Contribution to Development of Copper Free Automotive Brake Pad
When passenger vehicle drivers hit the brakes of their cars, the friction releases airborne wear particles from the contact between rotor and brake pad onto the road which are eventually washed down storm drains and into rivers. The wear particles includes copper, which functions as solid lubricant...
|When passenger vehicle drivers hit the brakes of their cars, the friction releases airborne wear particles from the contact between rotor and brake pad onto the road which are eventually washed down storm drains and into rivers. The wear particles includes copper, which functions as solid lubricant for increasing thermal heat fade as well as increasing friction coefficient for the brake pad. Nevertheless, copper not only endangers aquatic life, but it also directly affects the economy by lowering the supply of salmon. Copper is toxic to most aquatic life and is especially harmful to the sensory systems of salmon. Copper impairs salmon's sense of smell, thus reducing their ability to escape from predators. Up to half of the copper found in waterways from urban areas are from copper brake pads and is a key factor in the reduction of salmon population. In 2010, Washington and California each passed laws to ban production of brake pads containing more than 0.5% copper which will be effective in 2025. Since then, several other states including New York, Rhode Island, and Oregon have all introduced similar bills to ban copper brake pads. The raw materials that were added to the newly developed copper free sample brake pads are geopolymers; they are synthetic mineral products that combine properties of polymers, ceramics and cements. Geopolymers have the characteristic of behaving as adhesive rubber in order to replace phenolic resin matrix in the brake materials also it can be harden at room temperature which can increase friction coefficient of the brake pad. Sample brake pads manufactured on site with known constituents were tested with friction assessment and screening test machine, which measured and recorded the friction coefficient and wear of the brake pad. According to the experience in the past, the sample brake pads will be analyzed with density test and Shore Durometer test. The results presented in this report shows that geopolymers brake pad shows promising results for copper replacement for low-metallic friction material. Developed copper free friction sample shows promising result of coefficient of friction of 0.44 with thickness loss of 0.62 mm from friction assessment and screening test machine compare to commercial brake pad.