APRIMORAMENTO DE MATERIAL DE FRICÇÃO COM MATRIZ DE COBRE UTILIZANDO DESIGN OF EXPERIMENTS (DOE) PARA AVALIAR O EFEITO DO GRAFITE E DA SÍLICA NAS PROPRIEDADES TRIBOLÓGICAS

Brake pads are essential components in vehicle braking systems, converting kinetic energy into heat through friction and dissipating it. To ensure proper performance, the pads must maintain a stable and high coefficient of friction (COF), as well as possess wear resistance, high thermal conductivity, and smooth braking capability. The present study aimed to develop sintered brake pads with a homogeneous metallic matrix, using an effective powder mixture, and to optimize the friction material formulation through the use of Design of Experiments (DOE) between abrasive (silica) and solid lubricant (graphite). The manufacturing process of the pads involved three main stages: mixing, cold uniaxial compaction, and sintering. The mixture was designed to ensure particle homogeneity, using 0.5%wt. of kerosene to prevent graphite segregation. The samples were compacted at 500 MPa and sintered at 1050°C in a controlled atmosphere (95% Ar + 5% H₂). The tribology test was conducted using a Universal Mechanical Tester (UMT) 3MO tribometer, with specific parameters to measure the coefficient of friction and wear rate. The results showed that particle homogeneity was a critical challenge, resolved with the use of kerosene. The DOE varied the silica content (10 to 15% vol.) and graphite (15 to 20% vol.) to optimize tribological properties. Silica and graphite were statistically significant in the COF response and sample wear rate, while their interaction was not significant for COF. Silica increased the COF, while graphite reduced both the COF and the sample wear rate.