Physical Vapor Deposition (PVD) is a plasma coating deposition process. This process is a method used in order to deposit a thin film , effectively coating the substrate with a vaporized form of the desired coating material.
PVD includes a variety of vacuum deposition methods, including:
This process involves material to be ejected from the target material onto a substrate. Inside a vacuum chamber, the target material is bombarded by energetic particles, causing these sputtered atoms to be ejected from the target material into a gas phase. This gas now deposits onto the substrate, causing a thin film to be formed on the substrate. An argon plasma is commonly used in this process.
A thin-film deposition method, Evaporative Deposition involves the source material to be evaporated in the vacuum. This vacuum now allows for the vapor particles formed to travel to the substrate. After reaching the substrate, the particles condense back into a solid form, the result being a thin fil coating on the substrate.
Cathodic Arc Deposition
This process entails the use of an electric arc to vaporize material from a cathode target. This vaporized material then condenses on the substrate, causing the formation of a thin film. Cathodic Arc Deposition is used to deposit ceramic, composite and metallic films (or coatings).
Pulsed Laser Deposition
Here, a high-power pulsed laser beam is focused inside a vacuum chamber. This beam is used to strike the target of the material that is to be deposited on the substrate. This in turn causes the material to be vaporized from the target and deposited on the substrate, forming a thin film (or decorative coating). Note that this process can take place in the presence of a background gas (such as argon or oxygen) or it can occur in ultra high vacuum.
Electron Beam Physical Vapor Deposition
This vapor deposition process involves entails the target anode to be bombarded with an electron beam. This is done by a charged tungsten filament under high vacuum. The electron beam used causes atoms from the target to transform into a gaseous phase. These atoms now precipitate into solid form, effectively coating everything inside the vacuum chamber, resulting in the formation of a thin layer.
Apart from being one of the more advanced decorative metal coatings processes, PVD also creates a coating that offers:
- A resistance to wear,
- A superior hardness, and
- A coating that will not chip, corrode, tarnish or fade.
PVD coating is also an environmentally friendly decorative coatings process and offers a wide range of coating materials that result in vivid metallic colors. Coating created through this process offers a variety of advantages ranging from a coating that has an excellent scratch protection as well as a longer life span.
These decorative metal coatings are used for a number of applications, including interior and exterior automotive parts, domestic appliances, bathroom and kitchen fittings, as well as nautical and architectural hardware.
PVD product materials include stainless steel and titanium. Other materials, such as aluminum, brass, zinc, carbon steel and brass is, in many cases, chrome plated before PVD coatings are applied.
By combining different metals with reactive gases, a wide range of colors an be achieved. Typical metals used in PVD decorative coatings include chromium, titanium and zirconium, which create a wide range of colors, including black, bronze, gray, silver or gold tones, and brass tones.
Some of the colors produced by PVD include:
- PVD Black
- PVD Brass & Gold
- PVD Oil Rubbed Bronze (ORB)
- PVD Rainbow
- PVD Shadow Nickel
- PVD Shadow Sand
Electroplating is a process entailing the use of an electrical current to coat an electorally conductive material with a thin layer of metal. This process results in the formation of a smooth, thin and even coat of metal on the base material (substrate).
Electroless plating uses an autocatalytic reaction in order to deposit a thin layer of material onto the substrate – the use of an electrical current is not required.
The following plating processes are used to achieve decorative coatings:
An electroplating technique in which a thin layer of chromium is formed on the surface of a metal. Decorative in nature, chrome plating also increases surface hardness and provides a resistance to corrosion. Base materials (or substrate) chrome plated includes copper alloys, steel, zinc alloys and aluminum. Note that plating here is usually done over bright nickel plating.
Using an electric current, this process entails the deposition of copper onto the base material. Because copper is an ‘active material’, it is difficult to plate it onto a passivated surface – this means that the direct plating of iron based materials are difficult. These types of surfaces require a nickel strike base coat, forming a coat onto which the copper can adhere. For decorative coatings, and acid-(sulfate or fluoroborate) complexed bath is used.
Using either chemical or electrochemical plating, this process involves the deposition of a thin layer of gold onto a metal surface, commonly silver and copper. Often used for improving the conductivity of electronic parts and for the decoration of jewelry.
An electroplating technique used in order to electroplate a thin layer of nickel onto a base metal (substrate), it not only serves as a decorative coating, but can also provide a resistance to wear, a resistance to corrosion or be used to build up an undersized or worn part. Watts nickel plating baths and black nickel plating (commonly plated on steel, brass and bronze) is used to plate base materials for decorative purposes. Decorative bright nickel is used for a wide variety of applications as it offers protection against corrosion, a resistance to wear and a high luster finish.
Mid Phosphorous Electroless Nickel Plating is commonly used for creating a bright and uniform appearance, this form of electroless nickel plating is also used for electronic applications.
A type of platinum, rhodium provides a shiny, white lustrous appearance. Popular base metals that are rhodium plated includes copper, silver and platinum. Note however that, in high wear applications, these decorative coatings will wear away, leading to discoloration. Also note that, apart from from being a decorative process, rhodium also provides a resistance to tarnish and scratch.
Used in applications that require an improved electrical conductivity and a decorative appeal, Silver Plating is a more cost-effective solution as it not only plates brass well, but is also cheaper than gold. Note that silver plating does not work well in high humidity applications, as silver is likely to flake and crack in these conditions, exposing the base metal or substrate).
The following materials (substrates) can undergo electroplating processes in order to create decorative metal coatings:
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