ZrB2\u2013SiC based composites for thermal protection by reaction sintering of ZrO2+B4C+Si

R. V. Krishnarao,G. Madhusudhan Reddy,V. V. Bhanuprasad

doi:10.1007/s40145-017-0244-2

R. V. Krishnarao, G. Madhusudhan Reddy + Show 1 more

Open Access

https://doi.org/10.1007/s40145-017-0244-2

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Abstract

Synthesis and sintering of ZrB2–SiC based composites have been carried out in a single-step pressureless reaction sintering (PLRS) of ZrO2, B4C, and Si. Y2O3 and Al2O3 were used as sintering additives. The effect of ratios of ZrO2/B4C, ZrO2/Si, and sintering additives (Y2O3 and Al2O3), was studied by sintering at different temperatures between 1500 and 1680 °C in argon atmosphere. ZrB2, SiC, and YAG phases were identified in the sintered compacts. Density as high as 4.2 g/cm3, micro hardness of 12.7 GPa, and flexural strength of 117.6 MPa were obtained for PLRS composites. Filler material was also prepared by PLRS for tungsten inert gas (TIG) welding of the ZrB2–SiC based composites. The shear strength of the weld was 63.5 MPa. The PLRS ZrB2–SiC composites exhibited: (i) resistance to oxidation and thermal shock upon exposure to plasma flame at 2700 °C for 600 s, (ii) thermal protection for Cf–SiC composites upon exposure to oxy-propane flame at 2300 °C for 600 s.

Highlights

Zirconium diboride (ZrB2) is well known for its unique combination and high values of properties: melting point, chemical stability, hardness, strength, thermal conductivity, and electrical conductivity
Variety of synthesis routes which include: (i) reduction processes [10,11,12], (ii) chemical routes [13], and (iii) reactive processes [14] can be resorted to prepare ZrB2 powders using ZrO2 as a source of zirconium
pressureless reaction sintering (PLRS) of ZrB2–SiC composites has been carried out using ZrO2 and B4C with two different ratios of 1.6 and 2.0, Si, and sintering additives (Y2O3 and Al2O3)

Summary

Introduction

Zirconium diboride (ZrB2) is well known for its unique combination and high values of properties: melting point, chemical stability, hardness, strength, thermal conductivity, and electrical conductivity. The research on synthesis and sintering of ZrB2 based composites have been accelerated because ZrB2 is being considered for high speed aircraft leading edges, and for structural parts in high temperature environments. An attempt is made to synthesize and sinter ZrB2–SiC based composites in a single-step PLRS using ZrO2, B4C, and Si for synthesis and Y2O3 and Al2O3 for sintering. The resulted ZrB2–SiC based composite is exposed to plasma flame and oxy-propane flame to study its oxidation and thermal protection of carbon fibre reinforced silicon carbide (Cf–SiC)

Experimental

Results and discussion

Conclusions