Multi-Scale Analysis of a Refractory Composite

2005 ◽  
Author(s):  
Y. W. Kwon ◽  
T. Chu ◽  
D. Kim
Keyword(s):  
Coating Layer ◽  
Matrix Material ◽  
Design Tool ◽  
Scale Model ◽  
High Temperature Application ◽  
Multi Scale ◽  
Matrix Layer ◽  
The Matrix ◽  
Temperature Application ◽  
Refractory Composite

A refractory composite for a high temperature application was studied at various length scales, and its effective thermo-mechanical properties were computed. The analysis considered a micro-scale model made of a representative carbon fiber, a matrix layer, and a coating layer. The model included weak tangential bonding of the intra-layer of the matrix material in order to reduce the thermal stress occurring in the coating material caused by mismatch of coefficients of thermal expansions. In addition, unit-cell models for a 3-D braided composite and a plane-weave composite were also studied. The modeling technique developed in this study can be used as a design tool for an optimal refractory composite for a given application.

Effect of the Loading Rate on Failure of Composite Pressure Vessel

2013 ◽  
Author(s):  
Heng-Yi Chou ◽  
Anthony Bunsell ◽  
Georg Mair ◽  
Alain Thionnet
Keyword(s):  
Damage Accumulation ◽  
Loading Rate ◽  
Matrix Material ◽  
Pressure Vessels ◽  
Scale Model ◽  
Loading Rates ◽  
Multi Scale ◽  
Composite Pressure Vessel ◽  
The Matrix ◽  
Pressurisation Test

A multi-scale model has been successfully applied to the simulation of the effects of pressurisation rate on damage accumulation in carbon fibre/epoxy plates and composite pressure vessels. The results of the simulations agree with experimental results and reveal that the point at which the structures become unstable in a monotonic pressurisation test depends on the speed of loading. The faster the loading rate the higher the applied stress at which the composite structure becomes unstable. The mechanism which governs this behaviour is seen to be the viscoelastic nature of the matrix material through which stresses are transferred from broken to neighbouring intact fibres. At loading rates that allow greater relaxation of the resin around fibre breaks neighbouring fibres are subjected to increased loads over a significantly greater length, leading to further earlier breaks.

Performance of Dosage of Ceramic Chopped Fibers in Aluminous Cement-Based Composites after Exposure to High Temperatures

2016 ◽  
Vol 722 ◽  
pp. 38-43 ◽  
Author(s):  
Marcel Jogl
Keyword(s):  
Maximum Temperature ◽  
High Temperature Application ◽  
Temperature Resistance ◽  
Chemical Attack ◽  
Humid Environment ◽  
The Matrix ◽  
Temperature Application ◽  
Aluminous Cement ◽  
Different Levels ◽  
Excellent Chemical

The results of an experimental investigation of the influence of chopped alumina-silica bulk fibers on residual mechanical properties of lightweight cement-based composites for high temperature application are obtained. The matrix of studied specimens is based on aluminous cement, because of its sufficient temperature resistance over 1000 °C. Thermal ceramic bulk fiber offer a maximum temperature range of between 1200° to 1500 °C. They also provide excellent chemical stability and resistance to chemical attack. If wet by oil or water, thermal and physical properties will be fully restored after drying. The benefits of using ceramic bulk fibers were evaluated by the results of physical and mechanical testing; compressive strength, flexural strength and bulk density were determined on the different levels of temperature loading. The prismatic specimens, having dimensions of 40×40×160 mm3, are cured 28 days in humid environment and after that time dried and subjected to temperatures of 600 °C and 1000 °C for 3 hours. The experimental composites differed in doses of fibers, which are 0.0 %, 0.5 % and 2.0 % by volume.

Fabrication of highly reliable joint based on Cu@Ni@Sn double-layer powder for high temperature application

2019 ◽  
Vol 2019 (HiTen) ◽  
pp. 000075-000084
Author(s):  
Hongyan Xu ◽  
Yaochun Shen ◽  
Yihua Hu ◽  
Jianqiang Li ◽  
Ju Xu
Keyword(s):  
High Temperature ◽  
Double Layer ◽  
Network Structure ◽  
Coating Layer ◽  
Three Dimensional ◽  
Transient Liquid Phase ◽  
Interfacial Structure ◽  
High Temperature Application ◽  
Dimensional Network ◽  
Temperature Application

