开云体育

Evaporating aluminum from tungsten (or tantalum)

eosraptor1 All Messages By This Member #3726 Don, I don't have the ability to shutter all the coils so can you describe what a cleaning with an oxidizing agent would be ??? Are you describing a final cleaning of the coils with a spray with hydrogen peroxide ( household variety ) or a brushing on of a bleach solution ???? I was wondering if I could use a propane torch to locally heat the coils and wick the aluminum onto them before I close up the chamber.? Have you ever tried this kind of pre-wet of tungsten ???? Removing the coils from the holders can be done but it usually results in a broken coil.? Thanks Drew in soggy Florida ----------------------------------------------------------------------------------------------------------- toggle quoted message Show quoted text On Mon, Sep 26, 2011 at 11:11 PM, SVC <donmattox@...> wrote: ? When heating tungsten filaments to evaporate aluminum the first thing that is vaporized is the tungsten oxide. This is why you either need to strip the oxide off (electropolising or by chemical cleaning using an oxidizing agent) before heating or you should use a shutter (closed while premelting the aluminum on the tungsten).? The aluminum will melt and wet the tungsten at temperatures way below what is needed to evaporate the aluminum. When the temperature is increased the aluminum will evaporate Then open the shutter).? Don Precisely! ? Guy Brandenburg, Washington, DC? ============================ From: Andrew Aurigema <eosraptor@...> To: VacuumX@... Sent: Monday, September 26, 2011 4:44 PM Subject: Re: [VacuumX] Al sticking, Cr sticking, Cr stripping ? thanks for the tip.? So slowly on the current so the coils have a chance to heat up the aluminum and never got to bright glow till they are aluminum coated.? On Mon, Sep 26, 2011 at 4:03 PM, Guy Brandenburg <gfbrandenburg@...> wrote: ? Andrew, Try ramping up the current and voltage very slowly on your tungsten filament in the future. Take nearly a minute to reach full current. It worked for me; it might possibly work for you. Guy On Sep 26, 2011, at 3:08 PM, Andrew Aurigema <eosraptor@...> wrote: ? That is very clever actually.? Reverse electro plating.? I too ran into overly stuck on coatings this weekend.? I almost have my chamber back up and working but the pressure is still a little to high.? When I strip the coating off there is a thin film of dark looking soot on the glass.? This will not "green river" strip off.? In fact nothing took it off.? I was forced to set back up the polishing lap and do another 20 minutes of automated figuring to fully remove the film.? I am thinking that the problem is the first few seconds of heat to the first coils.? The tungsten is bright red / near white hot for a few seconds while the aluminum is melting and wicking up onto it.? In that time, the tungsten "burns" if the pressure is a little high.? That black film is now under the aluminum.? It is great for adhesion but taking it off is not possible without polishing.? It may be possible to use this mistake somehow.? Maybe set up one tungsten in the center of the chamber that you burn for 10 seconds at a pressure not quite as low as for coatings.? If there is no aluminum on the tungsten then it will burn and make that tungsten soot.? Aluminizing over that soot stuff is a sure fire way to get the aluminum to stick to the glass.? I dont know if any of this is any good but it may be worth a look if somebody is bored out there.???? Just remember, to get that film off you will be using CeO and pitch. Drew in soggy Florida --------------------------------------------------------------------- On Mon, Sep 26, 2011 at 1:54 PM, Attila <schneyolo@...> wrote: ? Hi All, I just would like to share some experience about these. Thank's for Vladimir I made the triangle glow discharge cleaning cathode as he described in his pdf file. And it seems the Al passed mostly the tape test. But just in case I tried to evapaorate 10nm Cr at 1,5nm/sec under the Al tn a piece of glass. And sticked very well. Later I was able to strip them by green river. So that is why Sunday I started to make some good coating for mirrors. Four of them was loaded and coated first 20nm Cr and than 120nm Al, and before I could coat the two oxide layer I had to terminate the process because of the shutter failure. No problem , let's strip off the Cr and Al by green river I guessed. But this time the Cr sticked so well the green river was not able to strip it. I have no HF acid. So I tried everything without succes. Suddenly I found an idea and tried it. And this one worked and I was able to strip off the Cr easily without eching the glass. The methode is the reverse electroplating. I used sulphur acid(battery acid), a lead plate for the negative and a sponge on the positive electrode. The power supply was my inverting welder. As I rubbed the surface of the immersed mirror the Cr solved and I was able to whipe it off. So at least for 20nm Cr it works. Have a nice day! Br. Attila __._,_. -- ____________________________________ 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? __._,_.__
