Protective and Thermophysical Characteristics of Plasma-Electrolytic Coatings on the Ultralight Magnesium Alloy

Abstract

Magnesium alloys are now widely used for various purposes due to their unique properties despite the significant disadvantage associated with low corrosion resistance. The plasma-electrolytic oxidation (PEO), which allows the formation of ceramic coatings on the surface of magnesium alloys, is the most advanced and effective method for their protection. But firstly, PEO process of magnesium alloys has some difficulties, and secondly, PEO coatings affect the thermophysical characteristics of the modified materials, in particular they reduce thermal diffusivity. The presented work is devoted to the development of the technological parameters for formation of protective coating on the ultra-light alloy Mg-8Li-1Al-0.6Ce-0.3Y by the PEO method. The results analyses of electrolytes acidity and specific electrical conductivity before and after PEO process and also investigation data of the coatings structure and surface morphology are presented. An integral assessment of the ability of thermal diffusivity and corrosion resistance of the modified alloy was made. Studying of protective and thermophysical characteristics of the obtained coating showed that it provides a sufficiently high corrosion protection, despite the relatively small thickness, and the presence of pores and slightly (not more than 5%) reduces the thermal diffusivity of the magnesium ultra-light alloy.

Obtaining and plasma-electrolyte modification of fibers of ultralight magnesium alloy

“…The fibers ignited and burned at the initial stages of initiation of the microdischarges. A similar situation was observed when using an electrolyte of the composition 10 mL/L (Na 2 O) m (SiO 2 ) n + 3 g/L КОН + 4 g/L KF⸱2H 2 O which showed its operability when treating a compact alloy Mg-8Li-1Al-0,6Ce [11].…”

“…The elemental composition of the alloy after conversion into the fiber state has not changed significantly (figure 3). Attempts of plasma-electrolyte treatment of fibers confirmed the presence of problems noted in our previously studies [11]. Using the electrolyte and the mode we tested earlier for ML10 alloy did not give an acceptable result.…”

“…To the encourage result was led by the treatment in electrolyte 1.2 g/L КОН + 15 g/L NaAlO 2 [11], but at the same time a softer electric mode was required. A more or less continuous coating with a thickness in range of 1-2 μm on the Mg-8Li-1Al-0.6Ce-0.3Y alloy were getting to form during processing for 5 minutes in the aluminum-alkaline electrolyte.…”

“…Before PET, fibers were degreased in ethanol and then dried in the open air during 5 min. The PET treatment technique and the equipment used are described in [10,11]. The PET process was carried out on the capacitor-type equipment in the anodic-cathodic mode at the different current densities in the voltage range of 300-500 V and the currents ratio I an /I cat range of 0.8-1.2.…”

Effects of Altering Magnesium Metal Surfaces on Degradation In Vitro and In Vivo during Peripheral Nerve Regeneration

“…PEO is a relatively inexpensive and environmentally friendly technique, especially when non-toxic elements are used. The resulting coatings from the PEO method possess sufficient wear and corrosion resistance as well as desirable electrical properties and high thermal stability [ 15 , 16 , 17 , 18 , 19 , 20 ].…”