Macro- to Atomic-Scale Tailoring of Si3N4 Ceramics to Enhance Properties

2005 ◽  
Vol 287 ◽  
pp. 233-241 ◽  
Author(s):  
Paul F. Becher ◽  
Gayle S. Painter ◽  
Naoya Shibata ◽  
Hua Tay Lin ◽  
Mattison K. Ferber
Keyword(s):  
Electronic Device ◽  
Atomic Level ◽  
Atomic Scale ◽  
Fracture Properties ◽  
Beta Particles ◽  
Preferential Segregation ◽  
Nitride Ceramics ◽  
Theoretical Predictions ◽  
The Matrix

Silicon nitride ceramics are finding uses in numerous engineering applications because of their tendency to form whisker-like microstructures that can overcome the inherent brittle nature of ceramics. Studies now establish the underlying microscopic and atomic-scale principles for engineering a tough, strong ceramic. The theoretical predictions are confirmed by macroscopic observations and atomic level characterization of preferential segregation at the interfaces between the grains and the continuous nanometer thick amorphous intergranular film (IGF). Two interrelated factors must be controlled for this to occur including the generation of the elongated reinforcing grains during sintering and debonding of the interfaces between the reinforcing grains and the matrix. The reinforcing grains can be controlled by (1) seeding with beta particles and (2) the chemistry of the additives, which also can influence the interfacial debonding conditions. In addition to modifying the morphology of the reinforcing grains, it now appears that the combination of preferential segregation and strong bonding of the additives (e.g., the rare earths, RE) to the prism planes can also result in sufficiently weakens the bond of the interface with the IGF to promote debonding. Thus atomic-scale engineering may allow us to gain further enhancements in fracture properties. This new knowledge will enable true atomic-level engineering to be joined with microscale tailoring to develop the advanced ceramics that will be required for more efficient engines, new electronic device architectures and composites.

scholarly journals Nanometer Scale Tomographic Investigation of Fine Scale Precipitates in a CuFeNi Granular System by Three-Dimensional Field Ion Microscopy

2012 ◽  
Vol 18 (5) ◽  
pp. 1129-1134 ◽  
Author(s):  
Sophie Cazottes ◽  
François Vurpillot ◽  
Abdeslem Fnidiki ◽  
Dany Lemarchand ◽  
Marcello Baricco ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Precise Determination ◽  
Atomic Scale ◽  
Granular System ◽  
Field Ion Microscopy ◽  
Mean Diameter ◽  
The Matrix ◽  
The Mean ◽  
Ion Microscopy

AbstractThe microstructure of Cu80Fe10Ni10 (at. %) granular ribbons was investigated by means of three-dimensional field ion microscopy (3D FIM). This ribbon is composed of magnetic precipitates embedded in a nonmagnetic matrix. The magnetic precipitates have a diameter smaller than 5 nm in the as-spun state and are coherent with the matrix. No accurate characterization of such a microstructure has been performed so far. A tomographic characterization of the microstructure of melt spun and annealed Cu80Fe10Ni10 ribbon was achieved with 3D FIM at the atomic scale. A precise determination of the size distribution, number density, and distance between the precipitates was carried out. The mean diameter for the precipitates is 4 nm in the as-spun state. After 2 h at 350°C, there is an increase of the size of the precipitates, while after 2 h at 400°C the mean diameter of the precipitates decreases. Those data were used as inputs in models that describe the magnetic and magnetoresistive properties of this alloy.

Development of a 200kV Atomic Resolution Analytical Electron Microscope

2009 ◽  
Vol 17 (3) ◽  
pp. 8-11 ◽  
Author(s):  
T. Isabell ◽  
J. Brink ◽  
M. Kawasaki ◽  
B. Armbruster ◽  
I. Ishikawa ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Atomic Structure ◽  
Spherical Aberration ◽  
Atomic Level ◽  
Atomic Scale ◽  
Atomic Resolution ◽  
Analytical Electron ◽  
Analytical Electron Microscope

Few electron optical inventions have revolutionized the TEM/ STEM as profoundly as the spherical aberration (Cs) corrector has. Characterization of technologically important materials increasingly needs to be done at the atomic or even sub-atomic level. This characterization includes determination of atomic structure as well as structural chemistry. With Cs correctors, the sub-Angstrom imaging barrier has been passed, and fast atomic scale spectroscopy is possible. In addition to improvements in resolution, Cs correctors offer a number of other significant improvements and benefits.

