What Are Corrosion Resistant Thin Films?
Many industrial applications for base materials require Thin Film Coatings that can help parts to sustain high temperatures, corrosive environments or both. In a previous BLOG we covered the need for high temperature protective layers to safeguard base materials from exposure to extreme thermal environments. Here we will cover similar requirements for materials that may not be capable of withstanding corrosive or caustic conditions. These will be generally classified as Corrosion Resistant Vacuum Deposited Thin Films.
By definition, corrosion is the irreversible damage or destruction of a material substance due to chemical or electrochemical reactions. Corrosion results from a metal or other material being oxidized by moisture or corrosive chemicals causing it to lose one or more electrons. This results in the gradual destruction of the material. In many cases this can lead to catastrophic failures. Through the application of a protective layer, it is possible to prevent such surface reactions and protect the material from being destroyed. Such a protective layer may often be applied through one of a variety of Physical Vapor Deposition (PVD) processes produced in a vacuum environment. This may be a single layer deposition or multiple layers deposited sequentially which adds to the overall durability of the coating.
Numerous commercial and industrial applications require materials that can sustain hostile corrosive environments. There are numerous metals, metal alloy and oxide coatings that have been developed to meet the stringent applications such as those encountered in jet propulsion engines (gas turbine blades), the gas and petroleum industries (pipes, valves, nozzles, drill bits, etc.) chemical production plants (strong oxidizers, acids and caustics). Sustaining the service ability of major components in very aggressive environments by reducing the rate of oxidation and metallic erosion is essential. In the “Offshore” Oil & Gas Industry for example, it is important that all associated equipment and tooling are corrosive resistant to saltwater exposure. Additionally, for drilling applications the drills and augers must withstand extremely high pressures in difficult or caustic environments. For such applications extremely hard and corrosive resistant thin films such as Diamond Like Coatings (DLC) or Industrial Hard Carbon (IHC) coatings are sputtered onto the surfaces that will be exposed to aggressively corrosive conditions.
Chemical producing machinery for pumping and mixing processes in corroding environments are often sputtered with ceramic or metal oxide layers to prevent the toxic contents of the material handling equipment from being eroded or destroyed over time. Printing and packaging applications where high speed interactive parts that come in physical contact with high pressure caustic fluid materials such as inks or dies can also be coated with a series of sputtered layers to prevent corrosive damage.
A vacuum deposited protective Thin Film layer can provide the necessary anti corrosive characteristics to preserve a material from a corrosive or caustic environment. In such cases, PVD Coatings provide a thin film layer which is deposited over the surfaces that will be exposed to a hostile environment and provide a protective coating that is inert to the caustic nature of the contacted environment. The need for oxidation and corrosion resistance can be readily met with layers of various thin films deposited via. Physical Vapor Deposition.