Modeling the Environmental Effects on Carbon Fibers in a Ceramic Matrix at Oxidizing Conditions PDF Download
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Author: Michael C. Halbig
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Carbon fiber/silicon carbide matrix composites (C/SiC) are promising materials for space applications such as nozzles, thrusters, and bladed disks. However the as-fabricated, cracked nature of the material makes it susceptible to environmental degradation due to fiber oxidation. Theoretical models can be used to gain a better understanding of how certain variables (i.e. temperature, environment, diffusion coefficient and reaction rate constant) are related to a specific process and to supplement or analyze experimental results. Methods for predicting the distribution of local oxygen concentration from the edge to the interior of an open column in a matrix bounded by carbon fiber tows will be discussed. The amounts and distribution of oxygen in a matrix and the gradients in oxygen concentration convey information regarding the oxidation kinetics. The models consider the case of a crack in a ceramic matrix that is bridged by carbon fiber tows. Two analytical solutions and differing finite difference models will be used to predict oxygen concentrations. Results from each prediction method will be presented and compared. The results and their relation towards oxidation kinetics will be discussed. Several geometries for the composite (square and rectangular) are considered in the finite difference models.
Author: Michael C. Halbig
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Carbon fiber/silicon carbide matrix composites (C/SiC) are promising materials for space applications such as nozzles, thrusters, and bladed disks. However the as-fabricated, cracked nature of the material makes it susceptible to environmental degradation due to fiber oxidation. Theoretical models can be used to gain a better understanding of how certain variables (i.e. temperature, environment, diffusion coefficient and reaction rate constant) are related to a specific process and to supplement or analyze experimental results. Methods for predicting the distribution of local oxygen concentration from the edge to the interior of an open column in a matrix bounded by carbon fiber tows will be discussed. The amounts and distribution of oxygen in a matrix and the gradients in oxygen concentration convey information regarding the oxidation kinetics. The models consider the case of a crack in a ceramic matrix that is bridged by carbon fiber tows. Two analytical solutions and differing finite difference models will be used to predict oxygen concentrations. Results from each prediction method will be presented and compared. The results and their relation towards oxidation kinetics will be discussed. Several geometries for the composite (square and rectangular) are considered in the finite difference models.
Author: Michael C. Halbig
Publisher:
ISBN:
Category :
Languages : en
Pages : 7
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Book Description
Carbon fiber/silicon carbide matrix composites (C/SiC) are promising materials for space applications such as nozzles, thrusters, and bladed disks. However the as-fabricated, cracked nature of the material makes it susceptible to environmental degradation due to fiber oxidation. Theoretical models can be used to gain a better understanding of how certain variables (i.e. temperature, environment, diffusion coefficient and reaction rate constant) are related to a specific process and to supplement or analyze experimental results. Methods for predicting the distribution of local oxygen concentration from the edge to the interior of an open column in a matrix bounded by carbon fiber tows will be discussed. The amounts and distribution of oxygen in a matrix and the gradients in oxygen concentration convey information regarding the oxidation kinetics. The models consider the case of a crack in a ceramic matrix that is bridged by carbon fiber tows. Two analytical solutions and differing finite difference models will be used to predict oxygen concentrations. Results from each prediction method will be presented and compared. The results and their relation towards oxidation kinetics will be discussed. Several geometries for the composite (square and rectangular) are considered in the finite difference models.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 14
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Book Description
Author: Narottam P. Bansal
Publisher: John Wiley & Sons
ISBN: 1118832892
Category : Technology & Engineering
Languages : en
Pages : 725
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Book Description
This book is a comprehensive source of information on various aspects of ceramic matrix composites (CMC). It covers ceramic and carbon fibers; the fiber-matrix interface; processing, properties and industrial applications of various CMC systems; architecture, mechanical behavior at room and elevated temperatures, environmental effects and protective coatings, foreign object damage, modeling, life prediction, integration and joining. Each chapter in the book is written by specialists and internationally renowned researchers in the field. This book will provide state-of-the-art information on different aspects of CMCs. The book will be directed to researchers working in industry, academia, and national laboratories with interest and professional competence on CMCs. The book will also be useful to senior year and graduate students pursuing degrees in ceramic science and engineering, materials science and engineering, aeronautical, mechanical, and civil or aerospace engineering. Presents recent advances, new approaches and discusses new issues in the field, such as foreign object damage, life predictions, multiscale modeling based on probabilistic approaches, etc. Caters to the increasing interest in the application of ceramic matrix composites (CMC) materials in areas as diverse as aerospace, transport, energy, nuclear, and environment. CMCs are considered ans enabling technology for advanced aeropropulsion, space propulsion, space power, aerospace vehicles, space structures, as well as nuclear and chemical industries. Offers detailed descriptions of ceramic and carbon fibers; fiber-matrix interface; processing, properties and industrial applications of various CMC systems; architecture, mechanical behavior at room and elevated temperatures, environmental effects and protective coatings, foreign object damage, modeling, life prediction, integration/joining.
