Study On The Friction And Wear Performance Of MAO BN、ZrO₂ Composite Coating On TC4 Alloy

BN and ZrO2 micro-arc oxidation ceramic coatings containing which can be prepared by on TC4 titanium alloy with DC pulse in Na2SiO3-Na2WO4-(NaPO3) 6-NaF electrolyte system.The effects of BN and ZrO2 composite particle in solution、current density、oxidation time、composite film thickness、suface morphology and roughness of the composite membrane was studied. Studied the friction and wear properties of the composite membrane layer and Wear-resisting antifriction mechanism be putted forward.Study the mechanism of micro-arc oxidation discharge hole, analysis of particles from the electrolyte to film layer on the surface of the control elements, analyze the particles into the coating process.The results show that:In 8 g/L Na2SiO3, 6 g/L(NaPO3) 6, 4 g/L Na2WO4,0.5 g/LNaF electrolyte with BN, ZrO2 particles, current density of 8 a/dm2, 500 hz frequency and duty ratio is 40%, to prepare a micro-arc oxidation coating containing BN and ZrO2 particles. With the oxidation time, membrane layer thickening, film growth rate decreases, and surface pore number decreases, and pore size increases, the film surface roughness increased. Oxidation time for 30 min of micro-arc oxidation BN composite membrane of the friction coefficient was 0.05 and the wear rate is 0.85 ×10-7 mm3/N.m. 100 min of ZrO2 composite membrane of the friction coefficient of about 0.125, the wear rate was 1.5×10-7mm3/N.m. ZrO2 particles content in the membrane layer was 23.59% of ZrO2 composite membrane of the friction coefficient at around 0.3, the wear rate of 2.7 ×10-7mm3/N.m.Micro-arc oxidation phase structure of anatase and rutile phase of TiO2, Al2TiO5 phase, diffraction peaks of the Ti, and respectively with ceramic particles phase BN, TiO2. Micro-arc oxidation film membrane mainly P, Si, W, Ti, etc in amorphous form exists in membrane layer. With the increase of oxidation time, deal with the increasing of voltage, decreasing TiO2 anatase phase diffraction peak, TiO2 rutile phase increasing. Micro-arc oxidation type friction and wear mechanism of the composite membrane layer is mainly adhesion wear, abrasive wear and fatigue wear. BN play a role in self-lubricating micro-arc oxidation ceramic layer, ZrO2 to wear micro-arc oxidation plays a certain role.Micro-arc oxidation plasma discharge process is: the electrolyte and substrate metal plasma body mechanics by O incentive electrochemical reaction, the porous structure of the oxide layer deep into the base metal, the plasma discharge accompanied by attenuation. Such an oxide film at the boundary with the substrate forming the external shape similar to a hemisphere convex lens, while the center of the crater with a recessed discharge passage formed. Electrolysis of molten metal in contact with the electrolyte surface thrown, produce complex chemical reaction of complex thermal, electrochemical, etc., constitute the film constituent substances. Sodium dodecyl benzene sulfonate can substantially increase the amount of ZrO2 composite film of the. Electro-migration in particle deposition to the micro-arc oxidation film which plays an important role.