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Aluminum bronze - conductivity

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stuart(at)stuarthutchison
Guest

Posted: Wed May 02, 2012 2:38 am Post subject: Aluminum bronze - conductivity

G'day  Bob,

  

 Do you reckon  aluminum bronze is suitable to be used in place of brass for the main  firewall ground ?  It has plenty of copper in it, but are there any known  nasties when it's used adjoining stainless steel -  I'd like to turn a  custom large-flanged firewall passthrough for the engine  ground.

  

 Kind regards,  Stu<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office"  />

  

  

F1 Rocket    VH-FLY        http://www.mykitlog.com/RockFLY      [url=about:www.teamrocketaircraft.com]www.teamrocketaircraft.com[/url]

   [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Wed May 02, 2012 6:19 am Post subject: Aluminum bronze - conductivity

At 05:33 AM 5/2/2012, you wrote:

  	  Quote: 	
		   G'day Bob,

  

 Do you reckon aluminum bronze is suitable to be used in place of brass for the main firewall ground ?  It has plenty of copper in it, but are there any known nasties when it's used adjoining stainless steel -  I'd like to turn a custom large-flanged firewall passthrough for the engine ground.

  	


    Hmmmm . . . I have no reason to believe it's

    any worse. Brass isn't the greatest of conductors

    but the way we use it (large cross-sections and/or

    short lengths) the electrical resistance doesn't

    raise concerns. I don't know any specifics about its

    reactivity with other metals but I think anything

    against stainless is pretty low risk . . . 



    Perhaps others on the List have experience foundations

    from which to advise you further . . .



    Bob . . .    [quote][b]

rparigoris

Joined: 24 Nov 2009
Posts: 791

Posted: Wed May 02, 2012 6:59 am Post subject: Aluminum bronze - conductivity

Hi Stu 

 	I compiled a number of links to galvanic and conductivity tables.: 

 	http://www.europaowners.org/main.php?g2_itemId=87240 

 	Click on "Download document", it's a word document with a number of links. 

 	It kinda amazed me how poor a conductor brass and bronze is, but aluminium is very good and for all practical purposes as good as gold. 

 	Stainless is a terrible conductor. Steel only slightly better. Guess what, lead and tin are very poor conductors! Did you ever see high amperage solder joints fail after time? It's because of the heating and cooling of the joint and fatigue failure of the solder  BTW you can often rectify this from happening again by leaving a tail on the component, taking a solid strand of copper wire and wrapping the tail (and solder) and then soldering the both ends of this wire onto the board on the lands or pad to give triple the path for electrons to flow. 

 	When you look at the galvanic tables, I forget if it was brass and stainless or aluminium and stainless, I think it was aluminium and stainless it is not a good choice. I forget if when I first made my 30,000,000 BTU Balloon Burner I used an aluminium restrictor for the pilot light inside stainless, or brass inside stainless. I think it was aluminium? Anyway it plugged up with white corrosion a few times and I lost the pilot light. After the second time I switched over to brass (of vise versa, you will be able to tell from the chart) I never had a problem again. 

 	Good Luck. 

 	Ron Parigoris 

 	     [quote][b]

henador_titzoff(at)yahoo.
Guest

Posted: Wed May 02, 2012 7:11 am Post subject: Aluminum bronze - conductivity

With copper and aluminum, it's bound to be extremely low resistance, but the aluminum will corrode on the surface to form alumina, which may interfere with good connections.  Why not send that puppy off to Eric at Perihelion Design to get it copper plated?  Or better yet, why not go with copper bar?  It's relatively cheap and known good material.  Beats ripping out something that didn't work that well.

 

Henador Titzoff



        From: "Robert L.  Nuckolls, III" <nuckolls.bob(at)aeroelectric.com>

 To: aeroelectric-list(at)matronics.com 

 Sent: Wednesday, May 2, 2012 10:18 AM

 Subject: Re: Aluminum bronze - conductivity

  

 

   At 05:33 AM 5/2/2012, you wrote:

  	  Quote: 	
		   G'day Bob,

  

 Do you reckon aluminum bronze is suitable to be used in place of brass for the main firewall ground ?  It has plenty of copper in it, but are there any known nasties when it's used adjoining stainless steel -  I'd like to turn a custom large-flanged firewall passthrough for the engine ground.

