Formation mechanism of ceramic/metal composite spherical magnetic abrasive prepared via gas-solid atomization

In order to prepare good magnetic abrasive particles (MAPs) and make it play a better role in magnetic abrasive finishing (MAF), an experimental investigation on the formation mechanism of Al2O3/Fe-based composite spherical MAPs prepared via gas-solid atomization is presented. The morphology of MAPs and the distribution of Al2O3 abrasives inside and outside the iron matrix were characterized by scanning electron microscopy and energy-dispersive spectroscopy. The breaking mechanism of gas-solid two-phase flow to molten metal was analyzed by comparing with the metal powder prepared via gas atomization. The formation mechanism of MAPs was studied by analyzing and calculating the mutual movement and cooling process between Al2O3 abrasive and metal droplet. The results show that the breaking mechanism of gas-solid two-phase flow to molten metal is quite different from that of pure gas. Under the same experimental conditions, the average particle size of MAPs prepared by gas-solid atomization is smaller than that of metal powders prepared by gas atomization. After observing the surface and cross-section of MAP, it is found that Al2O3 abrasives are only evenly and densely distributed on the surface of iron matrix, and there is almost no Al2O3 abrasives inside the iron matrix. The calculation shows that in the process of MAPs’ formation, the time of Al2O3 abrasive moving from the inside to the surface of the droplet is less than that of droplet cooling. •The breaking mechanism of gas-solid two-phase flow to molten metal is different from that of the pure gas to molten metal. When the molten metal is broken by pure gas, the droplets are stripped from the surface of the molten metal through the disturbance of gas, while the way that the molten metal is broken by the gas-solid two-phase flow is the disturbance breaking of gas, accompanied by the penetration breaking of ceramic abrasives.•After analyzing and calculating the movement process of Al2O3 abrasive in metal droplet and the cooling process of metal droplet, it is found that the time for most Al2O3 abrasives in droplet to move to the surface of droplet is less than the solidification time of droplet. Therefore, the ceramic/metal composite spherical MAP prepared by gas-solid atomization is closer to the ideal MAP.•This study reveals the breaking mechanism of gas-solid two-phase flow to molten metal and the formation mechanism of ceramic/metal composite spherical MAP, which provides theoretical support and metho