Corrosion of Silicon Nitride Ceramics by Nitric Acid

1992 ◽  
Vol 287 ◽  
Author(s):  
Kunihiko Kanbara ◽  
N. Uchida ◽  
K. Uematsu ◽  
T. Kurita ◽  
K. Yoshimoto ◽  
...  
Keyword(s):  
Weight Loss ◽  
Nitric Acid ◽  
Silicon Nitride ◽  
Glassy Phase ◽  
Strength Loss ◽  
Ionic Species ◽  
Corrosion Layer ◽  
Nitride Ceramics ◽  
Conventional Drying ◽  
Icp Analysis

ABSTRACTCorrosion of silicon nitride was studied in boiling nitric acid to examine its feasibility as a drying pan material in the reprocessing of nuclear fuel. Unlike stainless steel (a conventional drying pan material), the weight loss and strength degradation were negligible in the concentration of nitric acid. The corrosion increased with decreasing concentration of nitric acid. At the concentration of 1-6N, the maximum losses of weight and strength were 0.8% and over 40%, respectively, in 200 h. Ionic species dissolved in nitric acid were determined by ICP analysis and were found to be accurately correlated to the weight loss and thickness of the corrosion layer determined by micrography. In the corrosion layer, grain boundary glassy phase was selectively dissolved. Strength loss was correlated to the weight loss and was ascribed to the reduced load bearing area due to corrosion.

STRENGTH DEGRADATIONS FROM HERTZIAN CONTACT DAMAGES IN NITRIDED PRESSURELESS SINTERED SILICON NITRIDE CERAMICS

2008 ◽  
Vol 22 (09n11) ◽  
pp. 1819-1826 ◽  
Author(s):  
KIL HO GUAHK ◽  
IN SUB HAN ◽  
KEE SUNG LEE
Keyword(s):  
Silicon Nitride ◽  
Hard Spheres ◽  
Continuous Process ◽  
Theoretical Models ◽  
Strength Loss ◽  
Indentation Load ◽  
Hertzian Contact ◽  
Pressureless Sintering ◽  
Nitride Ceramics ◽  
Number Of Cycles

Strength degradations in silicon nitride ceramics subject to damage from contact with hard spheres are investigated. Strengths against indentation load, number of cycles in contact, or stress-rate parameter are reported and compared with theoretical models. Silicon nitride ceramics are prepared by nitride pressureless sintering (NPS) process, which process is the continuous process of nitridation reaction of Si metal combined with subsequent pressureless sintering. Microstructure characterizations reveal silicon nitride fabricated by NPS process exhibits a quasi-plastic mode, with continuous strength loss beyond a load above the onset of yield, and falloff at high number of cycles, > 105 at contact load, P = 950 N , using WC sphere r = 1.98 mm . The strength degradation is substantially faster by dynamic fatigue. Failures originated from contact damages, quasi-plastic microcrack zones, with developing radial cracks during strength test. The implication is that quasi-plastic damage of NPS silicon nitride itself can preserve benefits from the inherent higher damage tolerance at lower number of cycles of contacts, but fatigue susceptibility at multicycle contacts and lower stressing rate.

scholarly journals Quantitative Estimation of Intergranular Glassy Phase of Silicon Nitride Ceramics

1993 ◽  
Vol 101 (1172) ◽  
pp. 480-483
Author(s):  
Kazumasa TAKATORI ◽  
Shigetaka WADA ◽  
Nobuo KOBAYASHI
Keyword(s):  
Silicon Nitride ◽  
Glassy Phase ◽  
Quantitative Estimation ◽  
Nitride Ceramics

Hot-Pressed Silicon Nitride Ceramics With Rare-Earth Oxides Additives

1985 ◽  
Author(s):  
Xu Youren ◽  
Huang Liping ◽  
Fu Xiren ◽  
Yen Tungsheng
Keyword(s):  
Fracture Toughness ◽  
Rare Earth ◽  
Silicon Nitride ◽  
Room Temperature ◽  
Glassy Phase ◽  
Rare Earth Oxides ◽  
Bend Strength ◽  
Silicon Nitride Ceramic ◽  
X Ray ◽  
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.

Grain boundary glassy phase and abnormal grain growth of silicon nitride ceramics

2001 ◽  
Vol 27 (5) ◽  
pp. 603-605 ◽  
Author(s):  
Haitao Yang ◽  
Lin Gao ◽  
Gangqin Shao ◽  
Runze Xu ◽  
Peiyun Huang
Keyword(s):  
Silicon Nitride ◽  
Grain Boundary ◽  
Grain Growth ◽  
Glassy Phase ◽  
Abnormal Grain Growth ◽  
Nitride Ceramics

scholarly journals Novel pyrimidine-bichalcophene derivatives as corrosion inhibitors for copper in 1 M nitric acid solution

RSC Advances ◽  
2021 ◽  
Vol 11 (41) ◽  
pp. 25314-25333
Author(s):  
Mai A. Khaled ◽  
Mohamed A. Ismail ◽  
Ahmed. A. El-Hossiany ◽  
Abd El-Aziz S. Fouda
Keyword(s):  
Weight Loss ◽  
Electrochemical Impedance Spectroscopy ◽  
Nitric Acid ◽  
Impedance Spectroscopy ◽  
Acid Solution ◽  
Nitric Acid Solution ◽  
Potentiodynamic Polarization ◽  
Corrosion Inhibitors ◽  
Electrochemical Impedance ◽  
Pyrimidine Derivatives

This study targets the investigation of three pyrimidine derivatives (MA-1230, MA-1231, MA-1232) for the prevention of corrosion on copper in 1 M HNO3via weight loss (WL), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS) techniques.

Microstructure, toughness and flexural strength of self-reinforced silicon nitride ceramics doped with yttrium oxide and ytterbium oxide

2001 ◽  
Vol 201 (2) ◽  
pp. 238-249 ◽  
Author(s):  
Y. S. Zheng ◽  
K. M. Knowles ◽  
J. M. Vieira ◽  
A. B. Lopes ◽  
F. J. Oliveira
Keyword(s):  
Silicon Nitride ◽  
Flexural Strength ◽  
Yttrium Oxide ◽  
Ytterbium Oxide ◽  
Nitride Ceramics

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

2001 ◽  
Vol 16 (8) ◽  
pp. 2264-2270 ◽  
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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