For friction composite brake pads, the determination of usage and investigation of the effects of domestic fly ash contribution to the features of friction brake pads

Brake pad is one of the most important safety and performance parts for vehicles. Pad materials are categorized as metallic, semi-metallic, composite and carbon-based types. Many of brake pads are composite brake pads containing more than 10 additives. These additives include binders, rein forcefibers, friction modifiers and fillers. Pads are expected to have performance characteristics such as stable coefficient of friction, low wear rate, environmentally friend, light weight, long life, low noise, corrosion resistance along with acceptable costs. There are over 2000 publications regarding the brake pads mainly employed in automotive industry and aviation and railways. Many trials and experimentations have been carried out for composite brake pads with respect to many different additives and mixture ratios and different characteristics have been obtained at the end. It is important in the production of brake pads that optimal mixture formulation and process conditions for optimum functionality are applied for acceptable cost. Especially in recent years, regarding that the waste material "fly ash" from thermal power plants, which includes SiO2, Al2O3, Fe2O3 in its composition, are being used in the pad formulations, Studies have been carried out to employ the waste material hazardous to the environment by recycling it in the pads materials thus reducing the production costs. However, just like all the coal types used in the thermal power plants are not similar, the composition and the quantity of fly ash types are not the same. In this thesis first a detailed literature research was made in the topics of brake pads containing fly ash, characterization, testing, standards, formulation and process parameters. Commercial composite brake pad samples were investigated. Characterizations of fly ash samples obtained from different power plants were made and fly ash types which can be used in the production of brake pads were identified. In this thesis formulations that contain 5-40 %wt. fly ash were developed and samples were produced in laboratory scale. Physical, mechanical, chemical as well as tribological tests were applied to determine the optimum formulation and production terms. Result of thesis especially formulations which include Yeniköy and Kemerköy Power Plants fly ash 40 %wt. as filler exhibited the closest tribological properties to commercial brake pads. Proper brake lining composition which 40% wt. Yenikoy thermal power plant fly ash, 20% wt. novolac type phenolic resin, 5% wt. aramid wool, 15% wt. rock wool, 10% wt. graphite, 5% wt.petroleum coke, 5% wt. Sb2S3 has been determined. This compositions is mixed homogenly and the prepared composition is hot moulded under 25 MPa pressure at 150C in 10 minutes and the prepared sample is post cured in an air circulated oven 3 hours at 180C. Eventually prototype railway brake pads was produced.