Don Mattox All Messages By This Member #3727 Good point!! I left out the use of premelting the aluminum on the tungsten by heating it in vaciuum WITH NO SUBSTRATE in place.? Then open the chamber and mount the substrate - coat. I didn't think of this because it is obviously labor intensive. They use to sell prewetted filaments but I guess it wasn't profitable. If you use an evaporate-to-completion technique you can weigh the filament - prewet the tungsten with a small amount of aluminum then add enough Al to do the job. Aluminum will not evaporate much at its melting point. Tungsten coils break because they crystallize on heating and become brittle. Limiting heating (and time) makes the coils last longer. A general problem with evaporation from a filament or boat is that the evaporant is initally in poor thermal contact with the heated surface and so there is a tendency to over-heat the tungsten and as the aluminum melts, it spreads over the very hot surface and tends to spatter. Heat the filament slowly!! until the aluminum melts. Again - pre-cleaning the tungsten aids in wetting. To clean the tungsten you can heat it in CLOROX on the stove. DO NOT heat the tungsten/aluminum in air with a torch - you will only create a mess! I have a bunch of evaporating filaments and vacuum chamber feedthroughs that I will part with if anyone has a particular need. I also have two old (thyraton rectifier) high voltage (up to 5000 VDC) power supplies (no arc suppression) in ALBUQUERQUE for free if someone wants to pick them up (they are too heavy for me anymore). They are great for glow discharge cleaning or basic sputter deposition. They are AS IS WHERE IS!!!! ? * I have had the following inquiry about some aluminum coating if someone wants to help the guy. Thanks for taking a minute on the phone to discuss my coating need. ?I have a project that I am in need of some help in the way of coating some thin polycarbonate films. I have a very limited budget to work with. I am hoping to find someone to do a run for as little money as possible. The product should result in follow on work that will support paying full price on future runs. I need 1500 angstroms of aluminum coated on to some polymer films that are in the 1 micron thickness range and about 1" x 3" in size. They are free standing films that are mounted in frames. I can machine all of the hanging fixtures and I would also be willing to trade machine work in exchange for doing a coating run. I need to just get the proof of specification ?samples in the customers hands to get positioned where I will be getting ?follow on orders. ? I appreciate anything you can do to find someone willing and able to help. ? Thanks, ? Dan Petmecky TMI 505-293-6136 dan@... Don Don, I don't have the ability to shutter all the coils so can you describe what a cleaning with an oxidizing agent would be ??? Are you describing a final cleaning of the coils with a spray with hydrogen peroxide ( household variety ) or a brushing on of a bleach solution ???? I was wondering if I could use a propane torch to locally heat the coils and wick the aluminum onto them before I close up the chamber.? Have you ever tried this kind of pre-wet of tungsten ???? Removing the coils from the holders can be done but it usually results in a broken coil.? Thanks Drew in soggy Florida ----------------------------------------------------------------------------------------------------------- On Mon, Sep 26, 2011 at 11:11 PM, SVC <donmattox@...