Hydrochloric acid (30% - BE CAREFUL) will strip the chrome at room temperature but not the chomium oxide interfcial material which can be removed using HF. Various additives are used with the HCl they are mostly wetting agents. I might add that if the chrome has been around awhile it may be necessary to hit it first with the HF to remove the native oxide that has formed. Don Valdimir!
How can you strip off the Chrome from the glass?
In my experience, it comes off by polishing with pich or by grinding. I have not find any soultion which solves the Cr underlayer.
Br.
Attila
--- In VacuumX@..., Vladimir Chutko <chutko@...> wrote:
For Al and Ag I deposit 300 A Cr underlayer on glass at 20 A/s . Before
I make oxygen ion beam substrates pre-cleaning during 2-3 min.
Everything looks fine, adhesion is very good.
Vladimir Chutko
On 9/13/2011 7:17 PM, pjifl@... wrote:
> I need to do Cr coating which must adhere very well. But my evaporation
> rate may not be as high as I would like.
>
> Cr is always mentioned as holding on to glass well - better than
most other
> metals.
>
> But, after reading how evaporation rate influences the sticking of Al on
> glass, how important is it for Cr ?
>
> Peter Smith
>
>
>
>
>
>
>
> ------------------------------------
>
> Yahoo! Groups Links
>
>
>
>
------------------------------------
Yahoo! Groups Links
-- ____________________________________ Donald M. Mattox Society of Vacuum Coaters 71 Pinon Hill Place NE Albuquerque, NM 87122-1914 Telephone 505/856-7188 FAX 505/856-6716 E-mail donmattox@... WebSite
|
Hydrochloric acid (30% - BE CAREFUL) will strip the chrome at room temperature but not the chomium oxide interfcial material which can be removed using HF. Various additives are used with the HCl they are mostly wetting agents. Don Valdimir!
How can you strip off the Chrome from the glass?
In my experience, it comes off by polishing with pich or by grinding. I have not find any soultion which solves the Cr underlayer.
Br.
Attila
--- In VacuumX@..., Vladimir Chutko <chutko@...> wrote:
For Al and Ag I deposit 300 A Cr underlayer on glass at 20 A/s . Before
I make oxygen ion beam substrates pre-cleaning during 2-3 min.
Everything looks fine, adhesion is very good.
Vladimir Chutko
On 9/13/2011 7:17 PM, pjifl@... wrote:
> I need to do Cr coating which must adhere very well. But my evaporation
> rate may not be as high as I would like.
>
> Cr is always mentioned as holding on to glass well - better than
most other
> metals.
>
> But, after reading how evaporation rate influences the sticking of Al on
> glass, how important is it for Cr ?
>
> Peter Smith
>
>
>
>
>
>
>
> ------------------------------------
>
> Yahoo! Groups Links
>
>
>
>
------------------------------------
Yahoo! Groups Links
-- ____________________________________ Donald M. Mattox Society of Vacuum Coaters 71 Pinon Hill Place NE Albuquerque, NM 87122-1914 Telephone 505/856-7188 FAX 505/856-6716 E-mail donmattox@... WebSite
|
I would also like to know how to get rid of the Chromium layer. It sticks to regular pitch and rouge like ... pitch. I don't have any problem getting aluminum to stick to glass.? ? Guy Brandenburg, Washington, DC?
http://gfbrandenburg.wordpress.com/
http://home.earthlink.net/~gfbranden/GFB_Home_Page.html
============================
From: Attila
To: VacuumX@...
Sent: Friday, September 16, 2011 9:47 AM
Subject: [VacuumX] Re: Cr sticking on glass
?
Valdimir!
How can you strip off the Chrome from the glass?
In my experience, it comes off by polishing with pich or by grinding. I have not find any soultion which solves the Cr underlayer.
Br.
Attila
--- In VacuumX@..., Vladimir Chutko wrote:
>
> For Al and Ag I deposit 300 A Cr underlayer on glass at 20 A/s . Before
> I make oxygen ion beam substrates pre-cleaning during 2-3 min.
> Everything looks fine, adhesion is very good.
>
> Vladimir Chutko
>
>
> On 9/13/2011 7:17 PM, pjifl@... wrote:
> > I need to do Cr coating which must adhere very well. But my evaporation
> > rate may not be as high as I would like.
> >
> > Cr is always mentioned as holding on to glass well - better than most other
> > metals.
