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Guy Fawkes
science forum beginner
Joined: 15 Dec 2005
Posts: 5
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 Posted: Fri Jan 20, 2006 12:41 pm Post subject:
Re: O.T.- Chrome plating on salt water boat items??
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Andrew VK3BFA wrote:
| Quote: | curious on this one Guy - I am aware of electrolysis, and on a aerial I
am refurbishing, was planning to use stainless steel bolts and clamps
(Its all alumium construction...) - can you suggest something more
suitable?
Andrew VK3BFA.
|
if "it's all aluminium contruction" means the whole boat, eg something
like a stryker, start being very careful, throwing a handful of copper
into the bilge or fitting a bronze skinfitting can destroy the hull.
my objection to the current trend is that materials are chosen for
their visual appeal, not their suitability for the task in hand.
if the aerial is aluminium, whi not simply make up and aluminium
bracket to mount it on?
rubber seals work very well to avoid water ingress
anodising is cheap, simple, and gives an astonishingly tough and
protective surface finish.
choose the fasteners wisely, and always watch out for "gotchas" like
copper based thread lubes to do a job that could be done by (plain)
grease or tallow.
here's a list of metals, starting from the corroded / anodic / least
noble end, working down to the cathodic end, you'll see that the
chromes and 2xx series stainless which are used in boats cos they are
shiney are some of the worst metals you could choose, you'll also see
"it's made of aluminium I reckon" isn't good enough if you take the
subject seriously.
HTH etc
MAGNESIUM
MAGNESIUM ALLOYS
ZINC
ALUMINUM 5052, 3004, 3003, 1100, 6053
CADMIUM
ALUMINUM 2117, 2017, 2024
MILD STEEL (1018), WROUGHT IRON
CAST IRON, LOW ALLOY HIGH STRENGTH STEEL
CHROME IRON (ACTIVE)
STAINLESS STEEL, 430 SERIES (ACTIVE)
302, 303, 321, 347, 410,416, STAINLESS STEEL (ACTIVE)
NI - RESIST
316, 317, STAINLESS STEEL (ACTIVE)
CARPENTER 20CB-3 STAINLESS (ACTIVE)
ALUMINUM BRONZE (CA 687)
HASTELLOY C (ACTIVE) INCONEL 625 (ACTIVE) TITANIUM (ACTIVE)
LEAD - TIN SOLDERS
LEAD
TIN
INCONEL 600 (ACTIVE)
NICKEL (ACTIVE)
60 NI-15 CR (ACTIVE)
80 NI-20 CR (ACTIVE)
HASTELLOY B (ACTIVE)
BRASSES
COPPER (CA102)
MANGANESE BRONZE (CA 675), TIN BRONZE (CA903, 905)
SILICONE BRONZE
NICKEL SILVER
COPPER - NICKEL ALLOY 90-10
COPPER - NICKEL ALLOY 80-20
430 STAINLESS STEEL
NICKEL, ALUMINUM, BRONZE (CA 630, 632)
MONEL 400, K500
SILVER SOLDER
NICKEL (PASSIVE)
60 NI- 15 CR (PASSIVE)
INCONEL 600 (PASSIVE)
80 NI- 20 CR (PASSIVE)
CHROME IRON (PASSIVE)
302, 303, 304, 321, 347, STAINLESS STEEL (PASSIVE)
316, 317, STAINLESS STEEL (PASSIVE)
CARPENTER 20 CB-3 STAINLESS (PASSIVE), INCOLOY 825NICKEL - MOLYBDEUM -
CHROMIUM - IRON ALLOY (PASSIVE)
SILVER
TITANIUM (PASS.) HASTELLOY C & C276 (PASSIVE), INCONEL 625(PASS.)
GRAPHITE
ZIRCONIUM
GOLD
PLATINUM |
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Cliff
science forum beginner
Joined: 29 May 2005
Posts: 41
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| Posted: Fri Jan 20, 2006 12:41 pm Post subject:
Re: O.T.- Chrome plating on salt water boat items??
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On 20 Jan 2006 04:12:25 -0800, "Andrew VK3BFA" <ablight@alphalink.com.au> wrote:
| Quote: | curious on this one Guy - I am aware of electrolysis, and on a aerial I
am refurbishing, was planning to use stainless steel bolts and clamps
(Its all alumium construction...) - can you suggest something more
suitable?
|
Honking big Aluminum bolts <G>. Same exact alloy & temper?
But what are you bolting it TO?
--
Cliff |
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Andrew VK3BFA
science forum beginner
Joined: 08 Jan 2006
Posts: 3
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| Posted: Fri Jan 20, 2006 1:14 pm Post subject:
Re: O.T.- Chrome plating on salt water boat items??
