Evaluation of the methacrylamide/ N’N,-methylenebisacrylamide gel binder system for gel-casting of titanium powder

¹ Department of Mechanical and Mechatronic Engineering, University of Stellenbosch, South Africa,
² DSI-NRF Centre of Excellence in Strong Materials, University of the Witwatersrand, Johannesburg, South Africa

^* Corresponding author: 18269850@sun.ac.za

Abstract

Gel-casting, a near-net-shape manufacturing technique developed for ceramic powder processing, is investigated to produce titanium parts. In this study, the MAM/MBAM gel-binder system is used to develop a suitable slurry formulation and gel-casting procedure for commercially pure titanium powder. The polymeric binder system was evaluated by altering process parameters to produce a stable slurry of uniformly dispersed titanium powder that resists particle settling. Stable slurry formulations are gel-cast into rectangular bars to evaluate the green properties. The suitability of the binder system was studied by evaluating the gelation time and settling behaviour of the slurry for three dispersants at concentrations up to 0.6 wt% of the titanium powder, a range of MAM:MBAM ratios from 3:1 to 15:1 and monomer concentrations from 17 to 40 wt% of the premix solution. The green density and strength were evaluated for bars that were gel-cast from slurries with 37 vol% solids loading, 0.6 wt% Dolapix CE64 dispersant, a MAM:MBAM ratio of 3:1 and a monomer concentration of 23, 29 and 37 wt% in the premix solution. The 37 wt% monomer concentration gel-cast titanium bar produced the highest green density, 2.50 g/cm3 (55% relative density), with density gradients varying less than 4% from this average within the green part. This formulation also produced the highest green strength of 8.92 MPa.