ASTM C1835-16(2023)
(Classification)Standard Classification for Fiber Reinforced Silicon Carbide-Silicon Carbide (SiC-SiC) Composite Structures
Standard Classification for Fiber Reinforced Silicon Carbide-Silicon Carbide (SiC-SiC) Composite Structures
SIGNIFICANCE AND USE
4.1 Composite materials consist by definition of a reinforcement phase/s in a matrix phase/s. The composition and structure of these constituents in the composites are commonly tailored for a specific application with detailed performance requirements. For fiber reinforced ceramic composites the tailoring involves the selection of the reinforcement fibers (composition, properties, morphology, interface coatings, etc.), the matrix (composition, properties, and morphology), the composite structure (component fractions, reinforcement architecture, interface coatings, porosity structure, microstructure, etc.), and the fabrication conditions (assembly, forming, densification, finishing, etc.). The final engineering properties (physical, mechanical, thermal, electrical, etc) can be tailored across a broad range with major directional anisotropy in the properties. (5-9)
4.2 This classification system assists the ceramic composite designer/user/producer in identifying and organizing different types of silicon carbide-silicon carbide (SiC-SiC) composites (based on fibers, matrix, architecture, physical properties, and mechanical properties) for structural applications. It is meant to assist the ceramic composite community in developing, selecting, and using SiC-SiC composites with the appropriate composition, construction, and properties for a specific application.
4.3 This classification system is a top level identification tool which uses a limited number of composites properties for high level classification. It is not meant to be a complete, detailed material specification, because it does not cover the full range of composition, architecture, physical, mechanical, fabrication, and durability requirements commonly defined in a full design specification. Guide C1793 provides direction and guidance in preparing a complete material specification for a given SiC-SiC composite component.
SCOPE
1.1 This classification covers silicon carbide-silicon carbide (SiC-SiC) composite structures (flat plates, rectangular bars, round rods, and tubes) manufactured for structural components. The SiC-SiC composites consist of continuous silicon carbide fibers in a silicon carbide matrix produced by four different matrix densification methods.
1.2 The classification system provides a means of identifying and organizing different SiC-SiC composites, based on the fiber type, architecture class, matrix densification, physical properties, and mechanical properties. The system provides a top-level identification system for grouping different types of SiC-SiC composites into different classes and provides a means of identifying the general structure and properties of a given SiC-SiC composite. It is meant to assist the ceramics community in developing, selecting, and using SiC-SiC composites with the appropriate composition, construction, and properties for a specific application.
1.3 The classification system produces a classification code for a given SiC-SiC composite, which shows the type of fiber, reinforcement architecture, matrix type, fiber volume fraction, density, porosity, and tensile strength and modulus (room temperature).
1.3.1 For example, Composites Classification Code, SC2-A2C-4D10-33—a SiC-SiC composite material/component (SC2) with a 95 %+ polymer precursor (A) based silicon carbide fiber in a 2-D (2) fiber architecture with a CVI matrix (C), a fiber volume fraction of 45 % (4 = 40 % to 45 %), a bulk density of 2.3 g/cc (D = 2.0 g/cc to 2.5 g/cc), an apparent porosity of 12 % (10 = 10 % to 15 %), an average ultimate tensile strength of 350 MPa (3 = 300 MPa to 399 MPa), and an average tensile modulus of 380 GPa (3 = 300 GPa to 399 GPa).
1.4 This classification system is a top level identification tool which uses a limited number of composite properties for high level classification. It is not meant to be a complete, detailed material specification, because it does not cover the full rang...
