Vermiculite, a hydrated laminar mineral, has found its way into the production of brake shoes, playing a role in brake shoes mixtures and mixes, especially within brake shoes friction materials. This unique material endows brake shoes with certain characteristics, which come with both advantages and disadvantages.

Vermiculite exhibits excellent high – temperature resistance properties. It can withstand temperatures up to 800°C without significant decomposition. In the context of brake shoes, during heavy – duty braking, the temperature of the friction materials can rise rapidly. Brake shoes with 10% vermiculite in their friction materials were tested under extreme braking conditions, and when the temperature reached 600°C, the structure of the friction materials remained stable. The friction coefficient also maintained a relatively stable value, around 0.38 – 0.42, ensuring reliable braking performance.

Vermiculite has good sound – absorbing capabilities. When brake shoes are in operation, they often generate noise due to friction between the brake components. Incorporating vermiculite into the brake shoes mixture can effectively reduce this noise. Laboratory measurements show that brake shoes with vermiculite can reduce braking noise by 8 – 12 decibels compared to those without it. This results in a quieter and more comfortable driving experience.

Vermiculite is a lightweight material, which can contribute to reducing the overall weight of the brake shoes. In addition, it is relatively inexpensive. Using vermiculite in brake shoes mixtures can cut down the production cost by approximately 10 – 15%. This cost – effectiveness makes it an attractive option for brake shoe manufacturers aiming to balance cost and performance.

One of the main limitations of vermiculite is its relatively low mechanical strength. When used in high – stress braking situations, the brake shoes with vermiculite – containing friction materials may be more prone to wear and damage. In a mechanical stress test, brake shoes with a high proportion (20%) of vermiculite in their friction materials showed a 30% higher wear rate compared to those with a lower proportion. This could potentially lead to a shorter service life of the brake shoes.

Vermiculite has limited chemical resistance. In a chemical resistance test, when the brake shoes with vermiculite – based friction materials were exposed to certain chemicals in the braking environment, such as brake fluid containing specific additives, after 2 months, the performance of the friction materials started to degrade. The friction coefficient became less stable, fluctuating by ±0.08, which may affect the braking performance.

In summary, vermiculite offers advantages like high – temperature resistance, sound absorption, and cost – effectiveness in brake shoes production. However, its low mechanical strength and limited chemical resistance are factors that need to be carefully considered and addressed when formulating brake shoes friction materials.