> wrote: ? When heating tungsten filaments to evaporate aluminum the first thing that is vaporized is the tungsten oxide. This is why you either need to strip the oxide off (electropolising or by chemical cleaning using an oxidizing agent) before heating or you should use a shutter (closed while premelting the aluminum on the tungsten).? The aluminum will melt and wet the tungsten at temperatures way below what is needed to evaporate the aluminum. When the temperature is increased the aluminum will evaporate Then open the shutter).? Don Precisely! ? Guy Brandenburg, Washington, DC? ============================ From: Andrew Aurigema <eosraptor@...> To: VacuumX@... Sent: Monday, September 26, 2011 4:44 PM Subject:** Re: [VacuumX] Al sticking, Cr sticking, Cr stripping ? thanks for the tip.? So slowly on the current so the coils have a chance to heat up the aluminum and never got to bright glow till they are aluminum coated.? On Mon, Sep 26, 2011 at 4:03 PM, Guy Brandenburg <gfbrandenburg@...> wrote: ? Andrew, Try ramping up the current and voltage very slowly on your tungsten filament in the future. Take nearly a minute to reach full current. It worked for me; it might possibly work for you. Guy On Sep 26, 2011, at 3:08 PM, Andrew Aurigema <eosraptor@...> wrote: ? That is very clever actually.? Reverse electro plating.? I too ran into overly stuck on coatings this weekend.? I almost have my chamber back up and working but the pressure is still a little to high.? When I strip the coating off there is a thin film of dark looking soot on the glass.? This will not "green river" strip off.? In fact nothing took it off.? I was forced to set back up the polishing lap and do another 20 minutes of automated figuring to fully remove the film.? I am thinking that the problem is the first few seconds of heat to the first coils.? The tungsten is bright red / near white hot for a few seconds while the aluminum is melting and wicking up onto it.? In that time, the tungsten "burns" if the pressure is a little high.? That black film is now under the aluminum.? It is great for adhesion but taking it off is not possible without polishing.? It may be possible to use this mistake somehow.? Maybe set up one tungsten in the center of the chamber that you burn for 10 seconds at a pressure not quite as low as for coatings.? If there is no aluminum on the tungsten then it will burn and make that tungsten soot.? Aluminizing over that soot stuff is a sure fire way to get the aluminum to stick to the glass.? I dont know if any of this is any good but it may be worth a look if somebody is bored out there.???? Just remember, to get that film off you will be using CeO and pitch. Drew in soggy Florida --------------------------------------------------------------------- On Mon, Sep 26, 2011 at 1:54 PM, Attila wrote: ? Hi All, I just would like to share some experience about these. Thank's for Vladimir I made the triangle glow discharge cleaning cathode as he described in his pdf file. And it seems the Al passed mostly the tape test. But just in case I tried to evapaorate 10nm Cr at 1,5nm/sec under the Al tn a piece of glass. And sticked very well. Later I was able to strip them by green river. So that is why Sunday I started to make some good coating for mirrors. Four of them was loaded and coated first 20nm Cr and than 120nm Al, and before I could coat the two oxide layer I had to terminate the process because of the shutter failure. No problem , let's strip off the Cr and Al by green river I guessed. But this time the Cr sticked so well the green river was not able to strip it. I have no HF acid. So I tried everything without succes. Suddenly I found an idea and tried it. And this one worked and I was able to strip off the Cr easily without eching the glass. The methode is the reverse electroplating. I used sulphur acid(battery acid), a lead plate for the negative and a sponge on the positive electrode. The power supply was my inverting welder. As I rubbed the surface of the immersed mirror the Cr solved and I was able to whipe it off. So at least for 20nm Cr it works. Have a nice day! Br. Attila __._,_. `--` ____________________________________ 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? __._,_.__ -- ____________________________________ 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? http://www.svc.org
