Dual-Layer Corrosion-Resistant Conversion Coatings on Mg-9Li Alloy via Hydrothermal Synthesis in Deionized Water

Abstract

The formation of a corrosion-resistant coating by the hydrothermal method is an effective way to provide significant protection to magnesium alloys. However, it is a challenge to prepare such a coating on magnesium-lithium alloys because of its high chemical activity. Herein, the dual-layer structured corrosion-resistant conversion coating composed with Mg(OH)2 and LiOH was successfully synthesized on Mg-9Li alloy by the optimization of the hydrothermal reaction in deionized water. The coating synthesized at 140 °C for 2 h has the best anti-corrosion performance in all obtained coatings, which has a uniform and compact coating with thickness of about 3 μm. The improvement of the hydrophobicity due to the stacking structure of the surface layer, as well as the barrier effect of its inner compact coating on corrosive media, lead to the excellent anti-corrosion performance of the obtained hydrothermal conversion coating

The Preparation, Corrosion Resistance and Formation Mechanism of a New-Type Mo-Based Composite Conversion Coating on 6061 Aluminum Alloy

“…The i corr values of the Al alloy matrix, MoTiCC and MoTiZrCC were 5.13 × 10 −5 , 1.91 × 10 −5 and 1.04 × 10 −5 A/cm 2 , respectively. It is quite evident that the i corr of the MoTiZrCC was the lowest, indicating that the MoTiZrCC can significantly reduce the corrosion rate [25,26].…”

“…The icorr values of the Al alloy matrix, MoTiCC and MoTiZrCC were 5.13 × 10 −5 , 1.91 × 10 −5 and 1.04 × 10 −5 A/cm 2 , respectively. It is quite evident that the icorr of the MoTiZrCC was the lowest, indicating that the MoTiZrCC can significantly reduce the corrosion rate [25,26]. As a supplement, the polarization resistance (Rp) was introduced in order to characterize comprehensive effect of the interfacial charge transfer resistance and CC resistance, and further used to evaluate the drag force of the corrosion behavior.…”

Comparing three strategies for surface treatment of Mg coated by hexamethylene diamine tetra methylene phosphonic acid for corrosion protection

“…To deal with this problem, it is necessary to study some appropriate surface pretreatments on Mg such as phosphating, alkalization, and fluoridation. 12,13 Phosphating treatment is a conversion coating mostly adopted in industry to manipulate the corrosion rate of magnesium alloys due to many purposes: its low-cost, superiority, and operation convenience. 14,15 Furthermore, phosphating has the ability to enhance the biocompatibility of biomedical magnesium alloys.…”

“…However, direct coating for magnesium alloy is strongly inhibited because of the fast degradation of the substrate in the coating solution. To deal with this problem, it is necessary to study some appropriate surface pretreatments on Mg such as phosphating, alkalization, and fluoridation 12,13 …”

A Study on Functional Hydrophobic Stainless Steel 316L Using Single-Step Anodization and a Self-Assembled Monolayer Coating to Improve Corrosion Resistance

“…This means that the lower the value of the surface energy, the greater the water repellency; i.e., the higher the value, the more hydrophilic the surface. These characteristics are determined by the nano-and micro-sized structures of the surface [13,14]. Methods used to prevent the generation of these structures on the surface include the application of a chemical conversion coating, as well as plasma electrolytic oxidation [15].…”