Fabrication of Nanocrystalline Dense Silicon Nitride Ceramics

Hai Doo Kim; Seong Hyeon Hong

doi:10.4028/www.scientific.net/MSF.715-716.738

Paper Titles

Nonlinear Migration of Faceted Boundaries and Nonstationary Grain Growth in Ceramics
p.719

Sub-Boundary Mobilities during Recovery of Binary Al-Mn Alloys
p.725

The Weighted Burgers Vector: A Quantity for Constraining Dislocation Densities and Types Using Electron Backscatter Diffraction on 2D Sections through Crystalline Materials
p.732

Mean Field and Finite Element Modeling of Static and Dynamic Recrystallization
p.737

Fabrication of Nanocrystalline Dense Silicon Nitride Ceramics
p.738

Modelling the Static Recrystallisation Texture of FCC Metals Using a Phase Field Method
p.739

Zener Pinning Pressure in Tempered Martensite Lath Structure
p.745

A Rationale for SRX Regression Model of Hot-Deformed Austenite Using an Orthogonal Taguchi L8 Matrix Steels
p.751

Room Temperature Recovery in Rolled Polycrystalline Copper after many Years
p.758

HomeMaterials Science ForumMaterials Science Forum Vols. 715-716Fabrication of Nanocrystalline Dense Silicon...

Fabrication of Nanocrystalline Dense Silicon Nitride Ceramics

Abstract:

Since the properties of the bulk ceramics are dependent on the grain size the ceramic materials with nanoscale grain size is of interest. Sintering of nanosized powder compacts to full density with minimum grain growth is a difficult task to achieve due to its high surface energy. Two step sintering methode was developed to enhance densification with minimum grain growth for silicon nitride ceramics with liquid phase. Starting with nano-sized silicon nitride powder two step sintering methode gives rise to a very fine-grained b-Si₃N₄ matrix with large agglomerated Si₂N₂O grains due to its high surface oxygen content. Addition of Y₂O₃ shifts the composition point to a primary phase field with no Si₂N₂O, gives rise to b-Si₃N₄ with nano scale grain size and near full density. Carbothermal reduction method was employed to reduce the oxygen content in nano-sized silicon nitride powder to give nanocrystalline dense silicon nitride ceramics without Si₂N₂O formation. Use of SPS was effective to suppress the grain growth and to give near full density. Microstructural development and mechanical properties will be reported.