Influences of Current Density on Tribological Characteristics of Ceramic Coatings on ZK60 Mg Alloy by Plasma Electrolytic Oxidation

Abstract

Current density is a key factor of plasma electrolytic oxidation process. Its influences on structure, mechanical, and tribological characteristics of ceramic coatings on ZK60 Mg alloy by pulsed bipolar microplasma oxidation in Na(3)PO(4) solution were studied in this paper. Thickness, structure, composition, mechanical property, and tribological characteristics of the coatings were studied by eddy current coating thickness gauge, scanning electron microscope (SEM), X-ray diffraction (XRD), nanoindentation measurements, and ball-on-disk friction testing. The results show that all the coatings prepared under different current densities are composed of MgO phase. The amount of MgO phase, thickness and friction coefficient of the coatings increased with the increasing current density. Among three ceramic coatings produced under three current densities, the coating produced under the current density of 7 A/dm(2) got the highest nanohardness and lowest wear rate with the value of 1.7 GPa and 1.27 x 10(-5) mm(3)/Nm.

Influence of electrical parameters on particle uptake during plasma electrolytic oxidation processing of AM50 Mg alloy

“…Fe 3 O 4 and ZrO 2 ) can also be incorporated into the coatings by adding related metal salts to the electrolyte [21,22]. Besides the electrolyte parameters and treated matrix, the process parameters such as applied voltage/current density, frequency and duty cycle have a significant influence on the coating microstructure and properties [23][24][25], which will also determine the uptake and incorporation of particles during PEO processing. It is expected that the amount of incorporated particles will be in direct relation to the applied voltage and current density, since the dispersed particles in the alkaline electrolyte are negatively charged [26] and will move towards the anode continuously.…”

How deposition parameters affect corrosion behavior of TiO2-Al2O3 nanocomposite coatings

“…Ceramic coatings have been recently found promising for a variety of industrial applications in order to improve wear resistance [1][2][3], corrosion resistance [4][5][6][7][8], heat resistance [9], biocompatibility [10][11][12][13], and photocatalystic activity [14][15][16][17][18][19] of metals and alloys. These coatings are fabricated by different techniques such as oxidation of the metal surfaces [3,[20][21][22], sol-gel process [19], vapor phase deposition [23,24], electrophoresis [25], and thermal spray [26,27].…”

“…These coatings are fabricated by different techniques such as oxidation of the metal surfaces [3,[20][21][22], sol-gel process [19], vapor phase deposition [23,24], electrophoresis [25], and thermal spray [26,27]. To improve wear, corrosion and photocatalytic properties of valve metals including Al [7,28,29], Ti [4,[30][31][32][33], Mg [1,[34][35][36][37], and Zr [38][39][40], surface oxidation techniques, such as Micro Arc Oxidation have been successfully used. Micro Arc Oxidation (MAO) process [41][42][43] is a relatively new method to oxidize metallic surfaces which has attracted many research works in recent years.…”

Nanoindentation study of MAO coatings developed by dual electrolytes

“…This was achieved by utilising an appropriately designed cooling system. 8,9 In the MAO process, first an anodic film is formed due to the electrochemical reaction that prevails. Here, the applied voltage is appropriately chosen such that it can exceed the voltage value that is required to break the anodic film.…”