Abstract: The surfaces of TiB₂-alloy were modified with micro-arc oxidized(MAO)coatings.The influence of the concentration of Na₅P₃O₁₀ electrolyte on the MAO reaction and tribological properties of MAO coatings was investigated with X-ray diffraction,scanning electron microscopy and conventional mechanical probes.The results show that the Na₅P₃O₁₀-concentration had a major impact.For example,as the concentration increased from 10 to 50 g/L,the conductivity and oxidation rate of electrolyte increased,resulting in a shortened MAO reaction time.When it comes to tribological properties of the highly porous MAO coatings,comprising B₂TiO₅,B₂O₃ and rutile-phased TiO₂ grains,an increase of Na₅P₃O₁₀-concentration significantly enhanced the surface hardness,decreased the friction-coefficient,and reduced the wear-rate.Adhesive wear was found to be responsible for the wear mechanism of MAO coatings.