eosraptor1 All Messages By This Member #3728 Don, I am always looking for vac feed thru.? May I inquire what fittings you have ??? Pre-melting the aluminum in vacuum in a separate vacuum run is just too much effort.? I have to let my chamber sit under vacuum for 12 hrs to de-gas or it takes forever to pump down.? So I think I will pre-melt all the emitters before I evaporate any of them.? The tips you ( and others ) have given me are very useful.? I can heat the tungsten coils up to the aluminum melting / wicking point slowly and then shut them down and move on to the next group to do the same.?? After all of them are wetted out, I can run them at high power to do the depositon.? I have an old XMS-1 thickness meter that clearly shows the nanometer per second deposition rate.? I usually see around 15 nm / second deposition rate with a full coil of aluminum and the deposition rate drops off fast after 10 seconds of power.? That is about how long the aluminum last on the coils.? Hopefully a new procedure will reduce my tungsten oxide "soot" problem to just an annoying under layer that is covered by shiny aluminum.? I always fire my center coils last and shut them down early so the final layer of aluminum is as shiny as I can make it.? 5 years into vacuum coating and I still am not very proficient at? it.? Good thing I kept my day job :_)))))) Thanks again, Drew in soggy Florida ?------------------------------------------------------------------------------------------------------------- toggle quoted message Show quoted text On Tue, Sep 27, 2011 at 9:39 AM, SVC <donmattox@...> wrote: ? Good point!! I left out the use of premelting the aluminum on the tungsten by heating it in vaciuum WITH NO SUBSTRATE in place.? Then open the chamber and mount the substrate - coat. I didn't think of this because it is obviously labor intensive. They use to sell prewetted filaments but I guess it wasn't profitable. If you use an evaporate-to-completion technique you can weigh the filament - prewet the tungsten with a small amount of aluminum then add enough Al to do the job. Aluminum will not evaporate much at its melting point. Tungsten coils break because they crystallize on heating and become brittle. Limiting heating (and time) makes the coils last longer. A general problem with evaporation from a filament or boat is that the evaporant is initally in poor thermal contact with the heated surface and so there is a tendency to over-heat the tungsten and as the aluminum melts, it spreads over the very hot surface and tends to spatter. Heat the filament slowly!! until the aluminum melts. Again - pre-cleaning the tungsten aids in wetting. To clean the tungsten you can heat it in CLOROX on the stove. DO NOT heat the tungsten/aluminum in air with a torch - you will only create a mess! I have a bunch of evaporating filaments and vacuum chamber feedthroughs that I will part with if anyone has a particular need. I also have two old (thyraton rectifier) high voltage (up to 5000 VDC) power supplies (no arc suppression) in ALBUQUERQUE for free if someone wants to pick them up (they are too heavy for me anymore). They are great for glow discharge cleaning or basic sputter deposition. They are AS IS WHERE IS!!!! ? * I have had the following inquiry about some aluminum coating if someone wants to help the guy. Thanks for taking a minute on the phone to discuss my coating need. ?I have a project that I am in need of some help in the way of coating some thin polycarbonate films. I have a very limited budget to work with. I am hoping to find someone to do a run for as little money as possible. The product should result in follow on work that will support paying full price on future runs. I need 1500 angstroms of aluminum coated on to some polymer films that are in the 1 micron thickness range and about 1" x 3" in size. They are free standing films that are mounted in frames. I can machine all of the hanging fixtures and I would also be willing to trade machine work in exchange for doing a coating run. I need to just get the proof of specification ?samples in the customers hands to get positioned where I will be getting ?follow on orders. ? I appreciate anything you can do to find someone willing and able to help. ? Thanks, ? Dan Petmecky TMI 505-293-6136 dan@... Don Don, I don't have the ability to shutter all the coils so can you describe what a cleaning with an oxidizing agent would be ??? Are you describing a final cleaning of the coils with a spray with hydrogen peroxide ( household variety ) or a brushing on of a bleach solution ???? I was wondering if I could use a propane torch to locally heat the coils and wick the aluminum onto them before I close up the chamber.? Have you ever tried this kind of pre-wet of tungsten ???? Removing the coils from the holders can be done but it usually results in a broken coil.? Thanks Drew in soggy Florida ----------------------------------------------------------------------------------------------------------- On Mon, Sep 26, 2011 at 11:11 PM, SVC <donmattox@...