Pressureless sintering of (ZrB2–SiC–B4C) composites with (Y2O3 + Al2O3) additions. (September 2015)

• Record Type: Journal Article
• Authors: Krishnarao, R.V.; Alam, Zafir; Das, D.K.; Bhanu Prasad, V.V.; Madhusudan Reddy, G.
• Is Part Of: International journal of refractory metals & hard materials. Volume 52(2015:Sep.)
• Page Start: 55
• Page End: 65
• Publication Date: 2015-09
• Subjects: ZrB2 -- Composites -- Pressureless sintering -- Oxidation -- Thermal shock -- Joining; Heat resistant alloys -- Periodicals; Refractory materials -- Periodicals; Metallography -- Periodicals; Alliages réfractaires -- Périodiques; Matériaux réfractaires -- Périodiques; Métallographie -- Périodiques; Heat resistant alloys; Metallography; Refractory materials; Periodicals; Electronic journals; 669.73
• DOI: 10.1016/j.ijrmhm.2015.05.013
• Languages: English
• ISSNs: 0263-4368

Abstract

Abstract: Pressureless sintering of (ZrB2 –SiC–B4 C) composites with (Y2 O3 + Al2 O3 ) additions has been studied. The vol.% of SiC, B4 C, and (Y2 O3 + Al2 O3 ) was varied from (26, 24, and 16) to (5, 4, and 5) respectively. Hardness of composites has been found to decrease with a decrease in B4 C content. Flexural strength has been found to increase with decreasing (Y2 O3 + Al2 O3 ) content. No considerable decrease in flexural strength for composite with high vol.% of SiC, B4 C, and (Y2 O3 + Al2 O3 ) has been observed up to a temperature of 1500 °C. By optimizing the composition a composite possessing a density of 4.64 g cm − 3, flexural strength of 213 MPa, and Vickers hardness of 17.3 GPa has been sintered. Conical shapes could be made by manual shaping and sintering. A complex yttria-alumina-silicate (YAG) layer was found to protect the composite from oxidation at high temperature of 1700 °C. The composites exhibited good dimensional stability and thermal shock resistance at 2200 °C in oxy-acetylene flame and at 2700 °C in plasma flame. Formation of yttria stabilized zirconia embedded in the matrix of YAG has been identified on the flame exposed surfaces. The composite could be joined to itself by gas tungsten arc welding (GTAW) with a filler material containing (ZrB2 –SiC–B4 C–YAG). The shear strength of the weld was about 50% of the flexural strength of the parent composite. Highlights: Pressure less sintering of (ZrB2 -SiC-B4 C) composites with (Y2 O3 + Al2 O3 ) additions has been studied by changing the volume % of SiC, B4 C, and (Y2 O3 + Al2 O3 ) from (26, 24, and 16) to (5, 4, and 5) respectively. Conical shapes could be made by manual shaping and sintering. The composites exhibited good dimensional stability and thermal shock resistance at 2200 °C in oxy-acetylene flame and at 2700 °C in plasma flame. Formation of yttria stabilized zirconia embedded in the matrix of YAG has been identified on the flame exposed surfaces. The composite could be joined to itself by gas tungsten arc welding with a filler material containing (ZrB2 -SiC-B4 C-YAG).