Download or read book High Temperature Tensile Properties of Unidirectional Hi Nicalon Celsian Composites in Air written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-15 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: High temperature tensile properties of unidirectional BN/SiC-coated Hi-Nicalon SiC fiber reinforced celsian matrix composites have been measured from room temperature to 1200 C (2190 F) in air. Young's modulus, the first matrix cracking stress, and the ultimate strength decreased from room temperature to 1200 C (2190 F). The applicability of various micromechanical models, in predicting room temperature values of various mechanical properties for this CMC, has also been investigated. The simple rule of mixtures produced an accurate estimate of the primary composite modulus. The first matrix cracking stress estimated from ACK theory was in good agreement with the experimental value. The modified fiber bundle failure theory of Evans gave a good estimate of the ultimate strength. Gyekenyesi, John Z. and Bansal, Narottam P. Glenn Research Center NASA/TM-2000-210214, NAS 1.15:210214, E-12333

Download or read book Microstructure and Tensile Properties of BN SiC Coated Hi Nicalon and Sylramic SiC Fiber Preforms Revised written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-19 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: Batch to batch and within batch variations, and the influence of fiber architecture on room temperature physical and tensile properties of BN/SiC coated Hi-Nicalon and Sylramic SiC fiber preform specimens were determined. The three fiber architectures studied were plain weave (PW), 5-harness satin (5HS), and 8-harness satin (8HS). Results indicate that the physical properties vary up to 10 percent within a batch, and up to 20 percent between batches of preforms. Load-reload (Hysteresis) and acoustic emission methods were used to analyze damage accumulation occurring during tensile loading. Early acoustic emission activity, before observable hysteretic behavior, indicates that the damage starts with the formation of nonbridged tunnel cracks. These cracks then propagate and intersect the load bearing "0 deg" fibers giving rise to hysteretic behavior. For the Hi-Nicalon preform specimens, the onset of "0 deg" bundle cracking stress and strain appeared to be independent of the fiber architecture. Also, the "0 deg" fiber bundle cracking strain remained nearly the same for the preform specimens of both fiber types. TEM analysis indicates that the CVI BN interface coating is mostly amorphous and contains carbon and oxygen impurities, and the CVI SiC coating is crystalline. No reaction exists between the CVI BN and SiC coating. Bhatt, Ramakrishna T. and Chen, Yuan L. and Morscher, Gregory N. Glenn Research Center NASA/TM-2001-210695/REV1, E-12626-1/REV1, NAS 1.15:210695/REV1

Download or read book Effects of Interface Coating and Nitride Enhancing Additive on Properties of Hi Nicalon SiC Fiber Reinforced Reaction Bonded Silicon Nitride Composites written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-15 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: Strong and tough Hi-Nicalon SiC fiber reinforced reaction-bonded silicon nitride matrix composites (SiC/ RBSN) have been fabricated by the fiber lay-up approach. Commercially available uncoated and PBN, PBN/Si-rich PBN, and BN/SiC coated SiC Hi-Nicalon fiber tows were used as reinforcement. The composites contained approximately 24 vol % of aligned 14 micron diameter SiC fibers in a porous RBSN matrix. Both one- and two-dimensional composites were characterized. The effects of interface coating composition, and the nitridation enhancing additive, NiO, on the room temperature physical, tensile, and interfacial shear strength properties of SiC/RBSN matrix composites were evaluated. Results indicate that for all three coated fibers, the thickness of the coatings decreased from the outer periphery to the interior of the tows, and that from 10 to 30 percent of the fibers were not covered with the interface coating. In the uncoated regions, chemical reaction between the NiO additive and the SiC fiber occurs causing degradation of tensile properties of the composites. Among the three interface coating combinations investigated, the BN/SiC coated Hi-Nicalon SiC fiber reinforced RBSN matrix composite showed the least amount of uncoated regions and reasonably uniform interface coating thickness. The matrix cracking stress in SiC/RBSN composites was predicted using a fracture mechanics based crack bridging model. Bhatt, Ramakrishana T. and Hull, David R. and Eldridge, Jeffrey I. and Babuder, Raymond Glenn Research Center NASA/TM-2000-210211, E-12330, NAS 1.15:210211

Download or read book Silicon Effects on Properties of Melt Infiltrated Sic Sic Composites written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-09-25 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: Silicon effects on tensile and creep properties, and thermal conductivity of Hi-Nicalon SiC/SiC composites have been investigated. The composites consist of 8 layers of 5HS 2-D woven preforms of BN/SiC coated Hi-Nicalon fiber mats and a silicon matrix, or a mixture of silicon matrix and SiC particles. The Hi-Nicalon SiC/silicon and Hi-Nicalon SiC/SiC composites contained about 24 and 13 vol% silicon, respectively. Results indicate residual silicon up to 24 vol% has no significant effect on creep and thermal conductivity, but does decrease the primary elastic modulus and stress corresponding to deviation from linear stress-strain behavior. Bhatt, Ramakrishna T. and Gyekenyesi, John Z. and Hurst, Janet B. Glenn Research Center NASA/TM-2000-210034, E-12231, NAS 1.15:210034