General Information
- Status
- Published
- Publication Date
- 30-Apr-2023
- Technical Committee
- C28 - Advanced Ceramics
- Drafting Committee
- C28.07 - Ceramic Matrix Composites
Relations
- Effective Date
- 01-Jan-2024
- Effective Date
- 01-May-2020
- Effective Date
- 01-Feb-2020
- Effective Date
- 01-Jan-2020
- Effective Date
- 15-Oct-2019
- Refers
ASTM D6507-19 - Standard Practice for Fiber Reinforcement Orientation Codes for Composite Materials - Effective Date
- 15-Oct-2019
- Effective Date
- 01-Oct-2019
- Effective Date
- 01-Aug-2019
- Effective Date
- 01-Jul-2019
- Effective Date
- 15-Apr-2019
- Effective Date
- 01-Apr-2018
- Effective Date
- 01-Feb-2018
- Effective Date
- 01-Jan-2018
- Effective Date
- 15-Jul-2017
- Effective Date
- 01-Dec-2016
Overview
ASTM C1835-16(2023): Standard Classification for Fiber Reinforced Silicon Carbide-Silicon Carbide (SiC-SiC) Composite Structures provides a top-level framework for classifying SiC-SiC composite materials used in structural applications. Issued by ASTM International, this standard assists designers, manufacturers, and users in identifying, organizing, and selecting silicon carbide fiber-reinforced ceramic composites based on key characteristics such as fiber type, reinforcement architecture, matrix densification method, and essential physical and mechanical properties. The system is designed as an identification tool rather than a comprehensive material specification, supporting the systematic development and use of advanced SiC-SiC composite structures for demanding environments.
Key Topics
- Composite Constituents: SiC-SiC composites feature continuous silicon carbide fibers embedded in a silicon carbide matrix. Both fiber and matrix can be engineered for specific applications by controlling their composition, morphology, and microstructure.
- Classification Criteria: The standard groups composites by:
- Fiber type (e.g., stoichiometry, production method)
- Reinforcement architecture (1-D, 2-D, or 3-D fiber arrangements)
- Matrix densification method (e.g., chemical vapor infiltration, polymer infiltration and pyrolysis, silicon melt infiltration, hot press/sintering, or hybrid approaches)
- Physical and mechanical properties (fiber volume fraction, density, porosity, tensile strength, and modulus)
- Classification Code: Each composite is assigned a code indicating its key attributes-enabling quick, high-level identification and comparison.
Applications
SiC-SiC composites are widely utilized for their outstanding thermal stability, mechanical strength, and resistance to corrosion and wear, especially in high-temperature or harsh service environments. Key application areas include:
- Aerospace and Aviation: Structural components exposed to high temperatures and stress, such as turbine engine parts, heat shields, and brake discs.
- Nuclear Energy: Fuel cladding, structural components, and insulation materials requiring excellent radiation tolerance and minimal mass loss.
- Energy Generation: Components in power plants, particularly those subject to thermal cycling and corrosive atmospheres.
- Automotive and Industrial: Advanced brake systems, high-performance bearings, and parts for processing chemicals or hot gases.
The standard’s classification system enables engineers and materials scientists to match composite structures to application requirements by quickly referencing critical properties and construction methods. This supports streamlined communication between suppliers and end-users, simplifies component selection, and lays the groundwork for evolving technical requirements or more detailed specifications.
Related Standards
Professionals using ASTM C1835-16(2023) may also refer to several related ASTM standards and guides to complement their classification and selection activities:
- ASTM C1793: Guide for Development of Specifications for Fiber Reinforced Silicon Carbide-Silicon Carbide Composite Structures for Nuclear Applications
- ASTM C559, C1039: Methods for determining bulk density and porosity
- ASTM C1145: Terminology of Advanced Ceramics
- ASTM C1198, C1259, E111: Test methods for measuring mechanical and elastic properties
- ASTM D3878, D4850, D6507: Terminology and practices for composite and textile reinforcement materials
These documents collectively provide a robust framework for understanding, specifying, and testing SiC-SiC composites, ensuring reliable performance and consistent classification in a variety of advanced engineering applications.
Keywords: ASTM C1835, SiC-SiC composites, silicon carbide composites, fiber reinforced ceramics, composite classification, matrix densification, ceramic matrix composites, structural applications, mechanical properties, physical properties.