Author: Michael C. Halbig
Publisher:
ISBN:
Category :
Languages : en
Pages : 14
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Book Description
A finite difference model has been developed and was used to study the oxidation kinetics of carbon fibers exposed by the presence of a through-thickness matrix crack in a ceramic matrix composite. Air was the environment of interest so that the model could be compared to experimental testing. The limiting steps of diffusion controlled and reaction controlled kinetics were investigated by changing the value of the simulated temperature which, in turn corresponds to a change in the diffusion coefficient and reaction rate constant. The reaction rates for the oxidation of carbon fibers were compared to theoretical values and oxidation trends predicted by the model were compared to experimental trends.
Author: Todd Jessen
Publisher: John Wiley & Sons
ISBN: 0470295074
Category : Technology & Engineering
Languages : en
Pages : 777
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Book Description
This volume is part of the Ceramic Engineering and Science Proceeding (CESP) series. This series contains a collection of papers dealing with issues in both traditional ceramics (i.e., glass, whitewares, refractories, and porcelain enamel) and advanced ceramics. Topics covered in the area of advanced ceramic include bioceramics, nanomaterials, composites, solid oxide fuel cells, mechanical properties and structural design, advanced ceramic coatings, ceramic armor, porous ceramics, and more.
Author: Michael C. Halbig
Publisher:
ISBN:
Category :
Languages : en
Pages : 18
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Book Description
Carbon fiber reinforced silicon carbide matrix composites (C/SiC) are a ceramic matrix composite (CMC) material that offers benefits for use in a wide range of high temperature structural applications. However the susceptibility of the carbon fibers to degradation in oxidizing environments has hindered the material's use in certain applications requiring long lives under oxidizing conditions. The susceptibility of carbon fibers to oxidation will be discussed as well as the enhancement (improvement in oxidation resistance) of C/SiC materials. Thermogravimetric analysis of carbon fibers shows susceptibility to oxidation in two distinct kinetic regimes. However, in the thermogravimetric (wt. loss) analysis of unstressed, unenhanced, seal coated C/SiC coupons, the two regimes were not observed due to crack closure and matrix effects, which inhibited the oxidation process. Stressed oxidation (creep rupture) tests put the material under a stress, which is a more realistic condition for many applications. In stressed oxidation tests, the two oxidation kinetics regimes were observed. These tests can provide better insight into how the material will perform in applications involving stress. Stressed oxidation of enhanced materials containing oxidation inhibitors showed significantly improved lives at the specific test conditions considered, although there was susceptibility to oxidation at intermediate temperatures.
Author: Mrityunjay Singh
Publisher: John Wiley & Sons
ISBN: 0470295147
Category : Technology & Engineering
Languages : en
Pages : 746
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Book Description
This volume is part of the Ceramic Engineering and Science Proceeding (CESP) series. This series contains a collection of papers dealing with issues in both traditional ceramics (i.e., glass, whitewares, refractories, and porcelain enamel) and advanced ceramics. Topics covered in the area of advanced ceramic include bioceramics, nanomaterials, composites, solid oxide fuel cells, mechanical properties and structural design, advanced ceramic coatings, ceramic armor, porous ceramics, and more.
Author: I M Low
Publisher: Woodhead Publishing
ISBN: 0857098829
Category : Technology & Engineering
Languages : en
Pages : 735
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Book Description
Ceramic matrix composites (CMCs) have proven to be useful for a wide range of applications because of properties such as their light weight, toughness and temperature resistance. Advances in ceramic matrix composites summarises key advances and types of processing of CMCs.After an introductory chapter, the first part of the book reviews types and processing of CMCs, covering processing, properties and applications. Chapters discuss nanoceramic matric composites, silicon carbide-containing alumina nanocomposites and advances in manufacture by various infiltration techniques including heat treatments and spark plasma sintering. The second part of the book is dedicated to understanding the properties of CMCs with chapters on Finite Element Analysis, tribology and wear and self-healing CMCs. The final part of the book examines the applications of CMCs, including those in the structural engineering, nuclear and fusion energy, turbine, metal cutting and microelectronics industries.Advances in ceramic matrix composites is an essential text for researchers and engineers in the field of CMCs and industries such as aerospace and automotive engineering. - Reviews types and processing of CMCs, covering processing, properties and applications
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 22
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Book Description
Ten different ceramic matrix composite (CMC) materials were subjected to a constant load and temperature in an air environment. Tests conducted under these conditions are often referred to as stressed oxidation or creep rupture tests. The stressed oxidation tests were conducted at a temperature of 1454 deg C at stresses of 69 MPa, 172 MPa and 50% of each material's ultimate tensile strength. The ten materials included such CMCs as C/SiC, SiC/C, SiC/SiC, SiC/SiNC and C/C. The time to failure results of the stressed oxidation tests will be presented. Much of the discussion regarding material degradation under stressed oxidation conditions will focus on C/SiC composites. Thermogravimetric analysis of the oxidation of fully exposed carbon fiber (T300) and of C/SiC coupons will be presented as well as a model that predicts the oxidation patterns and kinetics of carbon fiber tows oxidizing in a nonreactive matrix.