   	


    Hmmmm . . . I have no reason to believe it's

    any worse. Brass isn't the greatest of conductors

    but the way we use it (large cross-sections and/or

    short lengths) the electrical resistance doesn't

    raise concerns. I don't know any specifics about its

    reactivity with other metals but I think anything

    against stainless is pretty low risk . . . 



    Perhaps others on the List have experience foundations

    from which to advise you further . . .



    Bob . . .    [quote][b]

bbradburry(at)bellsouth.n
Guest

Posted: Wed May 02, 2012 12:59 pm Post subject: Aluminum bronze - conductivity

“When you look at the galvanic tables, I forget if it was brass and stainless or aluminium and stainless, I think it was aluminium and stainless it is not a good choice. I forget if when I first made my 30,000,000 BTU Balloon Burner I used an aluminium restrictor for the pilot light inside stainless, or brass inside stainless. I think it was aluminium? Anyway it plugged up with white corrosion a few times and I lost the pilot light. After the second time I switched over to brass (of vise versa, you will be able to tell from the chart) I never had a problem again.”  

That’s pretty funny, Ron!  :>)  Clear, but funny!  

B2  

         

  

From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of rparigor(at)suffolk.lib.ny.us

 Sent: Wednesday, May 02, 2012 10:58 AM

 To: AeroelectricList

 Subject: Re: AeroElectric-List: Aluminum bronze - conductivity  

  

   

Hi Stu  

I compiled a number of links to galvanic and conductivity tables.:  

http://www.europaowners.org/main.php?g2_itemId=87240  

Click on "Download document", it's a word document with a number of links.  

It kinda amazed me how poor a conductor brass and bronze is, but aluminium is very good and for all practical purposes as good as gold.  

Stainless is a terrible conductor. Steel only slightly better. Guess what, lead and tin are very poor conductors! Did you ever see high amperage solder joints fail after time? It's because of the heating and cooling of the joint and fatigue failure of the solder  BTW you can often rectify this from happening again by leaving a tail on the component, taking a solid strand of copper wire and wrapping the tail (and solder) and then soldering the both ends of this wire onto the board on the lands or pad to give triple the path for electrons to flow.  

When you look at the galvanic tables, I forget if it was brass and stainless or aluminium and stainless, I think it was aluminium and stainless it is not a good choice. I forget if when I first made my 30,000,000 BTU Balloon Burner I used an aluminium restrictor for the pilot light inside stainless, or brass inside stainless. I think it was aluminium? Anyway it plugged up with white corrosion a few times and I lost the pilot light. After the second time I switched over to brass (of vise versa, you will be able to tell from the chart) I never had a problem again.  

Good Luck.  

Ron Parigoris  

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rparigoris

Joined: 24 Nov 2009
Posts: 791

Posted: Wed May 02, 2012 2:32 pm Post subject: Aluminum bronze - conductivity

Hi B2 

 	So you think having a power failure on your home built Hot Air balloon is funny? If you are not prepared they just like aeroplanes can in fact make a perfect 1 point landing! In other words balloons can and do in fact induce "P" factor", biological in nature (especially if you are over 50). No problem, I have that aspect pretty well "covered" if you know what I mean after you look at a few pictures     : 

 	http://www.europaowners.org/main.php?g2_itemId=28355 

 	  

 	Ron Parigoris 

 	Serious, I have a fully redundant pilot light that you can easily fly off of and deployable in seconds, and at least 3 other ignition sources that are a little more time consuming to use, but you can fly off of them as well. My two failures were pretty much non events. 

 	  

 	When you look at the galvanic tables, I forget if it was brass and 	> stainless or aluminium and stainless, I think it was aluminium and 	> stainless 	> it is not a good choice. I forget if when I first made my 30,000,000 BTU 	> Balloon Burner I used an aluminium restrictor for the pilot light inside 	> stainless, or brass inside stainless. I think it was aluminium? Anyway it 	> plugged up with white corrosion a few times and I lost the pilot light. 	> After the second time I switched over to brass (of vise versa, you will be 	> able to tell from the chart) I never had a problem again." 	> 	> That's pretty funny, Ron! :>) Clear, but funny! 	> 	> B2 	     [quote][b]

stuart(at)stuarthutchison
Guest

Posted: Thu May 03, 2012 12:08 am Post subject: Aluminum bronze - conductivity

Thanks guys.

