Microstructure and self-lubricating property of a novel Al2O3/La2P4O13/ MoS2 composite layer in-situ prepared by micro-arc oxidation

A novel Al2O3/La2P4O13/MoS2 composite layer was successfully in-situ prepared on 6082-T6 alloy surface utilizing micro-arc oxidation (MAO) technology by introducing Na2MoO4, Na2S, and C2H6LaO3 into the electrolyte. The microstructures, compositions, morphologies and tribological behavior of the composite layer are characterized by XRD, XPS, SEM, EDS, TEM and UMT. The results show that: with the increase of C2H6LaO3 concentration, the surface roughness changed from 1.447 to 2.588 mu m, the porosity changed from 3.79 to 2.45 % and the hardness rises from 737.66 to 1177.41-1260.44 HV1; the self-lubricating phases La2P4O13 and MoS2 were dispersed between the hard phase Al2O3; when the concentration was 5 g/L, the average friction coefficient is reduced by 41.66 % compared with the Al2O3/MoS2 composite layer at 0 g/L. There was no obvious mass or volume changes of coupled body (Si3N4 balls) before and after sliding wear. The in-situ formation of MoS2 and La2P4O13 in the MAO layer can have a coordinate effects for improving the compactness, hardness and selflubricating behavior.