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Cliff wrote:
| Quote: | On 20 Jan 2006 04:12:25 -0800, "Andrew VK3BFA" <ablight@alphalink.com.au> wrote:
curious on this one Guy - I am aware of electrolysis, and on a aerial I
am refurbishing, was planning to use stainless steel bolts and clamps
(Its all alumium construction...) - can you suggest something more
suitable?
Honking big Aluminum bolts <G>. Same exact alloy & temper?
But what are you bolting it TO?
--
Cliff
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Its going to be bolted to an aluminium tube, projecting out of the top
of the steel tower. I got NO IDEA what grade of aluminium the aerial (A
HYGAIN TH3Mk3, for those interested) - the original fittings were
steel (of SOME sort) and it stood up well to nearly 20 years outside.
Strangely, some fitting are rusted real bad, others no sign of
corrosion...I got it, very secondhand, and all the nuts bolts plastic
bits need replacing. HYGAIN offer (or did - not sure now) a rebuilt kit
containg all these bits - its expedient...but was curious re the
electrolysis action between stainless steel and aluminium - would have
thought it was less of a problem than plain gal. steel fittings.....ah
well. live and learn (or get more confused, not really sure....
Andrew VK3BFA. |
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beav
science forum addict
Joined: 18 Oct 2005
Posts: 63
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| Posted: Fri Jan 20, 2006 3:12 pm Post subject:
Re: O.T.- Chrome plating on salt water boat items??
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On 20 Jan 2006 05:14:36 -0800, "Andrew VK3BFA"
<ablight@alphalink.com.au> wrote:
| Quote: |
Cliff wrote:
On 20 Jan 2006 04:12:25 -0800, "Andrew VK3BFA" <ablight@alphalink.com.au> wrote:
curious on this one Guy - I am aware of electrolysis, and on a aerial I
am refurbishing, was planning to use stainless steel bolts and clamps
(Its all alumium construction...) - can you suggest something more
suitable?
Honking big Aluminum bolts <G>. Same exact alloy & temper?
But what are you bolting it TO?
--
Cliff
Its going to be bolted to an aluminium tube, projecting out of the top
of the steel tower. I got NO IDEA what grade of aluminium the aerial (A
HYGAIN TH3Mk3, for those interested) - the original fittings were
steel (of SOME sort) and it stood up well to nearly 20 years outside.
Strangely, some fitting are rusted real bad, others no sign of
corrosion...I got it, very secondhand, and all the nuts bolts plastic
bits need replacing. HYGAIN offer (or did - not sure now) a rebuilt kit
containg all these bits - its expedient...but was curious re the
electrolysis action between stainless steel and aluminium - would have
thought it was less of a problem than plain gal. steel fittings.....ah
well. live and learn (or get more confused, not really sure....
Andrew VK3BFA.
|
you have another problem: if the Al alloys are different, you'll
still get galvanic corrosion.
i think what the secondary poster didn't allude to is that if you want
to keep corrosion to a minimum, you have to religiously maintain the
parts clean and rinse then with fresh water at every opportunity.
salt water is its own conductive path. all you need is dissimilar
metals.... |
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beav
science forum addict
Joined: 18 Oct 2005
Posts: 63
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| Posted: Fri Jan 20, 2006 3:22 pm Post subject:
Re: O.T.- Chrome plating on salt water boat items??
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On Fri, 20 Jan 2006 05:17:24 -0500, Cliff <Clhuprich@aol.com> wrote:
| Quote: | On Fri, 20 Jan 2006 07:27:20 GMT, Michael <gailey@frontiernet.net> wrote:
Joe788 wrote:
Today I had a guy telling me that chrome does not stand up to the
weather and environment of a boat that is used in salt water. Now we
are not talking about a propeller here, but various chrome trinkets
around the boat, such as wakeboard racks, speaker enclosures, shifter
knobs, etc.
I was under the impression that chrome was a pretty good coating for
such applications, but did not want to argue for fear of jamming my
foot in my mouth. I know this is a pretty resourceful group when it
comes to random bits of manufacturing related information....(remember
the 900 post thread about the corrosion on the Fadal toolchanger??) .
So, does anybody know where to find any decent online reference
material for chrome plating's resistance to a salt water environment? I
searched around on Google for a few minutes, but could not find
anything of relevance.
