Dr. Federico Bertasi, Brembo S.p.A., ITALY

Dr. Marco Bandiera, Brembo S.p.A., ITALY

Dr. Arianna Pavesi, Brembo S.p.A., ITALY

Dr. Andrea Bonfanti, Brembo S.p.A., ITALY

Dr. Alessandro Mancini, Brembo S.p.A., ITALY

Investigation of the corrosion performance of friction materials (FMs) plays a central role in: a) evaluating the corrosion resistance of braking pads [1]; b) elucidating galvanic couplings among different braking system components [2]; c) designing FMs with a negligible sticking effect upon coupling with a cast iron brake disc [3].

Corrosion performance can be evaluated by measuring proper electrochemical figures of merit [4] such as the: 1) corrosion potential (Ecorr); 2) corrosion current (Icorr); and 3) galvanic current (Igc); in agreement with a suitable test specification. Nevertheless, particular attention should be paid when measuring these quantities since several experimental details can lead to inaccurate or misleading results.

At this regard, the work clarifies the effect of several test parameters (e.g. scan rate, stabilization time, potential ranges, etc.) on the measure of the corrodibility of a reference friction material. Most common errors and their effect on the electrochemical figures of merit are discussed, with the final aim of providing a solid guideline for designing braking pads with a reduced corrodibility.

References:

[1] Bertasi, F., Mancini, A., Bandiera, M., Pin, S., Casini, A., Bonfanti, A., “Interplay between Composition and Electrochemical Performance at the Pad-Disc Interface”, EUROBRAKE, Manuscript no. EB2019-MDS-018 (Stansted, UK: FISITA, 2019), p. 1.

[2] Bertasi, F., Bandiera, M., Bonfanti, A., “Toward a Corrosion Proof Braking System”, SAE Technical Paper, Manuscript no. 2020-01-1625, 2020.

[3] Bandiera, M., Mancini, A., Bonfanti A., Pavesi, A., Pin S., Bertasi, F. “Sticking Phenomena at the Brake Pad – Disc Interface: An Open Call for Electrochemists”, CORROSION/21, Manuscript no. C2021-16429, 2021. (under review).

[4] Bandiera, M., Pin, S., Bonfanti, A., Bertasi, F., Mancini, A., “Physico-Chemical Characterization of Corrosion Scales in Braking Systems”, CORROSION/20, Manuscript no. C2020-14687, 2020.