Frequently Asked Questions
ASTM C1835-16(2023) is a standard published by ASTM International. Its full title is "Standard Classification for Fiber Reinforced Silicon Carbide-Silicon Carbide (SiC-SiC) Composite Structures". This standard covers: SIGNIFICANCE AND USE 4.1 Composite materials consist by definition of a reinforcement phase/s in a matrix phase/s. The composition and structure of these constituents in the composites are commonly tailored for a specific application with detailed performance requirements. For fiber reinforced ceramic composites the tailoring involves the selection of the reinforcement fibers (composition, properties, morphology, interface coatings, etc.), the matrix (composition, properties, and morphology), the composite structure (component fractions, reinforcement architecture, interface coatings, porosity structure, microstructure, etc.), and the fabrication conditions (assembly, forming, densification, finishing, etc.). The final engineering properties (physical, mechanical, thermal, electrical, etc) can be tailored across a broad range with major directional anisotropy in the properties. (5-9) 4.2 This classification system assists the ceramic composite designer/user/producer in identifying and organizing different types of silicon carbide-silicon carbide (SiC-SiC) composites (based on fibers, matrix, architecture, physical properties, and mechanical properties) for structural applications. It is meant to assist the ceramic composite community in developing, selecting, and using SiC-SiC composites with the appropriate composition, construction, and properties for a specific application. 4.3 This classification system is a top level identification tool which uses a limited number of composites properties for high level classification. It is not meant to be a complete, detailed material specification, because it does not cover the full range of composition, architecture, physical, mechanical, fabrication, and durability requirements commonly defined in a full design specification. Guide C1793 provides direction and guidance in preparing a complete material specification for a given SiC-SiC composite component. SCOPE 1.1 This classification covers silicon carbide-silicon carbide (SiC-SiC) composite structures (flat plates, rectangular bars, round rods, and tubes) manufactured for structural components. The SiC-SiC composites consist of continuous silicon carbide fibers in a silicon carbide matrix produced by four different matrix densification methods. 1.2 The classification system provides a means of identifying and organizing different SiC-SiC composites, based on the fiber type, architecture class, matrix densification, physical properties, and mechanical properties. The system provides a top-level identification system for grouping different types of SiC-SiC composites into different classes and provides a means of identifying the general structure and properties of a given SiC-SiC composite. It is meant to assist the ceramics community in developing, selecting, and using SiC-SiC composites with the appropriate composition, construction, and properties for a specific application. 1.3 The classification system produces a classification code for a given SiC-SiC composite, which shows the type of fiber, reinforcement architecture, matrix type, fiber volume fraction, density, porosity, and tensile strength and modulus (room temperature). 1.3.1 For example, Composites Classification Code, SC2-A2C-4D10-33—a SiC-SiC composite material/component (SC2) with a 95 %+ polymer precursor (A) based silicon carbide fiber in a 2-D (2) fiber architecture with a CVI matrix (C), a fiber volume fraction of 45 % (4 = 40 % to 45 %), a bulk density of 2.3 g/cc (D = 2.0 g/cc to 2.5 g/cc), an apparent porosity of 12 % (10 = 10 % to 15 %), an average ultimate tensile strength of 350 MPa (3 = 300 MPa to 399 MPa), and an average tensile modulus of 380 GPa (3 = 300 GPa to 399 GPa). 1.4 This classification system is a top level identification tool which uses a limited number of composite properties for high level classification. It is not meant to be a complete, detailed material specification, because it does not cover the full rang...
SIGNIFICANCE AND USE 4.1 Composite materials consist by definition of a reinforcement phase/s in a matrix phase/s. The composition and structure of these constituents in the composites are commonly tailored for a specific application with detailed performance requirements. For fiber reinforced ceramic composites the tailoring involves the selection of the reinforcement fibers (composition, properties, morphology, interface coatings, etc.), the matrix (composition, properties, and morphology), the composite structure (component fractions, reinforcement architecture, interface coatings, porosity structure, microstructure, etc.), and the fabrication conditions (assembly, forming, densification, finishing, etc.). The final engineering properties (physical, mechanical, thermal, electrical, etc) can be tailored across a broad range with major directional anisotropy in the properties. (5-9) 4.2 This classification system assists the ceramic composite designer/user/producer in identifying and organizing different types of silicon carbide-silicon carbide (SiC-SiC) composites (based on fibers, matrix, architecture, physical properties, and mechanical properties) for structural applications. It is meant to assist the ceramic composite community in developing, selecting, and using SiC-SiC composites with the appropriate composition, construction, and properties for a specific application. 