The Difference Between Aluminum Hard Oxidation And Blackening
|Hard anodizing is a thick film anodizing method, which is a special anodizing surface treatment process for aluminum and aluminum alloys.|
With this anodizing coating process, the maximum thickness of the anodized film can reach about 250 microns, and a micro-hardness oxide film of 1500 kg / mm2 can be obtained on pure aluminum, while a display of 400-600 kg / mm2 can be obtained on aluminum alloy. Micro-hardness oxide film. Its hardness value is that the inner layer of the oxide film is larger than the outer layer, that is, the barrier layer is larger than the oxide film layer with pores.
Because the oxide film has loose pores, it can absorb various lubricants, which increases the friction reducing ability and oxidation The film has poor thermal conductivity, its melting point is 2050 ° C, its electrical resistivity is large, and its sealing voltage (impregnated with insulation or paraffin) can reach 2000V. It has a high corrosion resistance in the atmosphere and has a high resistance. Abrasiveness is also an ideal thermal insulation film.It also has good insulation properties, and has a series of advantages such as strong bonding with the base metal.It is therefore widely used in the defense industry and mechanical parts manufacturing industry.
Mainly used on aluminum and aluminum alloy parts that require high wear resistance, heat resistance, good insulation performance, such as various inner walls of cylinders, pistons, plugs, cylinders, bearings, flooring, roller bars and guide rails of aircraft cargo holds , Water conservancy equipment, steam impellers, levelers, gears and cushions.
The hard oxidation and chemical process is used to replace the traditional hard chromium plating. Compared with the hard chromium process, it has the advantages of low cost, firm film layer bonding, convenient plating solution, and convenient cleaning of waste liquid. The disadvantage is that when the film thickness is large, it affects the mechanical fatigue strength indicators of aluminum and aluminum alloys.
Blackening treatment is a commonly used method for metal heat treatment. The principle is to make an oxide film on the metal surface to isolate the air and achieve rust prevention. Blackening treatment can be used when the appearance requirements are not high.
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