scholarly journals Fabrication of Ni-Al/diamond composite based on layered and gradient structures of SHS system

2017 ◽  
Vol 49 (2) ◽  
pp. 149-158 ◽  
Author(s):  
Jiafeng Lu ◽  
Fenglin Zhang ◽  
Yumei Zhou ◽  
Huiping Huang ◽  
Chengyong Wang ◽  
...  
Keyword(s):  
Wave Velocity ◽  
Combustion Wave ◽  
Layered Structure ◽  
Mesh Size ◽  
Gradient Structure ◽  
Diamond Composite ◽  
Number Of Layers ◽  
The Matrix ◽  
Combustion Wave Velocity ◽  
Size Gradient

In this paper layered and gradient structures of Ni-Al SHS system were adopted to manufacture Ni-Al/diamond composites. The effect of the layered and the diamond mesh gradient structures of Ni-Al/diamond on the SHS process and the microstructure of the composites were investigated. It is found that with the increasing of the number of layers, the combustion wave velocity is decreased. The combustion wave velocity for diamond mesh size gradient structure of Ni-Al SHS is faster than that for the layered structure. A well bonding can be formed between diamond and the matrix in layered and gradient structure Ni-Al/diamond composites due to the melt of Ni-Cr brazing alloy.

Determination of the combustion wave velocity and polymerization

1985 ◽  
Vol 21 (2) ◽  
pp. 151-157
Author(s):  
V. A. Vol'pert ◽  
I. N. Megrabova ◽  
S. P. Davtyan
Keyword(s):  
Wave Velocity ◽  
Combustion Wave ◽  
Combustion Wave Velocity

scholarly journals Development of Embedded Element Technique for Permeability Analysis of Cracked Porous Media

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Peng Qian ◽  
Qianjun Xu
Keyword(s):  
Porous Media ◽  
Effective Permeability ◽  
Water Pressure ◽  
Crack Density ◽  
Mesh Size ◽  
Differential Method ◽  
Simulation Based ◽  
The Matrix ◽  
Element Technique ◽  
Cracked Porous Media

The widely used approach of mesoscale finite element modeling for permeability analysis is to simulate the matrix and cracks with continuum elements (CE), whereas this process brings technical difficulties in generating a satisfying mesh conformity at the interface. In this work, an alternative method based on embedded element (EE) technique is developed for the prediction of water pressure field and effective permeability in the numerical simulation. Based on the mathematical similarity between elasticity and seepage problems, water pressure can derive from the corresponding displacement through “elastic analogy.” To assess the capability of the EE technique, different cases are simulated and compared with the CE model. The results show that there is a satisfactory agreement in water pressures and velocities between the CE and EE modeling. In the CE model, different factors, such as permeability contrast between matrix and cracks (Kcrack/Kmatrix) and mesh size, are considered. It is obvious to find that results will become stable when Kcrack/Kmatrix reaches 104, and the mesh size has little impact. The effective permeability of 3D porous media with random cracks is evaluated and the results show that the differential method is accurate for 3D permeability analysis when the crack density is not large.

Alkaline Treatment on the Chemical and Morphological Properties of Kelempayan (Neolamarckia cadamba) Wood

2021 ◽  
Vol 1025 ◽  
pp. 319-324
Author(s):  
Wan Mohd Nazri Wan Abdul Rahman ◽  
Nor Yuziah Mohd Yunus ◽  
Nur Sakinah Mohamed Tamat ◽  
Siti Noorbaini Sarmin
Keyword(s):  
Chemical Analysis ◽  
Morphological Analysis ◽  
Tap Water ◽  
Mesh Size ◽  
Alkaline Treatment ◽  
Morphological Properties ◽  
The Matrix ◽  
Naoh Solution ◽  
Fine Size ◽  
Scanning Electron