4.3 This classification system is a top level identification tool which uses a limited number of composites properties for high level classification. It is not meant to be a complete, detailed material specification, because it does not cover the full range of composition, architecture, physical, mechanical, fabrication, and durability requirements commonly defined in a full design specification. Guide C1793 provides direction and guidance in preparing a complete material specification for a given SiC-SiC composite component. SCOPE 1.1 This classification covers silicon carbide-silicon carbide (SiC-SiC) composite structures (flat plates, rectangular bars, round rods, and tubes) manufactured for structural components. The SiC-SiC composites consist of continuous silicon carbide fibers in a silicon carbide matrix produced by four different matrix densification methods. 1.2 The classification system provides a means of identifying and organizing different SiC-SiC composites, based on the fiber type, architecture class, matrix densification, physical properties, and mechanical properties. The system provides a top-level identification system for grouping different types of SiC-SiC composites into different classes and provides a means of identifying the general structure and properties of a given SiC-SiC composite. It is meant to assist the ceramics community in developing, selecting, and using SiC-SiC composites with the appropriate composition, construction, and properties for a specific application. 1.3 The classification system produces a classification code for a given SiC-SiC composite, which shows the type of fiber, reinforcement architecture, matrix type, fiber volume fraction, density, porosity, and tensile strength and modulus (room temperature). 1.3.1 For example, Composites Classification Code, SC2-A2C-4D10-33—a SiC-SiC composite material/component (SC2) with a 95 %+ polymer precursor (A) based silicon carbide fiber in a 2-D (2) fiber architecture with a CVI matrix (C), a fiber volume fraction of 45 % (4 = 40 % to 45 %), a bulk density of 2.3 g/cc (D = 2.0 g/cc to 2.5 g/cc), an apparent porosity of 12 % (10 = 10 % to 15 %), an average ultimate tensile strength of 350 MPa (3 = 300 MPa to 399 MPa), and an average tensile modulus of 380 GPa (3 = 300 GPa to 399 GPa). 1.4 This classification system is a top level identification tool which uses a limited number of composite properties for high level classification. It is not meant to be a complete, detailed material specification, because it does not cover the full rang...
ASTM C1835-16(2023) is classified under the following ICS (International Classification for Standards) categories: 81.060.10 - Raw materials. The ICS classification helps identify the subject area and facilitates finding related standards.
ASTM C1835-16(2023) has the following relationships with other standards: It is inter standard links to ASTM C1793-15(2024), ASTM C559-16(2020), ASTM C242-20, ASTM C1198-20, ASTM D3878-19a, ASTM D6507-19, ASTM C242-19a, ASTM C242-19, ASTM C1145-19, ASTM D3878-19, ASTM D3878-18, ASTM C242-18, ASTM C1275-18, ASTM D4850-13(2017), ASTM C1275-16. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
ASTM C1835-16(2023) is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: C1835 − 16 (Reapproved 2023)
Standard Classification for
Fiber Reinforced Silicon Carbide-Silicon Carbide (SiC-SiC)
Composite Structures
This standard is issued under the fixed designation C1835; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope detailed material specification, because it does not cover the
full range of composition, architecture, physical, mechanical,
1.1 This classification covers silicon carbide-silicon carbide
fabrication, and durability requirements commonly defined in a
(SiC-SiC) composite structures (flat plates, rectangular bars,
full design specification. Guide C1793 provides extensive and
round rods, and tubes) manufactured for structural compo-
detailed direction and guidance in preparing a complete mate-
nents. The SiC-SiC composites consist of continuous silicon
rial specification for a given SiC-SiC composite component.
carbide fibers in a silicon carbide matrix produced by four
different matrix densification methods. 1.5 Units—The values stated in SI units are to be regarded
as standard. No other units of measurement are included in this
1.2 The classification system provides a means of identify-
standard.
ing and organizing different SiC-SiC composites, based on the
1.6 This standard does not purport to address all of the
fiber type, architecture class, matrix densification, physical
safety concerns, if any, associated with its use. It is the
properties, and mechanical properties. The system provides a
responsibility of the user of this standard to establish appro-
top-level identification system for grouping different types of
priate safety, health, and environmental practices and deter-
SiC-SiC composites into different classes and provides a means
mine the applicability of regulatory limitations prior to use.
of identifying the general structure and properties of a given
1.7 This international standard was developed in accor-
SiC-SiC composite. It is meant to assist the ceramics commu-
dance with internationally recognized principles on standard-
nity in developing, selecting, and using SiC-SiC composites
ization established in the Decision on Principles for the
with the appropriate composition, construction, and properties
Development of International Standards, Guides and Recom-
for a specific application.
mendations issued by the World Trade Organization Technical
1.3 The classification system produces a classification code
Barriers to Trade (TBT) Committee.
for a given SiC-SiC composite, which shows the type of fiber,
reinforcement architecture, matrix type, fiber volume fraction,
2. Referenced Documents
density, porosity, and tensile strength and modulus (room
2.1 ASTM Standards:
temperature).