> >
> > But, after reading how evaporation rate influences the sticking of Al on
> > glass, how important is it for Cr ?
> >
> > Peter Smith
> >
> >
> >
> >
> >
> >
> >
> > ------------------------------------
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
>
|
Valdimir!
How can you strip off the Chrome from the glass?
In my experience, it comes off by polishing with pich or by grinding. I have not find any soultion which solves the Cr underlayer.
Br.
Attila
toggle quoted message
Show quoted text
--- In VacuumX@..., Vladimir Chutko <chutko@...> wrote:
For Al and Ag I deposit 300 A Cr underlayer on glass at 20 A/s . Before
I make oxygen ion beam substrates pre-cleaning during 2-3 min.
Everything looks fine, adhesion is very good.
Vladimir Chutko
On 9/13/2011 7:17 PM, pjifl@... wrote:
I need to do Cr coating which must adhere very well. But my evaporation
rate may not be as high as I would like.
Cr is always mentioned as holding on to glass well - better than most other
metals.
But, after reading how evaporation rate influences the sticking of Al on
glass, how important is it for Cr ?
Peter Smith
------------------------------------
Yahoo! Groups Links
|
I have been messing up coatings a lot this week ( dialing in a new transformer ) so have been stripping them back off and analyzing the results.?
First off, I have noted that the coatings are massively stuck on.? I mean they are stuck on 10 times more than I normally see.? I have also noted that there is a bluish black soot like stuff seriously stuck to the glass.? I am guessing this is some form of tungsten from the emitters that are not heating correctly. I am having a lot of problems making aluminum thickness happen right now.? It could be from the vacuum not being deep enough or from the coils not heating up enough. ??
This dark layer of ( something tungsten ) is being over coated by the aluminum.? The soot layer is very thin ( like a few tens of nanometers ) but it is welded to that glass.? It is not taken off by the stripper.? The aluminum is dissolved away instantly by the copper sulfate based stripper leaving this dark film on the glass surface.? The film comes off with a weak solution of CeO and wiping but it takes several iterations to get it fully removed. ?
This soot is just like the stuff that my plasma discharge system made.? I don't run that system right now because of the soot it used to make.? But maybe that soot is part of good adhesion.? I am pretty sure once I get my transformer dialed in I will stop making this soot and go back to my normal adhesion of the aluminum.?
I just wanted to mention it and see if anybody has an idea what it is and maybe if it is a low tech solution to better adhesion.? Maybe if we figure out exactly how to make a uniform thin layer of this dark coating it could be the first thing deposited on the glass.? It really does seem to increase the adhesion of aluminum to the surface. ?
Drew in sunny Florida
------------------------------------------------------------------------?
toggle quoted message
Show quoted text
On Thu, Sep 15, 2011 at 9:53 PM, Vladimir Chutko <chutko@...> wrote:
?
For Al and Ag I deposit 300 A Cr underlayer on glass at 20 A/s . Before
I make oxygen ion beam substrates pre-cleaning during 2-3 min.
Everything looks fine, adhesion is very good.
Vladimir Chutko
On 9/13/2011 7:17 PM, pjifl@... wrote:
> I need to do Cr coating which must adhere very well. But my evaporation
> rate may not be as high as I would like.
>
> Cr is always mentioned as holding on to glass well - better than most other
> metals.
>
> But, after reading how evaporation rate influences the sticking of Al on
> glass, how important is it for Cr ?
>
> Peter Smith
>
>
>
>
>
>
>
> ------------------------------------
>
> Yahoo! Groups Links
>
>
>
>
|
For Al and Ag I deposit 300 A Cr underlayer on glass at 20 A/s . Before I make oxygen ion beam substrates pre-cleaning during 2-3 min. Everything looks fine, adhesion is very good.
Vladimir Chutko
toggle quoted message
Show quoted text
On 9/13/2011 7:17 PM, pjifl@... wrote: I need to do Cr coating which must adhere very well. But my evaporation
rate may not be as high as I would like.
Cr is always mentioned as holding on to glass well - better than most other
metals.
But, after reading how evaporation rate influences the sticking of Al on
glass, how important is it for Cr ?
Peter Smith
------------------------------------
Yahoo! Groups Links
|
Hoel, Chris (Boise LTL HWTL)
I¡¯m not sure about the best rate of deposition of Chrome by evaporation (have never done it)
But chrome deposited by magnetron sputtering at a rate of about 30 nM a minute will bond with
Soda lime glass well enough to tear glass off of a substrate when it¡¯s removed by force.
