Blacker than black: PVD technology makes it possible
How PVD coatings enable product innovation to fulfill expectations of modern customers
Decorative coatings began simply with an intention to provide a bright and metallic appearance aiming to differentiate products distinctively from its competitions. Consumers looking into several products of interest will generally have their attention drawn to packets that have a certain brightness in their design.
The current market for decorative coatings USD $67 bn is predicted to surge at a Compound Annual Growth Rate (CAGR) of 4.2% to reach USD $84 bn in 2024 (MarketsandMarkets, 2020)
For last two and half decades, different methods and technologies have emerged which enable products to be colored decoratively, particularly through the development of vacuum deposition techniques. Physical Vapor Deposition PVD, a most popularly used industrial vacuum deposition technique has been gaining a lot of attraction in recent years,
as a coating layer by PVD is durable both against corrosion and scratches.
Decorative coatings by PVD must pass through stringent demands such as,
attractive color
high hardness
stability in colour over time
resistance to corrosion and wear.
Among all the possibilities of PVD deposition, magnetron sputtering technology is gaining a pivotal attention to deposit coating of various colours at the temperatures lower than 180°C, presenting a major advantage over the rest of technologies to coat heat sensitive parts such as plastics, elements of watches with springs, bras faucets, door handles and automobile components etc.
Magnetron sputtering goes further:
it offers more advantages as 3-D substrates of complex shapes can be coated with extremely smooth multiple layers by cathodes of appropriate designs.
In order to develop unique and perfect coloured products it is needed to achieve intrinsic colour coatings and to avoid interferential colour coatings as much as possible. Intrinsic colours are uniform and exhibit a constancy of colour irrespective of how thick your coatings are.
For last one decade, the black color PVD coatings are widely used.
For a perfect black colour coating, you should have L* as low as possible while limiting the values of colour coordinates a*and b* close to zero.
With L < 34 , while having a* and b* very close to zero is the minimum goal to achive.
Most current methods to receive dark black colours is based on diamond-like carbon (DLC) layers. Deep black DLC coatings are extremely hard and wear resistant which provide a longer endurance and greater visual attraction with smooth and shiny appearance for your coated products.
Apart from its visual refinement, the chemical inertness and high hardness of deep black DLC coatings becomes a unique choice for
expensive eyewear frames
surgical scissors
cutting knives
watch casings
and similar small parts having constant interaction with body sweat or other chemicals
To achieve deep black DLC coatings ( with L< 30) we use superior quality sputtering targets or mixed metal targets for improved performance. We proved, that trimetallic targets bring excellent results and improved preciseness for dark colour with excellent durability.
Additionally, we could achieve more deep and black colour coatings by individually configuring customer systems to handle high density discharge on the sputtering target while feeding organic hydrocarbon gas.
The experience from several projects shows, that the key to success is to choose the right target material of perfect composition and to develop a process that is less polluting, extremely low internal stress and an excellent direct recoating on already coated products without de-coating by stripping or chemical dissolution.
Deep black coating is going to rule the decorative market for next few years, may be even for a couple of decades. Manufacturers would need to drive their efforts to tailor deep black colour on their products.
These market expectations can be fulfilled with PVD technology and a process based on sputtering of metals in hydrocarbon atmosphere, which is going to produce deep black colour that is also mechanically strong and chemically enduring.
I am happy to share more more information and experiences from several projects or to answer your individual questions on coating materials and coating technology. Just contact me directly on LinkedIn or use cpernagidis@avaluxe.de
Link to discussion: https://www.linkedin.com/pulse/blacker-than-black-pvd-technology-makes-possible-christos-pernagidis/