1、 Working principle

The low-temperature brittleness testing machine evaluates the brittle behavior of materials at low temperatures by simulating low-temperature environments. The core process includes:

Low temperature environment construction: Use a refrigeration system to reduce the temperature inside the test chamber to the target value (usually up to -70 ℃ to -120 ℃, with liquid nitrogen assistance for extended functions), and control temperature fluctuations within ± 0.5 ℃.

Sample processing: Fix the material sample (such as rubber or plastic) in the fixture, immerse it in a low-temperature medium (such as ethanol or coolant) and freeze for 5 minutes to ensure temperature uniformity.

Mechanical impact test: Apply impact force to the specimen at a standard speed (such as 2 ± 0.2m/s) and observe whether cracks, fractures, or fragmentation occur.

Data determination: Determine the brittle temperature range of the material through repeated experiments, that is, the critical point at which the sample transitions from toughness to brittleness.

2、 Key technologies of refrigeration system

Cascade compressor refrigeration:

Adopting a two-stage cycle (high pressure cycle+low pressure cycle), connected through an evaporative condenser, to achieve low temperatures below -70 ℃. For example, the French Taikang compressor combined with R404A/R23 environmentally friendly refrigerant has high refrigeration efficiency and strong stability.

The finned evaporator (with a 30% increase in heat transfer efficiency) is combined with air-cooled/water-cooled condensers to optimize the heat exchange process.

Precise temperature control technology:

PID microcomputer control combined with Pt100 temperature sensor achieves a resolution of ± 0.1 ℃ and fluctuation of ± 0.5 ℃.

The cold well agitator and circulating air supply system ensure temperature uniformity and avoid local overheating or overcooling.

Energy saving and reliability design:

Energy regulation technology dynamically matches the cooling capacity and load demand, reducing energy consumption and failure rate.

The entire system pipeline adopts oxygen free copper pipes, nitrogen filled welding, and high pressure anti leakage technology, ensuring sealing through 48 hour leak testing.

Security and maintenance optimization:

Equipped with protection functions such as over temperature, overload, and leakage, supporting automatic shutdown and alarm for faults.

Modular design facilitates regular maintenance, such as condenser cleaning, dry filter replacement, etc.