碳热还原法制备Cr3C2-WC复合粉末的研究

Study on CrC-WC Composite Powders Synthesized by Carbothermal Reduction Method

采用碳热还原法在1 400℃反应1 h制备了Cr3C2-30WC复合粉末。采用XRD和SEM对复合粉末的相成分和显微组织进行了分析表征,并以自制Cr3C2-10WC复合粉末为原料制备了Cr3C2基金属陶瓷。结果表明,Cr3C2-30WC复合粉末合成反应的相转变主要为:WO3→WO2.9→WO2.72→W(W2C)、Cr2O3→Cr7C3→Cr3C2以及W固溶到Cr3C2中形成(Cr,W)C固溶体。随着碳热还原温度的升高,复合粉末的粒度增大,在1 400℃下出现由3~5μm左右的小颗粒聚集熔合成的10~20μm大团粒。Cr3C2-10WC复合粉末能明显抑制传统Cr3C2-20Ni金属陶瓷的硬质相长大,使得金属陶瓷的抗弯强度由850 N/mm2提高到1 240 N/mm2,提高幅度达45.9%;HV30硬度从930 MPa提高到了1 030 MPa,提高约10.8%。

Cr3C2-30 WC composite powders were prepared by carbothermal reduction method at 1 400 ℃ for 1 h.The phase composition and microstructure of the composite powders were characterized by XRD and SEM,and then the Cr3C2-based cermets were prepared with self-made Cr3C2-10 WC composite powders.The results show that the phase transition during synthesis reaction of Cr3C2-30 WC composite powders is mainly WO3 → WO2.9 → WO2.72 →W(W2C),Cr2O3 → Cr7C3 → Cr3C2 and W solution into Cr3C2 to form(Cr,W) C solid solution.With the carbothermal reduction temperature increases,the grain size of compo-site powders increases,and about 3~5 μm small particles agglomerate and melt to form 10~20 μm large particles at 1 400 ℃.Cr3C2-10 WC composite powders can significantly inhibit growth of the hard phase in traditional Cr3C2-20 Ni cermets.The bending strength of cermets increases from 850 N/mm2 to 1 240 N/mm2,with an increase of 45.9%.At the same time,the HV30 hardness increases from 930 MPa to 1 030 MPa,with an increase of about 10.8%.