?
I was told (by a materials scientist) that the theory is that chrome bonds with the Oxygen in SiO2
Yielding an actual chemical bond between the chrome and the glass substrate.
?
The bond strength of any coating is highly dependent on the glass being free of organic contaminants
(wax, oil, etc.) ?
?
Chris Hoel
?
?
toggle quoted message
Show quoted text
From: VacuumX@... [mailto:VacuumX@...]
On Behalf Of pjifl@...
Sent: Tuesday, September 13, 2011 8:17 PM
To: VacuumX@...
Subject: [VacuumX] Cr sticking on glass
?
?
I need to do Cr coating which must adhere very well. But my evaporation
rate may not be as high as I would like.
Cr is always mentioned as holding on to glass well - better than most other
metals.
But, after reading how evaporation rate influences the sticking of Al on
glass, how important is it for Cr ?
Peter Smith
|
I need to do Cr coating which must adhere very well. But my evaporation rate may not be as high as I would like.
Cr is always mentioned as holding on to glass well - better than most other metals.
But, after reading how evaporation rate influences the sticking of Al on glass, how important is it for Cr ?
Peter Smith
|
Very low sticking coefficient of copper on glass?
Hi all!
Have recently made my fist aluminum first surface coated mirror which came out perfect but the sticking isnt perfect but quite all right and getting better but i havent really cleaned it in any way possible either which as a lot to do with it.
But then i wanted to test to coat with copper and it worked the very first time and got me a very nice copper mirror.
The interested part was when i accidentally chipped one edge (they are very small and thin glass plates im using) and the copper film loosened from the chipped piece but without breaking which suprised me. I was of course interested to se how hard it would hold on the glass since it was copper that i have heard doesnt stick so well without an underlayer. I took a tweezer and could actually with only a very small resistance peel of the coating that was extremely thin, would had be funny to measure it. I estimate it to be a tad thicker then gold foil but only just or so could it just have been that copper is harder then gold so it wouldnt move so much.
But my question is if copper doesnt stick any harder then this on glass without any underlayer so that you could peel it of if the surface would have been perfectly cleaned? In my case it wasnt extremely clean du to test phase but not to far from which absolutely could have affected it to some degree.
Regards Henry
|
Re: Why you don't burn tungsten dry
You could burn them dry if you keep the temperature on them under the tungsten boiling point at the desired vacuum, i always do like this and have never accidentally deposit tungsten if they happen to run dry.
The only thing to check is so that the energy in the aluminum vapor isnt to low so it wont stick and i havent checked this into detail yet but the boiling point for tungsten is much higher then for aluminum so based on this so shouldnt it really be a problem as i see it.
I have an homebuilt 1000A transformer to the tungsten and yes it could be quite easy to put to much power in bigger coils and especially in smaller but you have to check the amperage all the time so you know that it is the same power every time in the coils so they wont get to hot.
Regards Henry
|
Re: Why you don't burn tungsten dry
Nice tip.
I'm even more interested in how you made the mirror blank and from
what found materials.
?3.5 eh? Building a camera?
I've long had a desire to own a big "light bucket" telescope, but
can't afford to buy
the mirror, let along a finished scope. I once made a 6" Newtonian
from scratch when I was
in high school, sent the mirror off to Chicago to be coated. Maybe if
I can get a few
other projects done so I have room in my shop, I might try grinding
and coating a big
mirror. Some day...
toggle quoted message
Show quoted text
On Sep 13, 2011, at 7:35 AM, Andrew Aurigema wrote:
Hi all,
For your consideration I submit my reasons you don't want to burn
tungsten elements dry. I was trying out a new 1000 amp transformer
in my vacuum chamber electrical power supply setup and it had a wee
bit more power than I was used to. I burned all the aluminum off
the tungsten then started burning tungsten. Note the lovely
cerulean blue in the multi spectral effect. That was from a very hot
fulfillment that burned away to failure. The grayish arc near the
top left is an example of what was on the witness plates. I think
that is evaporated tungsten soot.
Aside from operator error, the coating was great. The ancient XMS-1
digital thickness indicator showed 300.6 nm of deposition at an
average rate of about 5 nm per second. It was super glued down
aluminum that no amount of tape testing could touch. But it all had
to come off and be re-coated. It took several itterations of
chemical stripper and dilute CeO wiping to get all the material off
the glass ( mirror and witness plates ). No amount of stripper
alone did the job.
