碳化钛基金属陶瓷的合成及其应用研究现状

综述了碳化钛金属陶瓷粉体的合成方法,分析了合成方法各自的特点,并较详细的介绍了碳化钛金属陶瓷在现代工业领域中的应用研究。     

材料的自蔓延高温合成过程中燃烧波特征的数字模拟

本文在建立了自蔓延高温合成过程燃烧动力学模型的基础上，用数值计算和计算机模拟方法，对燃烧波特征及其变化规律进行分析模拟。结果表明：随着参数条件的改变，自蔓延高温合成过程中燃烧波会出现各种时空有序的耗散结构。非线性动力学机理分析表明，体系中两个强烈耦合的非线性动力学过程是引起耗散结构的动力学原因。     

Ti-C-xFe体系自蔓延高温合成及机理

采用自蔓延高温合成新技术合成ＴｉＣ／Ｆｅ复合材料,研究了原料组份、粒度对合成过程及产物特征的影响。探讨了燃烧反应及结构形成机理。结果表明,随Ｆｅ含量的增大,燃烧合成温度降低,合成ＴｉＣ粒度变细,燃烧波速度在Ｆｅ含量为１０％（质量分数）时出现极大值。与碳黑作碳源对比,细粒石墨在反应合成过程中表现出更大的活性。用铜楔块燃烧波淬息法研究了合成过程。整个合成过程经历了金属的熔融、碳向熔融体中的溶解扩散、大团聚的形成、小的ＴｉＣｘ颗粒生长及ＴｉＣ长大等阶段。     

Synthesis and electrochemical performances of LiNi0.6Co0.2Mn0.2O2 cathode materials

LiNi_0.6Co_0.2Mn_0.2O₂ was prepared from LiOH·H₂O and MCO₃ (M=Ni, Co, Mn) by co-precipitation and subsequent heating. XRD, SEM and electrochemical measurements were used to examine the structure, morphology and electrochemical characteristics, respectively. LiNi_0.6Co_0.2Mn_0.2O₂ samples show excellent electrochemical performances. The optimum sintering temperature and sintering time are 850 °C and 20 h, respectively. The LiNi_0.6Co_0.2Mn_0.2O₂ shows the discharge capacity of 148 mA·h/g in the range of 3.0?4.3 V at the first cycle, and the discharge capacity remains 136 mA·h/g after 30 cycles. The carbonate co-precipitation method is suitable for the preparation of LiNi_0.6Co_0.2Mn_0.2O₂ cathode materials with good electrochemical performance for lithium ion batteries.     

石英块体表面制备氮化硅层的研究

高纯Si粉或Si3N4粉为反应原料,分别以SiO2粉、MgO粉、CaO粉,或者自制玻璃粉为粘结剂,按不同质量百分比与PVA饱和溶液混合,分层涂抹在石英块体表面.在N2气氛中,于1500℃高温氮化烧结180 min,在石英块体表面制备氮化硅层.XRD与EDS图谱的分析结果表明,以SiO2粉、MgO粉、CaO粉为粘结剂,产物层物相为氮化硅或氧氮化硅,产物层致密且有一定厚度和强度,但是产物层和石英块体的结合性差;以自制玻璃粉为粘结剂的实验结果表明:产物层主要物相为氮化硅,产物层有一定厚度和强度,而且与石英块体的结合性较好.     

Preparation of Fe-M Intermetallic/TiC-M_2O_3 Ceramic Composites from Ilmenite by SHS

Fe-Al intermetallic/TiC-Al_2O_3 ceramic composites were successfully prepared by self- propagating high-temperature synthesis(SHS)from natural ilmenite,aluminium and carbon as the raw materials.The effects of carbon sources,preheating time and heat treatment temperature on synthesis process and products were investigated in detail,and the reaction process of the FeTiO_3-Al-C system was also discussed. It is shown that the temperature and velocity of the combustion wave are higher when graphite is used as the carbon source,which can reflect the effect of the carbon source structure on the combustion synthesis; Prolonging the preheating time or heat treatment temperature is beneficial to the formation of the ordered intermetallics;The temperature and velocity of the combustion wave are improved,but the disordered alloys are difficult to eliminate with the preheating time prolonged.The compound powders mainly containing ordered Fe3Al intermetallic can be prepared through heat treatment at 750℃.