C242 Terminology of Ceramic Whitewares and Related
1.3.1 For example, Composites Classification Code, SC2-
Products
A2C-4D10-33—a SiC-SiC composite material/component
C559 Test Method for Bulk Density by Physical Measure-
(SC2) with a 95 %+ polymer precursor (A) based silicon
ments of Manufactured Carbon and Graphite Articles
carbide fiber in a 2-D (2) fiber architecture with a CVI matrix
C1039 Test Methods for Apparent Porosity, Apparent Spe-
(C), a fiber volume fraction of 45 % (4 = 40 % to 45 %), a bulk
cific Gravity, and Bulk Density of Graphite Electrodes
density of 2.3 g/cc (D = 2.0 g ⁄cc to 2.5 g/cc), an apparent
C1145 Terminology of Advanced Ceramics
porosity of 12 % (10 = 10 % to 15 %), an average ultimate
C1198 Test Method for Dynamic Young’s Modulus, Shear
tensile strength of 350 MPa (3 = 300 MPa to 399 MPa), and an
Modulus, and Poisson’s Ratio for Advanced Ceramics by
average tensile modulus of 380 GPa (3 = 300 GPa to 399 GPa).
Sonic Resonance
1.4 This classification system is a top level identification
C1259 Test Method for Dynamic Young’s Modulus, Shear
tool which uses a limited number of composite properties for
Modulus, and Poisson’s Ratio for Advanced Ceramics by
high level classification. It is not meant to be a complete,
Impulse Excitation of Vibration
C1275 Test Method for Monotonic Tensile Behavior of
This classification is under the jurisdiction of ASTM Committee C28 on
Advanced Ceramics and is the direct responsibility of Subcommittee C28.07 on
Ceramic Matrix Composites. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved May 1, 2023. Published June 2023. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 2016. Last previous edition approved in 2016 as C1835 – 16. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/C1835-16R23. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1835 − 16 (2023)
Continuous Fiber-Reinforced Advanced Ceramics with 3.1.6.1 Discussion—A fiber/filament forms the basic ele-
Solid Rectangular Cross-Section Test Specimens at Am- ment of fabrics and other textile structures. D3878
bient Temperature
3.1.7 fiber fraction (volume or weight), n—the amount of
C1773 Test Method for Monotonic Axial Tensile Behavior
fiber present in a composite, expressed either as a percent by
of Continuous Fiber-Reinforced Advanced Ceramic Tubu-
weight or a percent by volume. D3878
lar Test Specimens at Ambient Temperature
3.1.8 fiber preform, n—a preshaped fibrous reinforcement,
C1793 Guide for Development of Specifications for Fiber
normally without matrix, but often containing a binder to
Reinforced Silicon Carbide-Silicon Carbide Composite
facilitate manufacture, formed by distribution/weaving of fi-
Structures for Nuclear Applications
bers to the approximate contour and thickness of the finished
D3878 Terminology for Composite Materials
part. D3878
D4850 Terminology Relating to Fabrics and Fabric Test
3.1.9 hybrid, n—for composite materials, containing at least
Methods
two distinct types of matrix or reinforcement. Each matrix or
D6507 Practice for Fiber Reinforcement Orientation Codes
reinforcement type can be distinct because of its (a) physical or
for Composite Materials
mechanical properties, or both, (b) material form, or (c)
E6 Terminology Relating to Methods of Mechanical Testing
chemical composition. D3878
E111 Test Method for Young’s Modulus, Tangent Modulus,
and Chord Modulus 3.1.10 knitted fabric, n—a fiber structure produced by inter-
E1309 Guide for Identification of Fiber-Reinforced
looping one or more ends of yarn or comparable material.
