Classification of thermal spray coating sealing agent

Thermal spraying is the use of the heat source will be heated to melt coating material or semi-molten state, and at a certain speed to spray deposition after pretreatment of substrate surface coating method, special functions for the purpose of giving substrate. With common supersonic flame spraying (HVOF) spray method and atmospheric plasma spraying (APS) as an example, the methods of spraying process of coating is made of countless particles staggered into wave stack together and form of layered structure, thus coating of deformation between the particles and particle inevitably exists some pore. Porosity can be divided by its existence in the form of table face (hole), closed hole and through hole (hole). When used for corrosion resistant coating, if there are bore open or closed in coating, corrosion medium can't reach the surface of the substrate directly, it can not directly make corrosion to occur in the matrix; And if the coating exists in the hole, the corrosive medium will be protected through the pore to arrive on the surface of the substrate and the coating and substrate chemical or electrochemical erosion, corrosion products accumulated in the interface, can make the coating crack, fall off, eventually lead to coating failure. So in order to prevent the erosion of the corrosive medium of matrix, improve the corrosion performance of coatings and enlarge its range of application in special environment, must be to hole sealing coating processing.

 

Hole sealing treatment refers to using a brush or thermal spray equipment make the hole sealing agent such as pore, fill in the pore, strengthening internal in pore filling at the same time, the surface is smooth, the extra hole sealing agent into coating. Hole sealing agent must therefore has lower viscosity and good permeability, and is easy to curing and the matching with ceramic coating and chemical compatibility, and good chemical stability and good corrosion resistance in the environment. Hole sealing process mainly has three aspects: the purpose of a coating is the air tightness, improve the coating corrosion resistance, oxidation resistance and electrical insulation; The second is to avoid coating falling off the grinding wheel during grinding of abrasive coating is embedded into the pores of the coating pollution; Coatings have been given - three new features, such as paraffin wax, such as plastic antifriction self-lubrication effects of hole sealing agent, can give the antifriction lubricating coating.

 

Hole sealing agent is adopted to improve the hole sealing means by painting brush, dip coating or mechanical method such as good into the hole sealing liquid in the porosity of the coating, to achieve the purpose of blocking pore.