Identification of the Corrosion Mechanism of Brass-Coated Steel Wires in Cords Assembly
- PDF / 3,526,146 Bytes
- 10 Pages / 593.972 x 792 pts Page_size
- 73 Downloads / 209 Views
UCTION
NOWADAYS, composite materials are one of the solutions to improve the mechanical properties of structures such as in civil engineering and aerospace applications. In the automotive industry, composite polymer metals are used in cars and tires. The latter are defined as multi-material structures dealing with polymer chemistry and metals and involving complex interfaces. In the literature, the adhesion mechanisms between the cords and rubber are well documented[1–3] as they control the initial mechanical properties of the composite material. The strong adhesion is given by the crystallization and growth of copper sulfides.[1,4,5] Patil and Ooiji showed that the formulation of the polymer plays a role in the sulfide layers resulting in different bond properties.[4] They also showed that the sensitivity of the polymer to humidity aging is a crucial point in terms of adhesion properties. Indeed, the humidity affects the chemistry of the sulfide layers and causes
ALEXANDRE ROMAINE, MARTIAL CROZET, BERNARD NORMAND, JE´ROˆME ADRIEN, and NICOLAS MARY are with the Univ Lyon, INSA Lyon, MATEIS UMR 5510 CNRS, 69621 Lyon, France. Contact e-mail: [email protected] FABIEN DUFOUR and APOLLINE LECERCLE are with the Manufacture des pneumatiques MICHELIN, BP 63040, Clermont-Ferrand Cedex 9, France. Manuscript submitted February 13, 2020.
METALLURGICAL AND MATERIALS TRANSACTIONS A
locally iron dissolution. Also, long-term exposition experiments in liquid rubber (i.e., squalene) or using the filter paper technique show the role of the germination of corrosion scales enriched into iron in the degradation of the metal-polymer interface.[2,6] These works highlight that the corrosion mechanism is known to enhance the life cycle of polymer brass-coated steel composites.[7] For brass, the mechanism of degradation depends on the brass microstructure and is controlled by the concentration in Zn.[8,9] For a single-phase microstructure (mainly type a for Zn < 33 wt pct), the brass is subjected to a selective dissolution favored by a non-uniform distribution of copper and zinc. Within the first hours of immersion, zinc dissolves preferentially compared to copper because of its lower corrosion potential.[8,10,11] The dezincification kinetic is enhanced by the temperature confirming a thermodynamically activated mechanism.[12] Simultaneously to the dezincification, a copper enrichment on the surface is detected. This modification of the surface chemistry can be described by two models still under discussions. The first model is based on the precipitation of metastable compounds (e.g., Cu2SO4, CuCl2) and their stabilization into pure copper or oxide copper.[13,14] The second model suggests a natural copper enrichment of the surface due to a lower dissolution kinetic compared to zinc.[15–17] Irrespective of the model, environmental parameters such as the material potential in solution and the oxidant power of the solution (e.g., pH, redox
species) affect the kinetics formation of copper products and their thermodynamic stability.[14,18] The elec
Data Loading...