  

 I've made lots of aluminum and stainless parts for underwater  photography and yes, the galvanic corrosion between them can be brutal  immersed in an electrolyte liek sea water.  Ultra Tef-Gel  from B&C Specialty helps, but I suppose aluminum  adjoining stainless is very common at the firewall and doesn't seem to  present too many problems without an electrolyte ... I could be wrong, but  that area stays pretty dry and I haven't witnessed much corrosion at the  firewall on aircraft.  I'm less worried about the aluminium bronze  oxidising - a gas tight seal is obviously important because all  the usual metal options oxidise, but there must be tens of thousands of aircraft  with ground wires bonded direct to aluminium.  I guess I'll just use  di-electric grease to keep the air out at the point where the  stud meets with the firewall, or perhaps make a phenolic bush to insulate  it from the stainless, then bond the stud to a substantial part of the  aluminum structure on the inside (such as an engine mounting  bolt).

  

  

Kind regards,  Stu<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office"  /> 

  

F1 Rocket    VH-FLY        http://www.mykitlog.com/RockFLY      [url=about:www.teamrocketaircraft.com]www.teamrocketaircraft.com[/url]

  



   From:  owner-aeroelectric-list-server(at)matronics.com  [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of  Henador Titzoff

Sent: Thursday, May 03, 2012 1:11 AM

To:  aeroelectric-list(at)matronics.com

Subject: Re: AeroElectric-List:  Aluminum bronze - conductivity

 

  With copper and aluminum, it's bound to be extremely low resistance,  but the aluminum will corrode on the surface to form alumina, which may  interfere with good connections.  Why  not send that puppy off to Eric at Perihelion Design to get it copper plated?   Or better yet, why not go with copper bar?  It's relatively cheap and  known good material.  Beats ripping out something that didn't work that  well.

  

 Henador Titzoff



     From: "Robert L. Nuckolls, III"  <nuckolls.bob(at)aeroelectric.com>

To: aeroelectric-list(at)matronics.com  

Sent: Wednesday, May 2, 2012  10:18 AM

Subject: Re:  Aluminum bronze - conductivity

  At 05:33 AM 5/2/2012, you wrote:

  	  Quote: 	
		  G'day Bob,

 

Do you reckon aluminum bronze is suitable to be used    in place of brass for the main firewall ground ?  It has plenty of copper    in it, but are there any known nasties when it's used adjoining stainless    steel -  I'd like to turn a custom large-flanged firewall passthrough for    the engine ground.

 	


   Hmmmm . . . I  have no reason to believe it's

   any worse. Brass isn't the  greatest of conductors

   but the way we use it (large  cross-sections and/or

   short lengths) the electrical resistance  doesn't

   raise concerns. I don't know any specifics about  its

   reactivity with other metals but I think  anything

   against stainless is pretty low risk . . .  



   Perhaps others on the List have experience  foundations

   from which to advise you further . .  .



   Bob . . . [quote]



ank" href="http://www.matronics.com/Navigator?AeroElectric-List">http://w=========







href="http://www.matronics.com/Navigator?AeroElectric-List">http://www.matronics.com/Navigator?AeroElectric-List

href="http://forums.matronics.com">http://forums.matronics.com

href="http://www.matronics.com/contribution">http://www.matronics.com/c

[b]

nuckolls.bob(at)aeroelect
Guest

Posted: Thu May 03, 2012 5:28 am Post subject: Aluminum bronze - conductivity

At 03:06 AM 5/3/2012, you wrote:

 Thanks guys.

  

 I've made lots of aluminum and stainless parts for underwater photography and yes, the galvanic corrosion between them can be brutal immersed in an electrolyte liek sea water.  Ultra Tef-Gel from B&C Specialty helps, but I suppose aluminum adjoining stainless is very common at the firewall and doesn't seem to present too many problems without an electrolyte ... I could be wrong, but that area stays pretty dry and I haven't witnessed much corrosion at the firewall on aircraft.  



