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利用重力计,比重仪,SEM,XRD,碳素分析仪,XFS和氧氮分析仪检测了不同加热条件下碳热还原氮化法合成镁阿隆(MgAlON)的密度、微观结构、相组成以及Mg,Al,O,N和C含量,讨论了碳热还原氮化法合成MgAlON的机理.结果表明,加热温度为1100℃时,原料中所有的MgO反应生成镁铝尖晶石(MgAl_2O_(4ss));当加热温度高于1300℃时,发生碳热还原氮化反应,N固溶于MgAl_2O_(4ss)生成MgAlON;由于碳热还原氮化反应不断消耗Al_2O_3,加热温度为1600℃时试样中Al_2O_3大颗粒的尺寸较加热温度为1500℃时的小;随着石墨和Al_2O_3在反应过程被完全消耗,在1650℃下加热获得了单相MgAlON.另外,碳热还原氮化反应中N原子向尖晶石结构MgAl_2O_(4ss)中固溶时导致晶格畸变而使原子间隙扩大,从而Al在MgAlON的固溶量高于其在MgAl_2O_(4ss)中的固溶量.由于碳热还原氮化反应过程产生气体及高温下Mg蒸汽分压较高,即使加热温度提高至1800℃,试样中仍然存在大量密闭气孔.
The density, microstructure and phase composition of MgAlON synthesized by carbothermal reduction nitridation under different heating conditions were measured by gravimeter, specific gravity meter, SEM, XRD, carbon analyzer, XFS and oxygen and nitrogen analyzer Mg, Al, O, N and C. The results show that all the MgO in the raw materials react to form MgAl2O4 (Mg ); When the heating temperature is higher than 1300 ℃, the carbothermal reduction nitridation occurs, and N dissolves in MgAl_2O_ (4ss) to form MgAlON. As the carbothermal reduction and nitridation continue to consume Al_2O_3 and the heating temperature is 1600 ℃ The size of Al 2 O 3 particles is smaller than that at 1500 ℃, and single-phase MgAlON is obtained when the graphite and Al 2 O 3 are completely consumed in the reaction and heated at 1650 ℃ .In the process of carbothermal reduction and nitridation, When the solid solution to the spinel MgAl 2 O 4 (4ss) leads to the lattice distortion and enlarges the atomic gap, the solid solution amount of Al in MgAlON is higher than that in MgAl 2 O 4 (4ss) Gasification reaction process and high temperature Mg vapor partial pressure higher, even if the heating temperature mention To 1800 ℃, there is still a large number of sealed sample pores.