【摘要】 为了制备高α-Si3N4含量的原料,在机械活化-化学激励法燃烧合成氮化硅工艺中,研究了机械活化时间、氮气压力、稀释剂和化学激励剂等因素对燃烧合成产物的影响。结果表明:通过机械活化把硅粉研磨至亚微米级,能提高硅粉的表面能,有助于在加入大剂量铵盐时燃烧合成α-Si3N4,但机械活化时间太长会导致铵盐分解流失,研磨时间不宜超过5h;当铵盐加入量大于18%后,燃烧波将不稳定;稀释剂的加入量应控制在40~60%。通过产物微观形貌分析知,在控温活化燃烧合成α-Si3N4时存在VC和VLS两种反应机理。更多还原

【Abstract】 In order to obtain high α-Si3N4 content of raw materials,the method combining mechanical activation and chemical excitation was used for the combustion synthesis of α-Si3N4.Mechanical activation time,nitrogen pressure,diluent agent and chemical excitation agent were investigated in terms of their effects on the combustion synthesis.One of the results indicates that grinding silicon powder to submicron considerably increases the surface energy,thus benefiting the combustion synthesis of α-Si3N4,though large doses of chemical excitation agent ammonium salt were added.However,the longer time of the mechanical activation,the more loss of the ammonium salt decomposition.Therefore,to control the grinding time less than 5hours is necessary.At the same time,the more content of ammonium salt added,the less stable the combustion wave.Therefore,the ammonium salts should be added no more than 18wt%.Meanwhile,diluent agent should be added in the range of 40-60wt%.The microscopic morphology of combustion products implies that there are two reaction mechanisms:vapor-crystals(VC)and vapor-liquid-solid(VLS)in the process of combustion synthesis of α-Si3N4.更多还原