     Agreed.



 I'm less worried about the aluminium bronze oxidising - a gas tight seal is obviously important because all the usual metal options oxidise, but there must be tens of thousands of aircraft with ground wires bonded direct to aluminium.



     The legacy process involves putting a tin-plated copper    terminal down on a brightly buffed area of aluminum and    applying lots of pressure with the attach hardware. The    surface areas in gas-tight contact are, as you suggest,    not subject to environmental stresses. The outside of the    joint can get pretty cruddy with age without having the    connection go bad.



   I guess I'll just use di-electric grease to keep the air out at the point where the stud meets with the firewall, or perhaps make a phenolic bush to insulate it from the stainless, then bond the stud to a substantial part of the aluminum structure on the inside (such as an engine mounting bolt).



     I think clean, grease and lots of pressure are key. Additional    bonding is not useful.

 



   Bob . . .

     [quote][b]

Eric M. Jones

Joined: 10 Jan 2006
Posts: 565
Location: Massachusetts

Posted: Thu May 03, 2012 7:16 am Post subject: Re: Short course in metals.

 	  Quote: 	
		  Why not send that puppy off to Eric at Perihelion Design to get it copper plated?...Henador 	




The copper clad aluminum I sell is not plated. This wouldn't be good, plating always has pinholes and wears off. The Super-CCA I sell is "clad" which is a process where copper and aluminum are fused together. 10% of the diameter of the crossection is actually copper.  Copperweld Inc., historically made lots of different stuff clad with copper by this process. It is important to know that there is a long history of aluminum wiring problems, but essentially NO HISTORY of CCA problems. The wire behaves very much like copper



Some notes of metals:



1) In many applications the conductivity of the metal is less important than the surface reactivity with atmospheric oxygen (or in the case of  titanium only, with nitrogen). Impure aluminum oxide is the same as sapphire or corundum and is quite insulating. Copper oxide looks bad but still conducts electricity well. Same for silver. It can turn black and conduct well. Stainless steel, nickel, chrome and aluminum looks great initially but turns into an insulator. This usually happens slowly. Battery contacts made of stainless steel were once the bane of cheap electronics.



2) See: http://aerospacedefense.thomasnet.com/Asset/MIL-F-14072.pdf  Finishes for Ground Based Electronic Equipment. There is probably an aircraft-version of this but it is all the same chemistry.



3) Gold has zero reactivity with the atmosphere. Gold is only a fairly- good conductor but is great for low voltage electrical contacts. Silver is the best conductor followed by copper, then aluminum. 



4) Aluminum has over TWICE the conductivity per unit mass of any other metal. So learning how to use it can save weight. The electrical power industry uses far more aluminum than copper outside the home. Aluminum wiring in houses (that used electrical plugs and switches designed for copper) were retrofitted by adding a short pigtail of copper with special grease in a wirenut or crimp connector. 



5) Galvanic corrosion depends on the Electrode potential in the electro-chemical series AND presence of an electrolyte--saltwater perhaps but water will do. If you put dissimilar metals together, but keep them air-tight and dry, there is no problem.

Copper cables_Aluminum cables.pdf

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_________________
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net

stuart(at)stuarthutchison
Guest

Posted: Sat May 05, 2012 1:33 am Post subject: Aluminum bronze - conductivity

Hi  Bob,

  

 Maybe  I didn't explain myself well, I'm a bit intrigued by your last comment.  I  appreciate that keeping the number of joins down is priceless, but since  stainless is such a poor conductor, I would have expected to need to bond the  stud to something else and not rely on current radiating out through the  thin stainless firewall material?  Probably overkill, but I made mine  like the attached photo, which will have a short # 2 CCA fatwire between the  forrest of ground tabs and an engine mounting bolt where there is chrome-moly  structure bolted to a large part of the aluminium airframe.  All of the  bonding contact areas on my stud are at least 3/4", while the main shaft is 3/8  diameter, as are the threads and nuts.  There is an silicone insulating  washer on the front and back of the firewall for vibration absorbption as  well.

