电磁连铸颗粒增强铝基复合材料圆坯及其摩擦性能

Al-Zr(CO3)2体系原位反应合成法制备(Al2O3 Al3Zr)p/Al颗粒增强铝基复合材料圆坯,在合成及半连铸过程中施加低频电磁搅拌来改善增强相颗粒在铝基体内的分布状态,同时在结晶器初始凝固区域施加高频电磁场实现软接触连铸,以改善铸坯的表面质量.扫描电镜(SEM)分析显示:施加电磁搅拌后复合材料的凝固组织致密,颗粒增强相的体积分数增加,且颗粒细化、分布更趋于均匀.干滑动摩擦磨损实验表明:施加电磁搅拌后,复合材料的耐磨性能提高. 磨损表面的SEM分析显示粘着磨损比不施加电磁搅拌时明显减少,摩擦磨损机制以磨粒磨损为主.施加的高频磁场使得单纯使用低频电磁搅拌产生的表面粗糙现象消失,铸坯表面质量显著提高.

Electromagnetic Continuous Casting for Particle-reinforced Al Matrix Composites Billet and Its Wear Properties

(Al_2O_3+Al_3Zr)p/Al composite was prepared via in-situ synthetic reaction in Al-Zr(CO_3)_2 system.During the preparation and semi-continuous casting process,a low frequency electromagnetic field was employed to improve the distribution state of reinforced particles by electromagnetic stirring.At the same time, a high frequency electromagnetic field was applied at the initial solidification zone to realize the soft-contact state between the billets and the mold wall, so as to improve the billets surface quality.SEM analysis indicated that after being stirred by the low frequency electromagnetic field the microstructure of the composite got compact,the amount of reinforced phase was increased,and the reinforced particles grew finer and distributed more uniformly.The dry friction experiment showed that the wear resistance of the composite was greatly improved by electromagnetic stirring.The SEM analysis of the worn-out surface indicated that the adhesive wear was reduced and the wear mechanism was mainly abrasion after employing electromagnetic stirring.Furthermore,the problem of coarse billets surface resulted from low frequency electromagnetic stirring was resolved and the surface quality was improved remarkably via employing the high frequency electromagnetic filed.