Ablation and mechanical investigation of heat vulcanizing silicone rubber (HVSR) composite containing carbon fibers

2017 ◽  
Vol 37 (5) ◽  
pp. 521-528 ◽  
Author(s):  
Yanhui Liu ◽  
Jingyu Su ◽  
Zhengshuai Yin ◽  
Yong Li ◽  
Ye Zhi ◽  
...  
Keyword(s):  
Carbon Fibers ◽  
Silicone Rubber ◽  
Ablation Rate ◽  
Shielding Effect ◽  
Characterization Methods ◽  
Ablation Mechanism ◽  
Back Face ◽  
The Matrix ◽  
The Impact ◽  
Face Temperature

Abstract In this study, heat vulcanizing silicone rubber (HVSR) composites were prepared and the impact of the addition of carbon fibers (CFs) on the mechanical and ablation properties of the composite was demonstrated. It was found that with increasing content of CFs, the tensile property and the hardness of the composite increased significantly. The back-face temperature, the ablation rate and the ablation mechanism of the composite were discussed based on the data derived from several characterization methods, including oxygen-acetylene ablation device, scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR). Along with the increasing of the content of CFs, the mass and linear ablation rates both decreased, but the back-face temperature increased. The interaction between ablation layer and the composite became intense due to the addition of the CFs, which led to the difficult peel-off of the ablation layer. Four layers can be formed after the oxygen-acetylene ablation of the composite including the surface layer, the carbonization layer, the pyrolysis layer and the matrix layer. The ablation mechanism was also proposed. It mainly involves the carbonization of the composite, the ceramization of SiC and the shielding effect of the ablated layer.

scholarly journals Experimental Study of The Insulating Effectiveness of Silicone Rubber Composites by Oxyacetylene Ablation Testing

2020 ◽  
pp. 1-11
Author(s):  
Artem Andrianov ◽  
Jungpyo Lee ◽  
Gabriela Possa ◽  
Hiterson de Oliveira Silva
Keyword(s):  
Carbon Fibers ◽  
Silicone Rubber ◽  
Ablation Rate ◽  
Low Thrust ◽  
Flame Direction ◽  
Hybrid Propulsion ◽  
Silica Fibers ◽  
Back Face ◽  
Glass Carbon ◽  
Face Temperature

The objective of this study was to characterize the thermal insulation efficiency of the silicone rubber reinforced composites by oxyacetylene torch. These composites reinforced by glass, carbon, ceramics and silica fibers were intended to be used as ablators in a low-thrust hybrid propulsion motor. The back-face temperature measurements were used as a criterion for insulation efficiency of the specimens, whose frontal face is subjected to the oxyacetylene flame for 40 s. The paper includes the results of the ablation rate measurements and the influence of orientation of glass and carbon fibers relatively to the flame direction on the back-face temperature of the specimens.

scholarly journals Ablation Behavior of Silicone Rubber-Benzoxazine-Based Composites for Ultra-High Temperature Applications

Polymers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1844 ◽  
Author(s):  
Gao ◽  
Li ◽  
Li ◽  
Liu
Keyword(s):  
Thermal Stability ◽  
Ablation Rate ◽  
Shielding Effect ◽  
Zro2 Content ◽  
Ablation Resistance ◽  
Linear Ablation ◽  
Rubber Composite ◽  
Back Face ◽  
Ceramic Compounds ◽  
Face Temperature

A novel type of silicon rubber composite with benzoxazine resins (BZs) and ZrO2 was prepared. The ablative response of the composites was investigated. The results showed that the composites with BZs had superior thermal stability and higher resides compared to the pristine composites. The linear ablation rate of the composites decreased significantly with the increase in ZrO2 content. The maximum back-face temperature of the burnt samples was no more than 100 °C for the obtained composites. Three major ablation processes were carried out simultaneously during the ablation processing. These mainly involved the carbonization of the composite, and the formation of ceramic compounds such as SiC and ZrC, as well as the shielding effect of the ablated layer, which subsequently enhanced the ablation resistance of the composites.

scholarly journals Understanding the Role of Carbon Fiber Skeletons in Silicone Rubber-Based Ablative Composites

Polymers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 268
Author(s):  
Yuan Ji ◽  
Shida Han ◽  
Zhiheng Chen ◽  
Hong Wu ◽  
Shaoyun Guo ◽  
...  
Keyword(s):  
Silicone Rubber ◽  
Ablation Rate ◽  
Solid Rocket Motors ◽  
Rocket Motors ◽  
Linear Ablation ◽  
Dense Ceramic ◽  
Back Face ◽  
Solid Rocket ◽  
Ceramic Fillers

