氧化铁对氮化硅陶瓷烧结的影响

Effect of Iron Oxide on Sintering Behavior of Silicon Nitride Ceramics

以氧化铝和氟化镁作为烧结助剂,氧化锆为增强相,引入氧化铁,制备了不同氧化铁含量的氮化硅陶瓷,研究了氧化铁含量对氮化硅陶瓷的密度、机械性能和相组成的影响,并探究了氧化铁在氮化硅陶瓷烧结过程中的迁移转换规律。氧化铝和氧化铁在氮化硅陶瓷烧结过程中会有部分固溶到氮化硅晶格内部,氧化铁的加入会促进氮化硅的相变,使样品的硬度降低,抗弯强度和断裂韧性升高。不添加氧化铁的样品具有最高的相对密度和硬度,其相对密度、抗弯强度、硬度和断裂韧性分别为(93.47±0.28)%、(359.73±2.86)MPa、(13.40±0.48)GPa和(2.39±0.074)MPa·m^(1/2);添加1%氧化铁的样品具有最高的抗弯强度和断裂韧性,其相对密度、抗弯强度、硬度和断裂韧性分别为(92.17±0.17)%、(405.30±8.53)MPa、(11.36±0.56)GPa和(2.96±0.053)MPa·m^(1/2)。

Silicon nitride ceramics were prepared using alumina and magnesium fluoride as sintering aids and zirconia as the reinforcing phase.Additionally,iron oxide was introduced,with varying content.The relationship between the content of iron oxide and density,mechanical properties,and phase composition of the silicon nitride ceramics was studied.Furthermore,the migration and transformation of iron oxide within the silicon nitride matrix during the sintering process was examined.During the sintering process,partial dissolution of aluminum oxide and iron oxide into the silicon nitride lattice was observed.Interestingly,the introduction of iron oxide exerted a noteworthy influence on the phase transition of silicon nitride.This influence ultimately manifested as a reduction in hardness,coupled with an enhancement in strength and fracture toughness of the samples.The sample without iron oxide had the highest relative density and hardness,with relative density,flexural strength,hardness,and fracture toughness of(93.47±0.28)%,(359.73±2.86)MPa,(13.40±0.48)GPa and(2.39±0.074)MPa·m^(1/2),respectively.The sample with 1%iron oxide had the highest bending strength and fracture toughness,with relative density,bending strength,hardness,and fracture toughness of(92.17±0.17)%,(405.30±8.53)MPa,(11.36±0.56)GPa and(2.96±0.053)MPa·m^(1/2),respectively.