ASTM C1783-15(2024)

Standard Guide for Development of Specifications for Fiber Reinforced Carbon-Carbon Composite Structures for Nuclear Applications

SIGNIFICANCE AND USE
4.1 Composite materials consist by definition of a reinforcement phase in a matrix phase. In addition, carbon-carbon composites often contain measurable porosity which interacts with the reinforcement and matrix. The composition and structure of the C-C composite are commonly tailored for a specific application with detailed performance requirements. The tailoring involves the selection of the reinforcement fibers (composition, properties, morphology, etc), the matrix (composition, properties, and morphology), the composite structure (component fractions, reinforcement architecture, porosity structure, microstructure, etc.), and the fabrication conditions (forming, 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.  
4.2 Specifications for specific C-C composite components covering materials, material processing, and fabrication procedures are developed to provide a basis for fabricating reproducible and reliable structures. Designer/users/producers have to write C-C composite specifications for specific applications with well-defined composition, structure, properties and processing requirements. But with the extensive breadth of selection in composition, structure, and properties in C-C composites, it is virtually impossible to write a "generic" composite specification applicable to any and all C-C composite applications that has the same type of structure and details of the commonly-used specifications for metal alloys. This guide is written to assist the designer/user/producer in developing a comprehensive and detailed material specification for a specific CMC application/component with a particular focus on nuclear applications.  
4.3 The purpose of this guide is to provide guidance on how to specify the constituents, the structure, the desired engineering properties (physical, chemical, ...
SCOPE
1.1 This document is a guide to preparing material specifications for fiber reinforced carbon-carbon (C-C) composite structures (flat plates, rectangular bars, round rods, and tubes) manufactured specifically for structural components in nuclear reactor core applications. The carbon-carbon composites consist of carbon/graphite fibers (from PAN, pitch, or rayon precursors) in a carbon/graphite matrix produced by liquid infiltration/pyrolysis and/or by chemical vapor infiltration.  
1.2 This guide provides direction and guidance for the development of a material specification for a specific C-C composite component or product for nuclear reactor applications. The guide considers composite constituents and structure, physical and chemical properties, mechanical properties, thermal properties, performance durability, methods of testing, materials and fabrication processing, and quality assurance. The C-C composite materials considered here would be suitable for nuclear reactor core applications where neutron irradiation-induced damage and dimensional changes are a significant design consideration. (1-4)2  
1.3 The component specification is to be developed by the designer/purchaser/user. The designer/purchaser/user shall define and specify in detail any and all application-specific requirements for necessary design, manufacturing, and performance factors of the ceramic composite component. This guide for material specifications does not directly address component/product-specific issues, such as geometric tolerances, permeability, bonding, sealing, attachment, and system integration.  
1.4 This guide is specifically focused on C-C composite components and structures with flat panel, solid rectangular bar, solid round rod, or tubular geometries.  
1.5 This specification may also be applicable to C-C composites used for other structural applications discounting the nuclear-specific chemical purity and irradiation behavior f...

General Information

• Status: Published
• Publication Date: 31-Dec-2023
• ICS: 83.120 - Reinforced plastics
• Technical Committee: C28 - Advanced Ceramics
• Drafting Committee: C28.07 - Ceramic Matrix Composites

Relations

• Replaces: ASTM C1783-15 - Standard Guide for Development of Specifications for Fiber Reinforced Carbon-Carbon Composite Structures for Nuclear Applications
• Effective Date: 01-Jan-2024
• Referred By: ASTM C1836-16(2023) - Standard Classification for Fiber Reinforced Carbon-Carbon Composite Structures
• Effective Date: 01-Jan-2024

Overview

ASTM C1783-15(2024), titled Standard Guide for Development of Specifications for Fiber Reinforced Carbon-Carbon Composite Structures for Nuclear Applications, provides a comprehensive framework for preparing material specifications for fiber reinforced carbon-carbon (C-C) composite components, particularly for nuclear reactor core structural use. Developed by ASTM, this international standard outlines best practices for defining and documenting the requirements regarding the constituents, structure, engineering properties, processing methods, and quality assurance of C-C composites. These guidelines facilitate the fabrication of reliable, reproducible, and high-performing components where safety, durability, and tailored performance are crucial.

Key Topics

• Material Constituents and Structure

  • Carbon-carbon composites consist of a reinforcement phase (carbon/graphite fibers) embedded in a matrix phase (carbon/graphite matrix).
  • Specifications require detailed consideration of fiber types (precursors such as PAN, pitch, rayon), fiber architecture (1D, 2D, 3D), fiber surface treatments, and the method of matrix production (liquid infiltration/pyrolysis or chemical vapor infiltration).
  • Porosity, fiber-matrix bonding, and microstructure must be tailored to meet the demanding conditions of nuclear environments.

• Performance and Property Specification

  • Engineering properties (physical, mechanical, thermal, electrical) must be thoroughly defined, including directional anisotropy critical to C-C composites.
  • Specifications cover requirements and measurement methods for critical properties such as bulk density, porosity, thermal conductivity, electrical resistivity, mechanical strength, modulus, toughness, and durability.
  • Chemical purity and control of impurities (e.g., boron, lithium, iron, cobalt) are essential to minimize neutron absorption and degradation under irradiation.

• Quality Assurance and Testing

  • The standard emphasizes the importance of methods of testing, quality control, non-destructive evaluation (NDE), and traceability throughout the manufacturing process.
  • References relevant ASTM and industry test methods for consistency in property verification.

• Specification Development Process

  • Recognizes the impossibility of a one-size-fits-all generic specification for C-C composites due to extensive material and property variability.
  • Guidance is focused on enabling designers, manufacturers, and users to develop application-specific, detailed material specifications that address the unique needs of each nuclear or structural component.

Applications

• Nuclear Reactor Core Components

  • Structured guidance for specification development supports the use of C-C composites in reactor cores, where high temperature stability, radiation tolerance, and long-term durability are required.
  • Helps mitigate effects of neutron irradiation, dimensional change, and chemical attack in demanding nuclear environments.

