Powder Coatings
PTFE coatings can be applied by means of a powder coating, this application method is carried by the use of the electrostatic method. The range of PTFE coatings in powder form is far less than those based upon liquid carrier forms. One significant advantage for powder coating is that a greater deposition can be applied, particularly by applying just one coat. Powder coatings may be built upon over a series of applied coats, however, there are limits to the thickness of the coating. Care is taken to not overload the ability of the primer or the surface profile to perform each function to maintain the adhesion of the applied system. It is also noted that that not all requirements for PTFE coating can be satisfied by means of powder coating.
The method of application for powder is unlike that for liquid coatings. The use of specific equipment is required, this equipment will have the capacity to apply an electric charge to the powder, whilst the component has a negative charge applied. The result is that the charged powder particles will be attracted to those negatively charged surface areas. One limitation of this process of application is the ability for the powder to access small bores. Due to the charge applied to the powder the direction is less effective in small holes, this primarily caused by the Faraday Cage effect, where the charged particles of PTFE are disorientated as to the pull of the negative charge. Coating thicknesses can be adjusted not only by the number of applied coats, but by the level of charge within the powder, this is controlled by the specific equipment. One clear advantage over liquid coatings is that overspray of powder can be recovered, filtered and reused.
Controls applied to the handling of PTFE powder materials must include being retained within a dry environment.