In the manufacturing of brake shoes, corundum, a crystalline aluminum oxide, has emerged as a material with distinct properties that can enhance the performance of brake shoes friction materials when added to brake shoes mixtures and mixes.

Corundum ranks a remarkable 9 on the Mohs hardness scale. This extreme hardness endows the brake shoes friction materials with outstanding abrasion – resistance. In a simulated braking test with 200,000 cycles, brake shoes with 25% corundum content by volume exhibited a wear depth of merely 0.4 – 0.8 mm. In contrast, the control group without corundum had a wear depth of 2.5 – 3.5 mm, clearly demonstrating the significant contribution of corundum to wear resistance.

With a thermal conductivity ranging from 25 – 30 W/(m·K), corundum plays a crucial role in heat dissipation during the braking process. When a vehicle undergoes high – speed braking, the temperature at the friction interface can soar. In experiments, without corundum, the friction surface temperature reached 450°C. However, when corundum was incorporated, the peak temperature was reduced to approximately 320°C. This heat – dissipating property helps maintain the structural integrity and stable performance of the friction material.

Corundum has an extremely high melting point of around 2054°C. This high melting point ensures that during the most intense braking scenarios, where temperatures can spike, corundum in the brake shoes friction material remains in a stable state, without melting or losing its structural and functional properties.

The high – hardness corundum significantly extends the service life of brake shoes. In real – world applications, brake shoes with corundum can endure up to 3 times more braking cycles compared to those without it. This not only reduces the frequency of replacement for vehicle owners but also enhances the overall safety and reliability of the braking system, especially in heavy – duty vehicles that require frequent and intense braking.

Thanks to its high melting point and good thermal conductivity, corundum – based brake shoes can maintain stable braking performance even under extreme heat. In continuous high – speed braking tests, the friction coefficient of corundum – containing brake shoes remained within a stable range of 0.35 – 0.45, while that of non – corundum brake shoes dropped to 0.2 – 0.25 due to overheating. This stable friction coefficient is essential for ensuring consistent and reliable braking force.

Corundum is highly chemically stable and does not react readily with other components in the brake shoes mixture. This chemical inertness guarantees the long – term stability of the brake shoes’ performance. Over a period of 5 years of storage and normal use, the friction coefficient and mechanical strength of corundum – containing brake shoes showed less than a 5% change, indicating its excellent resistance to chemical degradation.

Despite its many advantages, corundum is brittle. Under sudden and intense mechanical stress during emergency braking, the corundum particles within the brake shoes may fracture. In a high – speed emergency braking simulation, cracks were observed in the friction material of corundum – containing brake shoes, which led to an uneven wear pattern and a 15 – 20% reduction in braking efficiency.

The production and refinement of high – quality corundum involve complex and energy – intensive processes, resulting in a relatively high cost. Incorporating corundum into brake shoes can increase the production cost by 50 – 70% compared to traditional friction materials. This cost factor can be a significant barrier to its widespread adoption, especially in price – sensitive mass – market brake shoe manufacturing.

Due to its hardness and irregular particle shape, corundum is challenging to disperse uniformly in the brake shoes mixture. Uneven dispersion can cause inconsistent performance. In some samples with poor corundum dispersion, certain areas of the brake shoes had excessive wear resistance but insufficient heat dissipation, while other areas experienced rapid wear and reduced braking performance.

In conclusion, corundum offers significant advantages in terms of wear resistance, heat resistance, and chemical stability in brake shoes production. However, its brittleness, high cost, and dispersion challenges must be carefully addressed. Brake shoe manufacturers need to conduct in – depth research and development to find solutions that can fully utilize the benefits of corundum while minimizing its drawbacks, based on the specific requirements of different vehicle types and market demands.