• Other Structural Applications

  • While focused on nuclear applications, the standard is applicable to other engineering uses of fiber reinforced C-C composites in non-nuclear settings, provided adjustments are made for chemical purity and irradiation considerations.
  • Suitable for specifying flat plates, bars, rods, and tubes in industries such as aerospace, defense, and high temperature processing.

• Custom Component Design

  • Enables tailored solutions where properties such as anisotropic strength, thermal conductivity, or specific geometries are required for optimal structural performance.

Related Standards

• ASTM C559: Test Method for Bulk Density of Manufactured Carbon and Graphite Articles
• ASTM C561: Ash in a Graphite Sample
• ASTM C611: Electrical Resistivity of Manufactured Carbon and Graphite
• ASTM C714, E1461: Thermal Properties by Pulse and Flash Methods
• ASTM C1292, C1275: Shear and Tensile Strengths for Advanced Ceramics
• ASTM D3878: Terminology for Composite Materials
• ASTM D5600: Test Method for Trace Metals in Carbon Materials
• ASTM C1233: Practice for Determining Equivalent Boron Contents (nuclear applications)

For industry professionals working with carbon-carbon composite structures, especially for high-performance nuclear applications, ASTM C1783-15(2024) is an essential resource for ensuring safety, reliability, and regulatory compliance through systematic material specification development. Leveraging this guide supports advanced composite design and robust quality assurance across the lifecycle of critical structural components.

