Understanding Electrostatic Spray Deposition

This paper is a primer for electrostatic spray deposition (ESD). Specifically, this article deals with an electrostatic spray deposition method (ESD) of coatings on thermoplastic (or polyethylene) substrates with epoxy, metal epoxies, or paint. A novel and previously unknown low speed electrostatic discharge system, applied at a thickness of just a few micrometers, deposited a conductive paint film on the surface of the thermoplastic substrate, making it reusable and lightweight. Electrostatic spray deposition provides high-quality surface finishes with low cost.

The term electrostatic spray deposition (ESD) was first coined in 1988 by J. E. Keene, although it was not popularized by that time. It is a spray process using high voltage that consists of an electrostatic charge and atomic charge on two opposite sides of a conductive material. The contact between the charges results in the generation of a vapor called the latent charge. This vapor is injected into the substrate by spraying. The thickness of the deposited coating depends on how the coating is to be laid. In the case of epoxies, the coating is applied over a clear polymer medium, while in the case of metals, the coating is applied over a metallic base.

Electrostatic spray deposition has applications in many areas of electrochemical technology. Some of these areas include energy dissipation, structure diagnostics, energy management, environmental monitoring, electronic components, and scanning electron microscopy. The technique can also be used to etch fine thin films of a wide range of substrates including plastics, metal oxides, and polymers. Because it can be used with a variety of substrates, the techniques can be applied to a wide variety of electrode configurations and compositions.

The electrostatic spray deposition of thin films has some limitations. Spray coatings will frequently fail if the substrate is too thin or too thick. Additionally, the thickness of the coating will depend largely on the type of support and other structural factors. Additionally, since this method can be a messy process and frequently damages surfaces during the deposition process, it must frequently be pre-treated to prevent it from damaging the workpiece while it is being deposited. These processes are typically referred to as cold processing.

An electrostatic spray deposition (see) is typically performed in two different methods. The first method is known as the vertical phase separation. This process separates the metallic electrolytes from the electrolytes in the medium, which includes the mixture of solvents and oils in the air. The second process is known as the mixed phase separation, which may include both the vertical phase separation and the mixed phase separation.

Electrostatic spray can also be used to deposit non-metallic blends. For instance, electrostatic spray is often used in conjunction with hot gas and oil degreasing sprays in order to deposit black oxide coatings on polished metal surfaces. The coating thicknesses achieved with these two types of treatments are not significantly different than that of typical electrostatic spray alone.

Electrostatic films are also used to protect glass and other vulnerable work surfaces. These particular films have been referred to as ESADi or electrostatic film diffusion in reference to the physical process by which they are deposited. This process of electron diffusion allows the minerals and other contaminates to become attached to the surface of the lava in a controlled manner. Usually, the thickness of these films is in the range of a few nanometers, but the actual deposition depth can vary greatly based upon the characteristics of the substrate being protected.

In electrostatic deposition, the electric field that exists in an electrically charged object is altered, which leads to the generation of localized heat. Heat diffusing dyes are used to create the localized heat that occurs during this process. The resulting heat is what transfers the material into a completed electrostatic deposition layer. When comparing the differences between traditional solar cell applications and the conversion of wang oxide to active solar cells using electrostatic deposition, one could say that traditional solar cell technology has been outdated for several years, while electrostatic deposition continues to grow more efficient.