In the production of brake shoes, silica powder has emerged as a significant additive in brake shoes mixtures and mixes, especially in the composition of brake shoes friction materials. This fine – grained powder brings a unique set of properties that have both positive and negative implications for the performance and manufacturing of brake shoes.

Silica powder can effectively improve the friction stability of brake shoes friction materials. In friction coefficient tests, when 5 – 8% (by weight) of silica powder is added to the brake shoes mixture, the friction coefficient fluctuation range is reduced by about 30 – 40% compared to the mixture without silica powder. For example, in a standard braking test with a speed range from 80 km/h to 0 km/h, the friction coefficient of the brake shoes with silica powder remains relatively stable at around 0.35 – 0.45, while that of the non – silica – containing ones fluctuates between 0.25 – 0.55. This stable friction coefficient ensures more reliable braking performance.

It has a reinforcing effect on the mechanical properties of the brake shoes friction materials. With the addition of silica powder, the tensile strength of the friction materials can increase by 15 – 20%. In a tensile – strength test, the sample without silica powder has a tensile strength of 10 MPa, while the sample with 6% silica powder addition shows a tensile strength of 11.5 – 12 MPa. This enhanced mechanical strength helps the brake shoes withstand the mechanical stress during braking better.

Silica powder also contributes to better heat dissipation in brake shoes. During braking, a large amount of heat is generated. Brake shoes with silica – containing friction materials can dissipate heat 20 – 30% faster than those without it. In a high – speed braking test where the brake shoes temperature rises rapidly, the maximum temperature of the silica – added brake shoes is 100 – 150°C lower than that of the non – silica – added ones, which effectively reduces the risk of brake fade due to overheating.

The use of silica powder increases the production cost of brake shoes. High – purity silica powder is relatively expensive, and adding 5 – 8% of it to the brake shoes mixture can raise the material cost by approximately 10 – 15%. This cost increase may put pressure on manufacturers, especially those in a price – sensitive market segment.

Silica powder has fine particles, which can cause processing difficulties in the preparation of brake shoes mixtures. For example, it is more likely to form agglomerates during mixing. In the mixing process, the probability of agglomeration in the silica – containing mixture is 40 – 50% higher than that in the non – silica – containing mixture. Agglomerates can lead to uneven distribution of components in the brake shoes friction materials, affecting the overall performance of the brake shoes.

In conclusion, silica powder offers significant advantages in terms of friction stability, mechanical property reinforcement, and heat dissipation in brake shoes production. However, the challenges of higher production cost and processing difficulties need to be addressed through appropriate production techniques and cost – control strategies to fully utilize its potential in manufacturing high – quality brake shoes.