Applying PVD coatings to medical devices can provide aesthetic and functional benefits. Here are answers to some frequently asked questions.

Physical Vapour Deposition (PVD) is a vacuum coating process that many people know is commonly used to improve the performance of cutting tools. However, Ningbo Zhike Coating Technology Co., Ltd.'s vacuum coating equipment offers cathodic arc PVD coating services that can provide a harder, more lubricious product that can increase tool life by up to 10 times compared to uncoated tools. Wear-resistant surfaces.

In addition, medical device manufacturers are increasingly using PVD coatings to differentiate the appearance of their devices from similar products and/or to enhance the performance of their devices, as hard inert coatings are biocompatible and do not react with bone, tissue or body fluids. Examples of medical devices coated with PVD coatings include jammers, drills and needles, and "wear" parts for various device components as well as dental applications.

PVD coatings provide better edge retention, so coated surgical instruments remain clear. For other devices, they reduce wear between mating stainless steel components and help prevent oxidation and corrosion.

Frequently asked questions about PVD coatings:

What is the cathodic arc PVD process?

Cathodic Arc PVD is the process of evaporating various metals from a solid source material in a vacuum chamber using an arc welder. The evaporated metals, such as titanium, chromium, zirconium, aluminium and a variety of other alloys, react with a gas (typically nitrogen and/or carbon-containing gases) to form a coating material that condenses on the part to be coated.

Cathodic arc PVD produces high levels of metal ionisation (over 95%), which helps to ensure a high degree of adhesion of the coating to the substrate material. The method typically has a wide operating window, allowing for the deposition of high quality coatings using a variety of process parameters. Other coating processes, such as sputtering or ion plating, are less robust and have smaller operating windows, making them more difficult to consistently produce high quality coatings.

The second most common medical coating is aluminium titanium nitride (AlTiN), often referred to as black nitride or black titanium coating. It is available in thicknesses ranging from 0.0001 to 0.0002 inches and hardnesses ranging from 4,000 to 4,200 Hv with a charcoal black finish.

The other two medical coatings are chromium nitride (CrN) and Alpha.CrN ranges from 0.0001 to 0.0005 inches in thickness, has a hardness range of 2,200 to 2,400 Hv, and a silver finish.Alpha is a multilayered coating with a top layer that has zirconium nitride (ZrN) and produces a silver-gold colour. It is available in thicknesses ranging from 0.0001 to 0.0002 in. and has the highest hardness, ranging from 4,400 to 4,600 Hv. Because of its higher hardness, lubricity, and wear resistance, this coating can outlast TiN by a factor of two to four.


What are the advantages of PVD over chemical vapour deposition (CVD) coating processes?

PVD coatings are applied at much lower temperatures than CVD, and PVD-coated parts do not have to be heat-treated again after coating. In addition, PVD replicates the surface finish that would otherwise be on the part, whereas CVD coatings produce a lusterless finish unless the part is polished after coating.

What are the advantages of PVD over anodising?

Applied to titanium coatings, PVD is more wear resistant than anodising and retains its colour better over time.

In addition to medical instruments and cutting tools, PVD coatings are commonly used to improve the performance and service life of stamping tools, forming tools and injection moulded wear parts.

What preparation is required before coating?

In order to obtain a well adhered coating, it is very important that the part to be coated is clean. The surface of the part must be free of oxides, EDM recasts and organic films as these contaminants can adversely affect the quality of the coating.

To remove contaminants prior to coating, coating companies use techniques such as polishing, tumbling, acid etching, and sand and glass bead blasting. However, some of these techniques can alter the surface finish of the coated part, so PVD coating companies often work with customers to develop processes that meet their needs for coating quality and part appearance.

Does the coating process adversely affect sharp edges?

If a part has sharp edges, a cleaning process that could adversely affect edge definition will not be used. In addition, if coating tiny or very fragile parts, coating process modifications can be made to reduce heating and coating rates. These modifications ensure that delicate features are not overheated and the coating is not too thick.