Pressureless Sintering of AIN
Pressureless sintering AlN ceramics of high density, high level of mechanical, electrical and thermal properties, of predetermined level of microwave absorption was achieved by the activation of the densification process as a result of simultaneous action of high temperatures, developed surface of nanopowder particles, increased defects density and fragmentation of nanopowder particles caused by the hydrodynamic treatment, action of sintering aids in submicron-powder systems, as well as based on formation of grains with high dislocation density and multilayer polytypes in nanopowder material, on selfstrengthening of the material by plate-like grains, and besides based on altering the dielectric properties of the materials via incorporating particles of high-melting-point metals and metal-like refractories into the ceramic matrix. Optimal technological routes are presented to manufacture either structural or functional components from ceramic AlN-based materials. Material from AlN nanopowder is used in components operating in shock and abrasive wear environment. Designed ceramic matrix composites with special thermal, mechanical and dielectric properties based on submicron AlN powder are used in vacuum microwave devices increasing mean power, widening the transmission band and enhancing the effectiveness of amplifiers and oscillators.
I. Fesenko et al., "Pressureless Sintering of AIN", Advances in Science and Technology, Vol. 45, pp. 639-642, 2006