Comparative Study on the Corrosion Resistance of 6061Al and SiC3D/6061Al Composite in a Chloride Environment.

Liang Yu,Shuangshuang Hao,Xiaodong Nong,Chen Zhang,Yanli Jiang,Yulong Yan,Yuan Liu,Xiuling Cao

doi:10.3390/ma14247730

Abstract

Interface problems and the destruction of the continuity of the oxide film in the Al matrix usually reduce the corrosion resistance of the material. In this paper, the corrosion resistance of Al matrix composites (AMCs) was improved by introducing the silicon carbide skeletons (SiC3D) obtained with polymer replica technology. SiC3D/6061Al was fabricated by infiltrating molten 6061Al alloy in the oxidized SiC3D using the low-pressure casting method. The corrosion resistance performances of 6061Al and SiC3D/6061Al in NaCl solution were studied by electrochemical, neutral salt spray corrosion (NSS), and salt leaching (SL) tests. Results show corrosion resistance of SiC3D/6061Al is higher than that of 6061Al alloys by open circuit potential (OCP), potentio-dynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS) tests. However, NSS and SL tests show the corrosion resistance of SiC3D/6061Al is lower than that of 6061Al alloy. The reason is a corrosion resistant and anti-oxidation network macrostructure with large interface recombination, few concentrated interfaces, and a small specific area that formed in SiC3D/6061Al. SiC3D cannot damage the continuity of the Al2O3 passivating film, and the network macrostructure greatly improves the corrosion resistance performance.

Highlights

Ceramic-reinforced metal matrix composites (MMCs) mainly include ceramic particlereinforced MMCs and ceramic skeleton-reinforced MMCs [1,2]
High residual stresses are generated at the composite interface during the preparation process due to the mismatch of the expansion coefficient and other physical properties between the Al alloy matrix and the silicon carbide (SiC) particles
A polyurethane open-cell sponge template (Shenzhen Lvchuang Environmental Filter Material Co., Ltd., Shenzhen, China) with 10 PPI (10 pores/inch) and dimensions of 360 × 280 × 7.5 mm3 was immersed into the as-prepared SiC slurry, followed by passing through a preset roller (XLKLYP4, Dongguan Xilong Electrical machinery Equipment Co., LTD, Dongguan, China) to remove the excess slurry

Summary

Introduction

Ceramic-reinforced metal matrix composites (MMCs) mainly include ceramic particlereinforced MMCs and ceramic skeleton-reinforced MMCs [1,2]. SiC particles are difficult to disperse uniformly in the AMCs due to the limitations of the preparation technology [3,4]. The inhomogeneity of the SiC particles’ dispersion may lead to weak parts in the material that severely reduce the corrosion resistance. High residual stresses are generated at the composite interface during the preparation process due to the mismatch of the expansion coefficient and other physical properties between the Al alloy matrix and the SiC particles. An increase in residual stress causes significant changes in the microstructure and properties of the Al alloys near the interface, which significantly reduces the corrosion resistance of the material [5,6,7,8]

Methods

Results

Conclusion