IEC 61788-18:2013

Overview

IEC 61788-18:2013 is an international standard developed by the International Electrotechnical Commission (IEC) that defines a precise method for measuring the mechanical properties of silver (Ag) or silver alloy-sheathed Bi-2223 and Bi-2212 composite superconducting wires at room temperature. These high-temperature superconductors are critical components used in electrical power devices and superconducting magnets, where their mechanical integrity under tensile stress is vital for reliability and performance.

This standard focuses specifically on tensile testing to determine key mechanical parameters such as the modulus of elasticity and 0.2% proof strength. It also covers testing procedures when the 0.2% proof strength cannot be measured due to early failure, by specifying tensile stresses at defined strain increments. IEC 61788-18:2013 ensures uniformity and reproducibility in assessing these composite superconductors, which typically have circular or rectangular cross sections with areas ranging from 0.3 mm² to 2.0 mm².

Key Topics

• Test Methodology: Details the tensile testing approach for Ag/Bi-2223 and Ag/Bi-2212 composite superconducting wires at room temperature.
• Mechanical Properties Measured:
  • Modulus of Elasticity (E): Quantifies the wire's stiffness.
  • 0.2% Proof Strength: The stress at which a 0.2% permanent strain occurs, indicating yield strength.
  • Tensile Stress at Specified Strains: Applicable when proof strength cannot be measured.
  • Fracture Strength and Elongation: Measures ultimate strength and ductility.
• Specimen Requirements: Applicable to samples with round or rectangular cross sections, typical of tape-shaped superconducting wires, ensuring practical relevance.
• Apparatus and Conditions: Specifies the necessary testing machines, extensometers, specimen preparation, gripping methods, and testing speed to assure data accuracy.
• Uncertainty Evaluation: Protocols for assessing measurement uncertainties, ensuring reliable characterization.
• Test Reporting: Guidelines on documenting specimen details, test conditions, and results for standard compliance and quality control.

Applications

IEC 61788-18:2013 is essential in multiple practical contexts involving Ag- and Ag alloy-sheathed Bi-2223 and Bi-2212 superconductors:

• Superconducting Magnet Manufacturing: Mechanical testing helps verify that superconducting wires can withstand the mechanical stresses and electromagnetic forces encountered during magnet winding and operation.
• Electrical Power Devices: Ensures wire mechanical properties support high current densities while maintaining performance and durability.
• Quality Assurance and Product Development: Enables manufacturers to perform consistent mechanical characterization to optimize conductor design and production processes.
• Research & Development: Provides a benchmark test method for investigating new alloy compositions or reinforcement techniques for composite superconductors.
• Standardized Compliance: Assists certification and regulatory bodies in evaluating superconducting wires against a recognized international testing protocol.

Related Standards

For comprehensive superconductivity testing and standardization, IEC 61788-18:2013 connects with other parts of the IEC 61788 series, including but not limited to:

• IEC 61788-1 to IEC 61788-17: Covering various aspects such as magnetic property measurements, critical current testing, and other mechanical or electrical characterizations for composite superconductors.
• ISO/IEC Directives Part 2: Governs international standard drafting practices ensuring consistency across standards.
• Material-Specific Standards: Other applicable mechanical testing standards for alloys or composite materials used as stabilizers or reinforcements in superconducting wires.

Keywords: IEC 61788-18, superconductivity, mechanical properties measurement, tensile test, Ag-sheathed Bi-2223, Ag alloy-sheathed Bi-2212, composite superconductors, modulus of elasticity, proof strength, fracture strength, room temperature testing, superconducting wire testing, superconducting magnets, electrical power devices, standard testing method.