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: C1783 − 15 (Reapproved 2024)
Standard Guide for
Development of Specifications for Fiber Reinforced Carbon-
Carbon Composite Structures for Nuclear Applications
This standard is issued under the fixed designation C1783; 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 1.5 This specification may also be applicable to C-C com-
posites used for other structural applications discounting the
1.1 This document is a guide to preparing material specifi-
nuclear-specific chemical purity and irradiation behavior fac-
cations for fiber reinforced carbon-carbon (C-C) composite
tors.
structures (flat plates, rectangular bars, round rods, and tubes)
1.6 Units—The values stated in SI units are to be regarded
manufactured specifically for structural components in nuclear
as standard. No other units of measurement are included in this
reactor core applications. The carbon-carbon composites con-
standard.
sist of carbon/graphite fibers (from PAN, pitch, or rayon
precursors) in a carbon/graphite matrix produced by liquid
1.7 This standard does not purport to address all of the
infiltration/pyrolysis and/or by chemical vapor infiltration.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
1.2 This guide provides direction and guidance for the
priate safety, health, and environmental practices and deter-
development of a material specification for a specific C-C
mine the applicability of regulatory limitations prior to use.
composite component or product for nuclear reactor applica-
1.8 This international standard was developed in accor-
tions. The guide considers composite constituents and
dance with internationally recognized principles on standard-
structure, physical and chemical properties, mechanical
ization established in the Decision on Principles for the
properties, thermal properties, performance durability, methods
Development of International Standards, Guides and Recom-
of testing, materials and fabrication processing, and quality
mendations issued by the World Trade Organization Technical
assurance. The C-C composite materials considered here
Barriers to Trade (TBT) Committee.
would be suitable for nuclear reactor core applications where
neutron irradiation-induced damage and dimensional changes
2. Referenced Documents
are a significant design consideration. (1-4)
2.1 ASTM Standards:
1.3 The component specification is to be developed by the
C242 Terminology of Ceramic Whitewares and Related
designer/purchaser/user. The designer/purchaser/user shall de-
Products
fine and specify in detail any and all application-specific
C559 Test Method for Bulk Density by Physical Measure-
requirements for necessary design, manufacturing, and perfor-
ments of Manufactured Carbon and Graphite Articles
mance factors of the ceramic composite component. This guide
C561 Test Method for Ash in a Graphite Sample
for material specifications does not directly address
C577 Test Method for Permeability of Refractories
component/product-specific issues, such as geometric
C611 Test Method for Electrical Resistivity of Manufactured
tolerances, permeability, bonding, sealing, attachment, and
Carbon and Graphite Articles at Room Temperature
system integration.
C625 Practice for Reporting Irradiation Results on Graphite
C709 Terminology Relating to Manufactured Carbon and
1.4 This guide is specifically focused on C-C composite
Graphite (Withdrawn 2017)
components and structures with flat panel, solid rectangular
C714 Guide for Thermal Diffusivity of Carbon and Graphite
bar, solid round rod, or tubular geometries.
by Thermal Pulse Method
C769 Test Method for Sonic Velocity in Manufactured
Carbon and Graphite Materials for Use in Obtaining an
This guide 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 Jan. 1, 2024. Published February 2024. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 2015. Last previous edition approved in 2015 as C1783 – 15. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/C1783-15R24. the ASTM website.
2 4
The boldface numbers in parentheses refer to the list of references at the end of The last approved version of this historical standard is referenced on
this standard. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1783 − 15 (2024)
Approximate Value of Young’s Modulus C1557 Test Method for Tensile Strength and Young’s Modu-
C816 Test Method for Sulfur Content in Graphite by lus of Fibers
Combustion-Iodometric Titration Method C1683 Practice for Size Scaling of Tensile Strengths Using
Weibull Statistics for Advanced Ceramics
C838 Test Method for Bulk Density of As-Manufactured
D2766 Test Method for Specific Heat of Liquids and Solids
Carbon and Graphite Shapes
(Withdrawn 2018)
C1039 Test Methods for Apparent Porosity, Apparent Spe-
D3171 Test Methods for Constituent Content of Composite
cific Gravity, and Bulk Density of Graphite Electrodes
Materials
C1179 Test Method for Oxidation Mass Loss of Manufac-
D3529/D3529M Test Methods for Constituent Content of
tured Carbon and Graphite Materials in Air
Composite Prepreg
C1198 Test Method for Dynamic Young’s Modulus, Shear
D3800 Test Method for Density of High-Modulus Fibers
Modulus, and Poisson’s Ratio for Advanced Ceramics by
D3878 Terminology for Composite Materials
Sonic Resonance
D4018 Test Methods for Properties of Continuous Filament
C1233 Practice for Determining Equivalent Boron Contents
Carbon and Graphite Fiber Tows
of Nuclear Materials
D4284 Test Method for Determining Pore Volume Distribu-
C1239 Practice for Reporting Uniaxial Strength Data and
tion of Catalysts and Catalyst Carriers by Mercury Intru-
Estimating Weibull Distribution Parameters for Advanced
sion Porosimetry
Ceramics
D4850 Terminology Relating to Fabrics and Fabric Test
C1259 Test Method for Dynamic Young’s Modulus, Shear
Methods
Modulus, and Poisson’s Ratio for Advanced Ceramics by
D5528 Test Method for Mode I Interlaminar Fracture Tough-
Impulse Excitation of Vibration
ness of Unidirectional Fiber-Reinforced Polymer Matrix
C1274 Test Method for Advanced Ceramic Specific Surface
Composites
Area by Physical Adsorption
D5600 Test Method for Trace Metals in Petroleum Coke by
C1275 Test Method for Monotonic Tensile Behavior of
Inductively Coupled Plasma Atomic Emission Spectrom-
Continuous Fiber-Reinforced Advanced Ceramics with
etry (ICP-AES)
Solid Rectangular Cross-Section Test Specimens at Am-
D5766 Test Method for Open-Hole Tensile Strength of
bient Temperature
Polymer Matrix Composite Laminates
C1291 Test Method for Elevated Temperature Tensile Creep
D5961 Test Method for Bearing Response of Polymer Ma-
Strain, Creep Strain Rate, and Creep Time to Failure for
trix Composite Laminates
Monolithic Advanced Ceramics
D6484 Test Method for Open-Hole Compressive Strength of
C1292 Test Method for Shear Strength of Continuous Fiber-
Polymer Matrix Composite Laminates
Reinforced Advanced Ceramics at Ambient Temperatures
D6507 Practice for Fiber Reinforcement Orientation Codes
C1337 Test Method for Creep and Creep Rupture of Con-
for Composite Materials
tinuous Fiber-Reinforced Advanced Ceramics Under Ten-
D6671 Test Method for Mixed Mode I-Mode II Interlaminar
sile Loading at Elevated Temperatures
Fracture Toughness of Unidirectional Fiber Reinforced
C1341 Test Method for Flexural Properties of Continuous
