Burner Rig Thermal Fatigue Failure of SiC Continuous Fiber/Si3N4 Ceramic Composites

1994 ◽  
Vol 365 ◽  
Author(s):  
T. Ertürk ◽  
K. Park ◽  
C. Sung
Keyword(s):  
Fatigue Failure ◽  
Thermal Fatigue ◽  
Thermal Stresses ◽  
Ceramic Composites ◽  
Columnar Structure ◽  
Fatigue Properties ◽  
Continuous Fiber ◽  
Sic Fiber ◽  
Transmission Electron ◽  
Fiber Matrix

ABSTRACTThe burner rig thermal fatigue properties of SiC continuous fiber/Si3N4 ceramic composites were examined under impinged jet fuel flame, a constant applied tensile stress and thermal cycling in the temperature range 500-1350 °C. The SCS-9 SiC fiber/Si3N4 composites failed within the flame impinged zone, whereas the SCS-6 fiber/Si3N4 composites failed outside the flame impinged zone due to the high thermal stresses resulting from high-temperature gradients. Analytical transmission electron microscopy was used to investigate the microstructure and chemistry of the fiber, matrix and fiber/matrix interface in the failed SCS-9 SiC fiber/Si3N4 composites. The partial degradation of columnar structure of the fiber was interpreted as the dominant mechanism of burner rig thermal fatigue failure of SCS-9 SiC fiber/Si3N4 composites.

A Probabilistic Approach for Predicting Thermal Fatigue Life of Wire Bonding in Microelectronics

1991 ◽  
Vol 113 (3) ◽  
pp. 275-285 ◽  
Author(s):  
Jun Ming Hu ◽  
Michael Pecht ◽  
Abhijit Dasgupta
Keyword(s):  
Fatigue Life ◽  
Fatigue Failure ◽  
Thermal Fatigue ◽  
Life Prediction ◽  
Probabilistic Approach ◽  
Mechanical Damage ◽  
Reliability Estimation ◽  
Fatigue Properties ◽  
Thermal Fatigue Life ◽  
Wire Bonds

Wire bond connections are susceptible to fatigue failure as a result of various thermo-mechanical damage mechanisms during the component operation life. Because of uncertainties arising from the random nature of temperature fluctuations, the assembly of wirebonds, and fatigue properties of bonding materials, a probabilistic analysis and reliability estimation are appropriate. This paper presents such an approach for predicting thermal fatigue life and reliability of wire bonds in electronic packages. To determine the behavior of wire bonds under thermal cycles, the stress amplitude due to the temperature fluctuation in each fatigue failure mechanism is derived based on stress analysis models, the uncertainties involved in stress determination and life prediction are analyzed, and a life prediction equation is proposed. Examples illustrating the application of the approach are discussed.

Techniques for Transmission Electron Microscopy of Fiber-Matrix Interfaces in Aluminum Alloy-Boron Composites by Ion Erosio

1971 ◽  
Vol 29 ◽  
pp. 204-205
Author(s):  
G. G. Shaw
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Aluminum Alloy ◽  
Electron Beam ◽  
Pure Aluminum ◽  
Ion Milling ◽  
Transmission Electron ◽  
Fiber Matrix ◽  
Ion Erosion ◽  
Row Of Fibers

The morphology and composition of the fiber-matrix interface can best be studied by transmission electron microscopy and electron diffraction. For some composites satisfactory samples can be prepared by electropolishing. For others such as aluminum alloy-boron composites ion erosion is necessary.When one wishes to examine a specimen with the electron beam perpendicular to the fiber, preparation is as follows: A 1/8 in. disk is cut from the sample with a cylindrical tool by spark machining. Thin slices, 5 mils thick, containing one row of fibers, are then, spark-machined from the disk. After spark machining, the slice is carefully polished with diamond paste until the row of fibers is exposed on each side, as shown in Figure 1.In the case where examination is desired with the electron beam parallel to the fiber, preparation is as follows: Experimental composites are usually 50 mils or less in thickness so an auxiliary holder is necessary during ion milling and for easy transfer to the electron microscope. This holder is pure aluminum sheet, 3 mils thick.

