An electrolyte used for anodizing magnesium products in accordance with a preferred embodiment of the present invention is provided. A magnesium alloy substrate material as an anode is put in the electrolyte, and another metal (such as stainless steel, or other infusible inert metal) as a cathode is put in the electrolyte. Supplying power between the anode and the cathode until a black coating is formed on the magnesium alloy substrate material by the means of spark discharge. The electrolyte includes a base solution, a main blackening agent, an auxiliary blackening agent, a complexing agent, and an inhibitor. Temperature of the electrolyte is preferably kept between 10 to 60 degrees Celsius (° C.).
The base solution includes alkali, fluoride, silicate, and water. Concentration of the alkali is from 2 to 25 grams per liter (g/l), and preferably from 8 to 12 g/l. Concentration of the fluoride is from 1 to 30 g/l, and preferably from 8 to 12 g/l. Concentration of the silicate is from 1 to 35 g/l, and preferably from 3 to 8 g/l. The alkali includes at least one item selected from the group consisting of potassium hydroxide, and sodium hydroxide. The fluoride includes at least one item selected from the group consisting of potassium fluoride, sodium fluoride, ammonium fluoride, and other compounds including fluorinion. The silicate includes at least one item selected from the group consisting of potassium metasilicate, sodium silicate, potassium fluosilicate, and sodium fluosilicate.
The main blackening agent mainly includes cupric salt. The cupric salt includes at least one item selected from the group consisting of cupric hydroxide, basic copper carbonate, cupric pyrophosphate, cupric citrate, and other metal salts including cupric ions. Concentration of the cupric salt is from 0.3 to 9 g/l, and preferably from 1 to 3 g/l.
The auxiliary blackening agent includes at least one item selected from the group consisting of nickel nitrate, ammonium molybdate, ammonium metavanadate, and other oxysalts. Concentration of the auxiliary blackening agent is from 0.1 to 8 g/l, and preferably from 2 to 4 g/l.
The complexing agent includes at least one item selected from the group consisting of acid and salt of ammonia, ethylenediamine tetracetic acid (EDTA), citric acid, tartaric acid, ethylenediamine, and trolamine. Concentration of the complexing agent is from 0.5 to 20 g/l, and preferably from 3 to 5 g/l.
The inhibitor included in the electrolyte works to increase blackening, and prevent corrosion of the magnesium product. The inhibitor includes at least one item selected from the group consisting of thiourea, sodium m-nitrobenzene sulfonate, and methenamine. Each of the group consisting of thiourea, sodium m-nitrobenzene sulfonate, and methenamine includes amido, hydroxyl, nitryl, or other adsorbing radicals. Concentration of the inhibitor is from 0 to 5 g/l, and preferably from 0.5 to 2 g/l.
The present invention may be explained by means of the following embodiment examples:
Composition of the electrolyte:
Composition of the electrolyte:
Composition of the electrolyte:
Composition of the electrolyte:
Composition of the electrolyte:
Composition of the electrolyte:
Composition of the electrolyte:
Composition of the electrolyte:
It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.
Number | Date | Country | Kind |
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200610060396.4 | Apr 2006 | CN | national |
Relevant subject matter is disclosed in the co-pending U.S. patent application (Attorney Docket No. US10093) filed on the same date and entitled “METHOD FOR ANODIZING MAGNESIUM PRODUCTS”, which is assigned to the same assignee with this patent application.