Abstract: The present invention is a method for covering an object with a film resulting from the melting of a thin layer of powder, in which method comprises: (a) having a bed of electrified fluidized powder in a tank, this powder being charged by a forced-circulation tribocharging device; (b) dipping the object, connected to zero or sufficient potential, into the tank in order to cover it with powder; (c) placing the object, covered with the powder, in an oven at a temperature high enough to obtain the coating film by melting the powder. According to one advantageous embodiment of the invention, the oven includes electrodes raised to a high electrical potential so as to cause a corona effect which compensates for the relaxation of the charge on the powder particles while they are being heated. The charge on the particles is maintained and therefore they remain on the object and thus can form the film by melting. The present invention also relates to the apparatus for implementing the method.

Abstract: The present invention relates to as triboelectric fluidized bed method and apparatus for coating an object with powder prior to heating to form a coating. The methods includes arranging a bed of fluidixed powder in a vat where the powder can be charged by a tribocharging device such as a honeycomb comprising prisms or vertical tubes open at both ends.

Abstract: Tribo-electrification of conveyed particles in a pipeline of a pneumatic conveying system is reduced by electrically isolating at least one portion of the inner surface of the pipeline, preferably the concave interior surface of at least one elbow. The isolated portion acquires an electric charge of opposite polarity to that of the conveyed particles.

Abstract: A method and apparatus for electrostatically spraying conductive coating material onto objects, primarily large extended objects, by charging with a relatively large charge the space behind the surface to be coated. With hollow objects, such as automobile bodies, the space within the body is charged. The space is charged by spraying an electrostatically charged atomized water mist into the space which evaporates charging the space and object surface. An electrostatic field is produced between the surface and the gun which, along with the supply of conductive material to which it is connected, is grounded. The gun discharges a film of coating which is atomized into droplets. The field inductively charges the film fringe and thus the droplets which are then attracted onto the large charged surface.

Abstract: Aerial spraying apparatus includes two sets of nozzles located at spaced locations on an aircraft. Each nozzle has an electrode associated with it to induce a charge on the cloud of droplets issuing from the nozzle. A high potential is maintained on each electrode by a power pack that induces an equal and opposite potential on the electrodes of each set. By virtue of the opposed polarity of the electrodes, the aircraft is maintained at a neutral potential. To prevent a potential being imposed due to spray being deposited on the electrodes, a pair of corona needles are provided to establish a leakage current and maintain the electrodes at the required potential. This prevents the system becoming imbalanced and a potential being established on the aircraft.