Effects of oxide addition on the microstructure and mechanical properties of lamellar SiC scaffolds and Al–Si–Mg/SiC composites prepared by freeze casting and pressureless infiltration

• Published in: Ceramics international Vol. 42; no. 8; pp. 9653 - 9659
• Main Authors: Shaga, Alateng, Shen, Ping, Guo, Rui-Fen, Jiang, Qi-Chuan
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.06.2016
• Subjects: Al–Si–Mg/SiC; Composites; Compressive strength; Elastic modulus; Freeze casting; Pressureless infiltration; Elastic modulus; Composites; Compressive strength; Al–Si–Mg/SiC; Pressureless infiltration; Freeze casting
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2016.03.052

Silicate-bonded porous SiC scaffolds with lamellar structures were prepared by freeze casting and liquid-phase sintering. It was found that the viscosity and solidification velocity of SiC water-based slurries with 30vol% solid loading decreased with increasing Al2O3–MgO (AM) addition. As the AM content increased from 10 to 30wt%, the lamellae of the sintered scaffolds became denser and the porosity decreased from 69±0.5% to 62±0.5%, while the compressive strength improved from 25±2 to 51±2MPa. The dynamics of pressureless infiltration for an Al–12 Si–10 Mg alloy on the SiC porous scaffold was measured and the composites with lamellar-interpenetrated structures were successfully produced. Both the compressive strength and the elastic modulus of the composites increased with increasing AM content. The maximum strength reached 952±24MPa and the highest elastic modulus about 156GPa, respectively, in a longitudinal direction, increasing about 32% and 11% as compared with those of the composites without AM.