At present, silicone rubber-based ablative composites are usually enhanced by carbon fibers (CFs) to protect the case of solid rocket motors (SRMs). However, the effect of the CFs’ length on the microstructure and ablation properties of the silicone rubber-based ablative composites has been ignored. In this work, different lengths of CFs were introduced into silicone rubber-based ablative composites to explore the effect of fiber length, and ceramic layers of various morphologies were constructed after ablation. It was found that a complete and continuous skeleton in ceramic layers was formed by CFs over 3 mm in length. In addition, the oxyacetylene ablation results showed that the linear ablation rate declined from 0.233 to 0.089 mm/s, and the maximum back-face temperature decreased from 117.7 to 107.9 °C as the length of the CFs increased from 0.5 to 3 mm. This can be attributed to the fact that successive skeletons concatenated and consolidated the ceramic fillers as well as residues to form an integrated, robust, and dense ceramic layer.

Initiation and Propagation of Impact-Induced Damage in CFRP Laminates

2007 ◽  
Vol 345-346 ◽  
pp. 437-440
Author(s):  
Seung Min Jang ◽  
Tadaharu Adachi ◽  
Akihiko Yamaji
Keyword(s):  
Impact Damage ◽  
Matrix Crack ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Element Analysis ◽  
Cfrp Laminates ◽  
Initiation And Propagation ◽  
Back Face ◽  
The Matrix ◽  
The Impact

This paper investigated the initiation and propagation characteristics of impact-induced damage in carbon-fiber-reinforced-plastic (CFRP) laminates with different stacking sequences and thicknesses under low-velocity impact. Impact force histories were measured with a drop-weight impact tester. A strain gauge was attached on the back face of CFRP laminates to measure exactly when a matrix crack on its back face was initiated. It was found from fractographic observation that impact-induced damage in CFRP laminates was initiated at the matrix crack on the back face of CFRP laminates due to bending deformation during impact. Finite element analysis was conducted using the impact forces derived from the experimental results of the impact test. Its results clarified that the tensile stress normal to the fiber on the back face of the specimen was the criterion to initiate impact damage in CFRP laminates.

Properties Characteristics of Silicone Inhibitors

2013 ◽  
Vol 750-752 ◽  
pp. 43-46 ◽  
Author(s):  
Zhu Chen ◽  
Dong Li ◽  
Ai Juan Shi ◽  
Yang Li ◽  
Shu Xin Wu
Keyword(s):  
Tensile Strength ◽  
Carbon Fiber ◽  
Carbon Fibers ◽  
Silicone Rubber ◽  
Room Temperature ◽  
Ablation Rate ◽  
Rubber Composites ◽  
Mechanical Mixing ◽  
Mixing Method ◽  
Short Carbon

The short carbon fibers/ room temperature vulcanizing silicone rubber composites were prepared by mechanical mixing method and vulcanization at room temperature for 7 days as internal insulator. The effects of the content of fiber on the mechanical , ablative and adhesive performances for the composites were investigated. The results show that with increasing content of carbon fiber filled, the tensile strength increases, the break elongation decreases, and the ablation rate (Rt) of the composites decreases rapidly at first, then increases. When carbon fiber content is 10phr, the ablation rate (Rt) is 0.076mm/s. no significant differences in adhesive values were obtained yet.

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.

scholarly journals The Interactions between Polyphenols and Microorganisms, Especially Gut Microbiota

Antioxidants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 188
Author(s):  
Małgorzata Makarewicz ◽  
Iwona Drożdż ◽  
Tomasz Tarko ◽  
Aleksandra Duda-Chodak
Keyword(s):  
Intestinal Bacteria ◽  
Research Data ◽  
Bioactive Metabolites ◽  
Human Organism ◽  
Comprehensive Knowledge ◽  
Bidirectional Relationship ◽  
The Matrix ◽  
Intestinal Pathogens ◽  
The Impact

