The effect of TiC additive with Al2O3-Y2O3 on the microstructure and mechanical properties of SiC matrix composites

Document Type: Original Research Article

Authors

1 Composite Materials & Technology Center, Malek Ashtar University of Technology, Tehran, Iran

2 Department of Materials Science and Engineering, Faculty of Technology and Engineering, Imam Khomeini International University, Qazvin 3414896818, Iran

3 a Composite Materials & Technology Center, Malek Ashtar University of Technology , Tehran, Iran.

4 Maleke Ashtar University of Technology

5 Department of Ceramic, Shahreza Branch, Islamic Azad University, Shahreza, Iran

Abstract

In this research, the SiC-matrix composite with various amounts of TiC (0, 2.5, 5, 7.5 and 10 wt. %), acompained with 4.3 wt% Al2O3 and 5.7 wt% Y2O3, as additives, were utilized to prepare the required liquid phase. The sintering process was conducted using pressureless sintering at 1900 °C for 1.5 hours under an argon atmosphere. The composition and microstructure of the obtained composites were analyzed using X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), and energy-dispersive X-ray spectroscopy (EDX). The results showed that TiC additives improved the densification of samples and impeded the growth of SiC grains. According to the phase analysis, the SiC was the main phase, while the TiC and YAG were characterized as partial phases. Additionally, due to the reaction of the TiC and Al2O3, the composition of the liquid phase contained YAG and YAM. Assessments revealed that the microstructure and the final properties of composites were affected by the density, the produced phases as well as their distribution in the matrix, and the grain size. Based on results, upon raising the TiC up to 5 wt%, all the measured properties, including the density, hardness, elastic modulus, and fracture toughness, enhanced and reached 97.40%, 26.73 GPa, 392 GPa, 5.80 MPa.m1/2. However, with introducing additives to more than 5 wt.%, these properties deteriorated. Microscopic evaluations demonstrated that crack deflection and crack bridging mechanisms improved the fracture toughness of SiC ceramics.

Keywords



Articles in Press, Accepted Manuscript
Available Online from 28 June 2020
  • Receive Date: 23 April 2020
  • Revise Date: 14 June 2020
  • Accept Date: 20 June 2020