Download or read book Microstructure and Tensile Properties of BN SiC Coated Hi Nicalon and Sylramic SiC Fiber Preforms written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-19 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: Batch to batch and within batch variations, and the influence of fiber architecture on room temperature physical and tensile properties of BN/SiC coated Hi-Nicalon and Sylramic SiC fiber preform specimens were determined. The three fiber architectures studied were plain weave (PW), 5-harness satin (5HS) and 8-harness satin (8HS) Results indicate that the physical properties vary up to 10 percent within a batch, and up to 20 percent between batches of preforms. Load-reload (Hysteresis) and acoustic emission methods were used to analyze damage accumulation occurring during tensile loading. Early acoustic emission activity, before observable hysteretic behavior, indicates that the damage starts with the formation of nonbridged tunnel cracks. These cracks then propagate and intersect the load bearing "0" fibers giving rise to hysteretic behavior, For the Hi-Nicalon preform specimens, the onset of "0" bundle cracking stress and strain appeared to be independent of the fiber architecture. Also, the "0" fiber bundle cracking strain remained nearly the same for the preform specimens of both fiber types. Transmission Electron Microscope (TEM) analysis indicates that the Chemical Vapor Infiltration (CVI) Boron Nitride (BN) interface coating is mostly amorphous and contains carbon and oxygen impurities, and the CVI SiC coating is crystalline. No reaction exists between the CVI BN and SiC coating. Bhatt, Ramakrishna T. and Chen, Yuan L. and Morscher, Gregory N. Glenn Research Center NASA/TM-2001-210695, NAS 1.15:210695, E-12626

Download or read book Effects of High Temperature Argon Heat Treatment on Tensile Strength and Microstructure of BN SiC Coated SiC Fiber Preforms written by and published by . This book was released on 1999 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Preforms of BN/SiC coated Hi-Nicalon and Sylramic SiC fibers were heat treated under 0.1 MPa argon pressure between 1000 deg to 1800 deg C for 1 and 100h. The effects of high temperature exposure on physical dimensions, weight, room temperature tensile strength, and microstructure of preforms have been studied. Both preforms showed shrinkage and weight loss, and microstructural changes beyond 1000 deg C. After 100 hr exposure, the Hi-Nicalon preforms showed strength degradation beyond 1200 deg C. The mechanisms of the strength degradation appear to be grain growth of the SiC fibers and crystallization of the BN coating. After 100 hr, the Sylramic preforms heat treated to 1000 deg C retained their as-produced strength while some of those heat-treated between 1000 deg and 1800 deg C showed strength degradation and others did not. At 1800 deg C, the ultimate tensile strength decreased with increasing time of exposure. Reasons for strength degradation of Sylramic preforms are being investigated.

Download or read book Raman Study of Uncoated and P Bn Sic Coated Hi Nicalon Fiber Reinforced Celsian Matrix Composites Part 1 Distribution and Nanostructure of Different written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-09-26 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hi-Nicalon fiber reinforced celsian matrix composites were characterized by Raman spectroscopy and imaging, using several laser wavelengths. Composite #1 is reinforced by as-received fibers while coatings of p-BN and SiC protect the fibers in composite #2. The matrix contains traces of the hexagonal phase of celsian, which is concentrated in the neighborhood of fibers in composite #1. Some free silicon was evident in the coating of composite #2 which might involve a {BN + SiC yields BNC + Si} "reaction" at the p-BN/SiC interface. Careful analysis of C-C peaks revealed no abnormal degradation of the fiber core in the composites. Gouadec, Gwenael and Colomban, Philippe and Bansal, Narottam P. Glenn Research Center NASA/TM-2000-210349, NAS 1.15:210349, E-12398

Download or read book SiC Fiber Reinforced Celsian Composites written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-11 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: Celsian is a promising matrix material for fiber-reinforced composites for high temperature structural applications. Processing and fabrication of small diameter multifilament silicon carbide tow reinforced celsian matrix composites are described. Mechanical and microstructural properties of these composites at ambient and elevated temperatures are presented. Effects of high-temperature exposures in air on the mechanical behavior of these composites are also given. The composites show mechanical integrity up to 1100 C but degrade at higher temperatures in oxidizing atmospheres. A model has been proposed for the degradation of these composites in oxidizing atmospheres at high temperatures.Bansal, Narottam P.Glenn Research CenterFABRICATION; MICROSTRUCTURE; SILICON CARBIDES; MECHANICAL PROPERTIES; GLASS; MATRIX MATERIALS; CERAMICS; TEMPERATURE DEPENDENCE; SHEAR STRENGTH; TENSILE STRENGTH; STRESS-STRAIN DIAGRAMS; SCANNING ELECTRON MICROSCOPY; BORON NITRIDES; VAPOR DEPOSITION

Download or read book Characterizing the Properties of a Woven Sic Sic Composite Using W Cemcan Computer Code written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-09-25 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: A micromechanics based computer code to predict the thermal and mechanical properties of woven ceramic matrix composites (CMC) is developed. This computer code, W-CEMCAN (Woven CEramic Matrix Composites ANalyzer), predicts the properties of two-dimensional woven CMC at any temperature and takes into account various constituent geometries and volume fractions. This computer code is used to predict the thermal and mechanical properties of an advanced CMC composed of 0/90 five-harness (5 HS) Sylramic fiber which had been chemically vapor infiltrated (CVI) with boron nitride (BN) and SiC interphase coatings and melt-infiltrated (MI) with SiC. The predictions, based on the bulk constituent properties from the literature, are compared with measured experimental data. Based on the comparison. improved or calibrated properties for the constituent materials are then developed for use by material developers/designers. The computer code is then used to predict the properties of a composite with the same constituents but with different fiber volume fractions. The predictions are compared with measured data and a good agreement is achieved. Murthy, Pappu L. N. and Mital, Subodh K. and DiCarlo, James A. Glenn Research Center NASA/TM-1999-209173, NAS 1.15:209173, E-11680