳酸钙陶瓷，有望获得高的孔隙率和孔连通性。     

生物活性无机颗粒增强聚乳酸材料的制备方法

无机颗粒增强聚乳酸复合材料能有效的改善聚乳酸的力学性能，并赋予其生物活性。本文系统介绍了各种无机颗粒增强聚乳酸复合材料的制备方法，并对其优劣性进行了初步探讨。     

Fabrication of polymer derived ceramic parts by selective laser curing

Polymer derived ceramic parts of complex shape were fabricated by selective laser curing (SLC). The ceramic parts were built similar to the selective laser sintering process by sequentially irradiating layers consisting of SiC loaded polysiloxane powder with a CO₂-laser beam (λ = 10.6 μm), which locally induces curing reaction of the polymer phase at moderate temperatures around 400 °C. The laser-cured bodies were converted to SiOC/SiC ceramic parts in a subsequent pyrolysis treatment at 1200 °C in argon atmosphere. The scanning speed and the power of the CO₂-laser beam were varied, leading to pronounced differences in material properties. Laser irradiating a powder mixture containing 50 vol.% polymer/50 vol.% SiC resulted in relative green densities between 38 and 60%. Relative densities decreased to 32–50% after pyrolysis due to the polymer shrinkage. A post-infiltration with liquid silicon was carried out in order to produce dense parts. While before infiltration the bending strength only attained 17 MPa as a result of both microcracks in the SiOC matrix and a pronounced porosity, an average value of 220 MPa was achieved after post-infiltrating with Si. In the case of 50 vol.% SiC content the linear shrinkage after pyrolysis was only 3%. Thus, the SLC approach can be considered as a near-net-shape forming process of ceramic components with complex geometries.