> wrote: ? When heating tungsten filaments to evaporate aluminum the first thing that is vaporized is the tungsten oxide. This is why you either need to strip the oxide off (electropolising or by chemical cleaning using an oxidizing agent) before heating or you should use a shutter (closed while premelting the aluminum on the tungsten).? The aluminum will melt and wet the tungsten at temperatures way below what is needed to evaporate the aluminum. When the temperature is increased the aluminum will evaporate Then open the shutter).? Don Precisely! ? Guy Brandenburg, Washington, DC? ============================ From: Andrew Aurigema <eosraptor@...> To: VacuumX@... Sent: Monday, September 26, 2011 4:44 PM Subject:** Re: [VacuumX] Al sticking, Cr sticking, Cr stripping ? thanks for the tip.? So slowly on the current so the coils have a chance to heat up the aluminum and never got to bright glow till they are aluminum coated.? On Mon, Sep 26, 2011 at 4:03 PM, Guy Brandenburg <gfbrandenburg@...> wrote: ? Andrew, Try ramping up the current and voltage very slowly on your tungsten filament in the future. Take nearly a minute to reach full current. It worked for me; it might possibly work for you. Guy On Sep 26, 2011, at 3:08 PM, Andrew Aurigema <eosraptor@...> wrote: ? That is very clever actually.? Reverse electro plating.? I too ran into overly stuck on coatings this weekend.? I almost have my chamber back up and working but the pressure is still a little to high.? When I strip the coating off there is a thin film of dark looking soot on the glass.? This will not "green river" strip off.? In fact nothing took it off.? I was forced to set back up the polishing lap and do another 20 minutes of automated figuring to fully remove the film.? I am thinking that the problem is the first few seconds of heat to the first coils.? The tungsten is bright red / near white hot for a few seconds while the aluminum is melting and wicking up onto it.? In that time, the tungsten "burns" if the pressure is a little high.? That black film is now under the aluminum.? It is great for adhesion but taking it off is not possible without polishing.? It may be possible to use this mistake somehow.? Maybe set up one tungsten in the center of the chamber that you burn for 10 seconds at a pressure not quite as low as for coatings.? If there is no aluminum on the tungsten then it will burn and make that tungsten soot.? Aluminizing over that soot stuff is a sure fire way to get the aluminum to stick to the glass.? I dont know if any of this is any good but it may be worth a look if somebody is bored out there.???? Just remember, to get that film off you will be using CeO and pitch. Drew in soggy Florida --------------------------------------------------------------------- On Mon, Sep 26, 2011 at 1:54 PM, Attila <schneyolo@...> wrote: ? Hi All, I just would like to share some experience about these. Thank's for Vladimir I made the triangle glow discharge cleaning cathode as he described in his pdf file. And it seems the Al passed mostly the tape test. But just in case I tried to evapaorate 10nm Cr at 1,5nm/sec under the Al tn a piece of glass. And sticked very well. Later I was able to strip them by green river. So that is why Sunday I started to make some good coating for mirrors. Four of them was loaded and coated first 20nm Cr and than 120nm Al, and before I could coat the two oxide layer I had to terminate the process because of the shutter failure. No problem , let's strip off the Cr and Al by green river I guessed. But this time the Cr sticked so well the green river was not able to strip it. I have no HF acid. So I tried everything without succes. Suddenly I found an idea and tried it. And this one worked and I was able to strip off the Cr easily without eching the glass. The methode is the reverse electroplating. I used sulphur acid(battery acid), a lead plate for the negative and a sponge on the positive electrode. The power supply was my inverting welder. As I rubbed the surface of the immersed mirror the Cr solved and I was able to whipe it off. So at least for 20nm Cr it works. Have a nice day! Br. Attila __._,_. `--` ____________________________________ 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? __._,_.__ -- ____________________________________ 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?
