Synthesis and mechanical properties of Al8B4C7

Aluminum boron carbide (Al8B4C7) was synthesized by heating a mixed Powder consisting of Al:B4C:C = 8:1:6 (molar ratio) at 1600 degrees C for 1 h. The synthesized Al8B4C7 Powder was ball milled for 24 h with alumina balls to prepare an Al8B4C7 powder with under 40 mu m diameter. The fine Al8B4C7 powder was then put into a carbon die, pressed, and sintered using PECS at 1650 degrees C for 10 min under an applied pressure of 60 MPa, resulting in an Al8B4C7 body with a relative density of 99.6%. The bending strength, Vickers hardness, and fracture toughness of the dense Al8B4C7 body were 500 MPa, 15.2 GPa and 2.3 MPa.m(1/2), respectively. The bending strength of the dense Al8B4C7 body increased during heating to 510 MPa at 1000 degrees C, but decreased to 440 MPa at 1200 degrees C. (C)2009 The Ceramic Society of Japan. All rights reserved.