GB/T 37246-2018 in English

Interpretation of GB/T 37246-2018 Test Method for Thermal Shock Resistance of Fine Ceramics

Standard Background and Significance

GB/T 37246-2018 "Test Method for Thermal Shock Resistance of Fine Ceramics" is an important national standard in the field of building materials in China, which is mainly used to evaluate and test the thermal shock resistance of fine ceramic materials under rapid temperature changes. This standard is managed by the National Technical Committee for Standardization of Industrial Ceramics and was officially released in 2018.

With the widespread application of ceramic materials in high-temperature environments, especially the high-performance requirements in aviation, aerospace, automobiles and other fields, it has become particularly important to test their thermal shock resistance. This standard provides a set of scientific and standardized test methods for scientific research institutions and production enterprises to ensure the consistency and reliability of products.

Test Principles and Methods

Fine ceramics will produce thermal stress during rapid temperature changes, resulting in a decrease in material strength. This standard adopts the rapid cooling method as the main test method and evaluates the thermal shock resistance of the specimen by measuring the bending strength decay rate of the specimen at high temperature.

Key steps:

• Heat the sample to the set temperature (usually above 1000°C) and keep it warm for 30 minutes
• Quickly cool (≤2 seconds) to room temperature
• Test the bending strength before and after thermal shock, and calculate the attenuation rate

Instruments and equipment and requirements

The instruments and equipment used in the test must meet the following technical requirements:

Sample requirements and treatment

The sample must meet the following requirements:

• Shape and size:According to GB/T6569
• Pretreatment:Remove surface organic contamination, which can be achieved by heating to 500°C for 1 hour
• Number of specimens: At least 30 specimens from the same batch, 6 specimens each before and after the thermal shock test

Test steps and data processing

The specific test steps are as follows:

1. Measure the specimen width b and thickness h, and test the initial bending strength σ_mo according to GB/T6569
2. Heat to the set temperature, keep warm and then quickly cool to room temperature
3. After drying and natural cooling, test the remaining bending strength σ_mth again
4. Calculate the bending strength attenuation rate σ_*

Formula:σ* = (σ_mo - σ_mth) / σ_mo

Calculation and evaluation of thermal shock resistance

Determine the maximum allowable temperature difference ΔT_c through the following steps:

1. Select two adjacent temperature points with attenuation rates of σ1* (<10%) and σ2* (10%-20%) respectively.
2. Calculation formula: ΔT_c = ΔT1 + [(10% - σ1*) / (σ2* - σ1*)] × (ΔT2 - ΔT1)

Comparison of standard frameworks

The following table compares the key differences between GB/T37246 and similar international standards:

Implementation suggestions

To ensure the accuracy and consistency of the test results, it is recommended to:

• Strictly control the temperature and flow rate of the cooling medium
• Select high-precision measuring instruments and calibrate them regularly
• Establish a complete quality control system to ensure that the sample processing meets the specifications
• Adjust the test parameters according to the specific application requirements