离心铸造初生Si及Si/Mg₂Si颗粒增强铝基复合材料的组织与性能

林雪冬^{1, 2}，刘昌明¹，吕循佳¹，郝旭红¹

(1. 重庆大学 材料科学与工程学院，重庆 400030；
2. 重庆工程职业技术学院 机械工程学院，重庆400037)

摘 要：采用离心铸造方法制备初生Si颗粒单独增强Al-18Si初生Si/Mg₂Si颗粒混合增强Al-18Si-5Mg铝基复合材料活塞。研究内浇口尺寸、浇注温度、模具温度、离心转速对Al-18Si-5Mg活塞的组织的影响，测试两种离心铸造活塞的硬度和耐磨性能，并与重力铸造Al-18Si活塞进行性能对比。结果表明：内浇口厚度尺寸为8mm，浇注温度为770 ℃，模具温度为400 ℃，离心转速为800 r/min时，离心铸造获得成形效果好且无铸造缺陷的Al-18Si、Al-18Si-5Mg活塞，活塞顶部及环槽区分别偏聚有大量的初生Si颗粒和初生Si/Mg₂Si颗粒，而活塞裙部为无颗粒的基体组织。离心铸造Al-18Si-5Mg活塞在顶部及环槽的硬度比离心铸造Al-18Si活塞的提高了10%，前者的耐磨性能略优于后者；离心铸造Al-18Si-5Mg活塞顶部及环槽的硬度比重力铸造Al-18Si活塞的提高了10%~20%，且前者的平均磨损量仅为后者的60%~68%.

关键词：初生颗粒；铝基复合材料活塞；硬度；耐磨性能；离心铸造

Structures and properties of aluminum matrix composite reinforced by primary Si and Si/Mg₂Si particles fabricated by centrifugal casting

LIN Xue-dong^{1, 2}, LIU Chang-ming¹, Lü Xun-jia¹, HAO Xu-hong¹

(1. College of Materials Science and Engineering, Chongqing University, Chongqing 400030, China；
2. College of Mechanical Engineering, Chongqing Vocational Institute of Engineering, Chongqing 40003)

Abstract:The Al-18Si and Al-18Si-5Mg aluminum matrix composite pistons reinforced by primary Si and primary Si/Mg2Si particles were fabricated by centrifugal casting, respectively. The influences of various ingate sizes, pouring temperatures, mold temperatures and rotational speed of the mold on the structures of Al-18Si-5Mg pistons were studied. The hardness and wear resistance of the two centrifugal casting of pistons were measured, and a comparison of properties was made between the centrifugal casting of Al-18Si-5Mg piston and the gravity casting of Al-18Si piston. The results show that the appropriate technological parameters are 770 ℃ for the pouring temperature, 400 ℃ for the preheating temperature of the mold, 800 r/min for the rotational speed of the mold and 8 mm for the ingate thickness. And plenty resistance property of primary Si and primary Si/Mg2Si were segregated in the top and the ring groove of the Al-18Si and Al-18Si-5Mg pistons, respectively, but no particle is observed in the piston skirt. The hardness at the top and the ring groove of the centrifugal casting of Al-18Si-5Mg piston is increased by 10% over that of the centrifugal casting of Al-18Si piston, and the wear resistance property of the former is slightly better than the latter. The hardness at the top and the ring groove of the centrifugal casting of Al-18Si-5Mg piston is improved by 10%-20% over that of the gravity casting of Al-18Si piston, and the wear loss of the former is about 60%-68% as that of the latter.

Key words:primary particle; Al matrix composites piston; hardness; wear resistance; centrifugal casting