Ablation Performance and Surface Texture of the Nitride Composites Reinforced by the Braided Silica Fibers

2008 ◽  
Vol 368-372 ◽  
pp. 980-982 ◽  
Author(s):  
Yong Gang Jiang ◽  
Chang Rui Zhang ◽  
Feng Cao ◽  
Si Qing Wang ◽  
Bin Li
Keyword(s):  
Surface Texture ◽  
Three Dimensional ◽  
Liquid Oxygen ◽  
Material Density ◽  
Heating Source ◽  
Silica Fibers ◽  
Ablation Resistance ◽  
Temperature Application ◽  
Shock Resistance ◽  
Resistance Performance

Braided silica fibers reinforced nitride composite (SFRN), which was prepared by the polymeric precursor infiltration and pyrolysis (PIP) process with the precursor polyborosilazane (PSBZ), was a new typed microwave transparent material with high mechanical and ablation resistance performance for high-temperature application. The thermal ablation performance of the SFRN was evaluated by the ablation equipment with the kerosene and liquid oxygen as the heating source. The ablation surface texture of the SFRN including macrostructure and roughness were measured by Three-dimensional Macrostructure and Contour Scale System (TMCSS). Results showed that there are no concurrent observation of thermal delaminations or cracks and the specimen remains intact. The SFRN has an excellent thermal shock resistance and good ablation resistance with the linear recession rate of 0.038mm/s. The ablation surface texture of the SFRN can be well illuminated by the TMCSS. And the ablation performance will be improved by enhancing material density and homogeneous intertextures.

A Transient Simulation of Heated Soil Vapor Extraction System

Volume 1 ◽  
2004 ◽  
Author(s):  
T. Roy ◽  
R. S. Amano ◽  
J. Jatkar
Keyword(s):  
Heat Source ◽  
Three Dimensional ◽  
Soil Vapor Extraction ◽  
Extraction System ◽  
Vapor Extraction ◽  
Predictive Tool ◽  
Heating Source ◽  
Time Required ◽  
Heated Soil ◽  
Remediation Process

Soil remediation process by heated soil vapor extraction system has drawn considerably attention for the last few years. The areas around chemical companies or waste disposal sites have been seriously contaminated from the chemicals and other polluting materials that are disposed off. Our present study is concentrated on modeling one transient Heated Soil Vapor Extraction System and predicting the time required for effective remediation. The process developed by Advanced Remedial Technology, consists of a heating source pipe and the extraction well embedded in the soil. The number of heat source pipes and the extraction wells depends on the type of soil, the type of pollutants, moisture content of the soil and the size of the area to be cleaned. The heat source heats the soil, which is transported in the interior part of the soil by means of conduction and convection. This heating of soil results in vaporization of the gases, which are then driven out of the soil by the extraction well. The extraction well consists of the blower which would suck the vaporized gases out of the system. A three-dimensional meshed geometry was developed using gambit. Different boundary conditions were used for heating and suction well and for other boundaries. Concentrations of different chemicals were collected from the actual site and this data was used as an initial condition. The analysis uses the species transport and discrete phase modeling to predict the time required to clean the soil under specific conditions. This analysis could be used for predicting the changes of chemical concentrations in the soil during the remediation process. This will give us more insight to the physical phenomena and serve as a numerical predictive tool for more efficient process.

scholarly journals Porous PLAs with Controllable Density by FDM 3D Printing and Chemical Foaming Agent

Micromachines ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 866
Author(s):  
A. R. Damanpack ◽  
André Sousa ◽  
M. Bodaghi
Keyword(s):  
3D Printing ◽  
Flow Rate ◽  
Three Dimensional ◽  
Poly Lactic Acid ◽  
Layer By Layer ◽  
Printing Technology ◽  
Material Density ◽  
Foaming Agent ◽  
3D Printing Technology ◽  
Fabrication Parameters

This paper shows how fused decomposition modeling (FDM), as a three-dimensional (3D) printing technology, can engineer lightweight porous foams with controllable density. The tactic is based on the 3D printing of Poly Lactic Acid filaments with a chemical blowing agent, as well as experiments to explore how FDM parameters can control material density. Foam porosity is investigated in terms of fabrication parameters such as printing temperature and flow rate, which affect the size of bubbles produced during the layer-by-layer fabrication process. It is experimentally shown that printing temperature and flow rate have significant effects on the bubbles’ size, micro-scale material connections, stiffness and strength. An analytical equation is introduced to accurately simulate the experimental results on flow rate, density, and mechanical properties in terms of printing temperature. Due to the absence of a similar concept, mathematical model and results in the specialized literature, this paper is likely to advance the state-of-the-art lightweight foams with controllable porosity and density fabricated by FDM 3D printing technology.

