ISSN 0862-5468 (Print), ISSN 1804-5847 (online) 

Ceramics-Silikáty 62, (1) 15 - 30 (2018)


MICROSTRUCTURE, THERMO-PHYSICAL, MECHANICAL AND WEAR PROPERTIES OF IN-SITU FORMED BORON CARBIDE - ZIRCONIUM DIBORIDE COMPOSITE
 
Murthy T. S. R. Ch. 1,4, Ankata Sairam 2, Sonber J. K. 1, Sairam K. 4, 1, Singh Kulwant 1, Nagaraj A. 3, Sengupta P. 4, 1, Bedse R. D. 1, Majumdar Sanjib 4, 1, Kain Vivekanand 1,4
 
1 Materials Group, Bhabha Atomic Research Centre, Mumbai, India
2 Dept. of Metallurgical and Materials Engineering, Indian Institute of Technology, Kharagpur, India
3 Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Mumbai, India
4 Homi Bhabha National Institute, Mumbai, India

Keywords: Boron Carbide, Microstructure, XRD, Electrical resistivity, Thermal conductivity, Wear resistance
 

Microstructure, thermos-physical, mechanical and wear properties of in-situ formed B₄C- ZrB₂ composite were investigated. Coefficient of thermal expansion, thermal diffusivity and electrical resistivity of the composite were measured at different temperatures up to 1000 °C in inert atmosphere. Flexural strength was measured up to 900 °C in air. Friction and wear properties have been studied at different loads under reciprocative sliding, using a counter body (ball) of cemented tungsten carbide (WC-Co) at ambient conditions. X-ray diffraction (XRD) and electron probe microanalysis (EPMA) confirmed the formation of ZrB₂ as the reaction product in the composite. Electrical resistivity was measured as 3.02 x 10-4Ω.m at 1000°C. Thermal conductivity measured at temperatures between 25°C and 1000 °C was in the range of 8 to 10 W/m-K. Flexural strength of the composite decreased with increase in temperature and reached a value of 92 MPa at 900°C. The average value of coefficient of friction (COF) was measured as 0.15 at 20 N load and 10 Hz frequency. Increase of load from 5 N to 20 N resulted in decrease in COF from 0.24 to 0.15 at 10 Hz frequency. Specific wear rate data observed was of the order of 10-6 mm³/N-m. Both abrasive and tribo-chemical reaction wear mechanisms were observed on the worn surface of flat and counter body materials. At higher loads (≥10 N) a tribo-chemical reaction wear mechanism was dominant.


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doi: 10.13168/cs.2017.0041
 
 
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