Thought you would be interested.
Drew in sunny Florida
( ps...... that is a 25" f/3.56, parabolic, 19 pound hyper lite
mirror that I made from raw materials in my shop )
<image.jpeg>
<image.jpeg>
|
Why you don't burn tungsten dry
Hi all,
For your consideration I submit my reasons you don't want to burn tungsten elements dry.? I was trying out a new 1000 amp transformer in my vacuum chamber electrical power supply setup and it had a wee bit more power than I was used to.? I burned all the aluminum off the tungsten then started burning tungsten.? Note the lovely cerulean blue in the multi spectral effect. That was from a very hot fulfillment that burned away to failure.? The grayish arc near the top left is an example of what was on the witness plates.? I think that is evaporated tungsten soot.
Aside from operator error, the coating was great.? The ancient XMS-1 digital thickness indicator showed 300.6 nm of deposition at an average rate of about 5 nm per second.? It was super glued down aluminum that no amount of tape testing could touch.? But it all had to come off and be re-coated.? It took several itterations of chemical stripper and dilute CeO wiping to get all the material off the glass ( mirror and witness plates ).? No amount of stripper alone did the job. ? ?
?
Thought you would be interested.
Drew in sunny Florida
( ps...... that is a 25"? f/3.56,? parabolic,? 19 pound hyper lite mirror that I made from raw materials in my shop )??
|
Re: Vacuum Pump Specifications
Gomez --
The roughing pump I have been evaluating is a Viot 2-stage, 1/3 hp, direct drive pump with a displacement of 2.75 cfm. They cost about $160 new on eBay.
After some more research on the xtremesystems.org web site, I see that someone else has reported a minimum useful pressure of about 150 microns for a similar Viot pump, so that is what I expect after the break-in period. This vacuum level will be adequate for my plasma experiments.
Thanks everyone for your help.
Bruce
toggle quoted message
Show quoted text
--- In VacuumX@..., Gomez Addams <gomez@...> wrote:
On Sep 9, 2011, at 12:47 AM, Thomas Janstrom wrote:
Yeah the pump will need to be run in, not too sure how long it will
take though. I seem to remember Gomez mentioning a numbered period
some time ago, but can't recall how long it was, maybe he can
elaborate? Oh boy, not from memory. And I'm sure it differs between belt drive
and direct-drive due to the difference in RPMs. I could swear there
was something about it in my Cenco manual... but I looked just now and
see nothing but the usual caution to change the oil annually starting
on the second year of service for "normal duty". This is for a belt
drive / oil-sealed rotary vane pump.
Bruce, did you say what kind of pump yours is?
I'd think the time frame would be in the 10's of hours rather than
100's, but I really don't know. That would be my guess. Actually, given what a new quality vacuum
pump costs, I would like to believe manufacturers actually run them
in, but that sort of attention to quality seems to be dying out. A
lot of manufacturers are starting to focus on dry pumps.
My system has a two stage Hitachi rotary pump roughing for a 6"
diffusion pump, so not too concerned with the vacuum pulled as the
volume moved. Both, I should think. It still has to reach a nice low backing
pressure for that DP to pump into.
But we knew that. :)
- G.
|
Re: Vacuum Pump Specifications
On Sep 9, 2011, at 12:47 AM, Thomas Janstrom wrote: Yeah the pump will need to be run in, not too sure how long it will take though. I seem to remember Gomez mentioning a numbered period some time ago, but can't recall how long it was, maybe he can elaborate? Oh boy, not from memory. And I'm sure it differs between belt drive and direct-drive due to the difference in RPMs. I could swear there was something about it in my Cenco manual... but I looked just now and see nothing but the usual caution to change the oil annually starting on the second year of service for "normal duty". This is for a belt drive / oil-sealed rotary vane pump. Bruce, did you say what kind of pump yours is? I'd think the time frame would be in the 10's of hours rather than 100's, but I really don't know. That would be my guess. Actually, given what a new quality vacuum pump costs, I would like to believe manufacturers actually run them in, but that sort of attention to quality seems to be dying out. A lot of manufacturers are starting to focus on dry pumps. My system has a two stage Hitachi rotary pump roughing for a 6" diffusion pump, so not too concerned with the vacuum pulled as the volume moved. Both, I should think. It still has to reach a nice low backing pressure for that DP to pump into. But we knew that. :) - G.