Polymer Matrix Composites
Fiber-Reinforced Advanced Ceramic Composites
D7136 Test Method for Measuring the Damage Resistance
C1358 Test Method for Monotonic Compressive Strength
of a Fiber-Reinforced Polymer Matrix Composite to a
Testing of Continuous Fiber-Reinforced Advanced Ce-
Drop-Weight Impact Event
ramics with Solid Rectangular Cross Section Test Speci-
D7137 Test Method for Compressive Residual Strength
mens at Ambient Temperatures
Properties of Damaged Polymer Matrix Composite Plates
C1359 Test Method for Monotonic Tensile Strength Testing
D7219 Specification for Isotropic and Near-isotropic
of Continuous Fiber-Reinforced Advanced Ceramics With
Nuclear Graphites
Solid Rectangular Cross Section Test Specimens at El-
D7542 Test Method for Air Oxidation of Carbon and Graph-
evated Temperatures
ite in the Kinetic Regime
C1360 Practice for Constant-Amplitude, Axial, Tension-
E6 Terminology Relating to Methods of Mechanical Testing
Tension Cyclic Fatigue of Continuous Fiber-Reinforced
E111 Test Method for Young’s Modulus, Tangent Modulus,
Advanced Ceramics at Ambient Temperatures
and Chord Modulus
C1425 Test Method for Interlaminar Shear Strength of 1D
E132 Test Method for Poisson’s Ratio at Room Temperature
and 2D Continuous Fiber-Reinforced Advanced Ceramics
E143 Test Method for Shear Modulus at Room Temperature
at Elevated Temperatures
E228 Test Method for Linear Thermal Expansion of Solid
C1468 Test Method for Transthickness Tensile Strength of
Materials With a Push-Rod Dilatometer
Continuous Fiber-Reinforced Advanced Ceramics at Am-
E261 Practice for Determining Neutron Fluence, Fluence
bient Temperature
Rate, and Spectra by Radioactivation Techniques
C1470 Guide for Testing the Thermal Properties of Ad- E289 Test Method for Linear Thermal Expansion of Rigid
vanced Ceramics Solids with Interferometry
C1525 Test Method for Determination of Thermal Shock
E408 Test Methods for Total Normal Emittance of Surfaces
Resistance for Advanced Ceramics by Water Quenching Using Inspection-Meter Techniques
C1783 − 15 (2024)
E423 Test Method for Normal Spectral Emittance at El- bers to the approximate contour and thickness of the finished
evated Temperatures of Nonconducting Specimens part. D3878
E1269 Test Method for Determining Specific Heat Capacity
3.1.10 fiber surface treatment, n—a coating applied to fibers
by Differential Scanning Calorimetry
to improve fiber/fabric handleability during weaving and
E1309 Guide for Identification of Fiber-Reinforced
fabrication.
Polymer-Matrix Composite Materials in Databases (With-
3.1.11 fill, n—in a woven fabric, the yarn running from
drawn 2015)
selvage to selvage at right angles to the warp. D3878
E1461 Test Method for Thermal Diffusivity by the Flash
3.1.12 graphite, n—allotropic crystalline form of the ele-
Method
ment carbon, occurring as a mineral, commonly consisting of
E1922 Test Method for Translaminar Fracture Toughness of
a hexagonal array of carbon atoms (space group P 63/mmc) but
Laminated and Pultruded Polymer Matrix Composite
also known in a rhombohedral form (space group R 3m). C709
Materials
E2586 Practice for Calculating and Using Basic Statistics
3.1.13 graphitization, n—in carbon and graphite
2.2 Non-ASTM Standards: technology, the solid-state transformation of thermodynami-
CMH-17 Composite Materials Handbook cally unstable amorphous carbon into crystalline graphite by a
ASME B46.1-2009 Surface Texture (Surface Roughness, high temperature thermal treatment in an inert atmosphere.
Waviness, and Lay) C709
3.1.13.1 Discussion—The degree of graphitization is a mea-
3. Terminology
sure of the extent of long-range 3D crystallographic order as
3.1 Definitions:
determined by diffraction studies only. The degree of graphi-
3.1.1 General—Many of the terms in this guide are defined
tization affects many properties significantly, such as thermal
in the terminology standards for graphite articles (C709),
conductivity, electrical conductivity, strength, and stiffness.
composite materials (D3878), fabrics and test methods
3.1.13.2 Discussion—A common, but incorrect, use of the
(D4850), and mechanical testing (E6).
term graphitization is to indicate a process of thermal treatment
3.1.2 apparent porosity, n—the volume fraction of all pores,
of carbon materials at T > 2200 °C regardless of any resultant
voids, and channels within a solid mass that are interconnected
crystallinity. The use of the term graphitization without report-
with each other and communicate with the external surface,
ing confirmation of long range three dimensional crystallo-
and thus are measurable by gas or liquid penetration. (Syn-
graphic order determined by diffraction studies should be
onym – open porosity) C242
avoided, as it can be misleading.
3.1.3 braided fabric, n—a woven structure produced by
3.1.14 hybrid, n—(for composite materials) containing at
interlacing three or more ends of yarns in a manner such that
least two distinct types of matrix or reinforcement. Each matrix
the paths of the yarns are diagonal to the vertical axis of the
or reinforcement type can be distinct because of its (a) physical
fabric. D4850
or mechanical properties, or both, (b) material form, or (c)
chemical composition. D3878
3.1.3.1 Discussion—Braided structures can have 2D or 3D
3.1.15 injection molding, n—in composite fabrication, the
architectures.
process of forcing liquid polymer under pressure into a closed
3.1.4 bulk density, n—the mass of a unit volume of material
including both permeable and impermeable voids. D7219 mold that contains a fiber preform.
3.1.5 fabric, n—in textiles, a planar structure consisting of 3.1.16 knitted fabric, n—a fiber structure produced by inter-
yarns or fibers. D4850 looping one or more ends of yarn or comparable material.
D4850
3.1.6 fiber, n—a fibrous form of matter with an aspect ratio
>10 and an effective diameter <1 mm. (Synonym – filament) A 3.1.17 laminate, n—any fiber- or fabric-reinforced compos-
fiber/filament forms the basic element of fabrics and other ite consisting of laminae (plies) with one or more orientations
textile structures. D3878 with respect to some reference direction. D3878
3.1.7 fiber areal weight, n—the mass per unit area of the 3.1.18 lay-up, n—a process or fabrication involving the
fibrous reinforcement of a composite material.
placement of successive layers of materials in specified se-
D3529/D3529M quence and orientation. E1309, D6507
3.1.8 fiber content/fraction (volume or weight), n—the
3.1.19 matrix, n—the continuous constituent of a composite
amount of fiber present in a composite, expressed as either a material, which surrounds or engulfs the embedded reinforce-
percent by weight or a percent by volume. D3878
ment in the composite and acts as the load transfer mechanism
between the discrete reinforcement elements.
3.1.9 fiber preform, n—a preshaped fibrous reinforcement,
normally without matrix, but often containing a binder to
3.1.20 matrix content, n—the amount of matrix present in a
facilitate manufacture, formed by distribution/weaving of fi-
composite expressed either as a percent by weight or a percent
by volume. D3878
3.1.21 ply, n—in 2D laminar composites, the constituent
Available from American Society of Mechanical Engineers (ASME), ASME
