scholarly journals Fractal Dimension of Fracture Surface in Rock Material after High Temperature

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Z. Z. Zhang
Keyword(s):  
Fractal Dimension ◽  
Electron Microscope ◽  
High Temperature ◽  
Fracture Surface ◽  
Scanning Electron Microscope ◽  
Fractal Dimensions ◽  
Threshold Value ◽  
Fracture Surfaces ◽  
Increasing Temperature ◽  
Scanning Electron

Experiments on granite specimens after different high temperature under uniaxial compression were conducted and the fracture surfaces were observed by scanning electron microscope (SEM). The fractal dimensions of the fracture surfaces with increasing temperature were calculated, respectively. The fractal dimension of fracture surface is between 1.44 and 1.63. Its value approximately goes up exponentially with the increase of temperature. There is a quadratic polynomial relationship between the rockburst tendency and fractal dimension of fracture surface; namely, a fractal dimension threshold can be obtained. Below the threshold value, a positive correlativity shows between rockburst tendency and fractal dimension; when the fractal dimension is greater than the threshold value, it shows an inverse correlativity.

Scanning Electron Microscope of Fatigue and Creep-Fatigue From Stress Concentrations in Plates

2012 ◽  
Author(s):  
Osamu Watanabe ◽  
Marina Kikuchi ◽  
Akihiro Matsuda
Keyword(s):  
Electron Microscope ◽  
High Temperature ◽  
Scanning Electron Microscope ◽  
Crack Propagation ◽  
Fatigue Test ◽  
304 Stainless Steel ◽  
High Temperature Fatigue ◽  
Fracture Surfaces ◽  
Creep Fatigue ◽  
Scanning Electron

Fatigue crack propagation forms a distinctive pattern which is observable on the fracture surfaces of materials. Purpose of this study is to analyze the fracture process of the materials received under cyclic distortion loading using scanning electron microscope. The test piece made of type 304 stainless steel with the hole of a different size is examined on the conditions of the high temperature fatigue and creep-fatigue. This study first takes a picture of the fracture with SEM, and measures the intervals of striation on fracture surfaces. Next, this study calculates the number of the crack propagation cycles and compares with the original experimental data defined by the load decrease condition or the crack length. Consequently, there is not so much differences at striation intervals regardless of the size of the root notch radius in the present tests. However, the striation spacing in the creep fatigue test has grown about twice of striation intervals in the high temperature fatigue-test.

The Effect of Different Colloidal Silica Binders on Strengths of Corundum-Mullite Castables

2015 ◽  
Vol 1094 ◽  
pp. 127-130
Author(s):  
Wen Jie Yuan ◽  
Qing You Zhu ◽  
Cheng Ji Deng ◽  
Hong Xi Zhu
Keyword(s):  
Electron Microscope ◽  
Fracture Surface ◽  
Scanning Electron Microscope ◽  
Size Distribution ◽  
Colloidal Silica ◽  
Modulus Of Rupture ◽  
Fracture Surfaces ◽  
The Difference ◽  
Slit Island Method ◽  
Scanning Electron

Three kinds of colloidal silica (GS-30, AM and HS-30) were applied as binders to corundum-mullite castables. The apparent porosity and cold modulus of rupture for samples fired at 800 oC and 1000 oC were compared. The fractography of colloidal silica bonded corundum-mullite castables was carried out by slit island method. The microstructure of fracture surface was characterized by scanning electron microscope. The results showed that castables by using imported colloidal silica (AM and HS-30) presented higher strength than those with domestic (GS-30), which was determined by the activity of silica and modified ion. The difference of the size distribution of the salient on the fracture surfaces indicated that the strength of castables was dependent on the bonding among the components.

A Comparison of TEM and SEM Fractography

1970 ◽  
Vol 28 ◽  
pp. 398-399
Author(s):  
James L. Hubbard
Keyword(s):  
Electron Microscope ◽  
Fracture Surface ◽  
Scanning Electron Microscope ◽  
Stress Corrosion ◽  
Surface Features ◽  
Fracture Surfaces ◽  
Mental Picture ◽  
Scanning Electron

For many years now, metallurgists have been using replica techniques for electron micrographic studies of the fracture surfaces of metals. The general features which are indicative of a certain mode of fracture, such as fatigue, overstress, or stress corrosion, have become quite familar in a wide variety of alloys. Although replicas are subject to many artifacts these features are usually recognized as such and disregarded in the analysis of the surface. Also since negative replicas are generally used one must reverse his perspective in order to obtain a true mental picture of the fracture surface.With the scanning electron microscope, micrographs of such samples can now be taken directly with no surface replication or preparation involved. The scanning micrographs, while limited in resolution, present a picture not only true to the surface but with a stereo perspective with which one can relate the surface features to reality.

Prediction of Fracture Toughness of Magnesia-Carbon Bricks Based on Fractography

2018 ◽  
Vol 768 ◽  
pp. 3-7
Author(s):  
Hai Tang ◽  
Guang Wei Guo ◽  
Qing You Zhu ◽  
Wen Jie Yuan
Keyword(s):  
Fracture Toughness ◽  
Electron Microscope ◽  
High Temperature ◽  
Fracture Surface ◽  
Scanning Electron Microscope ◽  
Carbon Content ◽  
Fractal Analysis ◽  
Fracture Mechanism ◽  
Temperature Performance ◽  
Scanning Electron

