Lightweight boron carbide materials with improved mechanical properties and process for their manufacture

US7309672B2 · kind B2 · utility

Assignee

• Ceradyne, Inc. · US

Inventors

• Biljana Mikijelj · Cerritos, US
• Georg P. Victor · Kempten, DE
• Karl Schwetz · Kempten (Allgäu), DE

Key dates

• Filing date: Jul 5, 2005
• Grant date: Dec 18, 2007
• Expiry date: Oct 25, 2025

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C04B2235/85
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

This disclosure describes sintered bodies comprising about 90 wt % to about 99 wt % of boron carbide, having a B:C atomic ratio ranging from 3.8 to 4.5:1; 0 to 1 wt % free carbon; 0 to 1 wt % BN or AlN, remainder an oxide binder phase; said sintered body having a uniform microstructure composed of substantially equiaxed grains of said boron carbide; the oxide binder phase comprising at least a rare earth aluminate and optionally Al2O3 or other ternary or binary phases of rare earth oxide-alumina systems; the binder phase being present in form of pockets at the multiple grain junctions and the density of no more than 2.6 g/cm3. Also described is a manufacturing process for the above described substantially pore-free, sintered boron carbide materials with high strength and fracture toughness, which can be used for production of large-area parts. This is achieved by liquid phase low temperature-low pressure hot pressing of boron carbide in an argon atmosphere.