Abstract
This article introduces the electrochemical deposition process of carbon-based films on metals. The technology of electrochemical deposition, also known as “Diffusion-controlled Chemical Vapor Deposition (DCVD)”, is a revolutionary method which combines the strength of catalyst materials with the deposition capability of Vapor Deposition. In this technique, different concentrations of reactant gas stream react directly with the reactor material surface to form a thin carbon film. The process of chemical reaction and deposition happen alternately without any extra step of post-processing. The introduced process has serval advantages like high operational simplicity, low cost and very uniform deposition. The key feature of this deposition process is that it has no need for chemical reactants, complicated device setup and chemical bonds control during the whole process. This article will provide further discussion of the related theories, principles and applications of the diffusion-controlled chemical vapor deposition with carbon films.
1. Introduction
Recently, diffusion-controlled chemical vapor deposition (DCVD) has attracted more and more attention from materials and surface engineers due to its ability to deposit uniform and thin films on various types of substrates. It is a revolutionary assisted chemical vapor deposition method that is capable of depositing carbonaceous films of organometallic precursor materials on both metallic and non-metallic substrates. The carbon films deposited using the DCVD method offers high adhesion and good electrical insulation properties.
The conceptual wall chart of DCVD technology is shown in Figure 1 [1]. The reactant gases are introduced directly into a chemical reaction chamber and react with the surface of the substrate to form an even, thin and uniform carbon film. As all reactions are carried out in closed chamber, it eliminates the need for any additional post-processing.
Figure 1: The conceptual wall chart of the DCVD method [1]
DCVD process uses electrochemistry to deposit carbon films with either hydrogen or oxygen as the reactant gas. On metals, the diffusion-controlled chemical vapor deposition (DCVD) process can also be used to perform carburization or nitridization on the surface. Aluminum, stainless steel, copper and titanium alloys are some of the substrates that are ideally suited for deposition with DCVD.
In DCVD process, the reactant gases have to diffuse directly into the chemical reaction chamber. As the reactant gases reach the substrate feedstock, they react with the surface to form the carbon film. The heat generated by the reaction will then be used to volatilize the organic reactant molecules and carburize or nitridize the substrate.
2. Theory
DCVD process uses two main types of reactant gases, which are either hydrogen gas (H2) or oxygen gas (O2). The hydrogen is used to break chemical bonds in the organic reactant molecules, while the oxygen is used to form the carbon films on the surface of the substrate.
The diffusion-controlled chemical vapor deposition process consists of three main stages, namely chemical reaction, thermal decomposition and carbon film deposition. In the first stage, the chemical reaction takes place in the reaction chamber. When the reactant gases come in contact with the substrate surface, chemical reactions occur on the surface resulting in chemical compounds. The energy released during these reactions is utilized for the further thermal decomposition of the compounds.
In the thermal decomposition stage, the compounds get further decomposed and gasified, releasing large amounts of energy. This heat energy is then used to deposit carbon films on the surface of the substrate. The energy released from the reaction is also used to carburize or nitridize the substrate.
3. Applications
The diffusion-controlled chemical vapor deposition process can be used for many different applications including coating, adhesion and surface treatment.
3.1 Coating
DCVD can be used to deposit carbon films on metals, plastics and other materials. The carbon films formed by the DCVD method are highly resistant to wear and corrosion and also provide good electrical insulation properties. It can be used to coat a variety of substrates including aluminum, stainless steel, copper and titanium alloys.
3.2 Adhesion
The adhesion of the deposited films can be further improved by adding binder materials into the reactant gas stream. These binder materials will react with the film and result in better surface adhesion and enhanced physical stability.
3.3 Surface treatment
The diffusion-controlled chemical vapor deposition process can also be used to carburize or nitridize the surfaces of metals, resulting in improved corrosion resistance and wear properties. This process can also modify the surface properties of metals, enhancing the mechanical properties of the material.
4. Conclusion
The diffusion-controlled chemical vapor deposition (DCVD) is a revolutionary method of depositing carbon films on both metallic and non-metallic substrates. It is a simple and cost-effective process, and also offers high operability, uniform deposition and excellent adhesion. The DCVD process can be used for a variety of applications including coating, adhesion and surface treatment. With its various advantages and applications, the diffusion-controlled chemical vapor deposition process is gaining more popularity in the area of thin-film deposition.