|
Re: Vacuum Pump Specifications
On Sep 8, 2011, at 11:11 PM, trikeflight wrote: @Thomas
The pump is new. Is a break-in period required before the best vacuum is reached. Right now, I only have about 2 hrs running time on it. Most likely.
|
Re: Vacuum Pump Specifications
Your pump is probably back-streaming but this is where my own
knowledge runs out - surely they take that into account when
stating ultimate pressures?
toggle quoted message
Show quoted text
On Sep 8, 2011, at 7:33 AM, trikeflight wrote: Thanks Gomez --
FYI, I bought a Viot 2-stage rotary vacuum pump (2.75 lpm) for some plasma experiments. To check out the pump's ultimate performance, I mounted a TIF9450D Digital Micron Gauge directly on the pump's 3/8" brass input port (with an isolation ball valve). With fresh oil and clean brass fittings, I am able to pump down to about 200 microns Hg after several out-gassing cycles lasting about an hour. It appears that 200 microns is the floor for this setup. With the ball valve shut, the small sensor chamber leaks only a few microns a day, so I know I have a tight chamber. This pump has an "ultimate vacuum" rating of about 15 microns, so I am trying to determine if my mediocre vacuum level of 200 microns is due to my inexperience with vacuum systems or if this performance is "normal" for an inexpensive 2-stage rotary vacuum pump. Comments and suggestions are welcome.
Bruce
--- In VacuumX@..., Gomez Addams <gomez@...> wrote:
On Sep 6, 2011, at 9:57 PM, trikeflight wrote:
The specifications for several two-stage, rotary vacuum pumps list
an "ultimate vacuum rating" of around 15-20 microns Hg. Has anyone
come close to these vacuum pressures with one of these commercial
pumps? If so, what pump make/model and what type of pressure sensor
did you use? From my limited experience and a lot of reading, those ultimate
pressures apply to a brand new pump fresh from the factory, with brand
new oil of the best available sort, dead-headed with a sensor at the
port (obviously).
And it will only do that after perhaps a hundred hours of break-in,
but only for the first 1,000 hours of operation maybe much less
depending on the design.
This is kind of a hand-wave estimate from memory tho. Why? Do you
want to try to achieve a moderately high vacuum without a high vacuum
pump? Doing so nearly always puts you on the edge of the mechanical
pump's performance, and will lead to tears as soon as it no longer
performs at its peak.
------------------------------------
Yahoo! Groups Links
|
Re: Aluminium adhesion problem
Hi Vladimir!
Thank's it looks very nice! It try these things and I let you know.
BR
Attila
toggle quoted message
Show quoted text
--- In VacuumX@..., Vladimir Chutko <chutko@...> wrote:
Hi Attila,
Please see attached paper - I done it a couple years ago for students.
BR
Vladimir
On 9/9/2011 2:38 AM, Attila wrote:
Hi Vladimir!
Well the graphite powder is no problem, I can make it!
But how can I shield the glow discharge cathode? How big should be the area of the cathode?
Best regards
Attila
--- In VacuumX@..., Vladimir Chutko<chutko@> wrote:
Good vacuum lubricant - MoS2. The lubricant is a mix of MoS2 black
powder and acetone. Bearings look very dirty but works. There are also a
lot of expensive special lubricants, but we used to use this one.
Graphite powder also works.
I don't think your glow discharge works good if the distance between
cathode and substrate is only 20 mm. It should be at least 100-150 mm
(and 250-300 mm is fine) at pressure in about 1 torr range. Of course,
there should be negative potential on cathode... Some people power it
with positive potential, it is wrong. Cathode must be plane, opened only
to substrate and shielded at the back side. So glow discharge must be
concentrated between cathode and substrate holder. Wrong glow discharge
may contaminate substrate surface.
BR,
Vladimir
On 9/8/2011 11:41 PM, Attila wrote:
Hi !
Well, actually I even don't think if there is as an oil backstreaming,because my DP has a water cooled cold cap and water cooled cold trap too, but I had to put some lubricant into my chamber. Because, the planetary substrate holder has two ball bearings in the chamber and these needs lubricant. I used a mix of high vacuum grease and some only drops of diffoil 20 ultra. But it is not really good.
I have to try another lubricant, just I dont know what...
My emitter for the glow discharge is about 20mm from the surface last time, before that was 250mm.
The source and substrate distance is 330mm. My best vacuum was ever 2x10-5 torr, this is the system best.
