Preparation of Al2O3 magnetic abrasives by combining plasma molten metal powder with sprayed abrasive powder

Abstract

Magnetic abrasives play a significant role in finishing processes; however, existing magnetic abrasive particles have limited their application in industry due to poor grinding performance and low service life. In this paper, high-performance iron-based spherical Al2O3 magnetic abrasives were prepared via combining plasma molten metal powder with sprayed abrasive power. Firstly, the effects of the co-gas flow rate and current on the overall melting state of the iron matrix powder were studied to obtain the suitable process parameters; then, the magnetic abrasives were prepared by increasing the hydrogen flow rate by 25% under this process parameter, and the microscopic morphology, phase composition, bonding mode, magnetic permeability and particle size distribution of the magnetic abrasives were analyzed; finally, the grinding experiments were conducted on 316 L stainless steel. The results show that the overall fusion state of the iron matrix powder is good under the parameters of current 700 A, argon flow rate 1000 L/h and hydrogen flow rate 80 L/h. The magnetic abrasives have a very high sphericity, and the alumina abrasives with sharp cutting edges are uniformly and compactly embedded into the iron matrix and form a tight mechanical bond with it; the particle size distribution of the magnetic abrasives accounts for 85% of the iron matrix; the magnetic abrasives have excellent grinding performance. The magnetic abrasives preparation approach described in this paper has the characteristics of economy and high performance, and is expected to be used for industrial mass production.