Powder Spray Guns

摘要

Two basic types of electrostatic powder guns are used for the spray application of powder coating materials. They are corona guns and tribo guns, where corona and tribo refer to the predominant process used in the guns for electrostatically charging the powder particles.rnCorona charging guns work by bombarding powder particles sprayed from the gun with charged particles called ions. The corona charging process is illustrated in Figure 1.rnThe corona charging process begins with a potential (or voltage) applied to one or more electrodes at or near the front of the gun. A high-voltage generator is used to produce this voltage of up to 100,000 V. As the voltage on the electrode is increased, an electric field is produced between the gun and the grounded work-piece. When the electric field in the vicinity of the electrode reaches a strength of about 30,000 V/cm, the field is strong enough to break down the air in the vicinity of the electrode. This electrical breakdown of air results in the creation of charged molecules or ions in the form of a continuous discharge known as a corona discharge. Powder particles exiting the gun travel near the electrode where they are bombarded by these ions and accumulate a charge.