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Participant

Join Date: Jun 2008
Posts: 2

Plasma spraying titanium

06/24/2008 6:25 PM

.Dear CR4,

I would like to know if there is a commercially available plasma spraying unit that can coat titanium structures with titanium beads. I know this process has been used to coat the surface of dental implants to assist in osseointegration (unsuccesfully). However, this resultant surface is ideal for the applications I require and thus far can only be achieved through casting the structure with the beading in the final wax pattern. Could you please advise me if what I am seeking is possible to achieve without having to send my castings to a specific workshop.

Regards,

Emmanuel

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Guru
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Join Date: May 2006
Location: Montreal, Canada
Posts: 632
Good Answers: 11
#1

Re: Plasma spraying titanium

06/26/2008 1:18 AM

There seems to be a lot in googling 'titanium plasma spray'.

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Member

Join Date: May 2008
Location: United Kingdom
Posts: 8
#2

Re: Plasma spraying titanium

06/26/2008 3:41 AM

Plasma spraying units are commercially available. I'm not 100% sure if the resulting surface will be what you are looking for as you mention spraying 'beads'. Plasma systems typically spray powders for boi-medical applications with particle sizes in the range of around 300-212 microns. You can choose more course or more fine powders but these are often tricky to get hold of.

Contact Metallisation Ltd in the UK for more details of a plasma spraying system (www.metallisation.com)

You can also use a twin wire arc spraying method to spray titanium wire. With the standard process, you tend to get a lot of oxide in the coating (which may or may not suit your requirement. There is also a process called Purecoat where twin wire arc spraying is combined with an inert gas shield to greatly reduce the oxide content.

I'm interested also to see your comment re unsuccessful osseointegration as it is a process widely used in the medical implant industry.

Good luck

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Participant

Join Date: Nov 2007
Posts: 3
#3
In reply to #2

Re: Plasma spraying titanium

06/26/2008 8:02 AM

I have an issue that sort of levers off of this thread. Bottling of isotonic ( read: high salt content ) beverages has caused some to switch from 316ss ( the standard ) to titanium to get better corrosion life. Not only is are the titanium components hellaciously more expensive, but finding welders experienced in it can be difficult as well. Reading this thread got me thinking: Is coating 316ss with titanium an economic, as well as technically feasible, alternative?

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Participant

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#4
In reply to #2

Re: Plasma spraying titanium

06/26/2008 8:35 AM

Plasma spray coated dental implants had a short lived success, if any, simply because the surface prevented adequate vascularisation around the implant for bone to even begin to osseointgrate. Although it wasn't successful and short lived, my evaluation of this surface texture was I found it absolutely perfect for the applicattion I need. In saying that, I am getting the nasty feeling it's going to be a long road and a very expensive exercise to find a unit small enough to be used in a dental laboratory like mine. My biggest concern at this stage is finding one and preparing myself for the price tag attached to it.

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Guru
Canada - Member - New Member

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Location: Montreal, Canada
Posts: 632
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#5
In reply to #4

Re: Plasma spraying titanium

06/26/2008 10:58 AM

It may be difficult for you to disclose your application, but have you considered other means of creating a surface compatible to your needs?

Laser or chemical etch for example or use titanium foam instead.

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Join Date: Nov 2006
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#6
In reply to #4

Re: Plasma spraying titanium

06/26/2008 2:05 PM

do you think you can use Nickel Aluminum as the material to spray in place of Titanium? If so, you can do this very easily, fast and the equipment to do this is very affordable. If you want I can send you sample of the spray pattern you can obtain with a very thin coating of this alloy on a steel surface and you can easily do this over titanuim implants as well. As for Plasma spraying, you will have use fine powders and so the coating will have a relatively smooth profile, which will not be suitable for your intent

vshwn7@aol.com

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Guru

Join Date: Dec 2006
Location: Germany 49° 26' N, 7° 46' O
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#7

Re: Plasma spraying titanium

06/26/2008 4:12 PM

Hi,

titanium is very reactive and is reacting at melting-temperature (also below) with oxygen, nitrogen, carbon, boron, hydrogen.

So if you want to have success with Ti-spraying you have either to use exceedingly pure Argon (or other noble gas) or operate the equipment in an equivalent vacuum.

I would estimate (from experiments with titanium containing brazing alloys in vacuum) that you may need 10-6 mbar vacuum or 99.9999 purity Ar.

As this is not feasible you can lower the requirements by a getter-pump: make a liquid or near liquid very hot bath of calcium or magnesium or titanium, maybe mixed, the synchrotron people use a heated strip of an AlNd-alloy. I used Al-foil and Ti-chips.

This may relieve the necessities by a factor 100.

Powder preparation and cleaning and degassing is certainly an important issue.

As this process: plasma spray in vacuum is used to produce arbitrary alloys for use as sputtering targets, there are people who know, but I don't know where they are located and if the technology is available.

The not successful trial of coating titanium for dental implants is very likely linked to the misinterpretation of Ti-alloys as titanium.

As the TiAl6V4 is now replaced by the TiAl6Nb7 alloy this will be a little bit better but any coating is likely to have pores and these pores will concentrate the corrosion current (small but existing) and give an attachment where bacteria can attack. (We got severe corrosion in testing carbon coatings on TiAl6V4 immersed in synthetic saliva. And I saw corrosion of titanium dental fixtures.

I would try to make the parts so that there is no need to coat.

RHABE

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gigaconcept.com (2); JimFGE (1); Milty (1); RHABE (1); vishmayor (1); Zorba (1)

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