scholarly journals Heating source localization in a reduced time

2016 ◽  
Vol 26 (3) ◽  
pp. 623-640 ◽  
Author(s):  
Sara Beddiaf ◽  
Laurent Autrique ◽  
Laetitia Perez ◽  
Jean-Claude Jolly
Keyword(s):  
Heat Conduction ◽  
Source Localization ◽  
Conjugate Gradient ◽  
Regularization Method ◽  
Three Dimensional ◽  
Gradient Algorithm ◽  
Iterative Regularization ◽  
Heating Source ◽  
Ill Posed ◽  
Reduced Time

Abstract Inverse three-dimensional heat conduction problems devoted to heating source localization are ill posed. Identification can be performed using an iterative regularization method based on the conjugate gradient algorithm. Such a method is usually implemented off-line, taking into account observations (temperature measurements, for example). However, in a practical context, if the source has to be located as fast as possible (e.g., for diagnosis), the observation horizon has to be reduced. To this end, several configurations are detailed and effects of noisy observations are investigated.

scholarly journals Bio-inspired design of ice-retardant devices based on benthic marine invertebrates: the effect of surface texture

2014 ◽  
Author(s):  
Homayun Mehrabani ◽  
Neil Ray ◽  
Kyle Tse ◽  
Dennis Evangelista
Keyword(s):  
Surface Texture ◽  
Marine Invertebrates ◽  
Freezing Point ◽  
Three Dimensional ◽  
Surface Pattern ◽  
Ice Formation ◽  
Cold Air ◽  
Three Dimensional Printing ◽  
Species Specific ◽  
Effect Of Surface

Growth of ice on surfaces poses a challenge for both organisms and for devices that come into contact with liquids below the freezing point. Resistance of some organisms to ice formation and growth, either in subtidal environments (e.g. Antarctic anchor ice), or in environments with moisture and cold air (e.g.vplants, intertidal) begs examination of how this is accomplished. Several factors may be important in promoting or mitigating ice formation. As a start, here we examine the effect of surface texture alone. We tested four candidate surfaces, inspired by hard-shelled marine invertebrates and constructed using a three-dimensional printing process. We screened biological and artifical samples for ice formation and accretion in submerged conditions using previous methods, and developed a new test to examine ice formation from surface droplets as might be encountered in environments with moist, cold air. It appears surface texture plays only a small role in delaying the onset of ice formation: a stripe feature (corresponding to patterning found on valves of blue mussels,Crassostrea gigas, or on the spines of the Antarctic sea urchinSterechinus neumayeri) slowed ice formation an average of 25% compared to a grid feature (corresponding to patterning found on sub-polar butterclams,Saxidomas nuttali). The geometric dimensions of the features have only a small (~6%) effect on ice formation. Surface texture affects ice formation, but does not explain by itself the large variation in ice formation and species-specific ice resistance observed in other work. This suggests future examination of other factors, such as material elastic properties and coatings, and their interaction with surface pattern.

scholarly journals Ablation Behaviour and Microstructure of Carbon/Carbon and Hybrid Carbon/Carbon Composites Based on Plasma Torch Heating

2017 ◽  
Vol 26 (4) ◽  
pp. 096369351702600 ◽  
Author(s):  
Li Ma ◽  
Lu Jv He ◽  
Cai Song Mo ◽  
Li Bin Zhang ◽  
Mao Sen Pan ◽  
...  
Keyword(s):  
Plasma Torch ◽  
Carbon Matrix ◽  
Ablation Rate ◽  
Carbon Composites ◽  
Carbon Fibres ◽  
Fibre Bundles ◽  
Composites Materials ◽  
Ablation Resistance ◽  
Resistance Performance ◽  
Hybrid Carbon

The ablation properties and morphologies of two kinds of fine Fine-woven pierced composites materials, carbon/carbon (C/C) and hybrid C/C with tungsten (W) filaments in z directional carbon fibre bundles, were investigated. A plasma torch was used to explore the ablative characteristics in terms of linear/bulk ablation rate and microscopic pattern of ablation. Surface and in-depth temperatures during ablation were measured by using optical pyrometers and thermocouples. The experimental results showed that the C/C composite presented the best ablation resistance performance, followed by the hybrid C/C composite, while that of graphite was the worst. It was found that the thermo-mechanical ablation resistance of carbon matrix is equal to that of carbon fibres. The existence of WC not only had a faster intrinsic ablation velocity, but also accelerated the ablation velocity of the carbon fibres and carbon matrix, and significantly improved the ablation velocity of the carbon fibres.

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