Effect of rare earth oxides addition on the mechanical properties and coloration of silicon nitride ceramics

A hot-pressed silicon nitride ceramic material with rare-earth oxides additive has been processed, its bend strength maintains 800–900 MPa up to 1300°C and measures 680 MPa at 1400°C, its fracture toughness at room temperature is 4.38–4.96 MPam. X-ray, SEM, EDS and electron probe analyses reveal that the microstructure of this material is composed of fine β-Si3N4 grains, α-Si3N4 whiskers, small tetragonal lanthanide crystals and La-containing glassy phase. Observation on fracture surface shows that the fracture path is mainly transcrystalline up to 1400°C. The effects of additives on strength and fracture toughness of HPSN obtained are also discussed.

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Substitution of pure Y2O3 by a mixed concentrate of rare earth oxides (CRE2O3) as sintering additive of Si3N4: a comparative study of the mechanical properties

Journal of Materials Processing Technology ◽

10.1016/s0924-0136(03)00807-0 ◽

2003 ◽

Vol 142 (3) ◽

pp. 697-701 ◽

Cited By ~ 18

Author(s):

C Santos ◽

S Ribeiro ◽

K Strecker ◽

C.R.M da Silva

Keyword(s):

Mechanical Properties ◽

Rare Earth ◽

Comparative Study ◽

Rare Earth Oxides ◽

Sintering Additive

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Effects of Sintering Additives on the Microstructure and Mechanical Properties of Silicon Nitride Ceramics by GPS

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.105-106.27 ◽

2010 ◽

Vol 105-106 ◽

pp. 27-30 ◽

Cited By ~ 2

Author(s):

Wei Ru Zhang ◽

Feng Sun ◽

Ting Yan Tian ◽

Xiang Hong Teng ◽

Min Chao Ru ◽

...

Keyword(s):

Mechanical Properties ◽

Fracture Toughness ◽

Phase Transformation ◽

Silicon Nitride ◽

Porous Silicon ◽

Flexural Strength ◽

Relative Density ◽

Sintering Additives ◽

Microstructure And Mechanical Properties ◽

Nitride Ceramics

Silicon nitride ceramics were prepared by gas pressure sintering (GPS) with different sintering additives, including La2O3, Sm2O3 and Al2O3. Effect of sintering additives on the phase-transformation, microstructure and mechanical properties of porous silicon nitride ceramics was investigated. The results show that the reaction of sintering additives each other and with SiO2 had key effects on the phase-transformation, grain growing and grain boundaries. With 9MPa N2 atmosphere pressure, holding 1h at 1850°C, adding 10wt% one of the La2O3, Sm2O3, Al2O3, porous silicon nitride was prepared and the relative density was 78%, 72%, 85% respectively. The flexural strength was less than 500MPa, and the fracture toughness was less than 4.8MPam1/2. Dropping compounds sintering additives, such as La2O3+Al2O3, Sm2O3+Al2O3 effectively improves the sintering and mechanical properties. The relative density was 99.2% and 98.7% with 10wt% compounds sintering additives. The grain ratio of length to diameter was up to 1:8. The flexural strength was more than 900MPa, and the fracture toughness was more than 8.9MPam1/2.

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Development of High Performance Silicon Nitride Ceramics and their Applications

MRS Proceedings ◽

10.1557/proc-287-189 ◽

1992 ◽

Vol 287 ◽

Cited By ~ 22

Author(s):

Yo Tajima

Keyword(s):

Mechanical Properties ◽

Silicon Nitride ◽

High Performance ◽

Future Prospect ◽

Cutting Tools ◽

Sintering Process ◽

Sintering Additives ◽

Nitride Ceramics ◽

Engine Components

ABSTRACTProgress in sintering process and improvement of mechanical properties of silicon nitride ceramics are reviewed. Emphases are placed on contributions of advanced sintering techniques and better understanding of sintering additives and microstructure-properties relations. Current applications as engine components and cutting tools are described, and future prospect is considered.

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