One suggestion is Stainless Steel. It looks much like chrome, maybe you
saw SS instead?
http://www.chromplate.com/flash_hard_chrome.html
[
Micro-Cracked Hard Chrome (Bright)
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hard chrome is an engineering coating used on hydraulic cylinders, oil
drilling operations, etc... where you need extraordinary hardness. i
suppose you could use it for appearance sake, but its very expensive.
you mention microcracked chrome and you might be referring to the
chrome over bright nickel over satin nickel. (chrome over duplex
nickel) THAT might offer you some serious protection...
automobile manufacturers came up with this method in the late 80's as
a reproducible means of cutting down on car chrome failure from road
salt.
if i recalll the anti corrosion mechanism, the very slight dissimilar
potential difference between the two Ni plates and cracks in the
chrome caused any localized corrosion cells to peter out before the
corrosion runs wild under the whole Ni plate.
you'd need to find a plating shop that was set up for this, perhaps a
job shop that supports the auto industry.
| Quote: |
This type of hard chrome offers a number advantages over the standard Hard
Chrome...
Harder and more wear resistant (hardness appox. 1050-1150 Vickers or 70 Rockwell
C).
Offers better corrosion protection than standard hard chrome
Brighter finish than hard chrome
These extra qualities make this mirco cracked hard chrome ideally suited for use
with hydraulic rams which may be operating in dirty environments, if dirt is
liable to lodge in seals, less harm may be done to the ram. For wet or
salt-water environments, an under coat of nickel plating provides a corrosion
resistant layer, that extends the working life of the ram considerably.
]
[
Special Note on Hard Chrome
It is a common misconception that chrome plating provides corrosion protection.
This is not the case, only slight protection is given. Hard Chrome is porous at
the microscopic level, which can let moisture and chemicals through to attack
the base material. If the item is to be used in a damp environment, or where
water based inks are used on printing machines, a layer of Nickel plating is
required, prior to hard chrome plating.
]
I'd think that any fasteners should be of the exact same surface material
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hard to do...
| Quote: | (or nonconductive plastics) (to avoid electrolytic corrosion) and that
such should not be joined to other metals (or in contact with them).
|
it may not even need to be in contact. crack a chemistry book or
google up "salt bridge" or "conductive salt bridge". i'll leave that
exercise to you...
| Quote: | I.E.: Use the same plating on any fasteners into a fiberglass boat hull,
don't even think of it with Aluminum or steel.
If this is a submerged application perhaps a sacrificial electrode
could be used as well?
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just keep everything extremely clean. way easier said than done. |
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Cliff
science forum beginner
Joined: 29 May 2005
Posts: 41
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| Posted: Fri Jan 20, 2006 10:49 pm Post subject:
Re: O.T.- Chrome plating on salt water boat items??
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On 20 Jan 2006 05:14:36 -0800, "Andrew VK3BFA" <ablight@alphalink.com.au> wrote:
| Quote: | but was curious re the
electrolysis action between stainless steel and aluminium - would have
thought it was less of a problem than plain gal. steel fittings
|
Both Stainless & Aluminum are protected by an oxide layer.
Aluminum Oxide dissolves in bases IIRC (see Draino).
Chromium Oxide in the case of Stainless IIRC. Did not
check to see what dissolves that <G>.
A chart of galvanic potentials was posted ... the closer two
things are on it the less the voltage to cause corrosion, usually.
But that depends on current too. More current ==> more
(bulk) corrosion. No current, no corrosion by this mechanism.
See electronegativity (fifth thing down on the left for each element):
http://www.physics.ohio-state.edu/~lvw/physics/bigpertable.jpg
http://www.tech.plym.ac.uk/sme/strc201/corrosion1.htm
http://www.efunda.com/materials/corrosion/electrochem_entry.cfm
What happens in alloys or things like Oxides is another matter
(and beyond my scope) <g>.
[
Mr. McGuire: I want to say one word to you. Just one word.
Benjamin: Yes, sir.
Mr. McGuire: Are you listening?
Benjamin: Yes, I am.
Mr. McGuire: Plastics.
]
- from "The Graduate"
--
Cliff |
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Cliff
science forum beginner
Joined: 29 May 2005
Posts: 41
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| Posted: Fri Jan 20, 2006 10:50 pm Post subject:
Re: O.T.- Chrome plating on salt water boat items??
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On Fri, 20 Jan 2006 15:12:58 GMT, beav <BEAVITH1@NETSCAPE.NET> wrote:
| Quote: | salt water is its own conductive path.
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??
--
Cliff |
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Cliff
science forum beginner
Joined: 29 May 2005
Posts: 41
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| Posted: Fri Jan 20, 2006 10:57 pm Post subject:
Re: O.T.- Chrome plating on salt water boat items??
