ASTM C1793-15(2024) PDF

Overview

ASTM C1793-15(2024), "Standard Guide for Development of Specifications for Fiber Reinforced Silicon Carbide-Silicon Carbide Composite Structures for Nuclear Applications," provides a comprehensive framework for drafting specifications for silicon carbide (SiC) fiber-reinforced SiC matrix composite components. Developed by ASTM International, this standard focuses on SiC-SiC composites used in nuclear reactor core structures, including flat plates, bars, rods, and tubular forms.

SiC-SiC composites are favored for nuclear settings due to their exceptional thermal stability, oxidation resistance, radiation tolerance, and mechanical robustness. The guide details how to define and document requirements for materials, processing, and quality control to ensure the reliable, repeatable production of these advanced composites.

Key Topics

• Composite Constituents:

  • SiC-SiC composites consist of silicon carbide fibers embedded within a silicon carbide matrix.
  • The selection of fiber type, matrix structure, fiber architecture, and interface coating is tailored based on performance demands.

• Specification Development:

  • Guides the creation of detailed material specifications for SiC-SiC composites with nuclear applications in mind.
  • Emphasizes the importance of defining composition, structure, properties, and processing requirements to match the intended use.

• Physical and Mechanical Properties:

  • Composites are engineered to specific requirements of density, porosity, thermal expansion, conductivity, electrical resistivity, and mechanical strength.
  • Properties may be tailored with significant anisotropy, depending on fiber architecture and intended directionality of use.

• Quality Assurance and Testing:

  • Recommends methods for testing chemical purity, mechanical strength, and physical characteristics using ASTM standards.
  • Includes direction on statistical sampling, quality assurance, and traceability for each production batch.

• Nuclear Application Specifics:

  • Outlines special considerations for controlling impurities to minimize neutron absorption and avoid undesired chemical reactivity.
  • Specifications must address requirements unique to nuclear service, such as radiation-induced dimensional changes and elevated temperature performance.

Applications

• Nuclear Reactor Core Structures:

  • SiC-SiC composites are primarily used in structural components and fuel cladding for nuclear reactors, where performance under irradiation and high temperature is critical.
  • Their low neutron absorption and high radiation tolerance make them suitable for advanced reactor designs.

• Other Structural Uses:

  • While focused on nuclear applications, the guide also supports the development of specifications for SiC-SiC composites in other high-temperature or corrosive environments, provided nuclear-specific factors are modified as required.

• Component Geometry:

  • Applicable to flat plates, solid bars (rectangular and round), and tubes; these shapes are common in nuclear reactor core construction and broader engineering applications.

Related Standards

To ensure consistency and accuracy in specification and testing, ASTM C1793-15(2024) references several related standards, including:

• ASTM C242: Terminology of Ceramic Whitewares and Related Products
• ASTM C559, C838, C1039: Testing of density and porosity in ceramic materials
• ASTM C1470, E228, E289: Methods for measuring thermal expansion and conductivity
• ASTM C1233: Determining equivalent boron content, important for nuclear-grade materials
• ASTM D3878, D4018: Terminology and properties for composite materials and fibers
• ASME B46.1: Surface texture (surface roughness) assessment

Consistent application of these standards ensures reliable characterization and repeatable quality for SiC-SiC composites used in demanding service environments such as nuclear reactors.

Keywords: ASTM C1793, SiC-SiC composites, silicon carbide fiber, ceramic matrix composites, nuclear reactor materials, material specification guide, mechanical testing ASTM, composite properties, fiber architecture, testing standards for composites, nuclear applications, ASTM standards for ceramics.