Effects of oxidation on the strength of debound SiC parts by powder injection moulding

In order to increase the production efficiency of powder injection moulding for SiC parts, thermal debinding was performed in air furnace without gas shield. Bending tests were performed to evaluate the strength of samples debound under different temperatures. The effects of oxidation on debinding process were also analyzed. Analysis indicates that air could accelerate the debinding rate of green parts without defects occurring. The bending strength of debound samples increases from 6.55 MPa to 11.58 MPa as the pre-sintering temperature increases from 550 °C to 850 °C. On the other hand, the bending strength of the samples pre-sintered at 1200 °C in argon atmosphere is only 11.52 MPa. It was found that, blanks have enough strength for transport after being pre-sintered in air atmosphere at 850 °C. The technology could reduce the requirement for heating equipment and enhance the efficiency of debinding for SiC parts.

In order to avoid the oxidation of SiC powder, thermal debinding is always performed with gas shielding. On the other hand, a pre-sintering at 1200–1300 °C usually follows the debinding to enhance the strength of debound parts. In order to increase the efficiency of debinding process for moulded SiC parts, debinding was performed in air atmosphere in this paper.Figure optionsDownload as PowerPoint slideResearch Highlights
► The debinding rate of SiC samples could be enhanced by heating in air furnace.
► No defect was found for samples pre-sintered under 850 °C.
► High strength could be got by pre-sintering samples in air at lower temperature.
► The bending strength of samples pre-sintered at 850 °C is 11.58 MPa.