single layer as used in fabricating, or occurring within, a
International Headquarters, Two Park Ave., New York, NY 10016-5990, http://
www.asme.org. composite structure. D3878
C1783 − 15 (2024)
3.1.22 prepreg, n—the admixture of fibrous reinforcement duced. Carbon fibers typically are carbonized at about 2400 °F
and polymeric matrix used to fabricate composite materials. Its (1300 °C) and assay at 93 % to 95 % carbon, while graphite
form may be sheet, tape, or tow. For thermosetting polymer, the fibers are graphitized at 3450 °F to 5450 °F (1900 °C to
polymer has been partially cured to a controlled viscosity 3000 °C) and assay at more than 99 % elemental carbon.
called “B stage.” D3878 CMH-17
3.1.23 selvage, n—the woven edge portion of a fabric
3.2.5 chemical vapor deposition or infiltration, n—a chemi-
parallel to the warp. D3878 cal process in which a solid material is deposited on a substrate
or in a porous preform through the decomposition or the
3.1.24 tow, n—in fibrous composites, a continuous, ordered
reaction of gaseous precursors.
assembly of essentially parallel, collimated continuous
3.2.5.1 Discussion—Chemical vapor deposition is com-
filaments, normally without twist. (Synonym – roving) D3878
monly done at elevated temperatures in a controlled atmo-
3.1.25 unidirectional composite, n—any fiber reinforced
sphere.
composite with all fibers aligned in a single direction. D3878
3.2.6 durability, n—the measure of the ability of a material
3.1.26 warp, n—the yarn running lengthwise in a woven
or structure to endure and maintain its essential and distinctive
fabric. D3878
chemical, physical, mechanical and other functional character-
3.1.27 woven fabric, n—a fabric structure produced by the
istics in a specific environment of use (temperature,
interlacing, in a specific weave pattern, of tows or yarns
atmosphere, stress, radiation, etc) for a designated period of
oriented in two or more directions.
time.
3.2.7 fiber interface coating, n—in carbon-carbon
3.1.27.1 Discussion—There are a large variety of 2D weave
styles, e.g., plain, satin, twill, basket, crowfoot, etc. composites, a coating applied to fibers to control the bonding
between the fiber and the matrix.
3.1.28 yarn, n—in fibrous composites, a continuous, ordered
assembly of essentially parallel, collimated filaments, normally 3.2.7.1 Discussion—The bonding between the carbon fibers
with twist, and of either discontinuous or continuous filaments. and the matrix is generally weak, because the covalent atomic
Single yarn – an end in which each filament follows the same bonding between carbon atoms prevents sintering and bonding,
even at high temperatures. A weak bond between the fiber and
twist. D3878
the matrix in the carbon-carbon composite permits the fibers to
3.2 Definitions of Terms Specific to This Standard:
bridge matrix cracks and promote mechanical toughness; a
3.2.1 1D, 2D, and 3D reinforcement, n—a description of the
strong bond between the matrix and the fiber produces low
orientation and distribution of the reinforcing fibers and yarns
strain, brittle failure. In some cases a controlled fiber-matrix
in a composite.
interfacial bond is needed; fiber interface coatings with con-
3.2.1.1 Discussion—In a 1D structure, all of the fibers are
trolled composition, phase content, morphology, and thickness
oriented in a single longitudinal (x) direction. In a 2D structure,
are used to control that interface strength. (5)
all of the fibers lie in the x-y planes of the plate or bar or in the
3.2.8 infiltration and pyrolysis densification, n—in carbon
circumferential shells (axial and circumferential directions) of
matrix composites, a matrix production and densification
the rod or tube with no fibers aligned in the z or radial
process in which a liquid organic precursor (thermosetting
directions. In a 3D structure, the structure has fiber reinforce-
resin or pitch) is infiltrated/impregnated into the porous per-
ment in the x-y planes and in the z-direction in the plate or bar
form or the partially porous composite. The organic precursor
and in the axial, circumferential, and radial directions in a tube
is then pyrolyzed in an inert atmosphere to convert the organic
or rod.
to a carbon form with the desired purity and crystal structure.
3.2.2 axial tensile strength, n—for a composite tube or solid
The infiltration/pyrolysis process may be iteratively repeated to
round rod, the tensile strength along the long axis of the rod or
fill the porosity and build up the density in the composite.
tube. For a composite flat plate or rectangular bar, the tensile
3.2.9 primary structural axis, n—in a composite flat plate or
strength along the primary structural axis/direction.
rectangular bar, the directional axis defined by the loading
3.2.3 carbon-carbon composite, n—a ceramic matrix com-
axis/direction with the highest required tensile strength. This is
posite in which the reinforcing phase consists of continuous
commonly the axis with the highest fiber loading. This primary
carbon/graphite filaments in the form of fiber, continuous yarn,
structural axis may not be parallel with the longest dimensional
or a woven or braided fabric contained within a continuous
axis of the plate/bar/structure.
matrix of carbon/graphite. (5-8)
3.2.10 pyrolysis, n—in carbon matrix composites, the con-
3.2.4 carbon fibers, n—Inorganic fibers with a primary
trolled thermal process in which the hydrocarbon precursor is
(>90 %) elemental carbon composition. These fibers are pro-
decomposed to elemental carbon in an inert atmosphere.
duced by the high temperature pyrolysis of organic precursor
(Synonym – carbonization)
fibers (commonly, polyacrylonitrile (PAN), pitch, and rayon) in
3.2.10.1 Discussion—Pyrolysis commonly results in weight
an inert atmosphere. (Synonym – graphite fibers) (8, 9)
loss and the release of hydrogen and hydrocarbon vapors.
3.2.4.1 Discussion—The term carbon is often used inter-
changeably with “graphite”; however, carbon fibers and graph- 3.2.11 rectangular bar, n—a solid straight rod with a rect-
ite fibers differ in the temperature at which the fibers are made angular cross-section, geometrically defined by a width, a
and heat-treated, and the amount of elemental carbon pro- thickness, and long axis length.
C1783 − 15 (2024)
3.2.12 round rod, n—a solid, straight elongated cylinder, applications, discounting the nuclear-specific chemical purity
geometrically defined by a outer diameter and an axial length. and irradiation behavior requirements.
3.2.13 round tube, n—a hollow elongated cylinder, geo-
5. Carbon-Carbon Composites for Nuclear Applications
metrically defined by a outer diameter, an inner diameter, and
an axial length.
5.1 Carbon-carbon composites are candidate structural ma-
terials for use in nuclear reactors, because of their high
3.2.14 surface seal coatings, n—an inorganic protective
temperature stability and radiation tolerance compared to
coating applied to the outer surface of a carbon-carbon
metals and for their damage tolerance, higher strength, and
composite component to protect against high temperature
tailored anisotropic mechanical properties, compared to mono-
oxidation or corrosion attack or to improve wear and abrasion
lithic graphite. (1-4)
resistance. Such coatings are commonly hard, impermeable
