Detecting the thermal shock stability of plug brick is an important means to evaluate its ability to resist cracking and crack propagation under rapid temperature change. The following are common methods and standards for testing the thermal shock stability of plug bricks:

I. Detection principle

The detection principle of thermal shock stability is to rapidly increase and decrease the temperature of refractory materials under certain temperature and time conditions, and then observe the cracks and fractures of the materials.

II. Common detection standards

GB/T 30873-2014: Test method for thermal shock resistance of refractories.

YB/T 376.3-2004: Test method for thermal shock resistance of refractory products (water quenching-crack determination method).

EN 993-11:2007: Test method of dense shaped refractory products, test method of thermal shock resistance (air quenching method).

III. Detection methods

(1) water quenching method

Sample preparation: sample from the same batch of plug bricks, and the size should meet the requirements of relevant standards.

Heating process: heat the sample to a specified temperature (such as 1100℃) and keep the temperature for a certain time (such as 30 minutes).

Cooling process: quickly immerse the sample in water at 20℃ for rapid cooling.

Cycle times: repeat the above heating and cooling processes until the sample is destroyed.

Evaluation standard: Record the strength retention rate of the sample after repeated thermal shock cycles. Usually, the strength retention rate ≥80% is qualified.

(2) air quenching method

Heating and cooling: after the sample is heated to the specified temperature, it is quickly cooled by compressed air.

Scope of application: Suitable for alkaline refractory products and silica refractory products.

IV. Evaluation indicators

Cracks and ruptures: Observe the number and degree of cracks on the surface and inside of the sample.

Strength loss rate: calculate the strength loss rate by measuring the strength change of the sample before and after thermal shock.

Mass loss rate: measure the mass change of the sample during thermal shock.

V. Precautions

Cooling water temperature control: in the water quenching method, the cooling water temperature should be controlled within the normal temperature range, and the water temperature increase should not exceed 10℃ during the quenching process.

Sample size: the sample size should meet the standard requirements to ensure the accuracy of the test results.

Through the above detection methods and standards, the thermal shock stability of plug bricks can be effectively evaluated, thus ensuring their reliability and durability in practical use.