Multiresolution Grid Connectivity-Based Transform for Efficient History Matching of Unconventional Reservoirs

SPE Journal ◽  
2020 ◽  
Vol 25 (04) ◽  
pp. 1895-1915 ◽  
Author(s):  
Hyunmin Kim ◽  
Akhil Datta-Gupta
Keyword(s):  
History Matching ◽  
Basis Functions ◽  
Unconventional Reservoirs ◽  
Hydraulic Fractures ◽  
Reservoir Model ◽  
Fracture Properties ◽  
Data Resolution ◽  
Matrix Properties ◽  
The Matrix

Summary Proper characterization of heterogeneous rock properties and hydraulic fracture parameters is essential for optimization of well spacing and reliable estimation of estimated ultimate recovery (EUR) in unconventional reservoirs. High resolution characterization of matrix properties and complex fracture parameters require efficient history matching of well production and pressure response. We propose a novel reservoir model parameterization method to reduce the number of unknowns, regularize the ill-posed problem, and enhance the efficiency of history matching of unconventional reservoirs. The proposed method makes a low-rank approximation of the spatial distribution of reservoir properties taking into account the varying model resolution of the matrix and hydraulic fractures. Typically, hydraulic fractures are represented with much higher resolution through local grid refinements compared to the matrix properties. In our approach, the spatial property distribution of both matrix and fractures is represented using a few parameters via a linear transformation with multiresolution basis functions. The parameters in transform domain are then updated during model calibrations, substantially reducing the number of unknowns. The multiresolution basis functions are constructed by using Eigen-decomposition of an adaptively coarsened grid Laplacian corresponding to the data resolution. Higher property resolution at the area of interest through the adaptive resolution control while keeping the original grid structure improves quality of history matching, reduces simulation runtime, and improves the efficiency of history matching. We demonstrate the power and efficacy of our method using synthetic and field examples. First, we illustrate the effectiveness of the proposed multiresolution parameterization by comparing it with traditional methods. For the field application, an unconventional tight oil reservoir model with a multistage hydraulic fractured well is calibrated using bottomhole pressure and water cut history data. The hydraulic fractures as well as the stimulated reservoir volume (SRV) near the well are represented with higher grid resolution. In addition to matrix and fracture properties, the extent of the SRV and hydraulic fractures are also adjusted through history matching using a multiobjective genetic algorithm. The calibrated ensemble of models are used to obtain bounds of production forecast. Our proposed method is designed to calibrate reservoir and fracture properties with higher resolution in regions that have improved data resolution and higher sensitivity to the well performance data, for example the SRV region and the hydraulic fractures. This leads to a fast and efficient history matching workflow and enables us to make optimal development/completion plans in a reasonable time frame.

TEM characterization of reaction zone in a SiC fiber-reinforced titanium alloy

1988 ◽  
Vol 46 ◽  
pp. 738-739
Author(s):  
G. Das ◽  
R. E. Omlor
Keyword(s):  
Titanium Alloys ◽  
Reaction Zone ◽  
Carbon Layer ◽  
Fiber Reinforced ◽  
Reaction Products ◽  
Sic Fibers ◽  
Sic Fiber ◽  
The Matrix ◽  
Immense Potential

Fiber reinforced titanium alloys hold immense potential for applications in the aerospace industry. However, chemical reaction between the fibers and the titanium alloys at fabrication temperatures leads to the formation of brittle reaction products which limits their development. In the present study, coated SiC fibers have been used to evaluate the effects of surface coating on the reaction zone in the SiC/IMI829 system.IMI829 (Ti-5.5A1-3.5Sn-3.0Zr-0.3Mo-1Nb-0.3Si), a near alpha alloy, in the form of PREP powder (-35 mesh), was used a茸 the matrix. CVD grown AVCO SCS-6 SiC fibers were used as discontinuous reinforcements. These fibers of 142μm diameter contained an overlayer with high Si/C ratio on top of an amorphous carbon layer, the thickness of the coating being ∽ 1μm. SCS-6 fibers, broken into ∽ 2mm lengths, were mixed with IMI829 powder (representing < 0.1vol%) and the mixture was consolidated by HIP'ing at 871°C/0. 28GPa/4h.

Digital image processing methods applied to the study of annealing time on semiconductor-metal eutectic composites

1988 ◽  
Vol 46 ◽  
pp. 848-849
Author(s):  
J. Hefter
Keyword(s):  
Image Processing ◽  
Digital Image Processing ◽  
Digital Image ◽  
Electronic Device ◽  
Processing System ◽  
Average Diameter ◽  
Eutectic Solidification ◽  
Metal Silicide ◽  
The Matrix ◽  
Microscopic Studies

Semiconductor-metal composites, formed by the eutectic solidification of silicon and a metal silicide have been under investigation for some time for a number of electronic device applications. This composite system is comprised of a silicon matrix containing extended metal-silicide rod-shaped structures aligned in parallel throughout the material. The average diameter of such a rod in a typical system is about 1 μm. Thus, characterization of the rod morphology by electron microscope methods is necessitated.The types of morphometric information that may be obtained from such microscopic studies coupled with image processing are (i) the area fraction of rods in the matrix, (ii) the average rod diameter, (iii) an average circularity (roundness), and (iv) the number density (Nd;rods/cm2). To acquire electron images of these materials, a digital image processing system (Tracor Northern 5500/5600) attached to a JEOL JXA-840 analytical SEM has been used.

CBED analysis of impurity distributions in AlN

1990 ◽  
Vol 48 (4) ◽  
pp. 214-215
Author(s):  
Daniel Callahan ◽  
G. Thomas
Keyword(s):  
Aluminum Nitride ◽  
Bulk Material ◽  
Strong Dependence ◽  
Lattice Parameter ◽  
Promising Technique ◽  
Nitride Ceramics ◽  
Surface Phases ◽  
Convergent Beam ◽  
Oxygen Impurities

Oxygen impurities may significantly influence the properties of nitride ceramics with a strong dependence on the microstructural distribution of the impurity. For example, amorphous oxygen-rich grain boundary phases are well-known to cause high-temperature mechanical strength degradation in silicon nitride whereas solutionized oxygen is known to decrease the thermal conductivity of aluminum nitride. Microanalytical characterization of these impurities by spectral methods in the AEM is complicated by reactions which form oxygen-rich surface phases not representative of the bulk material. Furthermore, the impurity concentrations found in higher quality ceramics may be too low to measure by EDS or PEELS. Consequently an alternate method for the characterization of impurities in these ceramics has been investigated.Convergent beam electron diffraction (CBED) is a promising technique for the study of impurity distributions in aluminum nitride ceramics. Oxygen is known to enter into stoichiometric solutions with AIN with a consequent decrease in lattice parameter.

Atomic scale characterization of GaInN/GaN multiple quantum wells in V-shaped pits

2011 ◽  
Vol 98 (18) ◽  
pp. 181904 ◽  
Author(s):  
Shigetaka Tomiya ◽  
Yuya Kanitani ◽  
Shinji Tanaka ◽  
Tadakatsu Ohkubo ◽  
Kazuhiro Hono
Keyword(s):  
Quantum Wells ◽  
Atomic Scale ◽  
Multiple Quantum Wells ◽  
Multiple Quantum ◽  
Scale Characterization

scholarly journals Characterization of the Structure, Mechanical Properties and Erosive Resistance of the Laser Cladded Inconel 625-Based Coatings Reinforced by TiC Particles

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2225
Author(s):  
Aleksandra Kotarska ◽  
Tomasz Poloczek ◽  
Damian Janicki
Keyword(s):  
Laser Cladding ◽  
Inconel 625 ◽  
Matrix Composites ◽  
Erosion Rates ◽  
Laser Cladding Process ◽  
Composition Variation ◽  
The Matrix ◽  
Reinforcing Material ◽  
Inconel 625 Superalloy

The article presents research in the field of laser cladding of metal-matrix composite (MMC) coatings. Nickel-based superalloys show attractive properties including high tensile strength, fatigue resistance, high-temperature corrosion resistance and toughness, which makes them widely used in the industry. Due to the insufficient wear resistance of nickel-based superalloys, many scientists are investigating the possibility of producing nickel-based superalloys matrix composites. For this study, the powder mixtures of Inconel 625 superalloy with 10, 20 and 40 vol.% of TiC particles were used to produce MMC coatings by laser cladding. The titanium carbides were chosen as reinforcing material due to high thermal stability and hardness. The multi-run coatings were tested using penetrant testing, macroscopic and microscopic observations, microhardness measurements and solid particle erosive test according to ASTM G76-04 standard. The TiC particles partially dissolved in the structure during the laser cladding process, which resulted in titanium and carbon enrichment of the matrix and the occurrence of precipitates formation in the structure. The process parameters and coatings chemical composition variation had an influence on coatings average hardness and erosion rates.

Mechanical characterization of LM25 alloy matrix composite reinforced with boron carbide

2021 ◽  
pp. 002199832110055
Author(s):  
Zeeshan Ahmad ◽  
Sabah Khan
Keyword(s):  
Tensile Strength ◽  
Boron Carbide ◽  
Mechanical Characterization ◽  
Stir Casting ◽  
Surface Mapping ◽  
Alloy Matrix ◽  
Casting Technique ◽  
The Matrix ◽  
Carbide Particles

Alumnium alloy LM 25 based composites reinforced with boron carbide at different weight fractions of 4%, 8%, and 12% were fabricated by stir casting technique. The microstructures and morphology of the fabricated composites were studied by scanning electron microscopy and energy dispersive spectroscopy. Elemental mapping of all fabricated composites were done to demonstrate the elements present in the matrix and fabricated composites. The results of microstructural analyses reveal homogenous dispersion of reinforcement particles in the matrix with some little amount of clustering found in composites reinforced with 12% wt. of boron carbide. The mechanical characterization is done for both alloy LM 25 and all fabricated composites based on hardness and tensile strength. The hardness increased from 13.6% to 21.31% and tensile strength 6.4% to 22.8% as reinforcement percentage of boron carbide particles increased from 0% to 12% wt. A fractured surface mapping was also done for all composites.

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