Si coating on SiC
07-18-2007, 01:56 PM, (This post was last modified: 07-18-2007, 01:57 PM by Sin.)
#1
Si coating on SiC
First time here.

I'm seeking a cost-effective process to deposit Si onto SiC targets to a thickness of 50?. We are able to prepare the SiC targets to an Ra of 5nm, or if necessary rough lap with 6? diamond (for a rougher surface). Individual target pieces will be ?15mm up to ?300mm. Bond strength needs to be to MIL-C-48497A, but the thickness tolerance and surface quality are unimportant because we will then optically polish post-depostion, and then optically coat with a specialised high-reflectivity coating. Max polishing temps will be under 80C. Max optical coating chamber temps will be under 230C. Speed of deposition, cost of machinery and consumables are an issue (having said that we have experimented with ion-beam... which is astonomical), as is bonding strength. Ideally we are looking for a machinery manufacturer who could assist R&D, take sub-contract in the short-term, and then sell us the machinery and consumables, and provide training for our operator/s. We need to be processing 10,000 parts pa by 2010.

Sin
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07-18-2007, 09:13 PM,
#2
RE: Si coating on SiC
Hi Sin

Sign0016 to the Surface Engineering Forum.

Don't think I can really help too much on this one. Sounds like you we need a PVD type process. Thermal spray I doubt would be suitable or clean enough unless vacuum plasma sprayed or possibly cold spray.
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07-18-2007, 09:37 PM,
#3
RE: Si coating on SiC
Thanks Gordon,

We've already discounted PVD due to production times and costs. Vacuum is possible, and of course the whole thing is easier being single axis.

Sin
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07-19-2007, 12:55 AM,
#4
RE: Si coating on SiC
Hi Sin

Thinking about it, Cold Spray or cold gas-dynamic spraying process may be worth looking into. It is still in it's R&D stage of development, not even sure if it would be pratical, but it would be significantly cheaper than vacuum plasma processing.
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07-19-2007, 01:10 PM,
#5
RE: Si coating on SiC
Thanks Gordon.

We are continuing to investigate five possible methods: APS, VPS, LPPS, HVOF and Detonation Thermal Spraying Process.

So far HVOF seems to give the overall requirements we need.

Can you please recommend suitable HVOF system manufacturers that could target a plano surface up to ?300mm?

Regards,
Sin
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07-20-2007, 10:18 AM,
#6
RE: Si coating on SiC
Dear Sin
Look at Uniquecoat Technology AC-HVAF equipment at http://www.uniquecoat.com/
br bjarne
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07-20-2007, 11:04 AM,
#7
RE: Si coating on SiC
Thanks bhellman

I will investigate your suggestion

Sin
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07-24-2007, 03:19 PM,
#8
RE: Si coating on SiC
Hi Sin

To balance things a little you should also look at HVOF equipment from Sulzer Metco, Praxair/Taffa and Metallisation to name a few. I do like Bjarne suggestion thoughToungue
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07-24-2007, 03:32 PM,
#9
RE: Si coating on SiC
Thank you Gordon

We have trials proceeding with one of your suggested contacts. I will report how we get on. Until then, all the best and thanks for your help.

Sin
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07-24-2007, 04:08 PM,
#10
RE: Si coating on SiC
Thanks Sin, it would be good to know how things go.
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08-06-2007, 07:59 AM,
#11
RE: Si coating on SiC
Hi,
One possible alternative is to use spark deposition process, using low voltage(50V) and low capacitance(30 microfarad) for thin smoth deposit of Si.For futher info, please check on my book on adv.surface enginering, chapter11.
Ram
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08-30-2007, 10:02 AM,
#12
RE: Si coating on SiC
I can now update the current situation:

We have SiC target blanks available for testing. We have a partner deposition company in Germany preparing to make the first trials using three methods: HVOF, CCG (cold cathode gauge?) and thermal plasma spray. But, we have a small problem which the forum may be able to help with:

We have tried Umicore, Sulzer, Praxair and Sonter (not sure if I have the spelling correct, but they are in Australia), but no luck as yet with what we require.

1. Does anybody have a recommendation for a supplier of Si powder with a grain size 20-40 microns?

2. Can anybody explain the CCG process?

Many thanks,
Sin
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09-04-2007, 03:18 PM,
#13
RE: Si coating on SiC
Hi Sin

Quote:1. Does anybody have a recommendation for a supplier of Si powder with a grain size 20-40 microns?
I would like to think Sulzer Metco or Praxair could be helpful here Rolleyes May be looking towards the electronics industry material suppliers, but this may be problematical if you are initially only after small quantities.

Quote:2. Can anybody explain the CCG process?
The only references I can find are 'cold cathode gauge' for very low pressure measurement instruments in vacuum type processes.

Sorry, not too helpful Ashamed0002
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