Download or read book Heat Treatment Effects on the Tensile Properties and Microstructures of a SiC RBSN Composite in Nitrogen written by R. T. Bhatt and published by . This book was released on 1995 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 Heat Treatment Effects on Microstructure of 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 Sylramic SiC fibers were heat treated at 1420 deg, 1600 deg, and 1800 deg C in 0.1 MPa argon or at 1800 deg C in 103 MPa nitrogen for 1 h. Optical, SEM, and TEM techniques were used to analyze the effects of environmental exposure on constituent microstructure of the preforms. TEM analysis of the as-received preforms indicates that the CVI BN coating is predominantly amorphous with small amounts of microcrystalline BN grains, and that the SiC coating on top of the BN coating and SiC fibers is polycrystalline. With increasing temperature of exposure from 1420 deg to 1800 deg C, the preforms heat treated in argon showed increasing amounts of crystalline BN in the CVI BN coating, and coarsening of SiC grains in the CVI SiC coating and SiC fibers. On the other hand, the preforms heal treated in 103 MPa nitrogen at 1800 deg C for 1 h showed microstructural changes inside the fiber tows similar to those heat treated at 1800 deg C in 0.1 MPa argon for 1 h, but the same preforms on the outer periphery of the tows showed reaction between nitrogen and the CVI SiC coating to form Si3N4.

Download or read book Tensile Properties and Microstructural Characterization of Hi Nicalon SiC RBSN Composites written by and published by . This book was released on 1998 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Thermal Effects on the Mechanical Properties of SiC Fiber Reinforced Reaction Bonded Silicon Nitride Matrix SiC RBSN Composites written by R. T. Bhatt and published by . This book was released on 1988 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: The elevated temperature four-point flexural strength and the room temperature tensile and flexural strength properties after thermal shock were measured for ceramic composites consisting of 30 vol % uniaxially aligned 142 microns diameter SiC fibers in a reaction bonded Si3N4 matrix. The elevated temperature strengths were measured after 15 min of exposure in air at temperatures to 1400 C. The thermal shock treatment was accomplished by heating the composite in air for 15 min at temperatures to 1200 C and then quenching in water at 25 C. The results indicate no significant loss in strength properties either at temperature or after thermal shock when compared with the strength data for composites in the as-fabricated condition. (jes).

Download or read book Heat Treatment Study of the SiC Ti 15 3 Composite System written by Bradley A. Lerch and published by . This book was released on 1990 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Heat Treatment Study of the Sic Ti 15 3 Composite System written by National Aeronautics and Space Adm Nasa and published by . This book was released on 2018-10-19 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: The oxidation and aging behaviors of a continuous fiber SiC/Ti-15V-3Cr-3Sn-3Al composite (SiC/Ti-15-3) were investigated. The aging characteristic of the composite were compared with those of the unreinforced Ti-15-3 matrix material, which was processed in the same manner as the composite. Various age hardened conditions of both the unreinforced matrix and the composite were evaluated by using optical microscopy, hardness measurements, and room temperature tensile tests (unreinforced matrix only). The Ti-15-3 material formed a thick surface oxide at temperature at or above 550 C when heat treated in air. The in situ composite matrix was softer than the unreinforced matrix for equivalent aging conditions. Both materials hardened to a maximum, then softened during overaging. The temperature at which peak aging occurred was approx. 450 C for both the in situ composite matrix and the unreinforced matrix. The room temperature elastic modulus and ultimate tensile strength of the unreinforced matrix varied as a function of aging treatment and paralleled the hardness behavior. The modulus and tensile strength showed little response to aging up to temperatures of 300 C; however, these properties increased after aging at 550 C. Aging at temperatures above 550 C resulted in a decrease in the modulus and tensile strength. The failure strain was a function of the precipitation state and of the amount of oxidation resulting from the heat treatment. Aging in air at the higher temperatures (greater than 550 C) caused the formation of a thick oxide layer and reduced the ductility. Aging in vacuum at these temperatures resulted in significantly higher ductilities. Long term exposures at 700 C caused the formation of a large grain boundary alpha-phase which reduced the ductility, even though the specimens were heat treated in vacuum. Lerch, Bradley A. and Gabb, Timothy P. and Mackay, Rebecca A. Glenn Research Center RTOP 510-01-01...

Download or read book Tensile Properties and Microstructural Characterization of Hi Nicalon SiC RBSN Composites written by Ramakrishna T. Bhatt and published by . This book was released on 1998 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effects of Thermal Treatment on Tensile Creep and Stress rupture Behavior of Hi Nicalon SiC Fibers written by Hee Mann Yun and published by . This book was released on 1995 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Tensile Properties of Advanced Nickel Base Disk Superalloys During Quenching Heat Treatments written by and published by . This book was released on 2001 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Properties of Silicon Carbide Fiber Reinforced Silicon Nitride Matrix Composites written by Ramakrishna T. Bhatt and published by . This book was released on 1988* with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: The mechanical properties of NASA Lewis Research Center developed SiC/RBSN composites and their thermal and environmental stability have been studied. The composites consist of nearly 30 vol % of aligned 142 um diameter chemically vapor-deposited SiC fibers in a relatively porous silicon nitride matrix. In the as-fabricated condition, the unidirectional and two-dimensional composites exhibited metal-like stress-strain behavior, graceful failure, and showed improved properties when compared with unreinforced matrix of comparable density. Furthermore, the measured room temperature tensile properties were relatively independent of tested volume and were unaffected by artificial notches normal to the loading direction or by thermal shocking from temperatures up to 1100C. The four point bend strength data measured as a function of temperature to 1400C in air showed that as-fabricated strength was maintained to 1200C. At 1400C, however, nearly 15 percent loss in strength was observed. Measurement of room temperature tensile strength after 100 hr exposure at temperatures to 1400C in a nitrogen environment indicated no loss from the as-fabricated composite strength. (JES).

Download or read book Microstructure and Tensile Properties of BN SiC Coated Hi Nicalon and Sylramic SiC Fiber Preforms written by and published by . This book was released on 2001 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Oxidation Effects on the Mechanical Properties of SiC Fiber Reinforced Reaction bonded Silicon Nitride Matrix Composites written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-09 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: The room temperature mechanical properties of SiC fiber reinforced reaction bonded silicon nitride composites were measured after 100 hrs exposure at temperatures to 1400 C in nitrogen and oxygen environments. The composites consisted of approx. 30 vol percent uniaxially aligned 142 micron diameter SiC fibers in a reaction bonded Si3N4 matrix. The results indicate that composites heat treated in a nitrogen environment at temperatures to 1400 C showed deformation and fracture behavior equivalent to that of the as-fabricated composites. Also, the composites heat treated in an oxidizing environment beyond 400 C yielded significantly lower tensile strength values. Specifically in the temperature range from 600 to 1000 C, composites retained approx. 40 percent of their as-fabricated strength, and those heat treated in the temperatures from 1200 to 1400 C retained 70 percent. Nonetheless, for all oxygen heat treatment conditions, composite specimens displayed strain capability beyond the matrix fracture stress; a typical behavior of a tough composite. Bhatt, Ramakrishna T. Glenn Research Center RTOP 510-01-0A...

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 Silicon Effects on Properties of Melt Infiltrated SiC SiC Composites written by Ramakrishna T. Bhatt and published by . This book was released on 2000 with total page 16 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.

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 An Investigation of the Effects of Heat Treatment on the Properties of Nitralloy G Modified written by Homer H. Breault and published by . This book was released on 1941 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: