Study on rheological properties and polishing performance of viscoelastic material for dilatancy pad

Abstract

Shear dilatancy polishing (SDP) is an emerging flat polishing method for hard and brittle materials, which can achieve high-efficiency and high-precision polishing of workpieces under high-pressure and high-speed conditions. In our research, a novel viscoelastic material (VM) with non-Newtonian fluid properties was prepared. The dilatancy pad was subsequently obtained based on VM, abrasives, and a polyurethane pad. The effects of abrasive size and abrasive concentration on the rheological properties of VM were analyzed. The mechanism of abrasives in VM was investigated, and the principle of SDP was revealed. VM-30 wt%Diamond (0.5 μm) with excellent shear hardening performance was selected in the polishing experiment to study the effects of polishing time, polishing speed, and polishing pressure on polishing performance, and the optimal polishing parameters of SDP for tungsten were determined. Compared with traditional abrasive free polishing (AFP), SDP can realize a higher material removal rate (MRR increased by 33.4%) and better surface quality (Sa reduced by 32.2%) due to the shear dilatancy effect under high-pressure and high-speed conditions. After 90 min of SDP, the surface roughness (Sa) of tungsten workpiece was reduced from 307.9 nm to 12.1 nm. Results show that SDP is a promising and feasible polishing method for hard and brittle materials.