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WHAT IS UNDERCORROSION ?
Undercorrosion is the phenomenon that causes the corrosion on inferior metal covered by a protective layer. The oxide increases in volume causing the coating to be separated from the substrate. Paint blisters on cars and rusty bike handles are daily examples. However high tech products such as anilox roll or other thermal sprayed layers can develop undercorrosion.
WHAT CAUSES UNDERCORROSION ?
Undercorrosion occurs when the inferior metal underground comes in contact with moisture for a period of time.
HOW CAN UNDERCORROSION BE AVOIDED ?
In general by keeping the substrate free of moisture. The following methods can be adopted :
1. Chemical nickel plating.
With this method a pore free coating of nickel is applied. This is an added, expensive operation.
2. Apply a thicker bond coat between substrate and layer.
This makes it more difficult for moist to penetrate to the substrate. Again this is expensive.
3. Apply a sealer.
A sealer seals the pores on the surface. However, the moist present will still cause undercorrosion. New cracks in the layer will mean a total liquidation of the protection.
4. Apply ROLL-A-CARE
WHAT IS AND HOW DOES ROLL-A-CARE WORK ?
ROLL - A - CARE is a low viscosity liquid, which prevents undercorrosion on flame sprayed and other porous layers.
ROLL - A - CARE penetrates even in the smallest pores and cracks, forging out the moist and leaves a moist repellent film behind on the substrate.
PROPERTIES
Layers treated with ROLL - A - CARE show excellent corrosion resistance when tested according to the following tests :
- Climate test?? ? ? ? ? ? ? ? acc. DIN 50 017
- Salt spray test? ? ? ? ? ? ?acc. DIN 50 021
- Sulfur dioxide test? ? ? ?acc. DIN 50 018
According to these tests ROLL - A - CARE gives far better protection than sealers.
ROLL - A - CARE is dissolvable in solvents based on petroleum, but will be, once applied, hard to remove from the layer.
APPLICATION
It's best to apply ROLL - A - CARE immediately after the flame spraying, at a layer temperature of about 80 o C. It can be applied with spray equipment or brushes, or by submerging. ROLL - A - CARE contains white spirit and is inflammable. While spraying use an exhaust system and breath protection.
CONSUMPTION
Because ROLL-A-CARE fills op the pores and does not form a protective film , the consumption is very little. The theoretical consumption is equal to the porosity multiplied with the volume of the applied layer. However losses due to the application method must be regarded.
SAFETY
Follow the safety instructions from the safety data sheet while working with ROLL - A - CARE.
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