In this report, the change of micro structure, crystalline phase, mechanical properties and then, are evaluated, changing the sintering additives and HIP sintering condition, according to α-Si3N4 and β-Si3N4 composite, in order to improve the mechanical properties and high temperature characteristics remarkably. .
As a result, it was recognized the sintering additives combination fabricates the various crystalline and the glassy phase which accelerates the densification, and Al2O3 is most effective especially, moreover HIP process is also very effective N2 gas pressure more than 60Mpa accelerates the α-Si3N4 to β-Si3N4
crystalline transformation of with densification.
Then, the squeezing roll for the steel pipes production made of Si3N4 reported, performed over 10 times more than conventional SKD rolls and over 2 times more than non-HIP-ed Si3N4 roll.