Electrophoretic Deposition
Electrophoretic deposition (EPD), a specific type of particle deposition in which the particles to be deposited are suspended in a liquid carrier and then transferred to the substrate by an electric field, has been successfully used for many engineering applications. Developed in the late 1960s and early 1970s, EPD has become one of the most widespread uses of electrophoretic technology. With the ever-increasing demand for thinner and lightweight materials and components, EPD has been recognized as an excellent means to produce thin film coatings with high uniformity, adhesion, and toughness.
In electrophoretic deposition, the particles to be deposited are suspended in a suitable liquid carrier and the suspension is placed between two electrodes. By applying the electric field, the particles are attracted towards the electrodes and migrate to the substrate
located between the two electrodes. The particles are then deposited onto the surface of the substrate, forming a thin film coating. The benefits of using EPD as a thin film coating technology include the use of low deposition temperatures, which provides improved adhesion; the ability to deposit coatings with uniform thickness and good mechanical properties; and the ability to deposit a wide range of materials, including ceramics and polymers.
The electrophoretic deposition process is highly tunable and the properties of the coatings can be tailored by adjusting several parameters, such as the magnitude of the electric field, the concentration and size distribution of the particles in the suspension, and the solution pH. The choice of the suspension carrier determines the adhesion, uniformity, and film microstructure, whereas the choice of the particles and their concentration determine the mechanical properties and optical properties of the deposited coating.
In addition to its wide range of applications, EPD has been used in the form of 3D printing, which has revolutionized the way products are manufactured. In this process, known as powder-bed fusion (PBF), the suspension containing the particles is placed between two electrodes and then an electric field is applied. This causes the particles embed into the substrate, forming a 3D structure. The advantages of this process include the ability to manufacture complex shapes with high accuracy and resolution; fast production times; and a low cost per part as compared to traditional manufacturing methods.
Overall, electrophoretic deposition is an excellent thin film coating process, with tunable properties that make it suitable for a wide range of applications, from wear-resistant coatings to additive manufacturing. Its advantages, such as low deposition temperatures, uniform film formation, and flexibility in the choice of material and quantity, have led to its widespread use for many engineering and manufacturing applications.
