Investigation of the effect of sepiolite clay, silica aerogel fillers and cnsl content on the properties of organic brake pad composites

Friction materials have an important place in both highways and railways. Brake pads are mainly produced by a mixture of four main groups of materials: binders, reinforcements, friction modifiers and fillers. Selecting these materials in appropriate ratios and optimizing them according to the desired properties of the final product has a crucial effect on both the mechanical and tribological properties of brake pads. It is seen in the literature that many different types of materials are used to improve these properties. In this study, sepiolite clay and silica aerogel, which to our knowledge was never used for this purpose, were used as alternative fillers in organic brake pad composite materials. Composites with different amounts of these fillers were prepared and their density, porosity, friction and wear properties were characterized. The effect of the content of cashew nut shell liquid (CNSL) on the properties of the composites was also investigated. The results show that, the sepiolite clay used as filler clearly increases the hardness of the composites, while the silica aerogel filler has a decreasing effect on the hardness. While both fillers did not show a significant effect on the friction coefficient level, they have a positive effect on the wear properties as they relatively decrease the specific wear rate. An improved friction stability was also observed for some compositions. It is well known that synergistic effects between different fillers can be used in friction materials. Sepiolite clay and silica aerogel combined with an optimum CNSL content are good candidate for future researches and uses in organik brake pad composites.