Anodization: Recent Advancements on Corrosion Protection of Brake Calipers

Brake calipers for high-end cars are typically realized using Aluminum alloys, with Silicon being the most common alloying element. Despite the excellent castability and machinability of AlSix alloys, anodization is often necessary in order to provide to AlSix components the required corrosion resistance or when the braking system has to withstand to severe chloride-rich environments [1]. Even if the anodization process is known for almost 100 years, a continuous research and process optimization can lead to the development of anodic layers with enhanced morphological and electrochemical properties, which enable a prolonged resistance of calipers under endurance corrosive tests (e.g. >1000hours Neutral Spray Tests). At this regard, in this work, a lab-scale anodization setup and electrochemical techniques are used in order to investigate the interplay between anodic oxidation parameters (e.g. current pulse shape), oxide layer morphology (e.g. porosity and homogeneity) and corrosion resistance of anodized aluminum-alloys. Electrochemical figures of merit (e.g. corrosion potential, corrosion current, breakdown potential, etc.) and metallographic techniques are used to: a) evaluate several oxide layers properties; and b) provide insights on the effect of anodization parameters on the anodic layer performance. This work identifies key points regarding the efficacy and efficiency of Aluminum anodization process, with the final aim of extending the corrosion resistance of future braking systems [2]. References: [1] M. Bandiera, A. Bonfanti, A. Mauri, A. Mancini, M. Bestetti, F. Bertasi, “Corrosion Phenomena in Braking Systems”, CORROSION/20, paper no. 14680 (Houston, TX: NACE, 2020) [2] F. Bertasi, A. Mancini, M. Bandiera, S. Pin, A. Casini, A. Bonfanti, “Interplay between Composition and Electrochemical Performance at the Pad-Disc Interface”, EUROBRAKE, paper no. EB2019-MDS-018 (Stansted, UK: FISITA, 2019)