Polymer-Matrix Composite Materials in Databases (With- D4850
drawn 2015)
3.1.11 laminate, n—any fiber- or fabric-reinforced compos-
ite consisting of laminae (plies) with one or more orientations
3. Terminology
with respect to some reference direction. D3878
3.1 General Definitions—Many of the terms in this classi-
3.1.12 lay-up, n—a process or fabrication involving the
fication are defined in the terminology standards for ceramic
placement of successive layers of materials in specified se-
whitewares (C242), advanced ceramics (C1145), composite
quence and orientation. D6507, E1309
materials (D3878), fabrics and fabric test methods (D4850),
3.1.13 matrix, n—the continuous constituent of a composite
and mechanical testing (E6).
material, which surrounds or engulfs the embedded reinforce-
3.1.1 apparent porosity, n—the volume fraction of all pores,
ment in the composite and acts as the load transfer mechanism
voids, and channels within a solid mass that are interconnected
between the discrete reinforcement elements. D3878
with each other and communicate with the external surface,
3.1.14 ply, n—in 2-D laminar composites, the constituent
and thus are measurable by gas or liquid penetration. (Syn-
single layer as used in fabricating, or occurring within, a
onym – open porosity) C242
composite structure. D3878
3.1.2 braided fabric, n—a woven structure produced by
3.1.15 tow, n—in fibrous composites, a continuous, ordered
interlacing three or more ends of yarns in a manner such that
assembly of essentially parallel, collimated continuous
the paths of the yarns are diagonal to the vertical axis of the
filaments, normally without twist. (Synonym – roving) D3878
fabric.
3.1.2.1 Discussion—Braided structures can have 2-D or 3-D 3.1.16 unidirectional composite, n—any fiber reinforced
architectures. D4850 composite with all fibers aligned in a single direction. D3878
3.1.3 bulk density, n—the mass of a unit volume of material 3.1.17 woven fabric, n—a fabric structure produced by the
including both permeable and impermeable voids. C559
interlacing, in a specific weave pattern, of tows or yarns
oriented in two or more directions.
3.1.4 ceramic matrix composite, n—a material consisting of
3.1.17.1 Discussion—There are a large variety of 2-D
two or more materials (insoluble in one another), in which the
weave styles, e.g., plain, satin, twill, basket, crowfoot, etc.
major, continuous component (matrix component) is a ceramic,
while the secondary component(s) (reinforcing component)
3.1.18 yarn, n—in fibrous composites, a continuous, ordered
may be ceramic, glass-ceramic, glass, metal, or organic in assembly of essentially parallel, collimated filaments, normally
nature. These components are combined on a macroscale to
with twist, and of either discontinuous or continuous filaments.
form a useful engineering material possessing certain proper-
3.1.18.1 single yarn, n—an end in which each filament
ties or behavior not possessed by the individual constituents.
follows the same twist. D3878
C1145
3.2 Definitions of Terms Specific to This Standard:
3.1.5 fabric, n—in textiles, a planar structure consisting of
3.2.1 1-D, 2-D, and 3-D reinforcement, n—a description of
yarns or fibers. D4850
the orientation and distribution of the reinforcing fibers and
3.1.6 fiber, n—a fibrous form of matter with an aspect ratio
yarns in a composite.
>10 and an effective diameter <1 mm. (Synonym – filament)
3.2.1.1 Discussion—In a 1-D structure, all of the fibers are
oriented in a single longitudinal (x) direction. In a 2-D
structure, all of the fibers lie in the x-y planes of the plate or bar
or in the circumferential shells (axial and circumferential
The last approved version of this historical standard is referenced on
www.astm.org. directions) of the rod or tube with no fibers aligned in the z or
C1835 − 16 (2023)
radial directions. In a 3-D structure, the structure has fiber 3.2.8 primary structural axis, n—in a composite flat plate or
reinforcement in the x-y-z directions in the plate or bar and in rectangular bar, the directional axis defined by the loading
the axial, circumferential, and radial directions in a tube or rod. axis/direction with the highest required tensile strength.
3.2.8.1 Discussion—The primary structural axis is com-
3.2.2 axial tensile strength, n—for a composite tube or solid
monly the axis with the highest fiber loading. This axis may not
round rod, the tensile strength along the long axis of the tube
be parallel with the longest dimension of the plate/bar/
or rod. For a composite flat plate or rectangular bar, the tensile
structure.
strength along the primary structural axis/direction.
3.2.9 pyrolysis, n—in SiC matrix composites, the controlled
3.2.3 chemical vapor deposition or infiltration, n—a chemi-
thermal process in which a silicone-organic precursor is
cal process in which a solid material is deposited on a substrate
decomposed in an inert atmosphere to form the silicon carbide
or in a porous preform through the decomposition or the
(SiC) matrix.
reaction of gaseous precursors.
