Preparation of W-B-C System Composites by Arc Melting and their Thermoelectric Properties

Abstract

W-B-C system composites were prepared by arc melting in an argon atmosphere using B4C, WC, WB, B and C powders. Lamella textures indicating eutectic reaction were observed at B4C contents of about 20mol% and 10mol% in the quasi-binary W2B5-B4C and WB4-B4C systems, respectively. Carbon phase in the W2B-B4C-C ternary system was needle-like. The Seebeck coefficient (α) generally decreased with increasing W2B5 and WB4 contents. However, the W2B5-B4C composites containing 2mol%W2B5 have slightly greater α values than those of B4C in the temperatures range between 200 and 1000K. The electrical (σ) and thermal conductivities (κ) increase with increasing W2B5 and WB4 contents. The figure of merit values (Z) increased with increasing temperature. The W2B5-B4C composites containing 2mol%W2B5 showed slightly greater Z values than B4C at temperatures between 200 and 1000K. The highest ZT value at T=1000K was about 0.1. © 1995, Japan Society of Powder and Powder Metallurgy. All rights reserved.