Construction points of thermal spray anti-corrosion coating topcoat

       After the thermal sprayed anti-corrosion metal coating is sealed, sometimes for decorative requirements, occasions where seawater splashes or soaks, and occasions that are directly subjected to strong corrosion, topcoat can be painted on the outside. The application method for the topcoat is similar to that of conventional paint application. Construction should be carried out in accordance with the construction requirements and safety requirements of paint coating.



Since some moisture will accumulate between the multi-layer coatings, under continuous corrosion conditions, the corrosion will be aggravated, so in general, only one topcoat is enough outside the coating. Do not apply topcoat directly to metal coated surfaces, apply topcoat to thermal spray coatings that have been sealed and primed. Repairing topcoats on thermally sprayed metal coated surfaces is much simpler than applying traditional paints, simply cleaning up the damaged parts of the topcoat and reapplying the same topcoat.



Thermal spray protective composite coating system topcoats are applied similarly to conventional paint applications. Since the components of thermal spraying anti-corrosion construction are usually large in volume and dusty in the construction environment, only some types of coatings cured at room temperature and simple coating construction methods such as brushing and roller coating are allowed to be used. The following points should be paid attention to in the construction of the topcoat.



(1) Be sure to apply the topcoat after the coating sealer and primer are completely cured.



(2) During the construction after painting, the appropriate paint brush should be selected according to the type of paint and the part to be painted. When painting, do not dip too much paint on the paintbrush, generally no more than 2/3 of the bristles, and then dab on the inner wall of the paint can to remove the excess paint to avoid flow and waste. There should be order when painting, generally from top to bottom, from left to right, do not smear horizontally, resulting in uneven thickness of the paint film.



(3) The method of manual roller coating can also be used for the construction of the topcoat of the large plane components. This method has uniform coating film, no sag, and high production efficiency. In the places where the corners are not easy to roll, it needs to be supplemented with a brush.



Many mechanical parts require machining after arc spraying. The machining performance of the arc sprayed coating is different from that of forgings or castings with the same composition. This is due to the presence of a certain amount of oxides in the coating, which will accelerate the wear of cutting tools and reduce the bonding between the coating and the substrate. Therefore, the main processing method of arc spray coating is grinding. The turning method is suitable for shaft and tube parts with hardness lower than 300HV. Carbide tools are recommended for turning coatings. In addition to tool selection, tool angle feed and workpiece speed are the key factors to prevent coating damage. For the coatings with high hardness that are not suitable for turning, use the grinding method. The thin coating must use the grinding method. Although high chromium stainless steel can be turned, it is still recommended to use the grinding method to ensure the quality of the coating. Moderately soft, sharp grinding wheels with effective cooling conditions.