Jarvis Krumbein All Messages By This Member #3729 Andrew, see if you can get a copy of "Proceedures in Experimental Physics" by John Strong.? Originally published by Prentiss-Hall and later reprinted , I think by Willmann-Bell.? While no longer in print it contains the answers to many of your problems.? The chapter on coating (evaporation & sputtering) includes detailed instructions for prepareing evaporation sources and prefusing aluminum to tungstan coils. ? Jarvis Krumbein toggle quoted message Show quoted text From: Andrew Aurigema To: VacuumX@... Sent: Tuesday, September 27, 2011 7:28 AM Subject: Re: [VacuumX] Evaporating aluminum from tungsten (or tantalum) ? Don, I am always looking for vac feed thru.? May I inquire what fittings you have ??? Pre-melting the aluminum in vacuum in a separate vacuum run is just too much effort.? I have to let my chamber sit under vacuum for 12 hrs to de-gas or it takes forever to pump down.? So I think I will pre-melt all the emitters before I evaporate any of them.? The tips you ( and others ) have given me are very useful.? I can heat the tungsten coils up to the aluminum melting / wicking point slowly and then shut them down and move on to the next group to do the same.?? After all of them are wetted out, I can run them at high power to do the depositon.? I have an old XMS-1 thickness meter that clearly shows the nanometer per second deposition rate.? I usually see around 15 nm / second deposition rate with a full coil of aluminum and the deposition rate drops off fast after 10 seconds of power.? That is about how long the aluminum last on the coils.? Hopefully a new procedure will reduce my tungsten oxide "soot" problem to just an annoying under layer that is covered by shiny aluminum.? I always fire my center coils last and shut them down early so the final layer of aluminum is as shiny as I can make it.? 5 years into vacuum coating and I still am not very proficient at? it.? Good thing I kept my day job :_)))))) Thanks again, Drew in soggy Florida ?------------------------------------------------------------------------------------------------------------- On Tue, Sep 27, 2011 at 9:39 AM, SVC <donmattox@...> wrote: ? Good point!! I left out the use of premelting the aluminum on the tungsten by heating it in vaciuum WITH NO SUBSTRATE in place.? Then open the chamber and mount the substrate - coat. I didn't think of this because it is obviously labor intensive. They use to sell prewetted filaments but I guess it wasn't profitable. If you use an evaporate-to-completion technique you can weigh the filament - prewet the tungsten with a small amount of aluminum then add enough Al to do the job. Aluminum will not evaporate much at its melting point. Tungsten coils break because they crystallize on heating and become brittle. Limiting heating (and time) makes the coils last longer. A general problem with evaporation from a filament or boat is that the evaporant is initally in poor thermal contact with the heated surface and so there is a tendency to over-heat the tungsten and as the aluminum melts, it spreads over the very hot surface and tends to spatter. Heat the filament slowly!! until the aluminum melts. Again - pre-cleaning the tungsten aids in wetting. To clean the tungsten you can heat it in CLOROX on the stove. DO NOT heat the tungsten/aluminum in air with a torch - you will only create a mess! I have a bunch of evaporating filaments and vacuum chamber feedthroughs that I will part with if anyone has a particular need. I also have two old (thyraton rectifier) high voltage (up to 5000 VDC) power supplies (no arc suppression) in ALBUQUERQUE for free if someone wants to pick them up (they are too heavy for me anymore). They are great for glow discharge cleaning or basic sputter deposition. They are AS IS WHERE IS!!!! ? * I have had the following inquiry about some aluminum coating if someone wants to help the guy. Thanks for taking a minute on the phone to discuss my coating need. ?I have a project that I am in need of some help in the way of coating some thin polycarbonate films. I have a very limited budget to work with. I am hoping to find someone to do a run for as little money as possible. The product should result in follow on work that will support paying full price on future runs. I need 1500 angstroms of aluminum coated on to some polymer films that are in the 1 micron thickness range and about 1" x 3" in size. They are free standing films that are mounted in frames. I can machine all of the hanging fixtures and I would also be willing to trade machine work in exchange for doing a coating run. I need to just get the proof of specification ?samples in the customers hands to get positioned where I will be getting ?follow on orders. ? I appreciate anything you can do to find someone willing and able to help. ? Thanks, ? Dan Petmecky TMI 505-293-6136 dan@... Don Don, I don't have the ability to shutter all the coils so can you describe what a cleaning with an oxidizing agent would be ??? Are you describing a final cleaning of the coils with a spray with hydrogen peroxide ( household variety ) or a brushing on of a bleach solution ???? I was wondering if I could use a propane torch to locally heat the coils and wick the aluminum onto them before I close up the chamber.? Have you ever tried this kind of pre-wet of tungsten ???? Removing the coils from the holders can be done but it usually results in a broken coil.? Thanks Drew in soggy Florida ----------------------------------------------------------------------------------------------------------- On Mon, Sep 26, 2011 at 11:11 PM, SVC <donmattox@...