Electrostatic spraying is a technology commonly used in the surface coating of magnesium forgings of construction machinery, which has the characteristics of high efficiency, environmental protection and uniformity. Through electrostatic spraying technology, a uniform and dense coating can be formed on the surface of magnesium forgings to improve the corrosion resistance and appearance quality. However, for magnesium forgings of construction machinery, the evaluation of coating adhesion is particularly important. This paper will discuss the electrostatic spraying technology and its adhesion evaluation method.
First of all, electrostatic spraying technology mainly includes the following steps: pretreatment, spraying, curing. Pretreatment is to clean and improve the adhesion properties of magnesium forgings. Common methods include surface cleaning, oil removal, rust removal, etc. During the spraying process, the coating particles are charged and adsorbed on the surface of the workpiece through the action of electrostatic field. Curing is the process of hardening and fixing the coating by heating or chemical reaction.
Secondly, the evaluation of coating adhesion is an important index to judge the bonding performance between the coating and the substrate. Common assessment methods are as follows:
- Bending test method: Score or cut on the coating, paste it on the substrate with tape, and then bend the workpiece. Observe the coating for peeling and cracking to assess adhesion.
- Cross-cutting test method: Cut a square grid with a certain distance on the surface of the workpiece, and then stick the adhesive tape on the line, and then quickly tear it off. The adhesion is assessed by observing whether the coating is torn off at the marking point.
- Conventional stripping test method: The use of stripping test equipment, according to the standard method to apply tension, determine the binding force between the coating and the substrate.
- Tensile sensitivity test method: Use special equipment to apply reciprocating tension to observe whether the coating peeling, cracking and so on.
In addition, methods such as microscopic observation and fracture analysis can be used to evaluate the adhesion of the coating.
It should be noted that the evaluation of coating adhesion should be carried out in strict accordance with relevant standards and methods, and in combination with the use environment of specific construction machinery magnesium forgings, the appropriate coating material and a reasonable pretreatment program should be selected to ensure that the adhesion of the coating meets the requirements.
In summary, electrostatic spraying technology is a common method for surface coating of magnesium forgings in construction machinery. The surface quality and corrosion resistance of magnesium forgings of construction machinery can be improved and their service life can be extended by reasonable spraying process and coating adhesion evaluation.