ceramic/glass coatings.
5.2 Carbon-carbon composites are composed of carbon/
graphite fiber reinforcement in a carbon/graphite matrix. The
4. Significance and Use
combination of fibers and carbon matrix, the fiber architecture
4.1 Composite materials consist by definition of a reinforce-
(the shape and morphology of the fiber preform, multidimen-
ment phase in a matrix phase. In addition, carbon-carbon
sional fiber distribution, and volume content of the fiber
composites often contain measurable porosity which interacts
reinforcement), the matrix phase composition, microstructure
with the reinforcement and matrix. The composition and
and the composite density and porosity are engineered to give
structure of the C-C composite are commonly tailored for a
the desired performance properties for the composite. The
specific application with detailed performance requirements.
fibers may have a surface treatment to improve fiber/fabric
The tailoring involves the selection of the reinforcement fibers
handleability or to control the bonding between the fiber and
(composition, properties, morphology, etc), the matrix
the matrix. (5-16)
(composition, properties, and morphology), the composite
5.3 The mechanical, thermal, and physical properties of
structure (component fractions, reinforcement architecture,
carbon-carbon (C-C) composites are determined by the com-
porosity structure, microstructure, etc.), and the fabrication
plex interaction of the constituents (fiber, matrix, porosity) in
conditions (forming, assembly, forming, densification,
terms of the constituent chemistry, phase composition,
finishing, etc.). The final engineering properties (physical,
microstructure, properties, and fractional content; the fiber
mechanical, thermal, electrical, etc.) can be tailored across a
architecture; the fiber-matrix bonding, and the effect of fabri-
broad range with major directional anisotropy in the properties.
cation on the constituent properties, morphology and their
4.2 Specifications for specific C-C composite components
physical interactions. Each of these factors can be tailored to
covering materials, material processing, and fabrication proce-
produce a structure/component with the desired mechanical,
dures are developed to provide a basis for fabricating repro-
physical, and thermal properties. The C-C composite properties
ducible and reliable structures. Designer/users/producers have
can be tailored for directional properties by the anisotropic
to write C-C composite specifications for specific applications
architecture of the carbon fiber reinforcement. (15-19)
with well-defined composition, structure, properties and pro-
5.4 Carbon/graphite fibers are commonly small diameter
cessing requirements. But with the extensive breadth of selec-
(5 μm to 20 μm) continuous filaments produced from
tion in composition, structure, and properties in C-C
polyacrylonitrile, pitch, or rayon precursors. The mechanical
composites, it is virtually impossible to write a "generic"
and thermal properties of the carbon fibers are strongly
composite specification applicable to any and all C-C compos-
dependent on the carbon content, the crystal structure, and the
ite applications that has the same type of structure and details
crystallite size and orientation in the fibers. These factors are
of the commonly-used specifications for metal alloys. This
determined by the precursor chemistry and the processing
guide is written to assist the designer/user/producer in devel-
(spinning, carbonization, and graphitization) conditions.
oping a comprehensive and detailed material specification for
Typically, carbon fibers are classified as either high strength
a specific CMC application/component with a particular focus
(tensile strength ~3 GPa to 5 GPa, elastic modulus ~200 GPa to
on nuclear applications.
400 GPa) or high modulus (elastic modulus >500 GPa, tensile
4.3 The purpose of this guide is to provide guidance on how
strength <3 GPa). Often the carbon fibers have marked
to specify the constituents, the structure, the desired engineer-
differences in mechanical and thermal properties in the axial
ing properties (physical, chemical, mechanical, durability, etc),
direction, compared to the radial direction, because of crystal
methods of testing, manufacturing process requirements, the
structure anisotropy. (8, 9)
quality assurance requirements, and traceability for C-C com-
5.5 The carbon fibers are commonly consolidated into high
posites for nuclear reactor applications. The resulting specifi-
count multifilament tows which can be wrapped or layed-up
cation may be used for the design, production, evaluation, and
into 1D structures, woven/layed-up/braided/knitted into 2D
qualification of C-C composites for structures in nuclear
structures, or woven/braided/knitted/stitched into 3D struc-
reactors.
tures. Each of these fiber structures are fabricated with defined
4.4 The guide is applicable to C-C composites with flat
fiber architectures, offering a wide range of bulk fiber content.
plate, rectangular bar, round rod, and round tube geometries.
Different fiber architectures may have marked reinforcement
4.5 This guide may also be applicable to the development of anisotropy, depending on the relative fiber content in each
specifications for C-C composites used for other structural orthogonal direction.
C1783 − 15 (2024)
NOTE 1—Most commercially available carbon-carbon composites have
7.2 The composite may have a surface coating to protect the
a two dimensional woven fabric architecture, consisting of stacked plies.
composite from oxidation or environmental degradation and to
The C-C composite is densified to produce a final structure with
seal the composite against gas and liquid penetration/escape.
orthotropic or quasi-isotropic mechanical and thermal properties.
5.6 The carbon matrix in C-C composites is commonly 7.3 The designer/purchaser/user shall specify the required
produced by two methods—an iterative liquid infiltration/ composite constituents and structures in terms of carbon/
pyrolysis process or a chemical vapor infiltration process. The graphite fibers, interface coatings, matrix, and surface seal
two matrix formation processes use different precursors and coatings. The specification should list sources, chemical and
different processing conditions, which produce differences in
phase compositions, component fractions and morphology,
the chemistry, crystallinity, morphology, and microstructure
reinforcement architecture, and coating requirements. Section
(density, pores, and cracks) in the carbon matrix. These two
11 describes the manufacturing process specification require-
matrix densification processes may be combined for a hybrid
ments in detail for fibers, matrix, architecture, interface
carbon matrix. (5-7)
coatings, and seal coatings.
5.7 The interaction of these three variable factor sets: [(1)
7.4 For nuclear applications impurity levels in carbon-
carbon fiber type, properties, coatings; (2) fiber content, tow
carbon composites (and any surface seal coatings) have to be
structure, and architecture; (3) matrix phase composition and
carefully controlled to minimize neutron absorption, oxidation-
properties, crystallinity, density, morphology, and porosity] can
