PVD treatment for gold-plated stainless steel

The terminology used in jewelry and goldsmithing can sometimes be quite confusing, especially for beginners (though even experienced people learn something new every day). PVD plating is one such term: behind this somewhat mysterious acronym lies one of the most reliable techniques for achieving a beautiful, durable, and long-lasting gold-plated stainless steel finish. We’ll explain everything, step by step.

What is PVD?

These three letters stand for Physical Vapor Deposition (or “Dépôt Physique en phase Vapeur” in French). This acronym refers to a method of metallization involving the physical deposition of vapor through sputtering.

There are several specific techniques for applying a PVD coating:

• vapor deposition: This method is also known as “vacuum evaporation.” It involves depositing a thin, uniform layer of metal onto a product in a vacuum using vapor. This process allows for precise control over the coating ’s thickness.
• sputtering: Microscopic particles are projected onto an object to coat it with a new layer. These particles are drawn to the jewelry, forming a very thin and uniform layer on its surface. This technique is renowned for its ability to produce highly adherent and uniform coatings on a wide range of materials
• Ionization or ion beam assistance: Instead of using simple particles, ions (atoms with a slight electrical charge) are used to “bombard” the surface of the jewelry. This bombardment does two things: it compacts and smooths the coating so that it is stronger and adheres better, and it eliminates small imperfections so that the coating is as flawless as possible. Ion beam assistance helps densify the coating, improve its adhesion, and reduce defects by bombarding the substrate with ions during the deposition process.

Many metals can be deposited using PVD (in fact, virtually all elements of the periodic table in their solid state). Typically, titanium and chromium are used as the base layers due to their high corrosion resistance. These are then coated with a layer of precious metal, such as gold, or metal alloys. The entire process is carried out in vapor form.

Widely used in industry and watchmaking, this process is increasingly being employed in the jewelry industry.

Which metals can be coated using PVD?

PVD can be applied to various metals and alloys that can withstand the pressure. However, it is particularly effective on stainless steel. Thanks to PVD metallization, we can offer you gold-plated stainless steel. The thickness of this coating on the stainless steel products we sell is not specified by the manufacturer. It can range from 0.01 to several microns.
In the case of a steel substrate, the applied layer is titanium nitride (TiN). The gold color remains stable: it does not flake off, and even if it may lighten slightly, it retains its golden appearance without taking on a silvery hue.

On a copper, brass, or zamac base, PVD is less practical because it would require a primer coat for the PVD coating to adhere, which would incur additional costs.

PVD: How Does It Work?

The entire process takes place in a vacuum chamber—a type of sealed, airtight metal machine. Inside this chamber is a carousel on which frames are mounted to hold the items to be coated.

Once the items are hung, the chamber is sealed and then evacuated of nearly all its air to reach a pressure of one hundred-millionth of atmospheric pressure, thereby preventing the presence of impurities. Next, the deposition phase begins: the process gas is released through the side walls of the chamber. The carousel rotates at a steady pace, allowing the coating to be evenly distributed over the products. When the process is complete, the frames are removed, followed by the items.

What are the advantages of PVD?

• A wide range of colors can be achieved. The sputtering process allows for different shades, depending on the reactive gases and temperatures used.
• Ion plating is a clean and environmentally friendly process. It is more environmentally friendly than electroplating. Unlike the electrolysis process, the PVD coating process is non-toxic. It requires no plating baths, no chemicals, no water consumption, and produces no gas emissions or other waste.
• The product becomes more durable. The product’s properties are not compromised. On the contrary! Its durability and strength are enhanced thanks to titanium nitride, a hard, corrosion-resistant metallic compound. PVD is much more durable than conventional electroplating, though it is more expensive.

A quick reminder: What is electroplating? Sometimes incorrectly referred to as galvanization, electroplating is a method of plating by electrolysis. This method uses an electric current passing through a liquid bath to coat a metal object with a thin layer of precious metal or a metal alloy.