The low-temperature brittleness testing machine is a key equipment in the field of materials science, and its core principle is based on the synergistic effect of precise temperature control and mechanical impact. The equipment uses a cascade compressor refrigeration technology to reduce the temperature of the test environment to -70 ℃ or even lower, and achieves thermal equilibrium by using freezing media such as ethanol. Combined with a circulating stirring system, it ensures temperature uniformity, and the temperature control accuracy can reach ± 0.5 ℃. After the material sample reaches thermal equilibrium in a low-temperature environment, the spring impact mechanism applies an impact load at a speed of 1.4-2.4m/s, and evaluates its low-temperature toughness by measuring the critical temperature at which the sample fractures.
The practical process is divided into four stages:
Equipment preparation: Check the power grounding, inject industrial ethanol until the liquid level submerges the refrigeration copper tube 5mm above the sample, start the refrigeration system to preheat for 2 hours, and wait for the temperature to stabilize to the set value (error ≤± 1 ℃).
Sample preparation: Cut vulcanized rubber or plastic samples according to standards, with typical dimensions of 25mm in length, 6mm in width, and 2mm in thickness, and no surface defects.
Test execution: Hold the sample vertically in the lifting device, freeze for 3 minutes, and the impactor completes the impact within 0.5 seconds. Record the fracture situation. If the sample is damaged, increase the temperature of the medium; On the contrary, cool down and repeat the test until the brittle temperature range is determined.
Data processing: According to the GB/T1682-2014 standard, the brittle temperature of the material is determined by the temperature difference between at least two non-destructive specimens and one destructive specimen being ≤ 1 ℃.
The technological advantages are reflected in three aspects:
High precision temperature control: The PID microcomputer temperature control system combined with imported sensors achieves temperature fluctuations of ≤± 0.5 ℃.
Automated operation: Some models support automatic rotation and positioning of samples and multiple parallel tests to improve efficiency.
Safety protection: equipped with over temperature alarm, leakage protection, and tempered glass observation window to ensure safe operation.
This device is widely used in aerospace, automotive manufacturing, and energy transmission fields, such as verifying the anti brittle fracture ability of spacecraft shell materials in extremely cold space, or evaluating the crack resistance of natural gas pipelines in low-temperature environments.