富硼渣碳热还原氮化合成(Ca,Mg)-α′-SiAlON-BN复合粉体

Synthesis of (Ca,Mg)-α′-SiAlON-BN composite powders from boron-rich slag by carbothermal reduction and nitridation

以富硼渣为主要原料,用硅灰和高铝矾土熟料调整成分,炭黑为还原剂,采用碳热还原氮化法合成了(Ca,Mg)-α′-SiAlON-BN复合粉体。利用正交试验对烧成温度、保温时间、氮气流量和配碳量4个工艺参数进行了优化设计,以确定合成过程的最优工艺参数,并采用XRD、SEM和EDX检测手段研究了合成粉体的相组成和显微形貌。结果表明:最优工艺参数为配碳量理论值的1.5倍,烧成温度1 500℃,保温12 h,氮气流量800mL.min-1,此工艺条件下合成产物中(Ca,Mg)-α′-SiAlON-BN的相对含量可达70%以上,且Ca2+的固溶量远大于Mg2+;配碳量不足时,合成产物的主相为β-SiAlON;配碳量充足的时候,α′-SiAlON成为合成产物的主相,并含有少量的BN、SiC和AlN。产物中的α′-SiAlON晶粒呈柱状。

α＇-SiAION -BN composite powders were prepared by carbothermal reduction and nitridation using boron- rich slag as main starting material and carbon black as reductant,composition-adjusted by gramminte and bauxite clinker. The experiment conditions were optimized by orthogonal experiment. The phase composition and microstructure of the synthesized products were investigated by X-ray Diffraction （XRD）, Scanning Electron Microscope（SEM） and Energy Dispersive X-ray（EDX）. The results showed that：The optimal ex- periment conditions were reaction temperature of 1 500℃, holding time of 12 h, 1.5 times of theoretical con- suming carbon mass and nitrogen gas flow of 400 mL · min^-1. The product synthesized in the optimal con- dition had a （Ca, Mg） -α＇-SiAION -BN content of 70% up, and the solid solution of Ca^2＋ was far more than that of Mg^2＋ .β-SiAION became the main phase of the product when carbon was insufficient. But when carbon was sufficient,α＇-SiAION became the main phase,and a small amount of BN,SiC and AIN were detected. The grains shape of α＇-SiAION was columnar.