Investigation of microstructure and mechanical strength of SiC/AlN composites processed under different sintering atmospheres

• Published in: Journal of alloys and compounds Vol. 756; pp. 175 - 181
• Main Authors: Besisa, Dina H.A., Ewais, Emad M.M., Ahmed, Yasser M.Z., Elhosiny, Fouad I., Fend, Thomas, Kuznetsov, Denis V.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 05-08-2018; Elsevier BV
• Subjects: Aluminum nitride; Aluminum oxide; Bonding strength; Cold crushing strength; Composite materials; Compressive strength; Densification; Densification parameters; Loose powder sintering; Mechanical properties; Microstructure; Morphology; SiC/AlN composites; Silicon carbide; Sintering; Sintering aids; Solid solutions; Temperature; Yttrium oxide; SiC/AlN composites; Cold crushing strength; Microstructure; Densification parameters
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2018.05.020

This work inspects the effect of different sintering atmospheres on the microstructure behavior and grains morphology of pressureless sintered SiC/AlN ceramic composites. Different SiC/AlN composites with different AlN content (0–40 wt%) were prepared by pressureless sintering at 2080 °C/2 h with addition of 2.5 wt% yttria and alumina as sintering aids. Microstructure investigation of the different carbide/nitride composites were studied under two different sintering atmospheres of argon (Ar)/vacuum and nitrogen (N2)/vaccum. Densification parameters of the different composites were measured and evaluated. Results showed that, SiC/AlN composites gave homogenous microstructure with expected high temperature properties. However they manifested different demeanors under the different atmospheres. Sintering of different composites in Ar/vacuum atmosphere was found the most suitable with high density and harmonic structure. Cold crushing strength (CCS) of the composites of the chosen atmosphere was studied and analyzed. Different SiC/AlN composites gave superior strength values resulted from the good bonding and diffusion between SiC and AlN besides their solid solution reaction. Results suggest using the investigated composites in aggressive high mechanical and high temperature applications.
•SiC/AlN composites with different AlN wt% were obtained by pressureless sintering.•Different sintering atmospheres of Ar/vacuum and N2/vacuum were investigated.•Sintering of SiC/AlN ceramics in Ar gave harmonic structure with high density.•SiC/AlN composites gave superior strength from the good diffusion between SiC and AlN.•SiC/AlN ceramics are attractive nominee in aggressive/high mechanical applications.