Deformation at interfaces of Ti-6Al-4V/SiC fiber composites

1992 ◽  
Vol 50 (1) ◽  
pp. 158-159
Author(s):  
Warren J. Moberly ◽  
Daniel B. Miracle ◽  
S. Krishnamurthy
Keyword(s):  
Thermal Stresses ◽  
Load Transfer ◽  
Coefficient Of Thermal Expansion ◽  
Hot Isostatic Pressing ◽  
Matrix Composites ◽  
Ongoing Research ◽  
Aerospace Applications ◽  
Sic Fiber ◽  
The Matrix ◽  
Intermetallic Matrix Composites

Titanium-aluminum alloy metal matrix composites (MMC) and Ti-Al intermetallic matrix composites (IMC), reinforced with continuous SCS6 SiC fibers are leading candidates for high temperature aerospace applications such as the National Aerospace Plane (NASP). The nature of deformation at fiber / matrix interfaces is characterized in this ongoing research. One major concern is the mismatch in coefficient of thermal expansion (CTE) between the Ti-based matrix and the SiC fiber. This can lead to thermal stresses upon cooling down from the temperature incurred during hot isostatic pressing (HIP), which are sufficient to cause yielding in the matrix, and/or lead to fatigue from the thermal cycling that will be incurred during application, A second concern is the load transfer, from fiber to matrix, that is required if/when fiber fracture occurs. In both cases the stresses in the matrix are most severe at the interlace.

Observation of solid-state reaction between a thin yttria film and a (0001) α-alumina substrate

1994 ◽  
Vol 52 ◽  
pp. 644-645
Author(s):  
J. R. Heffelfinger ◽  
C. B. Carter
Keyword(s):  
Electron Microscopy ◽  
Solid State ◽  
Solid State Reaction ◽  
Yttrium Aluminum Garnet ◽  
Secondary Phase ◽  
Ceramic Composites ◽  
Alumina Substrate ◽  
Transmission Electron ◽  
Alumina Fibers ◽  
Optical Applications

Transmission-electron microscopy (TEM), scanning-electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS) were used to investigate the solid-state reaction between a thin yttria film and a (0001) α-alumina substrate. Systems containing Y2O3 (yttria) and Al2O3 (alumina) are seen in many technologically relevant applications. For example, yttria is being explored as a coating material for alumina fibers for metal-ceramic composites. The coating serves as a diffusion barrier and protects the alumina fiber from reacting with the metal matrix. With sufficient time and temperature, yttria in contact with alumina will react to form one or a combination of phases shown by the phase diagram in Figure l. Of the reaction phases, yttrium aluminum garnet (YAG) is used as a material for lasers and other optical applications. In a different application, YAG is formed as a secondary phase in the sintering of AIN. Yttria is added to AIN as a sintering aid and acts as an oxygen getter by reacting with the alumina in AIN to form YAG.

Thermal fatigue failure of brass die-casting dies

2012 ◽  
Vol 20 ◽  
pp. 137-146 ◽  
Author(s):  
Dhouha Mellouli ◽  
Nader Haddar ◽  
Alain Köster ◽  
Hassine Ferid Ayedi
Keyword(s):  
Fatigue Failure ◽  
Thermal Fatigue ◽  
Die Casting

Formation process of interface states at grain boundaries in sputtered polycrystalline Si films

1999 ◽  
Vol 14 (2) ◽  
pp. 371-376 ◽  
Author(s):  
Yoshitaka Nakano ◽  
Jiro Sakata ◽  
Yasunori Taga
Keyword(s):  
Energy Levels ◽  
Columnar Structure ◽  
Systematic Investigation ◽  
Defect States ◽  
Electron Microscopic ◽  
Thermally Induced ◽  
Transmission Electron ◽  
Transmission Electron Microscopic ◽  
Si Films ◽  
Induced Changes

A systematic investigation has been made on surface defect states of crystallites in the crystallization process of sputtered amorphous silicon films by isothermal annealing. Transmission electron microscopic observations indicate a pronounced vertical columnar structure in the upper part of the films, where the crystallization is delayed. Admittance spectroscopy reveals that two newly generated energy levels with the crystallization are attributed to the crystallites in the lower and upper parts of the films in view of the anisotropic crystallization. These thermally induced changes can be well explained by Si–Si shearing modes at the interfaces of crystallites through the process of crystallization.

Observations of Damage and Transport of Hydrogen in Ion Bombarded Polycrystalline Silicon

1984 ◽  
Vol 33 ◽  
Author(s):  
D. J. Sharp ◽  
J. K. G. Panitz ◽  
C. H. Seager
Keyword(s):  
Polycrystalline Silicon ◽  
Ion Beam ◽  
Columnar Structure ◽  
Hydrogen Transport ◽  
Transport Mechanisms ◽  
Sheet Resistivity ◽  
Near Surface ◽  
Resistivity Measurements ◽  
Transmission Electron ◽  
Defect Passivation

ABSTRACTA combination of chemical etching and sheet resistivity measurements showed that intense (1.4 mA/cm2 ) low energy (1400 eV) ion beam hydrogenation of polycrystalline silicon having a columnar structure can produce electrical defect passivation to depths in the order of 100 μm. Transmission electron micrographs disclose surface and near-surface features resulting from the ion beam bombardment which suggest that one of the hydrogen transport mechanisms may be defect induced.

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