High temperature mechanical retention characteristics and oxidation behaviors of the MoSi2(Cr5Si3)—RSiC composites prepared via a PIP—AAMI combined process

• Published in: Journal of advanced ceramics Vol. 8; no. 2; pp. 196 - 208
• Main Authors: Gao, Peng-zhao, Cheng, Lei, Yuan, Zheng, Liu, Xiao-pan, Xiao, Han-ning
• Format: Journal Article
• Language: English
• Published: Beijing Tsinghua University Press 01.06.2019; Springer Nature B.V
• Subjects: Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Chromium base alloys; Composites; Composition; Crystal growth; Diffraction patterns; Fracture toughness; Glass; High temperature; high temperature mechanical characteristic; Infiltration; Materials Science; Mechanical properties; Modulus of elasticity; Molybdenum disilicides; MoSi2(Cr5Si3)—RSiC composites; Nanotechnology; Natural Materials; Oxidation; oxidation behavior; Oxide coatings; precursor impregnation pyrolysis and MoSi2—Si—Cr alloy active melt infiltration (PIP—AAMI); Pyrolysis; Research Article; Scanning electron microscopy; Stress relaxation; Structural Materials; Surface defects; Thermal stress; Three dimensional composites; X-ray diffraction; precursor impregnation pyrolysis and MoSi; oxidation behavior; Si; Si—Cr alloy active melt infiltration (PIP—AAMI); MoSi; high temperature mechanical characteristic; RSiC composites; Cr
• ISSN: 2226-4108; 2227-8508
• DOI: 10.1007/s40145-018-0305-1

In the present paper, MoSi 2 (Cr 5 Si 3 )—RSiC composites were prepared via a combination of precursor impregnation pyrolysis (PIP) and MoSi 2 —Si—Cr alloy active melt infiltration (AAMI) process. Composition, microstructure, mechanical retention characteristics, and oxidation behaviors of the composites at elevated temperature were studied. X-ray diffraction (XRD) pattern confirms that the composites mainly compose of 6H—SiC, hexagonal MoSi 2 , and tetragonal Cr 5 Si 3 . Scanning electron microscopy (SEM) image reveals that nearly dense MoSi 2 (Cr 5 Si 3 )—RSiC composites exhibiting three-dimensionally (3D) interpenetrated network structure are obtained when infiltrated at 2173 K, and the interface combination of the composites mainly depends on the composition ratio of infiltrated phases. Oxidation weight gain rate of the composites is much lower than that of RSiC matrix, where MoSiCr2 possesses the lowest value of 0.1630 mg·cm −2 , about 78% lower than that of RSiC after oxidation at 1773 K for 100 h. Also, it possesses the highest mechanical values of 139.54 MPa (flexural strength σ f and RT) and 276.77 GPa (elastic modulus E f and RT), improvement of 73.73% and 29.77% as compared with that of RSiC, respectively. Mechanical properties of the composites increase first and then decrease with the extension of oxidation time at 1773 K, due to the cooperation effect of surface defect reduction via oxidation reaction and thermal stress relaxation in the composites, crystal growth, and thickness increase of the oxide film. Fracture toughness of MoSiCr2 reaches 2.24 MPa·m 1/2 (1673 K), showing the highest improvement of 31.70% as compared to the RT value.