3.2.9.1 Discussion—Pyrolysis commonly results in weight
3.2.3.1 Discussion—Chemical vapor deposition is com-
loss and the release of hydrogen and hydrocarbon vapors.
monly done at elevated temperatures in a controlled atmo-
sphere. 3.2.10 rectangular bar, n—a solid straight rod with a rect-
angular cross-section, geometrically defined by a width, a
3.2.4 fiber interface coating, n—in ceramic composites, a
thickness, and a long axis length.
coating applied to fibers to control the bonding between the
fiber and the matrix. 3.2.11 round rod, n—a solid elongated straight cylinder,
3.2.4.1 Discussion—It is common practice in SiC-SiC com- geometrically defined by an outer diameter and an axial length.
posites to provide a thin (<3 micrometers) interface coating on
3.2.12 round tube, n—a hollow elongated cylinder, geo-
the surface of the fibers/filaments to prevent strong bonding
metrically defined by a outer diameter, an inner diameter, and
between the SiC fibers and the SiC matrix. A weak bond
an axial length.
between the fiber and the matrix in the SiC-SiC composite
3.2.13 silicon carbide–silicon carbide composite, n—a ce-
permits the fibers to bridge matrix cracks and promotes
ramic matrix composite in which the reinforcing phase consists
mechanical toughness; a strong bond between the matrix and
of continuous silicon carbide filaments in the form of fiber,
the fiber produces low strain, brittle failure. Fiber interface
continuous yarn, or a woven or braided fabric contained within
coatings with controlled composition, thickness, phase content,
a continuous matrix of silicon carbide. (5-9)
and morphology/microstructure are used to control that inter-
3.2.14 silicon carbide fibers, n—inorganic fibers with a
face strength. Fiber interface coatings may be multilayered
primary (≥80 weight %) silicon carbide (stoichiometric SiC
with different compositions and morphologies. (1, 2)
formula) composition.
3.2.5 hot press and sinter densification, n—in SiC matrix
3.2.14.1 Discussion—Silicon carbide fibers are commonly
composites, a matrix production and densification process in
produced by two methods—the high temperature pyrolysis and
which silicon carbide particulate in the preform are consoli-
sintering of silicone-organic precursor fibers in an inert atmo-
dated and sintered together to high density in a die press at high
sphere and the chemical vapor deposition of silicon carbide on
pressures and high temperatures.
a substrate filament. (10, 11)
3.2.5.1 Discussion—A sintering additive is often added to
3.2.15 surface seal coatings, n—an inorganic protective
the silicon carbide powders to produce liquid phase sintering
coating applied to the outer surface of a SiC-SiC composite
and promote/accelerate densification.
component to protect against high temperature oxidation or
3.2.6 infiltration and pyrolysis densification, n—in SiC ma-
corrosion attack, or both, or to improve wear and abrasion
trix composites, a matrix production and densification process
resistance. Such coatings are commonly hard, impermeable
in which a liquid silicone-organic polymer precursor is
ceramic coatings.
infiltrated/impregnated into the porous perform or the partially
porous composite and pyrolyzed to form the silicon carbide
4. Significance and Use
matrix.
4.1 Composite materials consist by definition of a reinforce-
3.2.6.1 Discussion—Pyrolysis of the silicone-organic pre-
ment phase/s in a matrix phase/s. The composition and
cursor in an inert atmosphere converts the precursor to a silicon
structure of these constituents in the composites are commonly
carbide form with the desired purity and crystal structure. The
tailored for a specific application with detailed performance
infiltration/pyrolysis process may be iteratively repeated to fill
requirements. For fiber reinforced ceramic composites the
the porosity and build up the density in the composite. (3)
tailoring involves the selection of the reinforcement fibers
3.2.7 melt infiltration, n—in SiC matrix composites, the
(composition, properties, morphology, interface coatings, etc.),
matrix production and densification process in which molten
the matrix (composition, properties, and morphology), the
silicon is infiltrated into a preform (containing SiC fibers and
composite structure (component fractions, reinforcement
SiC and carbon particulate) and the molten silicon reacts with
architecture, interface coatings, porosity structure,
the free carbon to form a bonding silicon carbide matrix.
microstructure, etc.), and the fabrication conditions (assembly,
(Synonyms – reaction sintering, liquid silicon infiltration) (4)
form
...
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