promoting catalysis, nuclear activation impurities, corrosion-
produce C-C composites with a wide range of mechanical and
promotion impurities, and fissionable elements. Each carbon-
physical properties, along with tailored anisotropic properties
carbon composite production lot sampled in accordance with
in the major directions.
Section 14 shall conform to the requirements for chemical
6. Product Specifications—Properties, Materials and purity (high purity and low purity) specified in Table 1 and to
Processing the requirements of the designer/purchaser/user.
6.1 The fibers, matrix, fiber architecture, fiber surface
7.5 The boron equivalent shall be calculated in accordance
treatments, any fiber interface coatings and/or component
with Practice C1233. The concentrations of at least the
surface seal coatings, and the method of manufacture, when
following elements shall be determined and used in the
combined as a composite structure, must produce a composite
calculation: Boron, Cadmium, Chlorine, Cobalt, Dysprosium,
that consistently and reliably meets the performance require-
Europium, Gadolinium, Lithium, Manganese, Nickel,
ments (chemical, physical, mechanical, and durability) speci-
Samarium, Silver, Titanium, Tungsten, and Vanadium. Speci-
fied by the designer/purchaser/user, applicable codes and
fied boron equivalent limits are given the “Boron Equivalent”
standards, and the controlling regulatory agency.
line in Table 1.
6.2 The engineering properties and characteristics of a
7.6 Table X1.1 (from Specification D7219) contains a list of
composite structure are manufactured into the structure as part
chemical impurities typically found in nuclear grade graphite
of the fabrication process. Specifications shall be written to
and carbon. The impurities are categorized as neutron absorb-
define requirements for end-product properties (chemical and
ing impurities, oxidation- promoting catalysts, activation rel-
phase composition, physical properties, mechanical properties,
evant impurities, metallic corrosion relevant impurities, and
durability), and manufacturing specifications for materials and
fissile/fissionable elements. The suggested limits represent the
fabrication. The manufacturing specifications shall include
reactor designer’s preferences for chemical purity.
sufficient information to ensure that critical factors and param-
eters in the starting materials and the manufacturing process
are identified and controlled to produce the final structure/
component to the defined specification.
TABLE 1 Chemical Purity Requirements for Carbon-Carbon
6.3 The designer/purchaser/user shall define the specifica-
Composites in Nuclear Applications (derived from Specification
tions for the constituents (chemistry, properties), architecture,
D7219)
final properties, and quality assurance for the carbon-carbon
High Purity Low Purity
Test ASTM Test
composite. (ppm) (ppm)
Ash Content C561 300 maximum 1000 maximum
6.4 The designer/purchaser/user and the manufacturer to-
Chemical Impurity - Ca D5600 <30 <100
gether shall define the specifications for the materials/
Chemical Impurity - Co D5600 <0.1 <0.3
Chemical Impurity - Fe D5600 <30 <100
processing manufacture and non-destructive testing (NDT) of
Chemical Impurity - Cs D5600 <0.1 <0.3
the carbon-carbon composite.
Chemical Impurity - V D5600 <50 <250
Chemical Impurity - Ti D5600 <50 <150
7. Product Specification—Composite Constituents,
Chemical Impurity - Li D5600 <0.2 <0.6
Chemical Composition, and Purity for Nuclear
Chemical Impurity - Sc D5600 <0.1 <0.3
Chemical Impurity - Ta D5600 <0.1 <0.3
Applications
Boron Equivalent C1233 2 maximum 10 maximum
7.1 A carbon-carbon composite shall consist of carbon/ Chemical Impurities - N TBD To be To be
determined determined
graphite reinforcement fibers in a carbon/graphite matrix. The
Chemical Impurities – S C816 To be To be
fibers may have a fiber interface coating to control the bonding
determined determined
between the fiber and the matrix.
C1783 − 15 (2024)
8. Product Specification—Physical Properties 8.7 Other physical properties may be specified by the
designer/purchaser/user [see Composite Materials Handbook
8.1 The designer/purchaser/user shall specify the required
CMH-17, Volume 5 (CMC Handbook)].
minimum/maximum values for the specified physical proper-
8.8 Each carbon-carbon composite production lot shall be
ties of carbon-carbon composites based on the desired perfor-
mance properties; the component constituents, fractions, and sampled in accordance with Section 14.
properties; the reinforcement architecture; and the final poros-
9. Product Specification—Mechanical Properties
ity fraction.
9.1 The designer/purchaser/user shall specify the required
8.2 The physical, thermal, and electrical properties, of
maximum/minimum values for the selected mechanical prop-
carbon-carbon composites that are of primary and secondary
erties of carbon-carbon composites considering anisotropy and
interest are listed in Table 2 with the recommended ASTM test
based on the desired performance properties, the component
standards. The selection of specific physical, thermal, and
constituents and fractions, and the reinforcement architecture.
electrical properties for the specification will depend on the
9.2 Mechanical property specifications for each stress con-
design requirements for the CMC component. Other properties
dition should include (per designer/purchaser/user require-
(not included in this list) may be specified by the designer/
ments) the ultimate strength and strain, the fracture strength
user/producer.
and strain, the proportional limit strength and strain, elastic
8.2.1 The designer/purchaser/user may define anisotropy
modulus, and representative stress-strain curves.
requirements and limits for designated physical properties.
9.3 The stress-strain response of a carbon-carbon composite
8.3 The designer/purchaser/user may specify requirements
can vary widely, ranging from linear elastic brittle failure to
for descriptive statistics and limits (test count, mean, standard
very high strain failure with major damage accumulation and
deviations, coefficient of variation, minimum/maximum
pseudo-ductility (see Fig. 1). The stress-strain response of the
values, etc) for the designated physical properties (see Practice
composite depends on the interaction of many factors—fiber
E2586).
properties, architecture, and volume fraction, matrix density
8.4 Elevated Temperatures—The designer/purchaser/user
and properties, matrix-fiber bonding, stress alignment with the
may also specify requirements for thermal and electrical
reinforcement axes, and deformation/damage mechanisms.
properties at specified elevated temperatures, determined by
9.4 The mechanical properties of carbon-carbon composites
the performance requirements.
that are of interest are listed in Table 3 with the recommended
8.5 The designer/purchaser/user may specify requirements
ASTM test standards. The selection of specific properties for
for anisotropy in thermal and electrical properties, determined
the specification will depend on the design requirements for the
by the performance requirements.
specific C-C component.
8.6 Variability in physical properties (in-piece anisotropy, 9.4.1 Elevated Temperatures—The designer/purchaser/user
