Influence of Film Casting Condition and Thermal Treatment on Order Structure of Polyurethane Block Copolymer

An attempt has been made to investigate the influence of film casting temperature and thermal ageing on order structure formation of segmented polyurethane (SPU) block copolymer. For this purpose films were casted at three different temperature of 60, 80, or 100°C and thermal aged at 100, 120, 130, or 150°C. The structure of films were investigated by Fourier-transform infrared (FT-IR), wide angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC). Film casted at slow solvent evaporation has more regular structure than the film casted at rapid solvent evaporation. Crystaline structure decreases with increase in casting temperature due to chain entanglement, which makes crystallization process tougher. The effect of ageing temperature on crystalline structure formation remains unclear. Decrease of ordered structure was observed when the samples were heat treated at 100 or 120°C, however, slight increase of ordered structures were observed for the samples heat treated at 130 or 150°C. Therefore, the influence of thermal ageing has been explained in terms of order-disorder temperature of block copolymer.     

凝胶挤出流延聚氟乙烯薄膜的研究

介绍了一种适合聚氟乙烯薄膜生产制造的新工艺——凝胶挤出流延法。该工艺克服了聚氟乙烯自身结构特性给成型带来的困难,得到的薄膜产品具有耐候性强、强度高、透光率大等优点,并有很好的应用前景。此外还系统讨论了树脂结构、潜溶剂及加工条件对薄膜制品的影响。     

氧化铝陶瓷基板工艺研究

本文主要介绍了流延法生产氧化铝陶瓷基板的工艺.研究了原料粒度分布对基板微观结构的影响,用流延法制备了96%氧化铝陶瓷基板,并对基板表面被釉,试验了基板的性能,研究了基板生产过程中一些关键的因素.     

Mechanical properties and wear behavior of Al5083 matrix composites reinforced with high amounts of SiC particles fabricated by combined stir casting and squeeze casting; A comparative study

Combined stir casting and squeeze casting processes were used to fabricate Al5083 matrix composites reinforced with 20, 25, and 30 wt% SiC_p. The microstructure, mechanical properties and wear behavior of the composites fabricated by combined stir casting and squeeze casting were compared with those fabricated by stir casting. The results revealed that the combined casting method improved the distribution of SiC particles through the reduction of the agglomeration of SiC particle and reduced the porosities of the samples from 2.32% to 1.29% in the sample containing 30 wt% SiC. These modifications led to the enhancement of mechanical properties i.e. increased the hardness to 85 BHN and the compressive strength to 350 MPa for the sample containing 30 wt% SiC fabricated by the combined casting method. In addition, the wear resistance of the samples fabricated by the combined casting method improved because of the reduced size of the wear debris as well as the smaller worn region. The dominant wear mechanism of all the composite samples fabricated by both methods was the delamination of the tribological layer while adhesion wear was dominant in the monolithic Al alloy.     

Preparation of BaZr0.1Ce0.7Y0.2O3–δ Based Solid Oxide Fuel Cells with Anode Functional Layers by Tape Casting

Solid oxide fuel cells (SOFCs) based on the proton conducting BaZr_0.1Ce_0.7Y_0.2O_3–δ (BZCY) electrolyte were prepared and tested in 500–700 °C using humidified H₂ as fuel (100 cm³ min^–1 with 3% H₂O) and dry O₂ (50 cm³ min^–1) as oxidant. Thin NiO‐BZCY anode functional layers (AFL) with 0, 5, 10 and 15 wt.% carbon pore former were inserted between the NiO‐BZCY anode and BZCY electrolyte to enhance the cell performance. The anode/AFL/BZCY half cells were prepared by tape casting and co‐sintering (1,300 °C/8 h), while the Sm_0.5Sr_0.5CoO_3–δ (SSC) cathodes were prepared by thermal spray deposition. Well adhered planar SOFCs were obtained and the test results indicated that the SOFC with an AFL containing 10 wt.% pore former content showed the best performance: area specific resistance as low as 0.39 Ω cm² and peak power density as high as 0.863 W cm^–2 were obtained at 700 °C. High open circuit voltages ranging from 1.00 to 1.12 V in 700–500 °C also indicated negligible leakage of fuel gas through the electrolyte.     

基于TRIZ的真空注型机改进设计

应用发明问题解决理论(TRIZ理论)的物质-场模型及冲突矩阵方法,分析制模硅胶脱气和树脂真空注型工艺过程,提出真空注型机关键工艺功能改进设计方案;开发了硅胶脱气自动除泡装置和真空注型多工位浇注系统。样机验证结果表明,改进设计的真空注型机功能设计合理有效,劳动强度明显降低,工作效率显著提高。     

不同电源模式下微弧氧化制备陶瓷膜的性能对比研究

在硅酸钠、钨酸钠、硼酸、偏铝酸钠和乙二胺四乙酸二钠的复合电解液中,分别采用交流电源和脉冲电源,利用微弧氧化方法,在ZL102铸造铝合金上制备了陶瓷膜层。通过扫描电镜（SEM）观察,交流电源模式制备的陶瓷膜层表面孔洞少,比用脉冲电源制备的陶瓷膜形貌好。利用电化学方法分析了陶瓷层的防腐蚀性能,交流电源制备的陶瓷膜层耐腐蚀性能好。     

用快干硅溶胶生产大型汽轮机导叶片的精铸工艺

介绍采用FOSECO公司生产的D COAT快干硅溶胶制壳工艺替代硅溶胶-硅酸乙酯复合制壳工艺，生产长为950mm、毛坯质量达42kg的汽轮机弯扭导叶片的制壳工艺，并对D COAT快干硅溶胶的快干机理和影响型壳性能的因素进行了探讨。D COAT快干硅溶胶采用水溶性高聚物增强，在湿度为30％～40％、风速为6～8m／s的干燥条件下，层间干燥时间仅为1～2h。D COAT快干硅溶胶型壳湿强度和高温强度高，残留强度低，透气性好，已成功应用于汽轮机大型叶片的批量生产。     

采用消失模铸造工艺生产蠕铁排气出口管

介绍了消失模法生产蠕铁排气出口管的工艺过程.试验发现,采用反直浇道结合侧注的模组形式为佳,每组8件、管口朝下;涂料直接影响铸件表面积碳及皱皮倾向;并采用消失模法批量生产了蠕铁排气出口管,材料性能及金相组织达到要求,铸件壁厚均匀,表面光滑,已用于红旗轿车的部分车型.     

A novel fading-resistant Al-3Ti-3B grain refiner for Al-Si alloys

Al-Ti-B refiners with excess-Ti perform adequately for wrought aluminum alloys but inefficiently in the case of foundry alloys. The high content of silicon in the latter, which forms silicides with Ti and severely impairs the refining potency of the nuclei, is known to be responsible for the poor performance. Hence, new grain refiners, such as Al-3B and Al-3Ti-3B master alloys with excess-B have been developed with well documented advantages for Al-Si alloys. It is very desirable to involve TiAl₃ particles in the Al-3Ti-3B master alloy to maximize its grain refining efficiency. However, fading phenomenon is a key drawback for application of the TiAl₃-containing refiners in aluminum foundry. In the present work, new Al-3Ti-3B grain refiners, containing TiB₂, AlB₁₂ and TiAl₃ particles were developed with an aim to prolong the acting time after inoculation. The results showed that inoculation of Al-7Si alloy with thus meliorated Al-3Ti-3B grain refiner has produced a fine grain structure which was approximately maintained up to 30 min.