粉末球磨时间对Mo2NiB2金属陶瓷组织与性能的影响

Effect of Powder Ball Milling Time on Microstructure and Properties of Mo_(2)NiB_(2)Cermet

将钼粉、镍粉和硼粉进行球磨混合,压制成型,采用液相烧结工艺制备Mo_(2)NiB_(2)金属陶瓷,研究了粉末球磨时间(1,12,24,36,48 h)对Mo_(2)NiB_(2)金属陶瓷显微组织、硬度和耐电化学腐蚀性能的影响。结果表明:不同粉末球磨时间下Mo_(2)NiB_(2)金属陶瓷均主要由Mo_(2)NiB_(2)、MoB和MoNi相组成,当粉末球磨时间为24 h时,原料粉末混合最均匀,反应生成的Mo_(2)NiB_(2)相含量最高,金属陶瓷的相对密度最大;随着粉末球磨时间的延长,金属陶瓷的硬度先减小再增加后减小,自腐蚀电流密度先增大后降低再增大,当粉末球磨时间为24 h时硬度最高,自腐蚀电流密度最小,耐腐蚀性能最好,这与此时金属陶瓷内部孔隙最少减少了腐蚀介质扩散通道以及Mo_(2)NiB_(2)相含量较多促进阳极极化有关。

Molybdenum powder,nickel powder and boron powder were mixed by ball milling and press molded,and then Mo_(2)NiB_(2)cermet was prepared by liquid phase sintering.The effects of powder ball milling time(1,12,24,36,48 h)on microstructure,hardness and electrochemical corrosion resistance of Mo_(2)NiB_(2)cermet were studied.The results show that under different powder ball milling times,Mo_(2)NiB_(2)cermets were all mainly composed of Mo_(2)NiB_(2),MoB and MoNi phases.When the powder ball milling time was 24 h,the raw material powder was most evenly mixed,the content of the Mo_(2)NiB_(2)phase generated by reaction was the highest,and the relative density of the cermet was the largest.With increasing powder ball milling time,the hardness of the cermet decreased first and increased and then decreased,and the free-corrosion current density increased first and decreased and then increased.When the powder ball milling time was 24 h,the hardness was the highest,and the free-corrosion current density was the smallest,indicating the corrosion resistance was the best.The best corrosion resistance was related to the reduction of diffusion channels of corrosive media due to the fewest pores in the cermet and the promotion of anodic polarization by the high content of Mo_(2)NiB_(2)phase.