Unfortunatelly the ion source does not work yet. First I have to change my diffusion pump, because the recent pumping speed is too low, it is not enough to operate the ion source too.
Best regards,
Attila
--- In VacuumX@..., Vladimir Chutko<chutko@> wrote:
Hi Attila,
230 A/s - in my opinion it is too much.....
Anyway I suppose that bad local adhesion is because of a bad cleaning.
If there would be oil backstreaming, oil vapor must cover a whole
surface and there shouldn't be areas with a good adhesion. But things
happen...
140 nm is not a problem. Doing Al mirrors I deposit 100 nm with no
problems. Do you pre-clean your substrate with ion beam?
What is your vacuum? For good layer it must be as low as possible, at
least less than (1-2)x10-5 torr.
Try to decrease deposition rate to 40 - 60 A/s and see what happen.
Maybe it helps.
Best regards,
Vladimir
On 9/8/2011 12:30 PM, Attila wrote:
Hi Vladimir!
Well thank you for the advises!
Yesterday I increased the evaporation rate up to 230 Anstr?m/sec(23nm/sec)
The adhesion is much better, but still not passing the tape test.Parts of the layer peals off another parts don't.
Maybe the layer is too thick, because it is 140nm thick. Maybe my precleaning methode is not good. Or could that cause an oil backstreaming from my diffusion pump?
Best regards
Attila
--- In VacuumX@..., Vladimir Chutko<chutko@> wrote:
Hi Attila,
1. Very low evaporation rate. For Al it should be at least tens A/s. I
evaporate Al on a cold substrate at 40 A/s.
2. 4x10-5 torr is not very good for Al. Actually than vacuum is better,
than Al coating is better. It is recommended to evaporate Al at pressure
below 10-5 torr.
3. Cr underlayer strongly improves adhesion.
Best regards,
Vladimir
On 9/2/2011 7:49 AM, Attila wrote:
Hi All,
I ran into a trouble during my evaporation session.
My aluminium coating doesn't pass the tape test for adhesion.
My cleaning methode is:
-First I clean the mirror with isopropanol
- Next I use Balzers substrate cleaner no.1.
-Then the Balzers substrate cleaner no.2 so as the manual said.
After this I immediately put the mirror into the chamber and evacuate to 0.02-0.03 Torr.
Then I let run Argon into the chamber and glow discharge for 15 min.
After this I go down to 6x10-5 Torr, and again let the Argon into the chamber to 0.1 Torr and low discharge at 10Kv and 20mA for another 15 min.
Then evacuate as deep as possible, last time 4x10-5 Torr.
I evaporate aluminium using e-beam at 5 Angstr?m per sec. Meantime the optics are turned by the planetary holder.
After this I can let the optic so or make an overcoat of Sio2 or Sio2 and Tio2, doesn't matter the adhesion does not pass the test(bare alu, protected or enhanched does not matter)
What could be wrong?
Or should I apply 10nm of chromium as an adhesive layer?
Just I don't know later how can I strip off the chromium?
Also does not matter the glass type of the substrate.
Thank's for the suggestions.
Attila
The Hun
------------------------------------
Yahoo! Groups Links
------------------------------------
Yahoo! Groups Links
------------------------------------
Yahoo! Groups Links
------------------------------------
Yahoo! Groups Links
|
Recently i have an order to make a vacuum furnace for composite heat treatments of composites. how much the pressure is in the vacuum chamber of furnace as respect the hot zone is made by graphite...?
|
Re: Aluminium adhesion problem
Hi Attila,
Please see attached paper - I done it a couple years ago for students.
BR
Vladimir
toggle quoted message
Show quoted text
On 9/9/2011 2:38 AM, Attila wrote: Hi Vladimir!
Well the graphite powder is no problem, I can make it!
But how can I shield the glow discharge cathode? How big should be the area of the cathode?
Best regards
Attila
--- In VacuumX@..., Vladimir Chutko<chutko@...> wrote:
Good vacuum lubricant - MoS2. The lubricant is a mix of MoS2 black
powder and acetone. Bearings look very dirty but works. There are also a
lot of expensive special lubricants, but we used to use this one.
Graphite powder also works.
