It is an application that increases the corrosion resistance of metal used in oxidation. Lubrication must be applied to metal before this product group working at high temperatures. A dark black appearance will appear on the coated metal and the treatment should be continued with protective oil.
Oxidation Applications Detail
Oxidation is the process of forming an oxide film with lubricating properties on the mold surface in metal injection applications where adhesion and adhesive wear are experienced. Fe2O3 and Fe3O4 iron oxide film formed on the surface after the process, forming a barrier between the mold and the molten metal, prevents adhesion due to mechanical and intermetallic phase formation. Particularly in complex figure molds where cooling may be inadequate or lubricant and cooling spray are difficult to reach, oxidation is essential before first use.
Pre-paint treatment: Black oxidation improves the adhesion quality of the metal, provides better adhesion and longer life of paint and other processes. Reduces paint spillage.
Conductivity: Black oxidation reduces conductivity by up to 1%, making it suitable for electrical components as well.
It is not brittle: Unlike painted or coated parts, black oxidation has no hydrogen brittleness. Caustic brittleness can be seen on very hard parts and very thin springs. This can be minimized by controlling the oxidation process times.
No welding fumes: During welding of black oxidized parts, there is no annoying, dangerous fume emission as can be seen in painted parts.
Price competition: It is very difficult to obtain the same protection, appearance and performance at prices as low as black oxidation with other surface treatments.
Oxidation process is applied especially in hot work tool steels to prevent adhesion and increase abrasion resistance. It does not apply to all kinds of molds. The knowledge and experience of the thermal processor gains importance in this regard. In addition, oxidation process can be applied to increase the shear life of high speed steels after special nitration process.
Some of the areas where oxidation is used
- Aluminum extrusion molds
- Aluminum injection molds
- Plastic injection molds
- Shock absorbers for gas
- Pump shafts
- Textile machinery parts
- Weapon parts
- Automotive mechanical parts
Advantages of Oxidation Process
Corrosion Protection: Depending on post-oxidation processes, black oxidation can provide corrosion resistance resistant to 144 hours salt test.
Dimensional stability: No increase in part dimensions after oxidation. This provides corrosion protection for critically sized parts.
Improved lubricity: Lubrication after oxidation not only protects against corrosion, but also provides a smooth surface and compatible working parts.
Prevents friction adhesion: When fitting the matching parts, the anti-friction surface is sacrificed during the first contact and wear of the outer slippery surface while the surfaces with working hardness are formed. The black oxidation itself has a hardness of 5.5 on the Moh scale.
Decorative: Glossy black surface gives the parts visual appeal and quality image at very low cost. 40 HRC and higher hardness of parts with high gloss, polished appearance is provided.