  

  

 .... I guess I'll just use di-electric grease to  keep the air out at the point where the stud meets with the firewall, or perhaps  make a phenolic bush to insulate it from the stainless, then bond the stud to a  substantial part of the aluminum structure on the inside (such as an engine  mounting bolt)" ...



         "I think clean, grease and lots of pressure are key.  Additional bonding is not useful."

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henador_titzoff(at)yahoo.
Guest

Posted: Sun May 06, 2012 3:50 pm Post subject: Aluminum bronze - conductivity

Eric,

Thank you for correcting me about copper plating vs. copper clad and also for the additional information after that. I continuously run into people, even engineers, who think gold is the metal with best conductance.  As you point out, gold has almost zero reactivity with the atmosphere, which makes it ideal for connector plating (or cladding!).  It is also ideal inside ICs for thin plating and very thin wires, because it is so ductile.

I'd like to point out something, though.  Below you say that silver is the best conductor, followed by copper then aluminum. Gold actually follows copper and then aluminum. What's really surprising is that calcium follows aluminum. The reasons calcium is not widely  used as a conductor are reactance to the atmosphere, easy dissolution in water, and insufficient mechanical strength.

 

Henador Titzoff



        From: Eric M. Jones <emjones(at)charter.net>

 To: aeroelectric-list(at)matronics.com 

 Sent: Thursday, May 3, 2012 11:17 AM

 Subject: Re: Aluminum bronze - conductivity

  

 

 --> AeroElectric-List message posted by: "Eric M. Jones" <emjones(at)charter.net (emjones(at)charter.net)>

 	  Quote: 	
		   Why not send that puppy off to Eric at Perihelion Design to get it copper plated?...Henador


	




The copper clad aluminum I sell is not plated. This wouldn't be good, plating always has pinholes and wears off. The Super-CCA I sell is "clad" which is a process where copper and aluminum are fused together. 10% of the diameter of the crossection is actually copper.  Copperweld Inc., historically made lots of different stuff clad with copper by this process. It is important to know that there is a long history of aluminum wiring problems, but essentially NO HISTORY of CCA problems. The wire behaves very much like copper



Some notes of metals:



1) In many applications the conductivity of the metal is less important than the surface reactivity with  atmospheric oxygen (or in the case of  titanium only, with nitrogen). Impure aluminum oxide is the same as sapphire or corundum and is quite insulating. Copper oxide looks bad but still conducts electricity well. Same for silver. It can turn black and conduct well. Stainless steel, nickel, chrome and aluminum looks great initially but turns into an insulator. This usually happens slowly. Battery contacts made of stainless steel were once the bane of cheap electronics.



2) See: http://aerospacedefense.thomasnet.com/Asset/MIL-F-14072.pdf  Finishes for Ground Based Electronic Equipment. There is probably an aircraft-version of this but it is all the same chemistry.



3) Gold has zero reactivity with the atmosphere. Gold is only a fairly- good conductor but is great for low voltage electrical contacts. Silver is the best conductor followed by copper, then aluminum. 



4) Aluminum has over TWICE the conductivity per unit mass of any  other metal. So learning how to use it can save weight. The electrical power industry uses far more aluminum than copper outside the home. Aluminum wiring in houses (that used electrical plugs and switches designed for copper) were retrofitted by adding a short pigtail of copper with special grease in a wirenut or crimp connector. 



5) Galvanic corrosion depends on the Electrode potential in the electro-chemical series AND presence of an electrolyte--saltwater perhaps but water will do. If you put dissimilar metals together, but keep them air-tight and dry, there is no problem.



--------

Eric M. Jones

www.PerihelionDesign.com

113 Brentwood Drive

Southbridge, MA 01550

(508) 764-2072

emjones(at)charter.net





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 [quote][b]

Eric M. Jones

Joined: 10 Jan 2006
Posts: 565
Location: Massachusetts

Posted: Sun May 06, 2012 4:32 pm Post subject: Re: Aluminum bronze - conductivity

Henador,



Thanks. Right you are. 



For elements that can be drawn into wires--Bulk Conductivity: Silver, Copper, Gold, Aluminium. And Mass Conductivity: Aluminum, Copper, Silver, Zinc, Gold.



Eric

_________________
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net

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