Chemical blackening solution by volume concentration is 90 ~ 120g/L sulfuric acid, 50 ~ 60g/L hydrofluoric acid, 100 ~ 120g/L lactic acid, 180 ~ 200g/L acetic acid, 8 ~ 12g/L citric acid, sodium 4 ~ 6g/L, the rest is distilled water. Including the following steps: titanium and titanium alloy workpiece chemical degreasing; The workpiece is taken out and washed with water; Titanium and titanium alloy workpiece etching black; Take the titanium and titanium alloy workpiece out of the air and stand; The work piece for water washing cleaning; Dry the cleaned workpiece. The invention has the advantages of simple preparation process, easy operation, high efficiency and low cost; The solution formula and the whole process is pollution-free, harmless to human body and environmentally friendly.
Titanium alloy has the characteristics of high specific strength, no magnetic, good corrosion resistance, wide use temperature (can work at 550 0C and minus 250° C for a long time and keep the performance unchanged), is widely used in aerospace, ships, weapons and other military industry departments. Titanium and its alloys are used in aircraft fuselage and skin, engine, tail cone, nozzle, ejection bay, fire wall, sandwich structure, connectors, aerospace cameras and other parts. In these fields, in order to reduce the thermal radiation of the equipment, improve the stealth ability of the equipment, improve the practical performance of corrosion resistance and wear resistance of the equipment, and other functional purposes such as extinction, it is necessary to carry out black coloring treatment on the titanium alloy surface. And the black coloring treatment of titanium alloy surface can also meet the needs of differentiation and decoration of medical instruments, daily necessities.
At present, there are four methods of black color on titanium alloy surface: electroplating or electroless plating, anodic oxidation, micro-arc oxidation and heat treatment. Electroplating or electroless blackening has the disadvantages of complicated process and high cost. And titanium alloy surface coating adhesion is poor, it is difficult to meet the requirements of use. Anodic oxidation blackening process is also too complex, and the main use of chromate solution, there is the disadvantage of environmental pollution, do not have the conditions of industrial production.The blackening of micro-arc oxidation also introduces vanadium salts, which poses a threat to the environment. In addition, the current micro-arc oxidation process costs too much and has no promotion value. Heat treatment blackening is through high temperature air oxidation, anodic oxidation or micro-arc oxidation, after obtaining a certain thickness of oxide layer on the surface of titanium alloy, and then through vacuum heat treatment to obtain black film layer.