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On Fri, 20 Jan 2006 15:22:52 GMT, beav <BEAVITH1@NETSCAPE.NET> wrote:
| Quote: | it may not even need to be in contact. crack a chemistry book or
google up "salt bridge" or "conductive salt bridge". i'll leave that
exercise to you...
|
"Solid NaCl did not conduct electricity .." ?
--
Cliff |
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David R Brooks
science forum beginner
Joined: 21 Jan 2006
Posts: 1
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| Posted: Sat Jan 21, 2006 12:57 am Post subject:
Re: O.T.- Chrome plating on salt water boat items??
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Guy Fawkes wrote:
| Quote: | disclaimer - spent years as a marine engineer catering to the private
yacht sector.
[snip]
bronze (various grades) - shiny and most suitable, will de zinc over
time if not protected by sacrificial anodes if installed badly
Isn't that brass? Afair, bronze is copper/tin, used in marine |
applications for exactly that reason, no zinc to leach out. |
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Martin H. Eastburn
science forum beginner
Joined: 24 Nov 2005
Posts: 20
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| Posted: Sat Jan 21, 2006 2:53 am Post subject:
Re: O.T.- Chrome plating on salt water boat items??
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Brass de zincs - dezincify - Bronze is Tin-Copper.
I have some Bronze portholes - big ones - that were under Salt water for almost 50 years.
One the equator at that. Only blemish is coral and dark brownish color. Beauty.
Old design faucet sets were brass and the seats went bad - due to the loss of zinc
with the chlorine in the water.
Martin
Martin Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
NRA LOH & Endowment Member
NRA Second Amendment Task Force Charter Founder
Guy Fawkes wrote:
| Quote: | disclaimer - spent years as a marine engineer catering to the private
yacht sector.
chrome plate - waste of time and money
galvanised - lovely stuff, but ooh, it's not shiny, yuck.
stainless (various grades) - ooh, it's shiny, personally speaking you
couldn't give me the stuff on a boat, nightmare when used with any
other metal, which it always is in practice, and breaks with little
warning, yet is still used for rigging cos it's shiny..
bronze (various grades) - shiny and most suitable, will de zinc over
time if not protected by sacrificial anodes if installed badly
aluminium - has it's uses, god help you when someone chrome plates it,
or worse still uses a stainless fastener in it, which happens all the
time
|
----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----
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Brent Philion
science forum beginner
Joined: 21 Jan 2006
Posts: 2
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| Posted: Sat Jan 21, 2006 6:18 am Post subject:
Re: O.T.- Chrome plating on salt water boat items??
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Active Versus passive Stainless?
Whats the difference?
And how do you flip them over between states?
I've had stainless practive peices here rust on me after welding and it
didnt make sense to me as to the diff
Guy Fawkes wrote:
| Quote: | Andrew VK3BFA wrote:
curious on this one Guy - I am aware of electrolysis, and on a aerial I
am refurbishing, was planning to use stainless steel bolts and clamps
(Its all alumium construction...) - can you suggest something more
suitable?
Andrew VK3BFA.
if "it's all aluminium contruction" means the whole boat, eg something
like a stryker, start being very careful, throwing a handful of copper
into the bilge or fitting a bronze skinfitting can destroy the hull.
my objection to the current trend is that materials are chosen for
their visual appeal, not their suitability for the task in hand.
if the aerial is aluminium, whi not simply make up and aluminium
bracket to mount it on?
rubber seals work very well to avoid water ingress
anodising is cheap, simple, and gives an astonishingly tough and
protective surface finish.
choose the fasteners wisely, and always watch out for "gotchas" like
copper based thread lubes to do a job that could be done by (plain)
grease or tallow.
here's a list of metals, starting from the corroded / anodic / least
noble end, working down to the cathodic end, you'll see that the
chromes and 2xx series stainless which are used in boats cos they are
shiney are some of the worst metals you could choose, you'll also see
"it's made of aluminium I reckon" isn't good enough if you take the
subject seriously.
