Advantages of PVD Coating over Electroplating

A. Hi, Murthy. Some materials can be applied by PVD but not by electroplating, including some very hard and wear resistant coatings. Plus there is usually a reduced potential for release of a toxic material to the environment from PVD compared to electroplating. You did not ask for the advantages of electroplating compared to PVD, and your teacher may grade your homework poorly if you leave it at that :-) Good luck.

A. Hi, Dave

Watchcases are very small high production items that happen to play well to the advantages of being applied by PVD. From the consumer's standpoint it may be of little importance how a coating was applied, but if a particular coating is ideal for an application, and that coating can only be applied by PVD, that would dictate the use of PVD.

Here is an example: gold is a beautiful precious metal that has long been electroplated onto watches, but it is often applied very thin because of its cost, and then it can wear away, especially off of exposed high points as shown:

Titanium nitride, the goldish-color hard coating you see on drill bits, is applied by PVD. If the watch maker had applied titanium nitride followed by gold electroplating, those exposed high points would have remained quite gold-ish looking even after the gold has worn off, instead of the unacceptable contrast of becoming nickel colored as shown.

Regards,

A. Hi Seb. Capital cost can be one of the serious disadvantages of PVD coating; a jeweler can do gold electroplating in a teacup in a pinch but will certainly not have the space and money to install PVD equipment. Electroplating and electroless plating can cover recessed area not reachable by PVD processes. Much thicker coatings are usually available from electroplating. Electroplating is generally easier to mask for selective plating. Electroplating can be done in-situ (brush plating).

There are some processes that can't be done by PVD, some that can't be done by electroplating, some that require both in sequence, and some that are close to a toss-up.

Although hobbyists often make vacuum chambers, I'm not personally aware of small and affordable PVD units.

Regards,

Thank you for your reply Ted

Having had no proper answer from the plating unit providers I contacted, I am going to go and see a few PVD service providers.

If I could have access to that technology despite my low volumes I would go for it, since in my opinion customers want durability above all else, even if it's titanium nitride.

Cheers

A. Hi Ahmed. I was not aware that zinc could be deposited by PVD, but I am not a PVD expert.

You have not described anything about your tanks, so I don't know what deposition techniques are possible and what isn't. What are the tanks for, and what is their shape, and are you coating the inside or outside, and what environment will they see? Please don't use the words electroplating and galvanizing interchangeably because they are very different processes. The corrosion resistance of zinc coated steel objects is roughy proportional to the thickness of the zinc coating. How thick a coating do you want to apply?

Regards,

A. Hi Sellappan. PVD stands for 'physical vapor deposition' -- essentially vacuum coatings where the coating metal is vaporized for deposition onto the substrate. One of the best known PVD coatings is titanium nitride, the gold colored coating you see on drill bits, and often on rings and jewelry.

I am not familiar with "high-end" chain link fences where the wire is made of stainless steel rather than plain carbon steel, but I do know that stainless steel building panels are sometimes PVD coated with titanium nitride or similar materials for a gold color.

PVD coating with titanium nitride is done in special vacuum chambers that cost a million dollars and up, and is usually done on a 'batch' basis, not a continuous process because of the need to maintain high vacuum conditions. But if the wire was properly presented, wound like a very large diameter compression spring, I don't see any particular reason, except for cost, that gold colored fencing could not be made from stainless steel wire PVD coated with titanium nitride.

Readers who are more familiar with PVD coating than me may be able to offer more detail or sounder ideas :-)

Luck & Regards,

A. Dear Sellappan,
Ted has answered all your questions. I just want to make a couple of points. PVD does not refer to any specific coating but to some processes by which coating is applied. Many coatings which are otherwise impossible to deposit can be deposited by PVD processes. Generally these coatings are more dense and stick better. Second, being a physical process PVD is more environmentally friendly compared to electroplating.
As pointed out by Ted, ss wires can be coated though you may have to build a machine specifically for this purpose.
But you have to first make it clear as to the role of coating -- decorative, wear resistant, anti-corrosion, etc., in your application.

Thank you very much for the detailed reply Mr. Ted & Mr. Prabhakara. Appreciated!!

A. It is possible to coat wire by PVD using a reel-to-reel process. Of course, you would want to have many strands going at a time and to do a thick coating would be extremely costly. Given that PVD is used to deposit titanium on mylar for microwave popcorn bags using a reel-to-reel method, anything is possible. Actually worked on reel-to-reel wire concept years ago but we never got to the reel-to-reel level. Some consideration has been given to reel-to-reel deposition of antimicrobial coatings on fabric.