This review presents the comprehensive knowledge about the bidirectional relationship between polyphenols and the gut microbiome. The first part is related to polyphenols’ impacts on various microorganisms, especially bacteria, and their influence on intestinal pathogens. The research data on the mechanisms of polyphenol action were collected together and organized. The impact of various polyphenols groups on intestinal bacteria both on the whole “microbiota” and on particular species, including probiotics, are presented. Moreover, the impact of polyphenols present in food (bound to the matrix) was compared with the purified polyphenols (such as in dietary supplements) as well as polyphenols in the form of derivatives (such as glycosides) with those in the form of aglycones. The second part of the paper discusses in detail the mechanisms (pathways) and the role of bacterial biotransformation of the most important groups of polyphenols, including the production of bioactive metabolites with a significant impact on the human organism (both positive and negative).

scholarly journals Reliability Assessment of a Multi-State HVDC System by Combining Markov and Matrix-Based Methods

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3097
Author(s):  
Roberto Benato ◽  
Antonio Chiarelli ◽  
Sebastian Dambone Sessa
Keyword(s):  
Current System ◽  
Estimation Method ◽  
Reliability Estimation ◽  
Voltage Source ◽  
Voltage Source Converter ◽  
Hvdc System ◽  
Critical Elements ◽  
The Matrix ◽  
The Impact

The purpose of this paper is to highlight that, in order to assess the availability of different HVDC cable transmission systems, a more detailed characterization of the cable management significantly affects the availability estimation since the cable represents one of the most critical elements of such systems. The analyzed case study consists of a multi-terminal direct current system based on both line commutated converter and voltage source converter technologies in different configurations, whose availability is computed for different transmitted power capacities. For these analyses, the matrix-based reliability estimation method is exploited together with the Monte Carlo approach and the Markov state space one. This paper shows how reliability analysis requires a deep knowledge of the real installation conditions. The impact of these conditions on the reliability evaluation and the involved benefits are also presented.

Thermal Response and Ablation Research of EPDM Thermal Protection Material in Ramjet

2015 ◽  
Vol 1092-1093 ◽  
pp. 534-538
Author(s):  
Xiong Chen ◽  
Hai Feng Xue ◽  
Hua Liang
Keyword(s):  
Heat Transfer ◽  
Heat Load ◽  
Thermal Protection ◽  
Thermal Response ◽  
Transfer Model ◽  
Back Face ◽  
Ground Test ◽  
Simulation Results ◽  
Face Temperature ◽  
Scanning Electron

Thermal protection materials are required to preserve the metal components of motor that suffer severe heat load. The research on thermal response of insulation of ramjet combustion chamber was carried out by the ground test and numerical simulation. During the working time of the ramjet, the back-face temperature of the thermal protection material was measured. The scanning electron microscope of samples was investigated. The calculation of thermo-chemical flow was solved by the CFD software FLUENT to provide the heat load boundary for simulation of heat transfer of EPDM insulation. The heat transfer model was solved by the FEA software ANSYS. Comparison of the temperature profile at the ablating surface between calculation and measurement shows the two results agree with each other. The simulation results can provide the temperature rising trend of insulation in a certain extent.

scholarly journals Evaluating the role of contracting and expanding rainforest in initiating cycles of speciation across the Isthmus of Panama

2012 ◽  
Vol 279 (1742) ◽  
pp. 3520-3526 ◽  
Author(s):  
Brian Tilston Smith ◽  
Amei Amei ◽  
John Klicka
Keyword(s):  
Bird Species ◽  
Tropical Regions ◽  
Isthmus Of Panama ◽  
Species Pairs ◽  
The Matrix ◽  
High Species Richness ◽  
The Rich ◽  
The Tropics ◽  
The Impact

Climatic and geological changes across time are presumed to have shaped the rich biodiversity of tropical regions. However, the impact climatic drying and subsequent tropical rainforest contraction had on speciation has been controversial because of inconsistent palaeoecological and genetic data. Despite the strong interest in examining the role of climatic change on speciation in the Neotropics there has been few comparative studies, particularly, those that include non-rainforest taxa. We used bird species that inhabit humid or dry habitats that dispersed across the Panamanian Isthmus to characterize temporal and spatial patterns of speciation across this barrier. Here, we show that these two assemblages of birds exhibit temporally different speciation time patterns that supports multiple cycles of speciation. Evidence for these cycles is further corroborated by the finding that both assemblages consist of ‘young’ and ‘old’ species, despite dry habitat species pairs being geographically more distant than pairs of humid habitat species. The matrix of humid and dry habitats in the tropics not only allows for the maintenance of high species richness, but additionally this study suggests that these environments may have promoted speciation. We conclude that differentially expanding and contracting distributions of dry and humid habitats was probably an important contributor to speciation in the tropics.

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