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.

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.

scholarly journals Probability of detection of internal voids in structural ceramics using microfocus radiography

1986 ◽  
Vol 1 (3) ◽  
pp. 457-467 ◽  
Author(s):  
George Y. Baaklini ◽  
Don J. Roth
Keyword(s):  
Silicon Carbide ◽  
Silicon Nitride ◽  
Focal Spot ◽  
Probability Of Detection ◽  
Structural Ceramics ◽  
Structural Ceramic ◽  
X Ray ◽  
Low X ◽  
Statistical Results ◽  
Sintered Silicon

The reliability of microfocus x radiography for detecting internal voids in structural ceramic test specimens was statistically evaluated. The microfocus system was operated in the projection mode using low x-ray photon energies (<20 keV) and a 10 μm focal spot. The statistics were developed for implanted internal voids in green and sintered silicon carbide and silicon nitride test specimens. These statistics were compared with previously obtained statistics for implanted surface voids in similar specimens. Problems associated with void implantation and characterization are discussed. Statistical results are given as probability-of-detection curves at a 95% confidence level for voids ranging in size from 20–528 μm in diameter.

Synthesis of Superhard and Ultrahard Materials by 3D-polymerization of C60, C70 Fullerenes Under High Pressure (15 GPa) and Temperatures up to 1820 K

2006 ◽  
Vol 61 (12) ◽  
pp. 1547-1554 ◽  
Author(s):  
Vladimir D. Blank ◽  
Sergei G. Buga ◽  
Gennadi A. Dubitsky ◽  
Nadejda R. Serebryanaya ◽  
Vyatcheslav M. Prokhorov ◽  
...  
Keyword(s):  
High Pressure ◽  
Sound Wave ◽  
Acoustic Microscopy ◽  
X Ray Diffraction ◽  
Quenching Rate ◽  
X Ray ◽  
Wave Velocities ◽  
Microscopy Techniques ◽  
Temperature Maps ◽  
Microscopy Images

Solid fullerenes C60 and C70 have been treated at high pressure of 15 GPa and high temperatures of 520 - 1820 K for a time of exposure of 60 s and a quenching rate of 300 K s−1 using a toroid-type apparatus. X-ray diffraction and Raman spectra confirm the realization of 3D-polymerized phases in these solids at 15 GPa. The pressure/temperature maps of synthesis of metastable carbon phases on the basis of C60 and C70 have thus been extended to 15 GPa. The longitudinal and shear sound wave velocities were measured by acoustic microscopy techniques. A maximum sound wave velocity of (21±1)×105 m s−1 was observed in the sample synthesized from C60 at T = 1170 K. The elastic constants were calculated using experimental data. The acoustic microscopy images of experimental samples have been investigated.

scholarly journals Synthesis of High Purity- Sicand- Si 3N4Fromricehulls

Quimica Hoy ◽  
2011 ◽  
Vol 1 (3) ◽  
pp. 7
Author(s):  
B. Treviño ◽  
I. Gómez ◽  
R. Colás
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Silicon Carbide ◽  
Infrared Spectroscopy ◽  
Silicon Nitride ◽  
High Purity ◽  
X Ray ◽  
Rice Hulls ◽  
N Compounds ◽  
Scanning Electron

Silicon carbide and silicon nitride were synthesized from ashes obtained by heating rice hulls at 800C for 3 hours in argon. -SiC was produced from the ashes by reheating them at l 400C for 8 hours in argon, whereas -Si,N, was obtained by heating the ashes at temperatures ranging from 1250C to l 400C for periods of 3 to 6 hours in a nitrogen rich atmosphere. Toe products were characterized by infrared spectroscopy, X-ray and scanning electron microscopy. High purity -SiC and -Si,N, compounds with whisker type morphology were obtained. It was possible to obtain -Si,N, without SiC by heating the ashes for 6 hours at 1250C.

scholarly journals Probability of Detection of Internal Voids in Structural Ceramics Using Microfocus Radiography

1985 ◽  
Vol 60 ◽  
Author(s):  
George Y. Baaklini ◽  
Don J. Roth
Keyword(s):  
Silicon Carbide ◽  
Focal Spot ◽  
Probability Of Detection ◽  
Structural Ceramics ◽  
Structural Ceramic ◽  
X Ray ◽  
Percent Confidence Level ◽  
Low X ◽  
Statistical Results ◽  
Sintered Silicon

AbstractThe reliability of mlcrofocus x-rad1ogrphy for detecting Internal voids 1n structural ceramic test specimens was statistically evaluated. The micro-focus system was operated in the projection mode using low x-ray photon energies (≤;20 keV) and a 10 μm focal spot. The statistics were developed for Implanted Internal voids 1n green and sintered silicon carbide and silicon nitride test specimens. These statistics were compared with previously-obtained statistics for implanted surface voids in similar specimens. Statistical results are given as probability-of-detection curves at a 95 percent confidence level for voids ranging in size from 20 to 528 μm in diameter.