I don't think your glow discharge works good if the distance between
cathode and substrate is only 20 mm. It should be at least 100-150 mm
(and 250-300 mm is fine) at pressure in about 1 torr range. Of course,
there should be negative potential on cathode... Some people power it
with positive potential, it is wrong. Cathode must be plane, opened only
to substrate and shielded at the back side. So glow discharge must be
concentrated between cathode and substrate holder. Wrong glow discharge
may contaminate substrate surface.
BR,
Vladimir
On 9/8/2011 11:41 PM, Attila wrote:
Hi !
Well, actually I even don't think if there is as an oil backstreaming,because my DP has a water cooled cold cap and water cooled cold trap too, but I had to put some lubricant into my chamber. Because, the planetary substrate holder has two ball bearings in the chamber and these needs lubricant. I used a mix of high vacuum grease and some only drops of diffoil 20 ultra. But it is not really good.
I have to try another lubricant, just I dont know what...
My emitter for the glow discharge is about 20mm from the surface last time, before that was 250mm.
The source and substrate distance is 330mm. My best vacuum was ever 2x10-5 torr, this is the system best.
Unfortunatelly the ion source does not work yet. First I have to change my diffusion pump, because the recent pumping speed is too low, it is not enough to operate the ion source too.
Best regards,
Attila
--- In VacuumX@..., Vladimir Chutko<chutko@> wrote:
Hi Attila,
230 A/s - in my opinion it is too much.....
Anyway I suppose that bad local adhesion is because of a bad cleaning.
If there would be oil backstreaming, oil vapor must cover a whole
surface and there shouldn't be areas with a good adhesion. But things
happen...
140 nm is not a problem. Doing Al mirrors I deposit 100 nm with no
problems. Do you pre-clean your substrate with ion beam?
What is your vacuum? For good layer it must be as low as possible, at
least less than (1-2)x10-5 torr.
Try to decrease deposition rate to 40 - 60 A/s and see what happen.
Maybe it helps.
Best regards,
Vladimir
On 9/8/2011 12:30 PM, Attila wrote:
Hi Vladimir!
Well thank you for the advises!
Yesterday I increased the evaporation rate up to 230 Anstrm/sec(23nm/sec)
The adhesion is much better, but still not passing the tape test.Parts of the layer peals off another parts don't.
Maybe the layer is too thick, because it is 140nm thick. Maybe my precleaning methode is not good. Or could that cause an oil backstreaming from my diffusion pump?
Best regards
Attila
--- In VacuumX@..., Vladimir Chutko<chutko@> wrote:
Hi Attila,
1. Very low evaporation rate. For Al it should be at least tens A/s. I
evaporate Al on a cold substrate at 40 A/s.
2. 4x10-5 torr is not very good for Al. Actually than vacuum is better,
than Al coating is better. It is recommended to evaporate Al at pressure
below 10-5 torr.
3. Cr underlayer strongly improves adhesion.
Best regards,
Vladimir
On 9/2/2011 7:49 AM, Attila wrote:
Hi All,
I ran into a trouble during my evaporation session.
My aluminium coating doesn't pass the tape test for adhesion.
My cleaning methode is:
-First I clean the mirror with isopropanol
- Next I use Balzers substrate cleaner no.1.
-Then the Balzers substrate cleaner no.2 so as the manual said.
After this I immediately put the mirror into the chamber and evacuate to 0.02-0.03 Torr.
Then I let run Argon into the chamber and glow discharge for 15 min.
After this I go down to 6x10-5 Torr, and again let the Argon into the chamber to 0.1 Torr and low discharge at 10Kv and 20mA for another 15 min.
Then evacuate as deep as possible, last time 4x10-5 Torr.
I evaporate aluminium using e-beam at 5 Angstrm per sec. Meantime the optics are turned by the planetary holder.
After this I can let the optic so or make an overcoat of Sio2 or Sio2 and Tio2, doesn't matter the adhesion does not pass the test(bare alu, protected or enhanched does not matter)
What could be wrong?
Or should I apply 10nm of chromium as an adhesive layer?
Just I don't know later how can I strip off the chromium?
Also does not matter the glass type of the substrate.
Thank's for the suggestions.
Attila
The Hun
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Re: Aluminium adhesion problem
Hi Vladimir!
Well the graphite powder is no problem, I can make it!
But how can I shield the glow discharge cathode? How big should be the area of the cathode?
Best regards
Attila
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--- In VacuumX@..., Vladimir Chutko <chutko@...> wrote:
Good vacuum lubricant - MoS2. The lubricant is a mix of MoS2 black
powder and acetone. Bearings look very dirty but works. There are also a
lot of expensive special lubricants, but we used to use this one.
