Complementary corrosion protection of cast AlSi7Mg0.3 alloy using Zr-Cr conversion and polyacrylic/siloxane-silica multilayer coatings

Peter Rodič (Author), Barbara Kapun (Author), Ingrid Milošev (Author)

Abstract

Aluminium cast alloy AlSi7Mg0.3 is a lightweight metal commonly used in automotive, aeronautical and mechanical applications. It has good corrosion resistance but, under harsh operative conditions, would benefit from additional protection. In this study, a corrosion-protective multilayer coating system for AlSi7Mg0.3 based on hexafluoro-zirconated trivalent chromium coating (Zr-CrCC) and polyacrylic/siloxane-silica (PEHA-SS) coating was developed. The Zr-CrCC was formed by immersion of the substrate in a commercial conversion bath (SurTec® 650). PEHA-SS synthesis was based on organic precursors (2-ethylhexyl acrylate and [3-(methacryloyloxy)propyl]trimethoxysilane) and an inorganic precursor, tetraethyl orthosilicate. After deposition on AlSi7Mg0.3, each coating was first characterised individually, followed by the analysis of the multilayer using scanning electron microscopy and energy-dispersive X-ray spectroscopy. The adhesion of the coatings was evaluated with a cross-hatch cut test. The corrosion studies in sodium chloride solution using electrochemical impedance spectroscopy and salt spray testing showed that the multilayer system is superior to individual Zr-CrCC and PEHA-SS coatings. After 4 months in 0.1 M NaCl, the multilayer-coated samples exhibited the impedance at 10 mHz in the range of GΩ cm2, while scribed samples withstood the corrosion attack in a salt spray chamber for one week. Thus, albeit only about 100 nm thick, the Zr-CrCC deposited between the substrate and a 9-micrometre thick barrier sol-gel PEHA-SS coating acts as an active corrosion protection interlayer and contributes to the overall protectiveness of the multilayer system.

Keywords

korozija;zaščita;aluminij;corrosion-protective;aluminium;material;

Data

Language:	English
Year of publishing:	2024
Typology:	1.01 - Original Scientific Article
Organization:	IJS - Jožef Stefan Institute
Publisher:	Springer Nature
UDC:	620.1/.2
COBISS:	197709827
ISSN:	2397-2106
Views:	112
Downloads:	58
Average score:	0 (0 votes)
Metadata:

Other data

Secondary language:	Slovenian
Secondary keywords:	korozija;zaščita;aluminij;
Source comment:	Nasl. z nasl. zaslona; Opis vira z dne 4. 6. 2024;
Pages:	str. 1-16
Issue:	ǂVol. ǂ8, article no. 58
Chronology:	May 2024
DOI:	10.1038/s41529-024-00467-5
ID:	26230455