| 摘要 |
FIELD: chemical industry. SUBSTANCE: new electrolyte for black chromium coating depositing has chromium (VI) oxide, boron-bearing inorganic salt, inorganic nitrogen-bearing compound, potassium silicofluoride. Distinguished property of the electrolyte is presence of sodium tetraborate in it as boron-bearing component, sodium nitrite - as nitrogen-bearing component and saturated monohydric alcohol (methanol, ethanol, propanol or butanol) under following ratio of components in g/l chromium (VI) oxide - 300 - 600; sodium tetraborate (borax) - 20 - 50; sodium nitrite - 2 - 4; potassium silicofluoride - 0.4 - 1.5; aliphatic alcohol - 0.5 - 1.5. Deposition of coating is recommended to exercise under current density of 20 - 150 A/dmand temperature of 15 - 40 C. In the case speed of electrical deposition is 20 - 25 mcm/h. The electrolyte allows to produce black chromium coatings of high quality with absorption factor exceeding 98 % and micro firmness of more than 630 kg/mm. Coatings have lower porosity and increased corrosion resistance. Electrolyte keeps its operational quality after 1600 A-hour/l current electricity passing through it. Measurements results of coatings properties and electrical deposition speed from the electrolyte under different ratio of components are described. EFFECT: increased quality of black chromium coatings. |