Alkaline treatment has a function to disrupt hydrogen bonding in network structure and to remove some hemicellulose, lignin and extractives for efficient contact with the matrix when preparing composites. Kelempayan (Neolamarkiacadamba) particles were treated using 0.5, 1 and 2% sodium hydroxide (NaOH) solution at a temperature of 90 °C for 60 minutes periods of immersion. The particles were washed with running tap water to neutralize excess NaOH and oven dried at 80 °C. The treated particles were then grounded to a fine size before being sieved to 60 mesh size of sawdust. Finally, the treated samples were air dried before chemical analysis. The sampling and preparation of sawdust were carried out according to the TAPPI Standard T257 cm - 02 (2002). The changes occurring on Kelempayan’s surface were assessed using Scanning Electron Microscopy (SEM). Chemical analysis indicated that hemicellulose, lignin and extractives became decreased by increasing alkaline concentration. Morphological analysis showed that treated surface was cleaner and rougher than that of untreated.

Grain-size gradient structure by abnormal grain growth

2021 ◽  
Author(s):  
He Li ◽  
Junpu Wang ◽  
Resta Agung Susilo ◽  
Hongliang Dong ◽  
Shun Wan ◽  
...  
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Abnormal Grain Growth ◽  
Gradient Structure ◽  
Size Gradient

Design and Manufacturing Bio Composite (Sugarcane Bagasse – Polyvinyl Acetate) Panel that Characterized Thermal Conductivity

2014 ◽  
Vol 893 ◽  
pp. 504-507 ◽  
Author(s):  
Pringgo Widyo Laksono ◽  
Taufiq Rochman ◽  
Hari Setyanto ◽  
Eko Pujiyanto ◽  
Kuncoro Diharjo
Keyword(s):  
Thermal Conductivity ◽  
Sugarcane Bagasse ◽  
Polyvinyl Acetate ◽  
Natural Fiber ◽  
Low Cost ◽  
Mesh Size ◽  
Raw Material ◽  
Composite Panel ◽  
The Matrix ◽  
Characteristic Resistance

The use of sugarcane bagasse for providing avaibility of raw material have been attracting attention. The benefits using natural fiber such as sugarcane bagasse are eco-friendly, low cost considerations because widespread avaibility, high stiffness, better thermal stability, and biodegradability. Sugarcane bagasse and (Polyvinyl acetate, PVAc) have been shown to possess the ability of being applied as raw material for manufacturing of bio composite panel at 10mm thickness (fixed variable) by three mesh sizes (20,30 dan 40) with ratio of the composition 95:5, 90:10 and 85:15%. The specimen have been emphasized at 3:2 and 2:1. This research was conducted to investigate possibility of manufacturing bio composite panel that its characteristic resistance to the thermal conductivity. This bio composite speciments were tested for thermal conductivity test according to ASTM E-1225. The results revealed that optimum design for bio composite panel obtained that emphasis at 3:2, filtered by mesh size 20, ratio composition sugarcane bagasse 85% and PVAc 15%. The test result shown that panel has thermal conductivity resistance value (R) 17,089 °C/W. Thus, it can be concluded that bio composite panel can be manufactured successfully from sugarcane bagasse and PVAc as the matrix mixture.

scholarly journals Laboratory study of ballast material reinforced by flat geogrid under the dynamic load

2019 ◽  
Vol 265 ◽  
pp. 01006 ◽  
Author(s):  
Alexander Abrashitov ◽  
Andrei Sidrakov
Keyword(s):  
Laboratory Study ◽  
Dynamic Load ◽  
Cyclic Load ◽  
Mesh Size ◽  
Optimal Parameters ◽  
Rapid Degradation ◽  
Rail Track ◽  
Number Of Layers ◽  
Load Tests ◽  
Open Question

Ballast material suffers from continuous degradation under cyclic load. This leads to rail track settlement and necessitates its constant maintenance. It is serious problem that costs Russia millions of dollars every year. Easily accessible plastic geogrid was proposed to reinforce ballast and to prevent its rapid degradation. However, the optimal parameters of geogrid (its mesh size, geometry and number of layers) remains an open question. In current work effects of number of geogrid layers and geogrid mesh size on ballast settlement are studied by laboratory dynamic load tests.

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