GB/T 34520.9-2021Test methods of continuous silicon carbide fibers—Part 9: Carbon content (English PDF)

Foreword

This document is in accordance with the provisions of GB/T 1.1-2020 "Guidelines for Standardization Work Part 1: Structure and Drafting Rules of Standardization Documents" Drafting.

This document is part 9 of GB/T 34520 "Continuous Silicon Carbide Fiber Test Method". GB/T 34520 has released the following section.

---Part 1: Bundle wire sizing rate;

---Part 2: Single fiber diameter;

---Part 3: Linear density and density;

---Part 4: Tensile properties of bundle yarn;

---Part 5: Single fiber tensile properties;

---Part 6: Resistivity;

---Part 7: High temperature strength retention rate;

---Part 8: Oxygen content;

---Part 9: Carbon content.

Introduction

Continuous silicon carbide fiber is a ceramic fiber with high strength, high modulus, high temperature resistance and oxidation resistance. It is mainly used in aviation, aerospace, military High-tech fields such as nuclear equipment and nuclear industry. With the rapid development of the domestic continuous silicon carbide ceramic fiber industry, fiber development units and production orders Positions and application units need unified test standards for assessment and evaluation. GB/T 34520 aims to establish the performance index of continuous silicon carbide fiber The test method is planned to consist of nine parts.

---Part 1: Bundle sizing rate. The purpose is to specify the determination of the sizing rate of continuous silicon carbide fiber bundles.

---Part 2: Single fiber diameter. The purpose is to specify the diameter test of near-circle solid continuous silicon carbide single fiber.

---Part 3: Linear density and density. The purpose is to specify the linear density and density test of continuous silicon carbide fibers.

---Part 4: Tensile properties of bundle yarn. The purpose is to specify the tensile strength, tensile modulus of elasticity and breakage of continuous silicon carbide fiber bundles Elongation test.

---Part 5: Single fiber tensile properties. The purpose is to specify the tensile strength, tensile modulus and fracture of continuous silicon carbide single fiber Elongation test.

---Part 6: Resistivity. The purpose is to specify the resistivity of silicon carbide single fiber and bundle wire resistivity test.

---Part 7: High temperature strength retention rate. The purpose is to specify the high temperature and strength of silicon carbide single fiber under inert gas above 800 °C Degree retention rate test.

---Part 8: Oxygen content. The purpose is to specify the determination of oxygen in continuous silicon carbide fibers.

---Part 9: Carbon content. The purpose is to specify the determination of carbon in continuous silicon carbide fibers.

In 2017, 7 related standards for the mechanical properties of continuous silicon carbide fibers have been released, and two tests of oxygen content and carbon content are planned to be supplemented in 2021. standard. This document is part 9 of this standard system, which can provide a universal test method for the carbon content test of continuous silicon carbide fibers, and promote Technical exchanges and cooperation among various units. Continuous silicon carbide fiber testing method Part 9: Carbon Content

1 Scope

This document specifies the sample preparation and sample measurement for the determination of carbon content in continuous silicon carbide fibers by the high-frequency induction combustion-infrared absorption method. Test, test result calculation, etc.

This document is applicable to the determination of the total carbon content of continuous silicon carbide fibers by the high frequency induction combustion-infrared absorption method. Discontinuous silicon carbide fiber Refer to this document for the carbon content test of the peacekeeping matrix. Refer to this document for carbon content testing of other ceramic fibers.

2 Normative references

The contents of the following documents constitute the indispensable clauses of this document through normative references in the text. Among them, dated quotations Only the version corresponding to that date is applicable to this document; for undated reference documents, the latest version (including all amendments) is applicable to this document.

GB/T 1446 General Principles of Test Methods for Performance of Fiber Reinforced Plastics

GB/T 6003.1 Technical requirements and inspection of test sieves Part 1: Metal wire woven mesh test sieves

GB/T 8170 Numerical rounding rules and the expression and determination of limit values

GB/T 14599 Pure oxygen, high-purity oxygen and ultra-pure oxygen

GB/T 26017 high purity copper

GB/T 34520.1 Continuous silicon carbide fiber test method Part 1: Bundle wire sizing rate

YS/T 659 Grade and chemical composition of tungsten and tungsten alloy processed products

YS/T 1221 tin grain

3 Terms and definitions

There are no terms and definitions that need to be defined in this document.

4 Test principle

The continuous silicon carbide fiber sample (hereinafter referred to as the sample) and flux are added to the crucible, and the sample is subjected to high-frequency induction under the combustion of carrier gas (oxygen).

Should be heated to combustion, the carbon element in it reacts with oxygen to produce carbon monoxide and carbon dioxide, which are then carried by the carrier gas into carbon monoxide and carbon dioxide.

The infrared absorption detection cell of carbon oxide, the infrared absorption detection cell respectively measures the concentration of carbon monoxide and carbon dioxide at 4670nm and 4260nm Absorb the light intensity and output the electrical signal value. The data receiving and processing system calculates the carbon of the sample according to the output electrical signal value and the sample quality. The content is displayed in mass fraction.

5 Test environment

The standard test environmental conditions are implemented in accordance with the standard environmental requirements specified in GB/T 1446, with a temperature of (23±2)°C and a relative humidity of (50±10)%.