Thanks to its thermal conductivity and coefficient of friction the Copper addition to the organic matrix of disc brake pads provides important functionalities such as
heat dissipation, improved fading resistance and reduction of noise. Due to recently adopted environmental regulations in the USA, in the last years several efforts have been made to replace Copper with alternative materials in braking pads for automotive applications but a direct substitute with a single material having similar characteristics is not yet available. In this research study an Iron-Aluminium composite material named MECHANOMADE FA25® containing 75 wt% Fe and 25 wt% Al has been tested. This material has been specifically designed for friction material applications and has been produced by high energy ball milling (HEBM) technology.
HEBM is a powder processing technique to produce homogeneous materials starting from blended elemental powder. This solid-state synthesis process allows the manufacture of alloys and composites with compositions not accessible by other routes and it creates unique fine microstructures and particle morphology.
The MECHANOMADE FA25® powder particles are made up of interconnected not agglomerated Iron and Aluminum layers and lamellas intimately mixed at micro and
submicro scale with a homogeneous distribution of elements and phases. When comparing to the simple blending of fine Fe and Al particles, the addition by HEBM of Aluminum in the stable Iron matrix develops uniform and outstanding characteristics, it prevents segregation, flammability issues and fast oxidation in the manufacturing cycle of pads as well as during braking operations.
The MECHANOMADE FA25® powder has been tested on low steel formulation disk brake pads substituting water atomized Copper metal powder in the ratio of 1:1 by volume. The physical and mechanical characteristics of the final product (like shear strength, porosity, compressibility, thermal transmission) have shown comparable values with the Copper benchmark. Performances of the material are constant even at high load, they show a low fade, a good recovery, low pad and disc wear.
The physical-mechanical and tribological test results presented in this study show that Mechanomade® FA25 enhances the overall performance of a friction material and can be considered a valid substitute of copper powder in existing formulations and also in future development.
Lorenzon Ivan, Colella Alberto, MBN Nanomaterialia S.p.A, Italy; Delsante, Alessandra, Itaprochim S.r.l, Italy