Xylan coatings provide tailored properties to functioning surfaces and provide lubrication, controlled friction, wear resistance, heat resistance, and at the same time, can also protect from corrosion.
Rollstud’s coating facilities include a computer programmed electro plating and phosphate line. In addition, Rollstud have a comprehensive plant system to apply Xylan P.T.F.E. coatings.
All metals will corrode under certain specific conditions. Common steel corrodes upon exposure to moisture. Other metals will corrode in varying degrees upon contact with dissimilar metals.
Chemicals contribute to corrosion as well as elevated temperatures. Even the stress to which metals are put may cause corrosion.
At Rollstud we continue to supply industry with both evolutionary and revolutionary coating products to solve surface related problems.
We include a number of quality assurance tests such as:
Thickness Checks
Adhesion Tests
Hydrogen Embrittlement
Hints for Minimising Corrosion
1. Select the metal most likely to resist the corrosive environment to which it will be subjected.
2. Use combinations of metals close together in the Galvanic Series.
3. Avoid making combinations where the area of the less noble material is relatively small (small anode, large cathode). This can cause very rapid rates of corrosion which can lead to premature failure.
4. Avoid irregular stresses in design. Even high stresses in bolted assemblies do not necessarily impair corrosion resistance as long as they are uniform.
5. Insulate, paint, or coat dissimilar metals wherever practical.
6. If practical, add suitable chemical inhibitors to a corrosive solution.
7. If you must use dissimilar materials, keep them far apart, and avoid joining them by threaded connections unless insulated (or electrically isolated).
8. Couple to the item you wish to protect, pieces of less noble metals which are not functional in the assembly. They can corrode sacrificially (cathodic protection).
Types of Corrosion
1. Uniform Corrosion:
The common type of corrosion that attacks iron or steel products exposed to the elements. Weathering processes act to combine the surface of the metal with oxygen resulting in the reddish-brown coating called rust.
2. Galvanic Corrosion:
This type of corrosion occurs when dissimilar metals in an electrolyte are coupled. This causes an electrical transfer of particles from one metal to another. One metal becomes the anode that corrodes and the more noble metal becomes the cathode.
3. Pitting:
Even passive (corrosion-resistant) metals will corrode in specialised environments. Extreme temperature, acids or other factors will cause a localised breakdown of the material. The weakened area then becomes the anode and loses metal locally to the passive or cathodic area. The result is pitting.
4. Stress Corrosion:
Stresses in metal caused either by internal or external pressures such as a bolt and nut assembly will create paths within the grain of the metal which tend to corrode more readily under certain conditions. Corrosion is accelerated along these boundaries resulting in premature failure.
5. Corrosion Fatigue:
This is similar to stress corrosion except that the stresses are cyclic. Repeated loading and unloading usually causes accelerated rates of corrosion over those found in static stress corrosion.
6. Stray Currents:
Fabricated metal sections either buried or in a solution sometimes come in contact with electric currents caused by extraneous influences such as generators or motors. This frequently causes an accelerated disintegration of the metal.
7. Concentration Cell Corrosion:
Sometimes called “deposit attack” or “crevice corrosion.” It refers to the tendency of corrosion to build up more rapidly in the cracks and crevices of an assembly.