Corundum, a crystalline form of aluminum oxide, has found its application in the production of brake shoes. When incorporated into brake shoes mixtures and mixes, it significantly impacts the performance of brake shoes friction materials. Let’s take a closer look at its technical parameters, advantages, and disadvantages.

Corundum is extremely hard, ranking 9 on the Mohs scale. This high hardness value provides excellent wear – resistance to the brake shoes friction materials. For example, in a wear – test over 100,000 braking cycles, brake shoes with 20% corundum by volume showed a wear depth of only 0.5 – 1 mm, while those without corundum had a wear depth of 2 – 3 mm.

It has a moderate thermal conductivity of about 25 – 30 W/(m·K). During the braking process, when the temperature at the friction surface can reach high levels, this thermal conductivity helps in dissipating heat. In a high – speed braking experiment where the temperature at the friction surface without corundum reached 400°C, the addition of corundum reduced the peak temperature to around 350°C, which helps in maintaining the integrity of the friction material.

The density of corundum is approximately 3.95 – 4.1 g/cm³. This relatively high density can contribute to the mass of the brake shoes, which affects the inertia during braking. However, when properly balanced in the mixture, it can enhance the overall braking performance.

Due to its high hardness, corundum significantly improves the wear resistance of brake shoes. In long – term use, brake shoes with corundum can last 2 – 3 times longer than those without it. This not only reduces the frequency of brake shoe replacement but also improves the safety and reliability of the braking system.

Corundum can withstand high temperatures without significant degradation. In extreme braking conditions where the temperature of the friction material can exceed 300°C, corundum – containing brake shoes can maintain their mechanical and frictional properties. This helps in preventing brake fade, ensuring consistent braking performance.

It is chemically stable and does not react easily with other components in the brake shoes mixture. This stability ensures the long – term performance of the brake shoes, as it does not cause any chemical changes that could affect the friction coefficient or mechanical strength of the friction material.

Corundum is brittle, which can be a drawback in the context of brake shoes. In some cases, under sudden and extreme mechanical stress during braking, the corundum particles in the brake shoes may break. This can lead to uneven wear of the brake shoes and potentially affect the braking performance. For example, in emergency braking situations, the brittleness of corundum may cause small cracks to form in the friction material, reducing its effectiveness.

The production and processing of high – purity corundum are relatively expensive. Incorporating corundum into brake shoes can increase the production cost by 40 – 60% compared to traditional friction materials without it. This cost factor may limit its widespread use, especially in mass – market brake shoes where cost – effectiveness is a crucial consideration.

Due to its hardness, corundum is difficult to process and disperse evenly in the brake shoes mixture. Uneven dispersion can result in inconsistent performance of the brake shoes. Some areas may have excessive wear resistance but poor heat dissipation, while others may have the opposite problem.

In summary, corundum offers remarkable wear resistance, heat resistance, and chemical stability in brake shoes production. However, its brittleness, high cost, and processing difficulties pose challenges. Brake shoe manufacturers need to carefully evaluate these factors based on the specific requirements of their products and the market they target.