Silicon Carbide Whiskers Interference on Silicon Nitride Based Composite

2008 ◽  
Vol 591-593 ◽  
pp. 543-547
Author(s):  
Sandro Aparecido Baldacim ◽  
Claudinei dos Santos ◽  
Olivério Moreira Macedo Silva ◽  
Cosme Roberto Moreira Silva
Keyword(s):  
Fracture Toughness ◽  
Silicon Carbide ◽  
Silicon Nitride ◽  
Neodymium Oxide ◽  
Crack Deflection ◽  
Alternative Route ◽  
Sintering Aids ◽  
X Ray ◽  
Silicon Carbide Whiskers ◽  
Scanning Electron

Silicon nitride based composite has been prepared, using a direct mixture process as alternative route. Silicon carbide whiskers were mixed directly to silicon nitride based powders containing yttrium and neodymium oxide as sintering aids. Uniaxial hot pressing was used to prepare sintered samples. Crystalline phases were identified using x-ray diffractometry. Intergranular phases were analyzed using Scanning Electron Microscopy. Some mechanical properties (microhardness and fracture toughness) were also evaluated. The obtained high values of fracture toughness were correlated to the activation of toughening mechanisms, such as crack bridging and crack deflection.

Microfocus Radiographic Characterization of Materials and Components for High Performance Applications

1988 ◽  
Vol 142 ◽  
Author(s):  
D J. Cotter ◽  
W. D. Koenigsberg ◽  
E. M. Dunn ◽  
M. Abdollahian
Keyword(s):  
Silicon Nitride ◽  
High Performance ◽  
Failure Stress ◽  
Modulus Of Rupture ◽  
X Ray ◽  
Power Transistors ◽  
Mechanics Model ◽  
Stress Prediction ◽  
And Performance ◽  
Characterization Of Materials

AbstractResults are presented from several studies where microfocus radiography has been applied to provide feedback necessary to improve reliability and performance of materials and components. Improving the reliability of advanced silicon nitride ceramics through the use of NDE was studied by exploring the relationship between process-related defects, radiography results, and fracture of test samples. Research in the areas of structural and electronic ceramic joining has been aided by monitoring the effects of process modifications with real-time microfocus radiography and computer- based image processing.Microfocus projection radiography was used to nondestructively examine a large quantity of silicon nitride modulus of rupture test bars for internal defects. Failure stress prediction was attempted using a fracture mechanics model and quantitative NDE data, and compared to actual failure stress.In-process NDE of silicon nitride ceramic to Incoloy 909 metal brazed test samples was performed. Correlation between NDE results, optical microscopy, and destructive mechanical strength levels of samples is discussed.Microfocus x-ray imaging was used to monitor the process of bonding microwave power transistors to metallized BeO ceramic substrates. Nonuniform distribution of the eutectic bond was readily detectable, thereby providing feedback for process improvement. Comparison is made between x-ray, optical, and infrared images.

Acoustic microscopy techniques for the inspection of integrated circuit devices and packages

1992 ◽  
Vol 50 (2) ◽  
pp. 966-967
Author(s):  
Thomas M. Moore
Keyword(s):  
Integrated Circuit ◽  
Acoustic Microscopy ◽  
Hybrid Technique ◽  
Frequency Scanning ◽  
Ic Packaging ◽  
Ic Package ◽  
Microscopy Techniques ◽  
Ic Package Inspection ◽  
Pulse Echo ◽  
Scanning Acoustic Microscope

In the last decade, a variety of characterization techniques based on acoustic phenomena have come into widespread use. Characteristics of matter waves such as their ability to penetrate optically opaque solids and produce image contrast based on acoustic impedance differences have made these techniques attractive to semiconductor and integrated circuit (IC) packaging researchers.These techniques can be divided into two groups. The first group includes techniques primarily applied to IC package inspection which take advantage of the ability of ultrasound to penetrate deeply and nondestructively through optically opaque solids. C-mode Acoustic Microscopy (C-AM) is a recently developed hybrid technique which combines the narrow-band pulse-echo piezotransducers of conventional C-scan recording with the precision scanning and sophisticated signal analysis capabilities normally associated with the high frequency Scanning Acoustic Microscope (SAM). A single piezotransducer is scanned over the sample and both transmits acoustic pulses into the sample and receives acoustic echo signals from the sample.

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