Titanium Coating Is Actually Pretty Straightforward

[Justin] enjoys tinkering in his home lab, working on a wide variety of experiments. Recently, he’d found much success in coating objects with thin layers of various metals with the help of a DC sputtering magnetron. However, titanium simply wouldn’t work with this setup. Instead, [Justin] found another way.

As it turns out, coating with titanium is quite achievable for even the garage operative. Simply run current through a titanium wire, heating it above 900 degrees in a vacuum. This will create a shower of titanium atoms that will coat virtually anything else in the chamber. [Justin] was able to achieve this with little more than some parts from Home Depot, a vacuum pump, and a cheap glass jar. He was able to produce a nice titanium oxide finish on a knife blade, giving that classic rainbow look. Coating crystals was less straightforward, but the jet black finish achieved was impressive nonetheless.

[Justin] plans to upgrade his vacuum rig further, and with better process control, we’d expect even better results. The earlier work is also very relevant if you’re interested in creating fine coatings of other materials. Video after the break.

26 thoughts on “Titanium Coating Is Actually Pretty Straightforward

    1. No, Venturis are useless for any kind of vacuum work, you are limited to the vapor pressure of water which is really high. You will need a dual stage rotary oil pump at a minimum.

    2. Nope lol. The explanation is kind of frustrating. It’s “straightforward” and “quite achievable for even the garage operative”—assuming you have access to a high vacuum pump. Well yeah, most things are achievable if you already have all the specialist hardware!

      1. No, it’s not *ultra high vacuum*. Venturi pumps just really don’t pull much vacuum at all – you use them if you’re worried about clogging typically, or if you don’t want vibration. The pump required is very accessible.

        Sputtering usually doesn’t need nearly as high vacuum as some other semiconductor processes. A HVAC pump is enough. That’s like $100-$200ish from Amazon. In his video that’s exactly what he uses.

        This is also why I hate the video format…if someone just wrote out the article, it’s only a ctrl-f away from knowing the answer to this question, instead of having to carefully rewatch for every tiny detail.

        1. i agree the video format is frustrating, relatively recently things got better.
          some (now most) youtube vids have a generated transcript that you can open using the three horizontal dots menu at the botom right of the video frame.

          this transcript can be searched and when clicked on will jump to the timestamp

          in this vid he mentions the pump six times. :)

  1. People I work for used to use variants of this in different ways for certain medical parts for implant. Can’t say anymore than that, and its a physically more complex operation that allows for bone growth into titanium. Its not done anymore I believe in industry but its still proprietary so mums the word.

    1. Are you referring to the company Synthes U.S.A? They produce a vast array of orthopedic fixation devices made from Ti and also S.S. varieties. They employ a standard Ti-anodizing technique to achieve different colors for product classification.

      1. First of all I would not tell you if that was my employer but it isn’t.

        Second of all- did you actually read my comment?
        Coloring is not involved. A special type of surface is created using the technique of this article in a more extreme way the creates a surface for artificial bone growth.

        I cannot describe how this is done even though I know how, because I believe it is still proprietary even though it is not used anymore in industry.

      1. Modern mirrors are coated with aluminum and then usually overcoated with other things to increase the already high reflectivity, “enhanced aluminum”. Plus a coating of SiO2 on that to protect it.

        1. Plain aluminum still produces a really nice finish and is easy enough to do that stripping it and re-coating when it starts to get marred isn’t really too bad. Most bigger observatory telescopes are just plain aluminum coatings and they just re-coat every so often. Strip with ferric chloride and water. A cheap used diffusion pump and small vacuum chamber will do well for this. You don’t really want to pump with an HVAC pump for this though, because you would need to get right down to the limits of that pump or below and running it that hard for long enough to coat the mirror would probably damage it.

          The trick with garage vacuum setups is to find old vacuum equipment and hacking it to your needs. Keep an eye out for vacuum setups with outdated control electronics (you can live without an automatic crossover control for hobby projects, for example) or attached to other non functioning equipment, ie, stealing the vacuum gear off a dead 1980s SEM or NMR or something.

    1. For a telescope mirror you use an electrical grade aluminum wire (99% pure). This is standard practice. In fact, the interconnect layer on ICs used to be laid down this way. Maybe it still is in some cases.

    2. No. You need a vacuum six to 8even orders of magnitude lower than what they can get with the setup he has. Generally for optical coatings you want to be 10^-6 torr or lower for good coatings. This is not too hard to do, you can do it with an old diffusion pump or a turbo pump. Or even cryoabsorption. There are quite a few people that have made systems for coating mirrors.

    3. I’ll go with “depends” … If you’re in big light bucket mirror cheap mode, for gawping, and have got your mirror ground on cheaper or obtanium glass blank, think you’ve probably got it to within a wavelength or two, and you’re perfectly happy with 98% shiny, then go for it, if it sucks scrub it off. If you’ve spent a helluva lot of money and time making your precision instrument type mirror to within half a wavelength, then this only might be okay for testing the optical shape of your mirror before you spend a lot out on a fully optimised coating or vacuum system to achieve such.

    1. titanium forms an oxide layer IMMEDIATELY when exposed to air. So coating anything in titanium is really coating it in titanium and a protective layer of titanium oxide. The oxide layer can be manipulated with heat or current to differing thicknesses and resulting color.

        1. Similar but not quite the same. Aluminum forms a protective oxide layer. Anodization of aluminum opens micropores in the aluminum oxide layer allowing dyes to penetrate….Its basically a dye receptive coating.
          Titanium anodization is different in that a coating of titanium oxide varies in thickness according to the voltage applied. As light passes through the titanium oxide layer, reflects off the underlying titanium and takes a second pass through the oxide layer more and more light is filtered the thicker the coating. Its a limited palette, you cant get red or black or some other colors that are easy to “anodyeZ” into aluminum, but its a pretty decent range http://www-personal.umich.edu/~bobden/titanium-spectrum-web-2.jpg

  2. Our electrodes are more robust in relief.

    Plot your traces with a diamond tip
    etch major features with a blaster or hydrofluoric
    coat your slide in your sputterjar
    Then wetsand on granite to remove the coating from the surface leaving the circuit

  3. Will this work to plate aluminum onto plastic? The quality of the exposed metal surface doesn’t matter because the metal will be viewed through the clear plastic, same as the silver or aluminum coating on normal mirrors is viewed through the glass.

    I’ve been using Spaz Stix Ultimate Mirror Chrome paint for some automotive reproduction plastic parts. When it works well it’s near indistinguishable from vacuum deposited aluminum.

    1. It would absolutely work!

      The aluminium wire would have to be wrapped around, or sitting on top of, something made from tungsten or molybdenum because aluminium will definitely melt. Unfortunately the chamber, aluminium wire and plastic part would have to be super clean or the film will come out golden brown (I’ve seen this happen). The “dirtiest” part of the film is the first part to be deposited, so the quality of the film will still need to be decent even to just view through the plastic. I helped someone make “disposable electrodes” for a plasma physics experiment by coating an acrylic disc with aluminium; they’d then blow it off will a few megavolts to study the plasma it made, then we’d re-coat it. It worked like a charm.

      You’d need more than just a rotary vacuum pump though: you could use a titanium evaporation in another part of the chamber to increase the vacuum :)

      You could also try using some gallium to coat the plastic part, that should leave a nice shiny plastic-metal interface if the gallium coats the plastic (it might not).

  4. Also, I wouldn’t rely on the aluminium itself as a conductor. Looking on youtube it seems that professional mirror silvering is done by hanging pieces of aluminium wire on tungsten heating elements. This video goes into a lot of detail about the entire process:

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