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利用直流电弧等离子体具有的高温、高反应活性和高的急冷速度等特点,通过氮等离子体与金属铝反应的方法,制备了平均粒径为50um的高纯氮化铝(AIN)超微细粉,并对氮化反应原理及AlN的成核机理进行了探讨。结果表明,等离子条件下的化学反应是极其复杂的,等离子态有利于氮化反应。AlN的成核速率与反应物的浓度和反应温度有关。实验中,通过控制反应气体的分压、反应的温度及冷却速度等工艺参数,制备出了粗径可控的AlN超微细粉。 相似文献
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The high purity of ultrafine power(UFP)of a-luminium nitride(AlN) are prepared by the reaction of nitrogenplasma with metal aluminium in D.C.plasma reactr.Both thenitriding principle and the AlN nucleation mechanism are stud-ied.The rusults,indicate that the chemical reaction in the forma-tion process of AlN UFP is very complicated and the nitridingreaction is corelated to the concentration of reactants and thetemperature.The particle size cav be adjusted by controlling thepartial pressure of the reactants,the temperature and the react-ing rate. 相似文献
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An investigation of the pressureless sintering of Si3N4 with MgO-CeO2 revealed that MgO-CeO2 is a most effective sintering aid for silicon nitride. The amount of MgO-CeO2 and sintering conditions have a strong influence on the densification behaviour and mechanical properties of the sintered materials. The effect of the additive and sintering conditions are discussed. The silicon nitride pressureless sintered with MgO-CeO2 retained a relative density of 98. 5% and a bending strength of 950 MPa. The Si Mg-Ce-O-N system is of great value for application and theoretical study. 相似文献
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中小企业在我国经济中具有十分重要的地位,但融资难题已成为制约其发展的首要问题,剖析了我国中小企业的融资困境的表现形式、产生的原因,并探讨了拓宽我国中小企业融资渠道的对策。 相似文献
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