Graphite powder also works.
I don't think your glow discharge works good if the distance between
cathode and substrate is only 20 mm. It should be at least 100-150 mm
(and 250-300 mm is fine) at pressure in about 1 torr range. Of course,
there should be negative potential on cathode... Some people power it
with positive potential, it is wrong. Cathode must be plane, opened only
to substrate and shielded at the back side. So glow discharge must be
concentrated between cathode and substrate holder. Wrong glow discharge
may contaminate substrate surface.
BR,
Vladimir
On 9/8/2011 11:41 PM, Attila wrote:
Hi !
Well, actually I even don't think if there is as an oil backstreaming,because my DP has a water cooled cold cap and water cooled cold trap too, but I had to put some lubricant into my chamber. Because, the planetary substrate holder has two ball bearings in the chamber and these needs lubricant. I used a mix of high vacuum grease and some only drops of diffoil 20 ultra. But it is not really good.
I have to try another lubricant, just I dont know what...
My emitter for the glow discharge is about 20mm from the surface last time, before that was 250mm.
The source and substrate distance is 330mm. My best vacuum was ever 2x10-5 torr, this is the system best.
Unfortunatelly the ion source does not work yet. First I have to change my diffusion pump, because the recent pumping speed is too low, it is not enough to operate the ion source too.
Best regards,
Attila
--- In VacuumX@..., Vladimir Chutko<chutko@> wrote:
Hi Attila,
230 A/s - in my opinion it is too much.....
Anyway I suppose that bad local adhesion is because of a bad cleaning.
If there would be oil backstreaming, oil vapor must cover a whole
surface and there shouldn't be areas with a good adhesion. But things
happen...
140 nm is not a problem. Doing Al mirrors I deposit 100 nm with no
problems. Do you pre-clean your substrate with ion beam?
What is your vacuum? For good layer it must be as low as possible, at
least less than (1-2)x10-5 torr.
Try to decrease deposition rate to 40 - 60 A/s and see what happen.
Maybe it helps.
Best regards,
Vladimir
On 9/8/2011 12:30 PM, Attila wrote:
Hi Vladimir!
Well thank you for the advises!
Yesterday I increased the evaporation rate up to 230 Anstr?m/sec(23nm/sec)
The adhesion is much better, but still not passing the tape test.Parts of the layer peals off another parts don't.
Maybe the layer is too thick, because it is 140nm thick. Maybe my precleaning methode is not good. Or could that cause an oil backstreaming from my diffusion pump?
Best regards
Attila
--- In VacuumX@..., Vladimir Chutko<chutko@> wrote:
Hi Attila,
1. Very low evaporation rate. For Al it should be at least tens A/s. I
evaporate Al on a cold substrate at 40 A/s.
2. 4x10-5 torr is not very good for Al. Actually than vacuum is better,
than Al coating is better. It is recommended to evaporate Al at pressure
below 10-5 torr.
3. Cr underlayer strongly improves adhesion.
Best regards,
Vladimir
On 9/2/2011 7:49 AM, Attila wrote:
Hi All,
I ran into a trouble during my evaporation session.
My aluminium coating doesn't pass the tape test for adhesion.
My cleaning methode is:
-First I clean the mirror with isopropanol
- Next I use Balzers substrate cleaner no.1.
-Then the Balzers substrate cleaner no.2 so as the manual said.
After this I immediately put the mirror into the chamber and evacuate to 0.02-0.03 Torr.
Then I let run Argon into the chamber and glow discharge for 15 min.
After this I go down to 6x10-5 Torr, and again let the Argon into the chamber to 0.1 Torr and low discharge at 10Kv and 20mA for another 15 min.
Then evacuate as deep as possible, last time 4x10-5 Torr.
I evaporate aluminium using e-beam at 5 Angstr?m per sec. Meantime the optics are turned by the planetary holder.
After this I can let the optic so or make an overcoat of Sio2 or Sio2 and Tio2, doesn't matter the adhesion does not pass the test(bare alu, protected or enhanched does not matter)
What could be wrong?
Or should I apply 10nm of chromium as an adhesive layer?
Just I don't know later how can I strip off the chromium?
Also does not matter the glass type of the substrate.
Thank's for the suggestions.
Attila
The Hun
------------------------------------
Yahoo! Groups Links
------------------------------------
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------------------------------------
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|