Abstract A highly reliable three-dimensional network structure joint was fabricated based on Cu@Ni@Sn core-shell powder and transient liquid phase bonding (TLPB) technology for high temperature application. Cu@Ni@Sn joint is characterized by Cu metal particles embedded in the matrix of (Cu,Ni)6Sn5/Ni3Sn4 intermetallics (IMCs), low level of voiding is achieved, they can be reflowed at a low temperatures (<260°C), but reliably working at high temperature up to 415°C. Cu@Ni@Sn double-layer microparticles with different Sn layer and Ni layer thickness were fabricated and compressed as preform used for TLPB joint bonding, the microstructure and phase composition evolution for Cu@Sn and Cu@Ni@Sn system were comparatively studied during reflowing and aging process. Different kinds of interfacial structure designs were made, interfacial microscopic morphology was analyzed and compared under once and twice reflowing soldering process. Results indicated that Sn coating layer was completely consumed to form (Cu,Ni)6Sn5/Ni3Sn4 IMCs, Cu@Ni@Sn bondline have lower void rate and higher shear strength than that of Cu@Sn. The mechanism of Ni coating layer inhibit Cu atom diffusing towards Cu6Sn5 to form Cu3Sn was studied. The high reliable three-dimensional network structure joint based on Cu@Ni@Sn double-layer powder was fabricated for high temperature application.

scholarly journals Fabrication of Highly Reliable Joint Based on Cu/Ni/Sn Double-Layer Powder for High Temperature Application

2019 ◽  
Vol 16 (4) ◽  
pp. 188-195 ◽  
Author(s):  
Hongyan Xu ◽  
Yaochun Shen ◽  
Yihua Hu ◽  
Jianqiang Li ◽  
Ju Xu
Keyword(s):  
High Temperature ◽  
Double Layer ◽  
Network Structure ◽  
Void Ratio ◽  
Coating Layer ◽  
Three Dimensional ◽  
Interfacial Structure ◽  
High Temperature Application ◽  
Dimensional Network ◽  
Temperature Application

Abstract A highly reliable three-dimensional network structure joint was fabricated based on Cu/Ni/Sn powder with double-layer coatings and transient liquid phase bonding (TLPB) technology for high temperature application. The Cu/Ni/Sn joint is characterized by Cu metal particles embedded in the matrix of (Cu,Ni)6Sn5/Ni3Sn4 intermetallic compounds (IMCs), with a low void ratio, and can be reflowed at low temperatures (<260°C), but it can reliably work at a high temperature up to 415°C. Cu/Ni/Sn double-layer powders with different Sn layer and Ni layer thickness were was fabricated and compressed as preform used for TLPB joint bonding. The microstructure and phase composition evolution for Cu/Sn and Cu/Ni/Sn systems during reflow and aging were comparatively studied. Two kinds of interfacial structure designs were made, and corresponding interfacial microscopic morphology was analyzed and compared under once and twice reflow soldering processes. The results indicated that the Sn-coating layer was completely consumed to form (Cu,Ni)6Sn5/Ni3Sn4 IMCs, and the Cu/Ni/Sn joint had a lower void ratio and a higher shear strength than those of Cu/Sn. The mechanism of the Ni-coating layer inhibiting phase transformation was studied. The high reliable three-dimensional network structure joint based on Cu/Ni/Sn double-layer powder was fabricated for high temperature application.

Polishing process effect on the image of dispersed precipitates

1984 ◽  
Vol 42 ◽  
pp. 534-535
Author(s):  
C.T. Hu ◽  
C.W. Allen
Keyword(s):  
Matrix Material ◽  
Specimen Preparation ◽  
Second Phase ◽  
Precipitate Particle ◽  
Polishing Process ◽  
Second Phase Particles ◽  
The Matrix ◽  
Surface Profiles ◽  
Thinning Process

One important problem in determination of precipitate particle size is the effect of preferential thinning during TEM specimen preparation. Figure 1a schematically represents the original polydispersed Ni3Al precipitates in the Ni rich matrix. The three possible type surface profiles of TEM specimens, which result after electrolytic thinning process are illustrated in Figure 1b. c. & d. These various surface profiles could be produced by using different polishing electrolytes and conditions (i.e. temperature and electric current). The matrix-preferential-etching process causes the matrix material to be attacked much more rapidly than the second phase particles. Figure 1b indicated the result. The nonpreferential and precipitate-preferential-etching results are shown in Figures 1c and 1d respectively.

