Investigation of hybrid PEO coatings on AZ31B magnesium alloy in alkaline K2ZrF6–Na2SiO3 electrolyte solution

Effect of Pulse Current Mode on Microstructure, Composition and Corrosion Performance of the Coatings Produced by Plasma Electrolytic Oxidation on AZ31 Mg Alloy

“…Thickness, phase composition, surface morphology and micro-structure are the important factors influencing the corrosion performance of PEO coatings in corrosive environments. In this way, the phase composition plays a crucial role at short times, while the porosity and thickness are influencing factors at long times [41,42]. MgF 2 is responsible to form a more compact barrier layer with less porosity on the surface of Mg alloy substrate [28].…”

Investigation on Corrosion Resistance and Formation Mechanism of a P–F–Zr Contained Micro-Arc Oxidation Coating on AZ31B Magnesium Alloy Using an Orthogonal Method

“…The reason behind this may result from the different moving speed of HF2 − or F − from NH4HF2 and ZrF6 2− from K2ZrF6 in a water solution. Due to a comparatively large spatial structure [43], ZrF6 2− moves slower in a water solution than HF2 − or F − . As shown in Figure 7, with the increasing K2ZrF6 concentration, the Zr amount in anodic coatings increases significantly, while the F amount slowly decreases.…”

Corrosion and wear resistance of coatings produced on AZ31 Mg alloy by plasma electrolytic oxidation in silicate-based K2TiF6 containing solution: Effect of waveform

“…Also, PEO coatings could be a basis for the formation of composite coatings, for example, by applying various substances and additives to a rough oxide surface and embedding them into the pores of the outer layer [ 4 , 8 ]. Compounds containing fluorine such as KF [9] , K 2 TiF 6 [10] , and K 2 ZrF 6 [11] are considered the most useful additives to form thick and dense coatings on Mg alloys with high hardness, corrosion, and wear resistance. Previous studies on PEO in phosphate and silicate-based electrolyte using DC or unipolar waveform revealed that the formation of the MgF 2 phase at the coating/substrate interface is promoted by the addition of K 2 TiF 6 in the electrolyte, with the consequently improved corrosion resistance of the coatings [12][13][14] .…”