Recai Kus

Investigation of microstructure and mechanical properties of steel fibre–cast iron composites

Abstract The aim of the present experimental study was to investigate improvement of the toughness and strength of grey cast iron by reinforcing with steel fibres. The carbon content of the steel fibres was chosen to be sufficiently low that graphite flakes behaving as cracks were removed by carbon diffusion from the cast iron to the steel fibres during the solidification and cooling stages. To produce a graphite free matrix, steel fibres with optimum carbon content were used and the reinforced composite structure was cast under controlled casting conditions and fibre orientation. Three point bend test specimens were manufactured from steel fibre reinforced and unreinforced flake graphite cast iron and then normalising heat treatments were applied to the specimens at temperatures of 800 and 850°C. The fracture toughness and strength properties of the steel fibre reinforced material were found to be much better than those of unreinforced cast iron. The microstructures of the composite at the fibre–matrix transition zone were examined.

Effect of Pressing Pressure on Density and Hardness of Powder Miscanthus Reinforced Brake Pads

The aim of this paper is to develop new natural fibre reinforced for automotive brake pad application. For this purpose, new brake pad sampleswere produced using Miscanthus as reinforcement ingredient. The other ingredients are Cashew, Alumina, Phenolic Resin, and Calcite. Three different laboratory formulations were prepared with varying Miscanthus fibre contents from 10, 25, and 40 (wt) and these formulations were moulded four different moulding pressure values such as 50, 100, 200, and 300 MPa. Sieve analysis, density, apparent density, and hardness properties of brake pad samples produced are examined.

Tribological performance characterization of brake friction materials: What test? What coefficient of friction?:

This article describes and explains the tribological tests and methods for the evaluation of the performance of the brake friction materials. It starts by discussing the particularities of these materials and the variation of characterization tests, which can experimentally simulate many aspects of brake situation but with a large field of tribo-test, from standard to specific protocol. Examples of preparation, procedures, instrumentation, and analysis results for the tribological aspect testing ranging from the scale of vehicle braking performance (by methods including inertia dynamometers, Krauss testing, friction assessment screening test, and Chase testing) to simplified test using reduced-scale prototypes for small-sample friction, are explained. A particular attention is attributed to the discussion of the viability of the friction coefficient report in relation to the material properties and brake compound performance. At the end of this article, the guarantee of the performance output or ranking evaluated by such experimental methods is discussed.

Investigation of Friction Coefficient for Twaron-Reinforced Brake Shoe Materials

After the adverse effects of asbestos used in brake shoes on vehicles were come up, the researches on ecological shoe material have been carried out by many researchers. From this point forth, four different twaron-reinforced composite materials, which could be brake shoes, were produced in this study. Samples were produced in double acting press at a pressure of 100 MPa at 160°C by mixing the components used in powder form in a mixer. The samples were cured at 160°C for 6 hours. After curing, produced samples and those taken from commercial shoes were compared by performing hardness pin-on-disc wear tests (ASTM G99-95). When the results are evaluated in terms of hardness, it was observed that 20% twaron-reinforced sample has the highest hardness (116,88 Rockwell-R), but when evaluated in terms of friction, it was seen that while 5% twaron-reinforced sample satisfies highest friction coefficient, 10% twaron-reinforced sample exhibits close values to the commercial brake shoe at varying loads and showed a stable friction performance.

The effect of the brake pad components to the some physical properties of the ecological brake pad samples

In this study, brake pad components in powder form such as miscanthus, cashew, alumina, phenolic resin and calcite, were used to manufacture ecological brake pads. In the brake pad applications trial and error method is often used to find the optimum proportion providing the best characteristics of the component in composite. The evaluation process became complicated and time consuming due to the number of components used for the manufacture of brake pad, randomly selected mixing ratios, many samples produced with trial and error method and a vast variety of results obtained from the measurements. Taguchi method was utilized in order to determine how the compositions of the brake pad components in the range of 5-20 wt. % had an effect on the properties of the brake pads. As a result of the experiments such as density, hardness, porosity and wear rate, the characteristics of the brake pad samples were more affected by the proportions of Miscanthus and phenolic resin in the mixture.