磨粒粒径对Si_3N_4结构陶瓷冲蚀磨损性能的影响

Effect of Abrasive Particle Size on Anti-Abrasion Performance of Si_3N_4 Ceramics

以冲蚀磨损工况下的典型应用材料Cr15Mo3高铬铸铁为对比材料,采用转盘式液-固双相流试验机研究了不同SiC磨粒粒径对Si3N4结构陶瓷抗冲蚀磨损性能的影响,分析了试验材料冲蚀磨损的微观失效机制.研究结果表明:在各种粒径磨粒的冲蚀磨损条件下,Cr15Mo3铸铁的冲蚀磨损率都比Si3N4结构陶瓷的高,Si3N4结构陶瓷的抗冲蚀磨损能力是Cr15Mo3铸铁的20倍左右;粗颗粒磨料冲蚀条件下试验材料的体积损失比细颗粒磨料冲蚀条件下的大,即磨粒越粗冲蚀磨损越严重;在微观上,Cr15Mo3的腐蚀坑、冲蚀坑多,基体材料冲刷磨损严重,W型失效形貌明显,而Si3N4结构陶瓷的冲蚀磨损面比较光滑,材料失效主要是晶界粘结相失去多所致;结构致密、晶粒细小并有细小柱状晶的存在等是Si3N4结构陶瓷抗冲蚀磨损性能优异的主要原因.

Erosion resistance of Si3N4 structure ceramics was investigated using water slurry with different SiC particle sizes on a liquid-solid dual phase erosion tester with a rotation disk, and Cr15Mo3 high chromium cast iron was taken as a contrast in the test. The erosive mechanism of the test materials in slurry erosion was also discussed. The results show that the slurry erosion of Cr15Mo3 is more severe than that of Si3N4 with varying abrasive particles diameters. The erosive resistance of Si3N4 ceramics is 20 times higher than that of Cr15Mo3 cast iron. The lost volume of the test materials eroded by larger particles is larger than that by smaller ones. SEM observation reveals that there exist more abrasive and erosive pits on worn surface of Cr15Mo3 iron, compared with smooth worn surface of Si3N4, and W-shaped fault feature appears on ,some failure surfaces of Cr15Mo3 iron. The better erosive resistance of Si3N4 lies in its finer granular and column grains, higher density and hardness.