The role of MgSiN2 during the sintering process of silicon nitride ceramic

ABSTRACTThe performance of reinforced ceramics, particularly the toughness and creep resistance, is often determined by the nature of the interface between the reinforcement and the ceramic matrix. Specially-designed experiments to investigate the role of the interfacial characteristics on toughening mechanisms and crack propagation in reinforced (silicon carbide whisker reinforced alumina) and self-reinforced (silicon nitride) ceramic composites will be described. In the whisker-reinforced composites, the interfacial topography and chemistry were of primary importance, whereas in the silicon nitride materials the formation of interfacial phases and glassy-phase chemistry influenced the interfacial debonding process. The composite interfaces were characterized by high resolution electron microscopy and high spatial resolution microchemical analysis, including energy-dispersive X-ray and electron energy loss spectroscopy. Results from energy-filtered images from ceramic interfaces will also be shown.

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On the Possibility of Chemo-Mechanical Action in Magnetic Float Polishing of Silicon Nitride

Journal of Tribology ◽

10.1115/1.2831600 ◽

1996 ◽

Vol 118 (4) ◽

pp. 721-727 ◽

Cited By ~ 19

Author(s):

R. Komanduri ◽

N. Umehara ◽

M. Raghunandan

Keyword(s):

Silicon Nitride ◽

Aluminum Oxide ◽

Chromium Oxide ◽

Surface Texture ◽

Material Removal ◽

Mechanical Action ◽

Removal Rates ◽

Silicon Nitride Ceramic ◽

Magnetic Float

Chromium oxide abrasive has been reported in the literature to provide efficient chemo-mechanical polishing action for silicon nitride ceramic. Since aluminum oxide and chromium oxide abrasives are nearly of the same hardness, magnetic float polishing tests were conducted on silicon nitride balls with these two abrasives to investigate mechanical versus chemo-mechanical aspects of polishing. Tests results show higher removal rates and smoother surface texture (with fewer pits) with chromium oxide abrasive compared to aluminum oxide abrasive. Formation of pits due to brittle fracture seems to be the more predominant mode of material removal with aluminum oxide abrasive than with chromium oxide abrasive. While there may be some mechanical action (abrasion) with chromium oxide abrasive initially, subsequent removal is believed to be due to chemo-mechanical action. This could be due to degeneration of the chromium oxide abrasive (both mechanical and chemical) during polishing. Various hypotheses for the material removal mechanism (both mechanical and chemo-mechanical) were considered. Based on that, the higher removal rates and smoother surface texture on the silicon nitride balls with chromium oxide abrasive in semifinish polishing is interpreted here as possibly due to chemo-mechanical action. Higher chemical stability of aluminum oxide abrasive (compared to chromium oxide abrasive) and the known role of chromium oxide as a catalyst for the oxidation of silicon nitride are some of the reasons attributed for this action.

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The role of pseudomorphic structure in sintering process

Materials Letters ◽

10.1016/j.matlet.2021.130307 ◽

2021 ◽

pp. 130307

Author(s):

Jiuhong Ma ◽

Huizhong Zhao ◽

Han Zhang ◽

Yang Yang ◽

Yichong Li ◽

...

Keyword(s):

Sintering Process

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Effect of α/β phase ratio on microstructure and mechanical properties of silicon nitride ceramics

Journal of Materials Research ◽

10.1557/jmr.2001.0311 ◽

2001 ◽

Vol 16 (8) ◽

pp. 2264-2270 ◽

Cited By ~ 27

Author(s):

Hirokazu Kawaoka ◽

Tomohiko Adachi ◽

Tohru Sekino ◽

Yong-Ho Choa ◽

Lian Gao ◽

...

