▎ 摘　　要

NOVELTY - Micro-arc oxidation electrolytic solution comprises main film-forming agent, auxiliary film-forming agent, main colored salt, complexing agent and deionized water. The main film-forming agent is potassium silicate, sodium silicate, sodium hexametaphosphate, sodium metaaluminate, and sodium stannate. The auxiliary film-forming agent is potassium hydroxide, sodium hydroxide, potassium fluoride, and sodium fluoride. The main coloring salt is ammonium metavanadate and sodium vanadate. The complexing agent is condensed phosphate, tartrate, citrate and ethylenediamine tetraacetic acid (EDTA). The condensed phosphate includes pyrophosphate, tripolyphosphate and polyphosphate various. The content of the main film-forming agent is 10-40 g/L, the content of the auxiliary film-forming agent is 3-15 g/L, the content of the main coloring salt is 5-15 g/L, and the content of the complexing agent 0.1-5 g/L. USE - Micro-arc oxidation electrolytic solution for aluminum alloy surface. ADVANTAGE - The coating blackness of the prepared black coating L less than 25, absorption rate greater than 90%, emissivity greater than 90%, hardness greater than 300 Hv, neutral salt spray resistance greater than 800 h, and has temperature resistance (300℃ for 3 hours without discoloration). DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a method for preparing black coating on the surface of aluminium alloy by using micro-arc oxidation electrolyte for aluminium alloy surface, which involves: pre-treating after polishing the aluminium alloy substrate and oil stains the surface of the aluminium alloy substrate; preparing electrolyte weighing main film- forming agent according to proportion auxiliary film- forming agent main colorings salt auxiliary coloring salt complexing agent auxiliary coloring particles and stabilizing agent then dissolving the main coloring salt auxiliary coloring salt and complexing agent in the deionized water solution of metal complex to obtain the water solution sequentially; adding main film-forming agent into the aqueous solution auxiliary film-forming agent stabilizing agent and auxiliary coloring particles and using magnetic stirrer for stirring for 30-60 minutes, then standing for 5-10 minutes to obtain the electrolyte; micro-arc oxidation treatment: taking the aluminium alloy substrate as the positive electrode graphite plate, or stainless steel plate as negative electrode pouring the electrolyte into the electrolytic tank and positive electrode then performing micro-arc oxidation treatment for 3-60 minutes; post- processing; after micro-arc oxidation treatment, taking out the aluminium alloy substrate then sequentially ethanol pure water ultrasonic cleaning, and cold air drying black coating on the surface of the aluminium alloy.