50% of the hard oxidized oxide film penetrates into the aluminum alloy and 50% adheres to the surface of the aluminum alloy. Therefore, the external size of the product becomes larger and the internal pores become smaller after hard oxidation.

(A) Differences in operating conditions:

1. The temperature is different: ordinary oxidation is about 18-22 ° C, and those with additives can reach 30 ° C. If the temperature is too high, powder or cracks are likely to occur; hard oxidation is generally below 5 ° C, and the lower the temperature, the higher the hardness.

2. Concentration difference: general oxidation is about 20%; hard oxidation is generally 15% or lower.
3. current / voltage difference: ordinary oxidation current density is generally: 1-1.5A / dm2; and hard oxidation: 1.5-5A / dm2; ordinary oxidation voltage ≤ 18V, hard oxidation sometimes up to 120V.

(B) the difference in film performance:

1. Film thickness: The thickness of ordinary oxide film is relatively thin; the thickness of hard oxide film is generally greater than 15μm, which is too low to meet the requirement of hardness ≥300HV.
2. Surface state: The ordinary oxidized surface is smoother, while the hard oxidized surface is rougher (microscopic, related to the surface roughness of the substrate).
3. Porosity is different: ordinary oxidation porosity is high; hard oxidation porosity is low.
4. Ordinary oxidation is basically a transparent film; hard oxidation is an opaque film due to its thickness.
5. Different application occasions: ordinary oxidation is suitable for decoration; hard oxidation is mainly for function, and it is generally used for wear-resistant and electric-resistant occasions. These are more performance comparisons we usually use, and there are many other differences.