The introduction of carbon greatly improves the high temperature performance of magnesia bricks. In order to explore the influence of carbon content on the fracture toughness and the fracture mechanism of magnesia-carbon bricks, two different carbon content (10wt% and 14wt%) magnesia-carbon bricks were investigated in this work. The fracture toughness and microstructure were characterized by fractal analysis of fracture surface and scanning electron microscope respectively. The results indicated that the strength of magnesia-carbon bricks was strengthened with the carbon content increasing. It was demonstrated that magnesia-carbon bricks with the higher carbon content presented higher fracture toughness as a consequence of lower apparent porosity and compact bonding between matrix and magnesia aggregates.

scholarly journals Micropore Structure and Fractal Characteristics of Low-Permeability Coal Seams

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Guang-zhe Deng ◽  
Rui Zheng
Keyword(s):  
Fractal Dimension ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Coal Seam ◽  
Linear Relationship ◽  
Surface Area ◽  
Pore Volume ◽  
Low Permeability ◽  
Coal Seams ◽  
Scanning Electron

With the raw coal from a typical low-permeability coal seam in the coalfield of South Junger Basin in Xinjiang as the research object, this paper examined six kinds of coal samples with different permeabilities using a scanning electron microscope and a low-temperature nitrogen adsorption test that employed a JSM-6460LV high-resolution scanning electron microscope and an ASAP2020 automatic specific surface area micropore analyzer to measure all characteristic micropore structural parameters. According to fractal geometry theory, four fractal dimension calculation models of coal and rock were established, after which the pore structure characteristic parameters were used to calculate the fractal dimensions of the different coal seams. The results show that (1) the low-permeability coal seam in the coalfield of South Junger Basin in Xinjiang belongs to mesoporous medium, with a certain number of large pores and no micropores. The varying adsorption capacities of the different coal seams were positively correlated with pore volume, surface area, and the mesoporous surface area proportions, from which it was concluded that mesopores were the main contributors to pore adsorption in low-permeability coal seams. (2) The raw coal pore fractal dimension had a negative linear relationship to average pore size, a positive linear relationship with total pore volume, total surface area, and adsorption capacity, and a positive correlation with the mesoporous surface area proportion; that is, the higher the fractal dimension, the larger the pore volume and surface area of the raw coal. (3) The permeability of the low-permeability coal seam had a phase correlation with the micropore development degree; that is, the permeability had a phase negative correlation with the pore distribution fractal dimension, and there was a positive correlation between permeability and porosity. These results are of theoretical significance for the clean exploitation of low-permeability coal seam resources.

INVESTIGATION ON HIGH-TEMPERATURE CORROSION BEHAVIOR OF INCONEL 600 UNDER SO2-BEARING GAS AT 650°C

2019 ◽  
Vol 27 (06) ◽  
pp. 1950155
Author(s):  
KWANG-HU JUNG ◽  
SEONG-JONG KIM
Keyword(s):  
Electron Microscope ◽  
Weight Gain ◽  
High Temperature ◽  
Scanning Electron Microscope ◽  
High Temperature Corrosion ◽  
X Ray Diffraction ◽  
Oxide Structure ◽  
X Ray ◽  
Inconel 600 ◽  
Scanning Electron

The corrosion characteristics of Inconel 600 were investigated at 650∘C in air and 76%[Formula: see text]%[Formula: see text]%[Formula: see text]%SO2 gas environment up to 500[Formula: see text]h. Specimens exposed to each condition were characterized by weight gain, scanning electron microscope, energy dispersive X-ray spectroscopy and X-ray diffraction. The oxide structure consisting of the thin Cr2O3 layer and Cr2O3 nodules was observed, which increased the weight gain of specimens. In the SO2-bearing gas, it showed a bigger weight gain due to the coarsening of Cr2O3 nodules. Therefore, it was suggested that the sulfur-accelerated coarsening of Cr2O3 nodules at the high temperature.

Failure Analysis on Heating Surface Tube Crackof High Temperature Reheater in Station Boiler

2013 ◽  
Vol 804 ◽  
pp. 333-336
Author(s):  
Yun Jian Jiang ◽  
Xiang Feng Zheng ◽  
Rong Gang Xue ◽  
Guo Zhen Dong ◽  
Ji Feng Zhao ◽  
...  
Keyword(s):  
Residual Stress ◽  
Electron Microscope ◽  
High Temperature ◽  
Chemical Analysis ◽  
Scanning Electron Microscope ◽  
Failure Analysis ◽  
Heating Surface ◽  
Welding Residual Stress ◽  
Microscope Analysis ◽  
Scanning Electron

Through methods, such as microscope analysis, chemical analysis, metallography examination and scanning electron microscope etc, the causes resulting in high temperature reheater tube cracking of station boiler have been analyzed. The result indicates the crack is reheat crack, and structure stress, higher hardness and excessive welding residual stress are the primary inducement of tube joint crack.

Research on the Ultra-Fine Titanium Dioxide Suspension Stability and Fractal

2011 ◽  
Vol 361-363 ◽  
pp. 288-295
Author(s):  
De Wei Chen ◽  
Xiao Ling Ge ◽  
Quen Tin Shi ◽  
Jiu Wang Tian
Keyword(s):  
Titanium Dioxide ◽  
Fractal Dimension ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Surface Sediments ◽  
Suspension Stability ◽  
Matlab Program ◽  
Different Types ◽  
Scanning Electron ◽  
Dioxide Suspension

Using scanning electron microscope, the microscopic pictures of the surface on sediment have been obtained from the sub-micron titanium dioxide suspensions without dispersant or adding different types of dispersants. Deposits of titanium dioxide suspension have been observed and the mechanism of the dispersant has been analyzed. Meanwhile, deposits of titanium dioxide gray distribution figure have been gained by self-compiled Matlab program, which proved that the surface sediments is fractal, and the fractal dimension has been calculated under different conditions. The rules between suspension stability and fractal dimension have been achieved.

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