Synthesis and characterization of environment-friendly spherical cubic boron nitride magnetic abrasives by plasma molten metal powders bonding with hard materials

Abstract

In this investigation, globular cubic boron nitride magnetic abrasive powders (cBN-MAPs) were synthesized with additive-free via plasma molten metal powders bonding with hard materials (PM2BH) for finishing hard and brittle materials. Experiments were carried out with cBN powder flow rates of 60–300 g/min, which significantly affected the performance and microstructure of the composites. It illustrates that: the composites are composed of cBN and α-Fe; the cBN is not transformed into hBN, which can be reused; a linear increase in the amount of cBN grains bound to the apparent layer of the ferrous substrate with increasing powder flow rate, the proportion of MAPs in the 180–230 μm size distribution and the magnetic permeability decrease; when the powder flow rate is maximum, the powder embedded in ferrous substrate completely covers the surface of the matrix, forming spherical MAPs, after 50 min of machining, surface finish of AlN ceramics improved from 342 nm to 93.5 nm, with cBN-MAPs showing normal wear within 80 min. A novel, highly efficient strategy for additive-free cBN/Fe composites is presented in this paper.