scholarly journals Interlaboratory Comparison of Flexural Strength of Structural Ceramics

1985 ◽  
Author(s):  
E. M. Lenoe ◽  
D. Neal ◽  
M. Vangel ◽  
M. Boehmer ◽  
J. E. Siebels
Keyword(s):  
Silicon Nitride ◽  
Flexural Strength ◽  
Interlaboratory Comparison ◽  
Statistical Evaluation ◽  
Experimental Methods ◽  
The Body ◽  
Statistical Techniques ◽  
Structural Ceramics ◽  
Silicon Nitrides ◽  
Silicon Carbides

This paper presents results of statistical evaluation of flexural strength of various silicon nitrides and silicon carbides. The interlaboratory comparison involved both analytical and experimental procedures. For instance, two types of reaction bonded silicon nitride from the same production lots were evaluated using different test fixtures and experimental methods. A fairly extensive data base on five types of nitrides and carbides was evaluated using both conventional and advanced statistical techniques. The various differences observed are discussed in the body of the paper.

scholarly journals NDE Reliability and Process Control for Structural Ceramics

1987 ◽  
Vol 109 (3) ◽  
pp. 263-266 ◽  
Author(s):  
G. Y. Baaklini
Keyword(s):  
Silicon Carbide ◽  
Silicon Nitride ◽  
Flexural Strength ◽  
Process Control ◽  
Room Temperature ◽  
Acoustic Microscopy ◽  
Modulus Of Rupture ◽  
Scanning Laser ◽  
Radiographic Evaluation ◽  
Structural Ceramics

The reliability of microfocus x-radiography and scanning laser acoustic microscopy for detecting microvoids in silicon nitride and silicon carbide was statistically evaluated. Materials and process-related parameters that influenced the statistical findings in research samples are discussed. The use of conventional x-radiography in controlling and optimizing the processing and sintering of an Si3N4-SiO2-Y2O3 composition designated NASA 6Y is described. Radiographic evaluation and guidance helped develop uniform high-density Si3N4 modulus-of-rupture bars with improved four-point flexural strength (857, 544, and 462 MPa at room temperature, 1200°C, and 1370°C, respectively) and reduced strength scatter.

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

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

2010 ◽  
Vol 105-106 ◽  
pp. 27-30 ◽  
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.

Cyclic Fatigue of Silicon Nitrides and a Whisker-Reinforced Silicon Nitride

1992 ◽  
pp. 468-475
Author(s):  
T. A. Mäntylä ◽  
A.-P. Nikkilä ◽  
P. T. Vuorinen ◽  
M. Enoki ◽  
T. Kishi
Keyword(s):  
Silicon Nitride ◽  
Cyclic Fatigue ◽  
Silicon Nitrides

Effect of Sm2O3 Additives on the Rod-Like β-Si3N4 Crystal of Porous Silicon Nitride Fabricated by Reaction-Bonded

2010 ◽  
Vol 105-106 ◽  
pp. 42-45
Author(s):  
Jian She Yue ◽  
Hong Jie Wang
Keyword(s):  
Silicon Nitride ◽  
Porous Silicon ◽  
Aspect Ratio ◽  
Flexural Strength ◽  
High Aspect Ratio ◽  
Liquid State ◽  
Theory Testing ◽  
Strength Testing ◽  
Xrd Diffraction ◽  
Crystal Content

Sm2O3 and MgO as a sintering additives to fabricated porous silicon nitride by reaction-bonded. The phase of as-produced silicon nitride characterized by XRD-diffraction. The microstructure of product was investigated by SEM. The samples were machined into test bar for flexural strength testing. Using Archimedes theory testing the porosity of porous silicon nitride. MgO have restrain effect on the growth of rod-like silicon nitride, because of produce a restrain layer which is MgO reacted with SiO2 on the surface of silicon., the microstructure of crystal is particle like, the maximum flexural strength is 48MPa with porosity of 35%. Sm2O3 can assistant the growth of high aspect ratio Si3N4 crystal at beginning temperature of 1300°C for it’s low melt point and low viscidity in liquid state, the as-product’s morphology is rod-like and the flexural strength is as high as 300 MPa when the porosity is 30%, high than the sample that of low rod-like crystal content.

NDE of Structural Ceramics

1986 ◽  
Author(s):  
Stanley J. Klima ◽  
Alex Vary
Keyword(s):  
Silicon Carbide ◽  
Silicon Nitride ◽  
Ultrasonic Velocity ◽  
Detection Probability ◽  
Ultrasonic Attenuation ◽  
Acoustic Microscopy ◽  
Modulus Of Rupture ◽  
Structural Ceramics ◽  
X Ray ◽  
Microscopy Techniques

Radiographic, ultrasonic, scanning laser acoustic microscopy (SLAM), and thermo-acoustic microscopy techniques were used to characterize silicon nitride and silicon carbide modulus-of-rupture test specimens in various stages of fabrication. Conventional and microfocus x-ray techniques were found capable of detecting minute high density inclusions in as-received powders, green compacts, and fully densified specimens. Significant density gradients in sintered bars were observed by radiography, ultrasonic velocity, and SLAM. Ultrasonic attenuation was found sensitive to microstructural variations due to grain and void morphology and distribution. SLAM was also capable of detecting voids, inclusions, and cracks in finished test bars. Consideration is given to the potential for applying thermo-acoustic microscopy techniques to green and densified ceramics. The detection probability statistics and some limitations of radiography and SLAM also are discussed.

Attempts to establish New Experimental Methods to study Antitumoral Drugs

1967 ◽  
Vol 17 (1) ◽  
pp. 60-66 ◽  
Author(s):  
S. Garattini ◽  
M. G. Donelli ◽  
L. Morasca ◽  
C. Rainisio ◽  
R. Rosso
Keyword(s):  
Tissue Culture ◽  
Cancer Chemotherapy ◽  
Experimental Methods ◽  
The Body ◽  
Duration Of Action ◽  
Study Duration ◽  
Cancer Dissemination ◽  
Perfuse Tissue

SummaryThis paper summarizes some studies recently carried out in this Institute in the field of cancer chemotherapy.Three main groups of data are reported:a) different sensitivity to chemotherapy of the same tumor transplanted in different sites of the body;b) a method to study cancer dissemination as a basis for cancer chemotherapy;c) a system to perfuse tissue culture with the blood of living animals as an approach to study duration of action of antitumoral drugs.

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