It is too hard to avoid corrosion completely. But it can be retarded with some implementations to the metal. The base of the corrosion prevention is to generate a protective layer on the metal surface and to prevent air contact with the metal surface. Thereby it prevents reaction with metal and water molecules, oxygen where is existed at the ambient.
Protective treatments are such as powder or wet coating, surface treatments, anodic or catodic coating, lubrication etc.
The long lasting protection can be provided by the appropriate surface treatment and powder or wet coating method depending on usage area and purpose of the metal. For instance, appliances such as white goods or decorative metals for indoor applications are treated proper surface treatment chemicals thereafter wet/powder coating is applied which are also provided long-term protection. However, this process is not applicable for all sectors and materialsFor instance, wet/powder coating application is not applicable for some sectors such as the automotive sector and the machinery equipment sector. At this point, protective oils are become a part of the process.
Wet/powder coating applications for related parts such as motor parts which are in contact with each other will cause thickness and this is an undesirable situation. Also, when moving parts are rub against each other, the coating layer will leave the surface and after a while the protective layer will be lost its protectiveness. Such a problem will not be the case if proper surface treatment and subsequent utilisation of suitable protective oils are used.
There is an another important advantage of protective oil usage. Untreated raw parts surface are not as smooth as they seem. On the surfaces of these parts there are a set of indented roughnesses that can be seen in microscopic size. Those roughnesses put up resistance to the movement of moving parts within each other. As a result, the movement of the parts become difficult and after a while the part surfaces start to attrition due to the friction. The task of the protective oil is to reduce friction and provide a sliminess on the surface of the material. The same process is also applied to the surface layers in crystalline form such as manganese phosphate, zinc phosphate.
Protective oils are generally used in automotive, metal, weapons and general industry for protecting all types of engines and spare parts, unpainted cover sheets, painted or unpainted parts during overseas shipping and heat treated parts.
Protective oils are generally used in automotive, metal, weapons and general industry to protect for all types of engines and spare parts, unpainted cover sheets, painted or unpainted parts during overseas shipping and heat treated parts.
Oil Based Concentrated Products
It is found in concentrated form. It forms a thick film layer on the surface.
Water – Dilutable Protective Oils
It forms an emulsion, blended with water between 15-40%.
Solvent Based Oils
After application, the solvent in the oil is evaporated and protective film layer is remained.
The most reliable method of measuring the resistance to corrosion of protective oils is the salt spray test. This test can also be called accelerated corrosion test. The salt spray test is designed to simulate a marine environments. The ASTM B117 standard is generally used to measure. 5% salty water solution in a pH range of 6.5 as a fog is atomized into the heated chamber at the 35°C. The test period is usually applied at 24 hour intervals.
Depending on the surface treatment applied on the metal, the protective oils are resulted in a salt spray test between 24 hours and 96 hours.
References : Net Kimya – R&D Departmant / Reyhan ÇELİK
We suggest you visit our www.netkimya.com.tr website to obtain more information about protective oils..