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31.
自蔓延熔附成型陶瓷涂层的组织结构及性能分析 总被引：3，自引：0，他引：3
采用自蔓延熔附成型技术在普通碳素钢管内壁涂覆一层较为均匀致密的陶瓷层。对复合管的组织结构进行研究发现：陶瓷层呈枝晶结构特征，为复相结构，主晶相为α－Ａｌ２Ｏ３，还有ＦｅＡｌ２Ｏ４、ＺｒＳｉＯ４、ＺｒＯ２和Ｆｅ等相。陶瓷层其它相结构取 决于添加剂的种类。 相似文献
32.
内衬陶瓷钢管陶瓷层中铁铝尖晶石的形成机理 总被引：3，自引：0，他引：3
通过理论分析和试验，研究了内衬陶瓷复合钢管陶瓷层中铁铝尖晶石的含量、分布和形成机理，结果表明：陶瓷层中铁铝尖晶石含量降低到５．６％，并孤立分布于Ａｌ２Ｏ３晶界，从而显著提高了陶瓷层的耐蚀性能。 相似文献
33.
从理论和工艺两个方面讨论了自蔓延高温合成反应火焰喷涂技术的基本规律和影响因素.提出了自蔓延高温合成反应喷涂的基本过程和热喷涂工艺条件下的反应机理,即经历反应孕育、飞行燃烧、碰撞、结构转变与凝固4个阶段形成目标涂层,研究了各工艺参数对涂层组织结构和机械物理性能的影响规律. 相似文献
34.
本文概述了材料的自蔓延高温合成（ＳＨＳ）的主要概念，并详细介绍ＳＨＳ过程中蔓延波的特征。根据温度分布及产物转化过程，蔓延波可分为四类：（１）具有很窄的反应区，在这个区域反应物迅速转变为产物；（２）具有较宽的反应区，反应过程强烈地受动力学控制；（３）在ＳＨＳ过程中具有相变发生；（４）在生成最终产物之前有中间化合物生成。 相似文献
35.
The paper discusses the fundamentals and the requirements for layer-by-layer manufacturing of three-dimensional porous parts from complex metal oxide systems (piezoceramics PbTi1?xZrxO3; hexaferrites – BaFe12?xCrxO19 and SrFe12O19; spinels – Li0.5Fe2.5?xCrxO4 and high-temperature superconducting ceramics (HTSC) – YBa2Cu3O7?y) and examines the main aspects of the overlapped processes associated with the self-propagated high-temperature synthesis (SHS) and selective laser sintering (SLS). These two techniques presently offered are joined as the original solutions in this external magnetic field. The perovskite phase compositions, morphology, and element distribution of the fabricated samples were analyzed by the X-ray diffraction (XRD), scanning electron microscopy (SEM) equipped the EDX analysis. Optimal regimes for the three-dimensional (3D) parts laser synthesis and some of their electro physical properties were estimated for conducting the concurrent SHS-SLS reactions, both for the case with the applied dc magnetic field and without it. 相似文献
36.
Samuel Goroshin Lorena Camargo John H.S. Lee 《Proceedings of the Combustion Institute》2005,30(2):2561-2568
Thermodynamic calculations show that some metals can react with sulfur without the formation of gaseous products at normal pressure and yet demonstrate sufficiently high flame temperatures to support the propagation of stable flames. For example, a stoichiometric ternary mixture of iron, manganese, and sulfur demonstrates gasless combustion at an equimolar concentration of iron and of manganese with an adiabatic flame temperature of about 2000 °C. Differential thermal analysis of the mixture shows no exothermic reactions below 280 °C. Therefore, sulfur in the mixture can be safely melted (m.p. 119 °C), converting a powder blend into a liquid suspension that is free from gas bubbles. Symmetrical cylindrical flames in shallow pools of suspensions of Fe and Mn powders in liquid sulfur and combustion of the same liquid mixtures in preheated narrow steel tubes have been studied to determine flame propagation speeds as a function of mixture composition. It was found that, contrary to the behavior of the calculated flame temperature, flame speed decreases with the increase of the manganese content in the mixture and is not affected by mixture dilution with the combustion product. Direct measurements of the flame temperatures by thermocouples indicated a weak dependence of the peak flame temperature on mixture composition and revealed a two-stage flame structure. The existence of the two distinct reaction zones in the mixture of two reactive metals with sulfur is in accordance with qualitative theoretical predictions by the theory of flame with parallel reactions existing in the literature. According to theory, the reaction with the higher flame speed in a corresponding binary single-metal–sulfur mixture will form the leading stage of the complex flame front and will govern the flame propagation speed in the ternary composition. The speed of flame propagation in pure Fe–S mixture is almost three times higher than the flame speed in Mn–S mixture. As a result, the iron–sulfur reaction dominates the flame propagation mechanism in Fe–Mn–S suspension. 相似文献
37.
在对TiC陶瓷的性能及其制备工艺进行分析研究的基础上,利用SHS/PHIP技术制备了致密的TiC-TiB2复相陶瓷材料,并对材料进行切割加工成型和清洗,得到和所需滤片形状相同的TiC-TiB2复相陶瓷片,然后再根据TiC和TiB2化学性能的差异,用王水的强腐蚀性溶解其中的TiB2陶瓷相从而得到孔隙大小均匀的、性能优异的TiC陶瓷滤片.用该方法制备的TiC陶瓷滤片,孔隙的直径范围在2～3μm,分布均匀,可以在任何性质的液体中使用,也可用于熔融金属液的过滤. 相似文献
38.
通过有限元模拟分析了轴压作用下薄壁方钢管的局部屈曲失稳形式．通过对一系列不同高宽比的方钢管模型的屈曲模态分析,研究了薄壁方钢管在轴压作用下发生局部屈曲失稳的规律．通过有限元模型分析,发现在轴向压力作用下,方钢管发生局部失稳破坏时,其临界荷载的大小主要受方钢管的宽厚比影响,而其高宽比对临界荷载的影响可以忽略不计．轴压作用下方钢管发生屈曲破坏时的屈曲系数非常接近于4,与四边简支的薄板在轴压作用下失稳的屈曲系数相同．这一结论对于薄壁方钢管在轴压作用下的屈曲分析具有参考价值． 相似文献
39.
杨国涛 《中南大学学报(自然科学版)》1995,(1)
在高真空条件下，进行了ＴＮ１２Ｍ１０合金的高温自蔓延合成（ＳＨＳ）试验研究。发现在真空条件下的ＳＨＳ过程，自始至终都有气体放出，特别在ＳＨＳ反应期间放出的气体更多；该条件下的ＳＨＳ产品比在Ａｒ气保护下的ＳＨＳ产品具有较高的密度。 相似文献
40.
Silvia?GennariEmail author Filippo?Maglia Umberto?Anselmi-Tamburini Giorgio?Spinolo 《Monatshefte für Chemie / Chemical Monthly》2005,136(11):1871-1875
Summary. Computer simulation results for the Self-propagating High-temperature Synthesis (SHS) of the intermetallic compound NbSi2 are discussed in comparison with experiments for SHS of mechanically activated powders. The variation of wave speed of the
propagation front is considered while varying Nb grain size and thermal conductivity of the starting mixture. A co-operating
effect of these two parameters (due to the change in morphology of reactants after milling) is outlined. 相似文献