Keyword(s):

Fracture Toughness ◽

Silicon Nitride ◽

Phase Ratio ◽

Phase Content ◽

Sintering Process ◽

Β Phase ◽

Nitride Ceramics ◽

Pulse Electric ◽

Sintering Condition ◽

Sintered Materials

Highly densed silicon nitride ceramics with various α/β phase ratios were produced by pulse electric current sintering process. The β-phase content of Si3N4 in sintered materials varied from 20 to 100 wt% depending on the sintering condition. The microstructure was observed by scanning electron microscopy and investigated by image analysis. Young's modulus, hardness, fracture toughness, and strength were strongly dependent on the α/β phase ratio. The fracture toughness increased from 4.6 MPa m1/2 for 20-wt% b-phase content to 8.2 MPa m1/2 for 95-wt% β-phase content, and the fracture strength showed a maximum value of about 1.6 GPa at 60-to-80-wt% β-phase content.

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Role of Sintering Temperature in Production of Nepheline Ceramics-Based Geopolymer with Addition of Ultra-High Molecular Weight Polyethylene

Materials ◽

10.3390/ma14051077 ◽

2021 ◽

Vol 14 (5) ◽

pp. 1077

Author(s):

Romisuhani Ahmad ◽

Mohd Mustafa Al Bakri Abdullah ◽

Wan Mastura Wan Ibrahim ◽

Kamarudin Hussin ◽

Fakhryna Hannanee Ahmad Zaidi ◽

...

Keyword(s):

Molecular Weight ◽

High Molecular Weight ◽

Sintering Temperature ◽

Ceramic Materials ◽

Microstructural Properties ◽

Sintering Process ◽

Final Microstructure ◽

Change Of Microstructure ◽

Ultra High Molecular Weight

The primary motivation of developing ceramic materials using geopolymer method is to minimize the reliance on high sintering temperatures. The ultra-high molecular weight polyethylene (UHMWPE) was added as binder and reinforces the nepheline ceramics based geopolymer. The samples were sintered at 900 °C, 1000 °C, 1100 °C, and 1200 °C to elucidate the influence of sintering on the physical and microstructural properties. The results indicated that a maximum flexural strength of 92 MPa is attainable once the samples are used to be sintered at 1200 °C. It was also determined that the density, porosity, volumetric shrinkage, and water absorption of the samples also affected by the sintering due to the change of microstructure and crystallinity. The IR spectra reveal that the band at around 1400 cm−1 becomes weak, indicating that sodium carbonate decomposed and began to react with the silica and alumina released from gels to form nepheline phases. The sintering process influence in the development of the final microstructure thus improving the properties of the ceramic materials.

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Experiment on Foreign Object Damage of Gas Turbine-Grade Silicon Nitride Ceramic

Volume 2: Aircraft Engine; Marine; Microturbines and Small Turbomachinery ◽

10.1115/98-gt-399 ◽

1998 ◽

Cited By ~ 3

Author(s):

Hiro Yoshida ◽

Takashi Nakashima ◽

Makoto Yoshida ◽

Yasushi Hara ◽

Toru Shimamori

Keyword(s):

Elevated Temperature ◽

Silicon Nitride ◽

Elevated Temperatures ◽

Tensile Load ◽

Strength Degradation ◽

Spall Fracture ◽

Silicon Nitride Ceramic ◽

Impact Tests ◽

The Impact ◽

Bending Fracture

A new high quality turbine system using monolithic silicon-nitride ceramic is under development. In this study particle impact tests of the silicon-nitride have been tried at room and elevated temperatures with and without tensile load, which simulates centrifugal force of blade rotation. In the experiment 1 mm diameter particle is impacted at velocities up to 900 m s−1. In this paper, critical velocities for bending fracture and Hertzian cracks are examined. Moreover, strength degradation at elevated temperature and spall fracture of the blade are discussed. The main results are: 1) The bending fracture mode critical impact velocity for soft particles is higher than that for hard particles. 2)The impact parameter ϕ for initiation of Hertzian cracks ranges 1.08×10−5 – 1.56×10−5 for the materials tested. 3)Strength degradation at elevated temperature was clearly observed. 4) In the impact tests on blades spall fracture, which was caused by interaction of stress waves, appeared.

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