Author: Marie Christine Willson
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Book Description

Author: Penelope A. Huber
Publisher:
ISBN:
Category : Silicon carbide
Languages : en
Pages : 250

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Book Description

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description
The Los Alamos Structural Ceramics Program is a multi-faceted program with an overall objective of producing superior strength and fracture toughness in ceramic bodies for load bearing applications. One phase of the program is pursuing the development of silicon carbide whiskers which are used to prepare ceramic matrix composites. The purpose of this work is to investigate strengthening and toughening mechanisms in ceramic composites. In the following we describe some elements of the whisker development program in which we are endeavoring better to characterize the whisker growth process in order to scale up its production potential. We have used these whiskers in the preparation of four types of ceramic matrix representative of a range of materials. The nature and reasons for choosing these materials are described. Composites have been prepared by dry-blending followed by hot pressing which yields high density bodies. In addition we are beginning an investigation of wet processing (slip casting) to produce a silicon-silicon carbide body which will be reaction sintered in nitrogen. Composites of glass-, hot pressed silicon nitride -, and molybdenum disilicide - silicon carbide whiskers have been tested in flexure to determine strength and fracture toughness. Results have been promising, with substantial toughening exhibited in all systems, and strengthening in the glass and MoSi2 composites. The reaction bonded silicon nitride is not yet to the testing stage.

Author: STEPHEN DOUGLAS NUNN
Publisher:
ISBN:
Category :
Languages : en
Pages : 368

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Book Description
MgAl\sb2Si\sb4O\sb6N\sb4$, and the matrix and reinforcing phases. The fracture toughness appeared to be controlled by the ability of cracks to propagate along the intergranular phase.

Author: Narottam P. Bansal
Publisher: Springer Science & Business Media
ISBN: 0387239863
Category : Technology & Engineering
Languages : en
Pages : 547

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Book Description
This valuable handbook has been compiled by internationally renowned researchers in the field. Each chapter is focused on a specific composite system or a class of composites, presenting a detailed description of processing, properties, and applications.

Author: David Belitskus
Publisher: CRC Press
ISBN: 1482293471
Category : Technology & Engineering
Languages : en
Pages : 369

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Book Description
Examines all important aspects of whisker and fibre reinforced ceramic science and technology, offering a balanced account of developments in the field. The work shows how to improve the strength and stiffness of ceramic composites, at very high temperatures, without brittleness.

Author: Ramakrishna T. Bhatt
Publisher:
ISBN:
Category : Additives
Languages : en
Pages : 24

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Book Description
Strong and tough Hi-Nicalon SiC fiber reinforced reaction-bonded silicon nitride matirix 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 ~24 vol % of aligned 14 ♯m 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 strenght properties of SiC/RBSN matrix composites were evaluated. Results indicate that all three coated fibers, the thickness of the coating 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.

Author: Ramakrishna T. Bhatt
Publisher:
ISBN:
Category :
Languages : en
Pages : 15

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Book Description
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).

Author: Pin Go
Publisher:
ISBN:
Category : Fiber-reinforced ceramics
Languages : en
Pages : 224

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Book Description

Author: Harold N. Barr
Publisher:
ISBN:
Category : Aluminum alloys
Languages : en
Pages : 67

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Book Description
A technique was developed for orienting silicon carbide whiskers in a metal matrix which involves the preparation of a liquid slurry of the whiskers and matrix metal powder followed by the extrusion of the slurry through a fine orifice die. The technique was further developed for the fabrication of aluminum alloy-silicon carbide whisker composites with oriented whiskers. The fabrication of such shapes as strip, tubes, bushings, and cones with oriented whiskers was demonstrated. Mechanical properties of the aluminum alloy-silicon carbide whisker composites were measured at room temperature and at 204 to 427C. The effect of silicon carbide whisker loading, whisker type, and metal powder particle size was studied. (Author).