Application of cross correlation to HREM images of surfaces

1987 ◽  
Vol 45 ◽  
pp. 754-755
Author(s):  
D. E. Luzzi ◽  
L. D. Marks ◽  
M. I. Buckett
Keyword(s):  
Cross Correlation ◽  
A Priori ◽  
Matrix Material ◽  
Correlation Method ◽  
Accurate Knowledge ◽  
Complex Image ◽  
Fourier Filtering ◽  
The Matrix ◽  
Low Pass ◽  
Data Reduction Technique

As the HREM becomes increasingly used for the study of dynamic localized phenomena, the development of techniques to recover the desired information from a real image is important. Often, the important features are not strongly scattering in comparison to the matrix material in addition to being masked by statistical and amorphous noise. The desired information will usually involve the accurate knowledge of the position and intensity of the contrast. In order to decipher the desired information from a complex image, cross-correlation (xcf) techniques can be utilized. Unlike other image processing methods which rely on data massaging (e.g. high/low pass filtering or Fourier filtering), the cross-correlation method is a rigorous data reduction technique with no a priori assumptions.We have examined basic cross-correlation procedures using images of discrete gaussian peaks and have developed an iterative procedure to greatly enhance the capabilities of these techniques when the contrast from the peaks overlap.

Three-dimensional Reconstruction of Microscopic Image Based on Multi-ST Algorithm

2020 ◽  
Vol 64 (2) ◽  
pp. 20506-1-20506-7
Author(s):  
Min Zhu ◽  
Rongfu Zhang ◽  
Pei Ma ◽  
Xuedian Zhang ◽  
Qi Guo
Keyword(s):  
3D Reconstruction ◽  
Three Dimensional ◽  
Scale Model ◽  
Microscopic Image ◽  
Multi Scale ◽  
Gaussian Pyramid ◽  
Cost Aggregation ◽  
Dimensional Reconstruction ◽  
Image Pairs ◽  
Accurate Matching

Abstract Three-dimensional (3D) reconstruction is extensively used in microscopic applications. Reducing excessive error points and achieving accurate matching of weak texture regions have been the classical challenges for 3D microscopic vision. A Multi-ST algorithm was proposed to improve matching accuracy. The process is performed in two main stages: scaled microscopic images and regularized cost aggregation. First, microscopic image pairs with different scales were extracted according to the Gaussian pyramid criterion. Second, a novel cost aggregation approach based on the regularized multi-scale model was implemented into all scales to obtain the final cost. To evaluate the performances of the proposed Multi-ST algorithm and compare different algorithms, seven groups of images from the Middlebury dataset and four groups of experimental images obtained by a binocular microscopic system were analyzed. Disparity maps and reconstruction maps generated by the proposed approach contained more information and fewer outliers or artifacts. Furthermore, 3D reconstruction of the plug gauges using the Multi-ST algorithm showed that the error was less than 0.025 mm.

Spring and piston system for high temperature application

1997 ◽  
Author(s):  
R. Spivey ◽  
S. Breeding ◽  
J. Andrews ◽  
D. Stefanescu ◽  
S. Sen ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperature Application ◽  
Piston System ◽  
Temperature Application

Impact Strength, Flexural Modulus and Wear Rate of PMMA Composites Reinforced by Eggshell Powders

2020 ◽  
Vol 38 (7A) ◽  
pp. 960-966
Author(s):  
Aseel M. Abdullah ◽  
Hussein Jaber ◽  
Hanaa A. Al-Kaisy
Keyword(s):  
Impact Strength ◽  
Wear Rate ◽  
Flexural Modulus ◽  
Matrix Material ◽  
Weight Fraction ◽  
Pure Pmma ◽  
Calcination Process ◽  
The Matrix ◽  
The Impact ◽  
Interface Bond

In the present study, the impact strength, flexural modulus, and wear rate of poly methyl methacrylate (PMMA) with eggshell powder (ESP) composites have been investigated. The PMMA used as a matrix material reinforced with ESP at two different states (including untreated eggshell powder (UTESP) and treated eggshell powder (TESP)). Both UTESP and TESP were mixed with PMMA at different weight fractions ranged from (1-5) wt.%. The results revealed that the mechanical properties of the PMMA/ESP composites were enhanced steadily with increasing eggshell contents. The samples with 5 wt.% of UTESP and TESP additions give the maximum values of impact strength, about twice the value of the pure PMMA sample. The calcination process of eggshells powders gives better properties of the PMMA samples compared with the UTESP at the same weight fraction due to improvements in the interface bond between the matrix and particles. The wear characteristics of the PMMA composites decrease by about 57% with increases the weight fraction of TESP up to 5 wt.%. The flexural modulus values are slightly enhanced by increasing of the ESP contents in the PMMA composites.

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