Abstract This research is focused on the effect of porosity on the friction-wear properties of automotive brake pads. Waste Tire Dust (WTD) was used as a new friction material in brake pads. Newly formulated brake pad materials with five different components have been produced by conventional techniques. In the experimental studies, the change of the friction coefficient, the temperature of the friction surface, the specific wear rate, and the hardness, density and porosity were measured. In addition, the micro-structural characterizations of brake pads are determined using Scanning Electron Microscopy (SEM). The mean coefficient of friction, porosity and specific wear are increased due to a WTD rate increases, on the other hand, hardness and density are decreased. As a result, WTD can be considered as an alternative to revalorize this kind of waste products in the brake pads and the amount of porosity of the brake pad affected the friction coefficient and wear behavior of the pad.

PURPOSE: To investigate the effect of platelet rich fibrin (PRF) and beta tricalcium phosphate (β-TCP), alone or in combination, on bone regeneration in pig tibial defects.METHODS: Four standardized defects were prepared in both tibias of three adult male pigs. The first defect was left unfilled as a control; the others were grafted with either PRF, β-TCP or PRF mixed with β-TCP. All animals were sacrificed on the 12th postoperative week and the tibial bones were removed, histologic sections were prepared and the experimental sites were examined microscopically and stereologically.RESULTS: Histologic and stereologic examination revealed more new bone formation in the defects filled with PRF mixed β-TCP than in the defects grafted with either β-TCP or PRF alone.CONCLUSION: The platelet rich fibrin and beta tricalcium phosphate combination effectively induces new bone formation.