Aluminum and its alloy porcelain oxide characteristics and process recipes?

Porcelain oxidation of aluminum and its alloys is one of the faster developing new processes in the electroplating industry. Since the appearance of the oxide film is similar to porcelain glazes and enamels, it is referred to as ceramic oxidation or imitation glaze oxidation. It has the following characteristics:

(1) The film is smooth and has good adsorption ability. It can be dyed into various colors. The surface color is like plastics and ceramics, which is unmatched by other oxidation methods;

(2) The film has good adhesion to the substrate and is not easily peeled off under impact or pressure load;

(3) Strong anti-pollution ability, easy to remove dirt and keep it clean;

(4) The film layer has stable performance and can provide a new way for food containers. It has no pollution effect or odor on general food quality;

(5) The film has high hardness and good wear resistance;

(6) Good corrosion resistance;

(7) The film is dense and has thermal insulation and insulation properties.

Porcelain oxidizing electrolytes have many domestic formulations at present, but they can generally be divided into two major categories. First, rare earth metals such as titanium, cobalt, and zirconium are added to oxalic acid or sulfuric acid. These rare salts are hydrolyzed and deposited in the pores of the oxide film to form a ceramic oxide film. Although the porcelain oxide film layer is thin, but very dense, wear resistance, corrosion resistance, and high hardness, but the process conditions must be strictly controlled, and the cost is expensive, it is subject to certain restrictions in the industrial production. Another kind of reality is the chromic acid oxidation method, that is, adding oxalic acid, boric acid, etc. in the general chromic acid oxidation solution, the resulting oxide film has translucent or transparent gray, dark gray and milky colors, similar to the appearance of porcelain enamel . This film has good performance, low electrolyte cost and easy operation, so it has been widely used in daily production, stationery and other industrial production. The following formula is recommended:

(1) Chromic acid 5%

Oxalic acid 0.5%

Boric acid 0.5%

Anode current density 0.8 to 1 A/dm2

Voltage 35 to 40V

Temperature 30～50°C

Time 60min

(2) Chromic acid 3.6%

Oxalic acid 4%

Boric acid 0.65%

Anode current density 0.5A/dm2

Temperature 48～53°C

45~55min

(3) Titanium oxalate 35～45g/L

Oxalic acid 2~5g/L;

Boric acid 8～10g/L

Citric acid 1～1.5g/L

pH 1.6 to 2.6

Anode current density l~1.5A/dm2

Voltage 30～90V

Temperature l6～28°C

Time 20 ~ 50min (air stirring)

(4) Citric acid 1g/L

Oxalic acid 2g/L

Boric acid 8g/L

Titanium oxalate 40g/L

Anode current density l~1.5A/dm2

Voltage 30～90V

pH 1.6 to 2.0