> wrote: ? When heating tungsten filaments to evaporate aluminum the first thing that is vaporized is the tungsten oxide. This is why you either need to strip the oxide off (electropolising or by chemical cleaning using an oxidizing agent) before heating or you should use a shutter (closed while premelting the aluminum on the tungsten).? The aluminum will melt and wet the tungsten at temperatures way below what is needed to evaporate the aluminum. When the temperature is increased the aluminum will evaporate Then open the shutter).? Don Precisely! ? Guy Brandenburg, Washington, DC? ============================ From: Andrew Aurigema <eosraptor@...> To: VacuumX@... Sent: Monday, September 26, 2011 4:44 PM Subject:** Re: [VacuumX] Al sticking, Cr sticking, Cr stripping ? thanks for the tip.? So slowly on the current so the coils have a chance to heat up the aluminum and never got to bright glow till they are aluminum coated.? On Mon, Sep 26, 2011 at 4:03 PM, Guy Brandenburg <gfbrandenburg@...> wrote: ? Andrew, Try ramping up the current and voltage very slowly on your tungsten filament in the future. Take nearly a minute to reach full current. It worked for me; it might possibly work for you. Guy On Sep 26, 2011, at 3:08 PM, Andrew Aurigema <eosraptor@...> wrote: ? That is very clever actually.? Reverse electro plating.? I too ran into overly stuck on coatings this weekend.? I almost have my chamber back up and working but the pressure is still a little to high.? When I strip the coating off there is a thin film of dark looking soot on the glass.? This will not "green river" strip off.? In fact nothing took it off.? I was forced to set back up the polishing lap and do another 20 minutes of automated figuring to fully remove the film.? I am thinking that the problem is the first few seconds of heat to the first coils.? The tungsten is bright red / near white hot for a few seconds while the aluminum is melting and wicking up onto it.? In that time, the tungsten "burns" if the pressure is a little high.? That black film is now under the aluminum.? It is great for adhesion but taking it off is not possible without polishing.? It may be possible to use this mistake somehow.? Maybe set up one tungsten in the center of the chamber that you burn for 10 seconds at a pressure not quite as low as for coatings.? If there is no aluminum on the tungsten then it will burn and make that tungsten soot.? Aluminizing over that soot stuff is a sure fire way to get the aluminum to stick to the glass.? I dont know if any of this is any good but it may be worth a look if somebody is bored out there.???? Just remember, to get that film off you will be using CeO and pitch. Drew in soggy Florida --------------------------------------------------------------------- On Mon, Sep 26, 2011 at 1:54 PM, Attila <schneyolo@...> wrote: ? Hi All, I just would like to share some experience about these. Thank's for Vladimir I made the triangle glow discharge cleaning cathode as he described in his pdf file. And it seems the Al passed mostly the tape test. But just in case I tried to evapaorate 10nm Cr at 1,5nm/sec under the Al tn a piece of glass. And sticked very well. Later I was able to strip them by green river. So that is why Sunday I started to make some good coating for mirrors. Four of them was loaded and coated first 20nm Cr and than 120nm Al, and before I could coat the two oxide layer I had to terminate the process because of the shutter failure. No problem , let's strip off the Cr and Al by green river I guessed. But this time the Cr sticked so well the green river was not able to strip it. I have no HF acid. So I tried everything without succes. Suddenly I found an idea and tried it. And this one worked and I was able to strip off the Cr easily without eching the glass. The methode is the reverse electroplating. I used sulphur acid(battery acid), a lead plate for the negative and a sponge on the positive electrode. The power supply was my inverting welder. As I rubbed the surface of the immersed mirror the Cr solved and I was able to whipe it off. So at least for 20nm Cr it works. Have a nice day! Br. Attila __._,_. `--` ____________________________________ 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? __._,_.__ -- ____________________________________ 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?

Previous Topic Next Topic