HTH etc
MAGNESIUM
MAGNESIUM ALLOYS
ZINC
ALUMINUM 5052, 3004, 3003, 1100, 6053
CADMIUM
ALUMINUM 2117, 2017, 2024
MILD STEEL (1018), WROUGHT IRON
CAST IRON, LOW ALLOY HIGH STRENGTH STEEL
CHROME IRON (ACTIVE)
STAINLESS STEEL, 430 SERIES (ACTIVE)
302, 303, 321, 347, 410,416, STAINLESS STEEL (ACTIVE)
NI - RESIST
316, 317, STAINLESS STEEL (ACTIVE)
CARPENTER 20CB-3 STAINLESS (ACTIVE)
ALUMINUM BRONZE (CA 687)
HASTELLOY C (ACTIVE) INCONEL 625 (ACTIVE) TITANIUM (ACTIVE)
LEAD - TIN SOLDERS
LEAD
TIN
INCONEL 600 (ACTIVE)
NICKEL (ACTIVE)
60 NI-15 CR (ACTIVE)
80 NI-20 CR (ACTIVE)
HASTELLOY B (ACTIVE)
BRASSES
COPPER (CA102)
MANGANESE BRONZE (CA 675), TIN BRONZE (CA903, 905)
SILICONE BRONZE
NICKEL SILVER
COPPER - NICKEL ALLOY 90-10
COPPER - NICKEL ALLOY 80-20
430 STAINLESS STEEL
NICKEL, ALUMINUM, BRONZE (CA 630, 632)
MONEL 400, K500
SILVER SOLDER
NICKEL (PASSIVE)
60 NI- 15 CR (PASSIVE)
INCONEL 600 (PASSIVE)
80 NI- 20 CR (PASSIVE)
CHROME IRON (PASSIVE)
302, 303, 304, 321, 347, STAINLESS STEEL (PASSIVE)
316, 317, STAINLESS STEEL (PASSIVE)
CARPENTER 20 CB-3 STAINLESS (PASSIVE), INCOLOY 825NICKEL - MOLYBDEUM -
CHROMIUM - IRON ALLOY (PASSIVE)
SILVER
TITANIUM (PASS.) HASTELLOY C & C276 (PASSIVE), INCONEL 625(PASS.)
GRAPHITE
ZIRCONIUM
GOLD
PLATINUM
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Mark Jones
science forum beginner
Joined: 24 Mar 2005
Posts: 11
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| Posted: Sat Jan 21, 2006 8:42 pm Post subject:
Re: O.T.- Chrome plating on salt water boat items??
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David R Brooks wrote:
| Quote: | Guy Fawkes wrote:
disclaimer - spent years as a marine engineer catering to the private
yacht sector.
[snip]
bronze (various grades) - shiny and most suitable, will de zinc over
time if not protected by sacrificial anodes if installed badly
Isn't that brass? Afair, bronze is copper/tin, used in marine
applications for exactly that reason, no zinc to leach out.
|
Is bronze capable of exhibiting the effects of "tin pest?" (Tin Pest is where
tin "decomposes" when exposed to temperatures below freezing - do a google
search for more info.) |
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Mark Thorson
science forum Guru Wannabe
Joined: 04 May 2005
Posts: 102
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| Posted: Sat Jan 21, 2006 9:08 pm Post subject:
Re: O.T.- Chrome plating on salt water boat items??
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Mark Jones wrote:
| Quote: |
Is bronze capable of exhibiting the effects of "tin pest?"
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No, tin has to be rather pure to exhibit tin pest.
Tin alloys like solder and bronze do not exhibit
tin pest. |
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Andy Dingley
science forum beginner
Joined: 03 Jun 2005
Posts: 11
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| Posted: Sun Jan 22, 2006 3:03 pm Post subject:
Re: O.T.- Chrome plating on salt water boat items??
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On Sat, 21 Jan 2006 15:42:15 -0500, Mark Jones <abuse@127.0.0.1> wrote:
| Quote: | Is bronze capable of exhibiting the effects of "tin pest?" (Tin Pest is where
tin "decomposes" when exposed to temperatures below freezing
|
No - like most alloys, it stabilises the lattice against this. I think
you actually have to have quite pure tin before you can demonstrate it.
Napoleon's mistake was to specify those extra-shiny buttons for his
army. |
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beav
science forum addict
Joined: 18 Oct 2005
Posts: 63
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| Posted: Mon Jan 23, 2006 3:21 pm Post subject:
Re: O.T.- Chrome plating on salt water boat items??
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On Fri, 20 Jan 2006 17:57:12 -0500, Cliff <Clhuprich@aol.com> wrote:
| Quote: | On Fri, 20 Jan 2006 15:22:52 GMT, beav <BEAVITH1@NETSCAPE.NET> wrote:
it may not even need to be in contact. crack a chemistry book or
google up "salt bridge" or "conductive salt bridge". i'll leave that
exercise to you...
"Solid NaCl did not conduct electricity .." ?
|
a salt bridge in chemsitry is a U shaped glass tube filled with NaCl
solution with gelatin plugs at either end of the U to hold the
solution in.
a real world slat bridge could be a simple as salt water sitting
between two dissimilar metals.
and "dissimilar" might be a simple as two different alloys of the same
metal. |
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