The Structure and Properties of Si6-zAlzOzN8-z Sialons Hot-Pressed from Powders with Activating Oxide Additions

 
A.Panasyuk,
 
O.V.Pshenichnaya,
 
V.Lavrenko,
 
V.Lavrenko
 

I. M. Frantsevich Institute for Problems of Materials Science of the NAS of Ukraine, Omeliana Pritsaka str.,3, Kyiv, 03142, Ukraine
Powder Metallurgy - Kiev: Frantsevich Institute for Problems of Materials Science NASU, 2014, #07/08
http://www.materials.kiev.ua/article/1255

Abstract

The densification and phase formation during hot pressing of three compositions of β'-sialons powders produced from natural raw materials (kaolin) by carbothermal reduction in nitrogen atmosphere are studied. It is determined that the onset temperature of shrinkage decreases with increase in z index. The influence of Y2О3, La2O3, and Sc2O3 additives as activators of sintering is examined. Additives of eutectic Sc2O3–А12O3, La2O3–А12O3, and Y2О3–А12O3 activate densification at the initial stage of sintering. It is established that the material based on sialon with Y2О3–А12O3 additive has the best properties, whose strength, fracture toughness, and hardness are close to those of the materials produced by reaction hot pressing from Si3N4, A1N, А12O3, and Y2О3 preliminary synthesized components.


FRACTURE TOUGHNESS, HARDNESS, HIGH-TEMPERATURE OXIDATION RESISTANCE, INFLUENCE OF RARE-EARTH METAL OXIDE ADDITIONS, KAOLIN, NATURAL RAW MATERIAL, PRESSING OF β'-SIALON POWDERS, STRENGTH