Ultrasonic Treatment Induced Fluoride Conversion Coating without Pores for High Corrosion Resistance of Mg Alloy

Abstract

Fluoride conversion (MgF2) coating with facile preparation and good adhesion is promising to protect Mg alloy, but defects of pores in the coating lead to limited corrosion resistance. In this study, a compact and dense MgF2 coating was prepared by the combination of fluoride treatment and ultrasonic treatment. The ultrasonically treated MgF2 coating showed a compact and dense structure without pores at the frequency of 28 kHz. The chemical compositions of the coating were mainly composed of F and Mg elements. The corrosion potential of the ultrasonically treated Mg alloy shifted towards the noble direction in the electrochemical tests. The corrosion current density decreased due to the protectiveness of MgF2 coating without defects of pores or cracks. During immersion tests for 24 h, the ultrasonically treated Mg alloy exhibited the lowest H2 evolution (0.32 mL/cm2) and pH value (7.3), which confirmed the enhanced anti-corrosion ability of MgF2 coating. Hence, the ultrasonically treated fluoride coating had great potentials for their use in anti-corrosion applications of Mg alloy.

Potential bioactive coating system for high-performance absorbable magnesium bone implants

“…Another bioactive chemical conversion coating is fluoride conversion coating which forms an insoluble Mg fluoride (MgF 2 ) layer. Ultrasonic fluoride treatment and double layer Mg/fluoride-Mg/phosphate treatments increased Mg alloys’ corrosion resistance, biocompatibility and bioactivity [ 155 , 156 ].…”

A Comprehensive Review on Surface Modifications of Biodegradable Magnesium-Based Implant Alloy: Polymer Coatings Opportunities and Challenges

“…As a result, the future focus may be on enhancing the barrier effect and binding force for a full-life corrosion-resistant service. In this regard, composite coating may be a viable option for increasing the adhesion force of organic biopolymer coating [117][118][119][120][121][122][123][124][125][126][127][128][129][130][131][132][133][134]. Furthermore, the formation of composite coatings not only improves corrosion resistance but also endows the Mg alloys with potential bioactivity and biocompatibility in long-term tests.…”

Progress in bioactive surface coatings on biodegradable Mg alloys: A critical review towards clinical translation

“…Under chronic exposure, significant loss of dendrite and soma of neurons induced down-expressions and other behavioural deficits [ 6 , 100 ]. Fluoride Conversion Coatings (FCCs): Several authors [ [101] , [102] , [103] , [104] ] reported the development of FCCs on Mg alloys for biomedical implant applications. The coating procedure is typically performed by immersing Mg or Mg alloy substrates in 40%–48% hydrofluoric (HF) acid solution [ 69 , 105 ].…”