Reaction-bonding of aluminum oxide processed by binder jetting

Abstract

Abstract The combination of additive manufacturing based on the binder jetting and reaction-bonding aluminum oxide (RBAO) techniques can produce fully ceramic specimens near net shape. This study developed powder formulations composed of stearic acid coated aluminum (Al) powder and dextrin coated aluminum oxide (Al2O3) powder, in order to be processed via binder jetting, and post-processed via RBAO. The coated powders were mixed with different volume ratios of Al to Al2O3. After the printing process, the specimens were heat treated from room temperature to 1200\u2009°C, in an oxidative atmosphere. Increasing Al volume ratio from 0.25 to 0.50 generated a significant flexural strength improvement, reaching about 20%. This increase had no influence on apparent porosity or density, which averaged at 64% and 1.35\u2009g\u2009cm−3, respectively. A complex geometry model was built to prove the feasibility of producing sophisticated parts. As expected, post-RBAO parts shrinkage was nearly zero, proving the feasibility of the additive manufacturing, by binder jetting, and RBAO combination.