in-piece volumetric, piece-to- piece, and lot-to-lot) may be of may specify requirements for mechanical properties at specific
direct interest to the manufacturer and the designer/purchaser/ elevated temperatures, determined by the performance require-
user. ments.
TABLE 2 Physical, Thermal and Electrical Properties of Carbon-Carbon Composites
NOTE 1—For round rods and tubes, anisotropy should be defined in terms of axial, radial, and tangential (hoop) directions, not x, y, and z.
NOTE 2—Thermal expansion, thermal conductivity, electrical resistivity, and emissivity data may be anisotropic depending on fiber architecture and
should be measured in the major directions.
NOTE 3—Physical properties may be strongly dependent on bulk porosity content and on localized porosity concentrations (which may be
inhomogeneously distributed).
Units ASTM Test Priority Anisotropy
Bulk Density by Physical Measurement g/cm C559, C838 Primary No
Apparent Porosity and Bulk Density by Immersion % and g/cm C1039 Primary No
Constituent (Fiber, Matrix) Bulk Fraction % D3171 (Method 2) Primary No
Fiber Fraction –Directional % By calculation Primary Yes (x,y,z)
A
Electrical Resistivity Ohm-m C611 Secondary Yes (x,y,z)
Linear Thermal Expansion ppm/°C C1470, E228, E289 Secondary Yes (x,y,z)
Thermal Conductivity – (Diffusivity) W/(m-K) – (m /s) C1470, C714, E1461 Secondary Yes (x,y,z)
Specific Heat J/(g-K) C1470, D2766, E1269 Secondary No
Emittance, Emissivity nd C1470, E408, E423 Secondary Yes
Porosity Content and Structure (Mercury Porosimetry) TBD D4284 Secondary No
2 A
Permeability L /(m -s) C577 Secondary Yes (x,y,z)
Surface Area (BET) m /g C1274 Secondary No
Surface Roughness TBD Surface Profilometry Secondary Yes (x,y,z)
ASME B46.1
A
Modification of this test method may be required for C-C composites.
TBD = to be determined.
C1783 − 15 (2024)
S = ultimate strength, MPa
U
ɛ = ultimate strain, %
U
S = fracture strength, MPa
F
ɛ = fracture strain, %
F
σ = proportional limit stress, MPa
O
ɛ = proportional limit strain, %
O
E = elastic modulus, GPa
U = modulus of resilience (J/m ) integral of σ from 0 to ɛ strain
R O
U = modulus of toughness (J/m ) integral of σ from 0 to ɛ strain
T F
FIG. 1 Examples of Different Carbon–Carbon Composite Stress-Strain Curves
TABLE 3 Mechanical Properties of Carbon-Carbon Composites
NOTE 1—Mechanical properties may be strongly anisotropic (axial, transverse, off-axis, etc) depending on fiber architecture and directional fiber
fraction and should be measured in the major directions.
ASTM Test – ASTM Test –
Units
Flats-Bars Rods/Tubes
Tensile Properties (ultimate, fracture, PropL) MPa & strain C1275, C1359 C1773
B
Flexure Properties (ultimate, fracture, PropL) MPa & strain C1341
B
Compression Properties (ultimate, fracture, PropL) MPa & strain C1358
B
Shear Properties (ultimate, fracture, PropL) MPa & strain C1292, C1425
B
Transthickness Tensile Properties (ultimate, fracture, PropL) MPa & strain C1468
B
Hoop Strength Properties (ultimate, fracture, PropL) MPa & strain NA
A A
Elastic/Shear Modulus by Mechanical Loading GPa E111 E111 , E143
A
Elastic/Shear Modulus by Sonic Resonance GPa C1198 C1198
A
Elastic/Shear Modulus by Impulse Excitation GPa C1259 C1259
A
Elastic Modulus by Sonic Velocity GPa C769 C769
B
Poisson’s Ratio nd E132
Modulus of Resilience (in Tension) J/m C1275, C1359 C1773
Modulus of Toughness (in Tension) J/m C1275, C1359 C1773
A B
Open Hole Tensile Strength Properties MPa & strain D5766
A B
Open Hole Compression Strength Properties MPa & strain D6484
B B
Notch Tensile Strength Properties MPa & strain
B B
Notch Compression Strength Properties MPa & strain
A B
Pin Bearing Strength Properties MPa & strain D5961
2 A A A B
Fracture Toughness / Strain Energy Release Rate kJ/m D5528 , D6671 , E1922
A
Modification of this polymer matrix composite test method may be required.
B
New test methods are required.
nd = no dimensions.
9.4.2 Anisotropy—The designer/purchaser/user may define
anisotropy requirements and limits for designated mechanical
properties.
C1783 − 15 (2024)
9.4.3 The designer/purchaser/user shall specify require- cracking that may degrade the physical and mechanical prop-
ments for descriptive statistics and limits (test count, mean, erties and the functionality of the composite.
standard deviations, coefficient of variation, minimum/ NOTE 2—Different carbon fibers and graphite matrices will have
different susceptibility to radiation damage based on crystal structure and
maximum values, etc) for the designated mechanical properties
impurities. The radiation damage effects should be assessed and under-
(see Practice E2586).
stood for each specific component, including matrix, fiber, interface
9.4.4 The designer/purchaser/user may specify require-
coating, and surface seal coating.
ments for Weibull modulus and Weibull characteristic strength
10.3 Oxidation/corrosion effects at elevated temperatures
for selected mechanical properties (see Practices C1239 and
within the reactor must by controlled and managed in terms of
C1683).
chemical reactions, mass loss/gain, dimensional changes, and
9.5 Variability in mechanical properties (in-piece
corrosion product. Any degradation of physical and mechanical
volumetric, in-piece anisotropy, piece-to- piece, and lot-to-lot)
properties of the composite as a whole, must be managed and
may be of direct interest to the manufacturer and the designer/
minimized, including any fiber interface coatings and surface
purchaser/ user. The designer/purchaser/user may specify
seal coatings effects.
statistically-based requirements to characterize variability
10.4 Stress effects must be understood and controlled in
across the different factors.
terms of crack growth, flaw initiation, fatigue degradation,
9.6 Other mechanical property requirements may be speci-
creep strain, and stress-rupture, all as a function of
fied by the designer/purchaser/user [see Composite Materials
temperature, time, stress levels, and oxidation/corrosion con-
Handbook CMH-17, Volume 5 (CMC Handbook)].
ditions.
9.7 Each C-C composite production lot shall be sampled in
10.5 The designer/purchaser/user shall specify the durabil-
accordance with Section 14.
ity requirements (physical, mechanical, etc.) of the carbon-
carbon composites under defined conditions of time, neutron
10. Product Specification—Durability Properties
irradiation, temperature, stress, oxidation conditions, and cor-
10.1 The durability of C-C composites over time under
rosion concentrations. Durability requirements are commonly
reactor environment conditions is a principal engineering
defined as a “not-to-exceed” maximum % change in designated
design concern. In a nuclear reactor, the composites must
properties as a function of exposure conditions and time. The
maintain a defined set of chemical, physical, and mechanical
specification shall define the experimental test methods and the
properties for extended periods of time under defined condi-
required exposure conditioning parameters for determining the
tions of fast neutron radiation exposure, static and cyclic stress
physical, chemical, and mechanical durability. (Table 4 is a list
at elevated temperatures, and high temperature oxidation/
of durability factors that need to be considered
...