Thermal decay refers to the phenomenon that the brake effect decreases or even fails after the temperature of the brake pad (or brake disc) rises to a certain extent (this is quite dangerous, so the critical temperature of thermal decay is very important)，The obvious feeling is that the effect of stepping on the brakes is not obvious. Different brake pads have different thermal decay temperatures, Original brake pads are generally at 250°C-280°C, and good brake pads must be at least above 350°C. You can imagine which one is safer. 

When the braking strength and time continue to increase and the temperature continues to rise, the internal material of the brake pad will undergo chemical changes, causes a change in the molecular structure that affects the braking effect, this is called ablation. The symptom of ablation is that the surface of the brake is shiny and mirror-like, which is the high-temperature crystallization structure of the brake pad material after ablation. After the heat decay cools down, the brake pads will naturally recover their braking ability, but the ablation is different, it is not recoverable. Once the brake pad is ablated, its braking ability is almost completely lost. In order to ensure safety, it must be dealt with immediately. If the situation is mild, it must be polished with sandpaper, and if the situation is serious, it can only be replaced.