FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups 
 ProfileProfile   PreferencesPreferences   Log in to check your private messagesLog in to check your private messages   Log inLog in 
Forum index » Science and Technology » Chem » Coatings
Water based primer for OPP
Post new topic   Reply to topic Page 3 of 6 [78 Posts] View previous topic :: View next topic
Goto page:  Previous  1, 2, 3, 4, 5, 6 Next
Author Message
beav
science forum addict


Joined: 18 Oct 2005
Posts: 63

PostPosted: Mon Jan 23, 2006 3:26 pm    Post subject: Re: O.T.- Chrome plating on salt water boat items?? Reply with quote

On Fri, 20 Jan 2006 17:49:13 -0500, Cliff <Clhuprich@aol.com> wrote:

Quote:
On 20 Jan 2006 05:14:36 -0800, "Andrew VK3BFA" <ablight@alphalink.com.au> wrote:

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.

not that easy. thse are lab comparisons. the real world is, well,
"real".

the oxide coat on Al is physically very tough. chemically, its at the
mercy of its surroundings.

stainless is a whole differnt story.
there are several varieties of stainless. for instance, 400 series
contains enough iron to rust. 300 series, once passivated (soaked in
strong acid to dissolve out any surface acitve iron sites) is
extremely durable. that being said, in a chloride environment, iron
can "unpassivate" and spot.
and then, of course, there are things like aircraft alloys (hastelloy,
mulitmet, etc that are mainly nickel chrome alloys that are incredibly
durable. and incredibly expensive.


Quote:

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"
Back to top
beav
science forum addict


Joined: 18 Oct 2005
Posts: 63

PostPosted: Mon Jan 23, 2006 3:26 pm    Post subject: Re: O.T.- Chrome plating on salt water boat items?? Reply with quote

On Fri, 20 Jan 2006 17:50:09 -0500, Cliff <Clhuprich@aol.com> wrote:

Quote:
On Fri, 20 Jan 2006 15:12:58 GMT, beav <BEAVITH1@NETSCAPE.NET> wrote:

salt water is its own conductive path.

??


see my first post response.
Back to top
beav
science forum addict


Joined: 18 Oct 2005
Posts: 63

PostPosted: Mon Jan 23, 2006 3:28 pm    Post subject: Re: O.T.- Chrome plating on salt water boat items?? Reply with quote

On Fri, 20 Jan 2006 20:53:46 -0600, "Martin H. Eastburn"
<lionslair@consolidated.net> wrote:

Quote:
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


that's why brass and bronze have ben used on ships since time
immemorial. oh. yeah. and that's why swabbies have been polishing
and buffing it for just as long.
its durable, but it needs to be cleaned all the time....


Quote:

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:
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==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----
Back to top
beav
science forum addict


Joined: 18 Oct 2005
Posts: 63

PostPosted: Mon Jan 23, 2006 3:31 pm    Post subject: Re: O.T.- Chrome plating on salt water boat items?? Reply with quote

On Sat, 21 Jan 2006 01:18:43 -0500, Brent Philion
<brent_p@sympatico.ca> wrote:

Quote:
Active Versus passive Stainless?

Whats the difference?


iron sites on active stainless can spot rust and act as corrosion
loci. the trick is to soak the 300 series stainless in hot strong
acid to dissolve out the iron hot spots.


Quote:

And how do you flip them over between states?


soak the part in hot strong acid to repassivate


Quote:

I've had stainless practive peices here rust on me after welding and it
didnt make sense to me as to the diff


what alloy of stainless? 400 series is hardly stainless. if it was
300 series, it needed to be soaked in acid.

Quote:

Guy Fawkes wrote:
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
Back to top
Cliff
science forum beginner


Joined: 29 May 2005
Posts: 41

PostPosted: Mon Jan 23, 2006 4:03 pm    Post subject: Re: O.T.- Chrome plating on salt water boat items?? Reply with quote

On Mon, 23 Jan 2006 15:21:19 GMT, beav <BEAVITH1@NETSCAPE.NET> wrote:

Quote:
On Fri, 20 Jan 2006 17:57:12 -0500, Cliff <Clhuprich@aol.com> wrote:

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.

""Solid NaCl did not conduct electricity .." ?"
--
Cliff
Back to top
Brent Philion
science forum beginner


Joined: 21 Jan 2006
Posts: 2

PostPosted: Mon Jan 23, 2006 9:01 pm    Post subject: Re: O.T.- Chrome plating on salt water boat items?? Reply with quote

308 And it makes sense now

how Strong an acid?

Sulphuric?
Hydrochloric?
Acetic?

And what the proper name for the process so i can figure out what i need
ot buy to do it safely within a home shop



beav wrote:
Quote:
On Sat, 21 Jan 2006 01:18:43 -0500, Brent Philion
brent_p@sympatico.ca> wrote:


Active Versus passive Stainless?

Whats the difference?



iron sites on active stainless can spot rust and act as corrosion
loci. the trick is to soak the 300 series stainless in hot strong
acid to dissolve out the iron hot spots.



And how do you flip them over between states?



soak the part in hot strong acid to repassivate



I've had stainless practive peices here rust on me after welding and it
didnt make sense to me as to the diff



what alloy of stainless? 400 series is hardly stainless. if it was
300 series, it needed to be soaked in acid.


Guy Fawkes wrote:

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


Back to top
Glenn Ashmore
science forum beginner


Joined: 23 Jan 2006
Posts: 13

PostPosted: Mon Jan 23, 2006 10:30 pm    Post subject: Re: O.T.- Chrome plating on salt water boat items?? Reply with quote

I am using Citrisurf, a line of citric acid based passivating solutions on
my stainless welds. For basic passivating you just soak the part for a few
minutes but I have been doing some deep passivating using an adjustable DC
power supply. For smaller stuff I have a 5 gallon bucket and use a graphite
rod on the negative side. The result is not truly electropolishing because
my power supply is not that big and I don't use heat but it leaves a stain
free matt surface that buffs up very easily. Good test for your welding
ability too. When you grind down a weld the pits often get smeared over.
10 minutes in the Citrisurf at max amps will reveal any voids.

For big stuff like the welds on the bow pulpit I grind until the weld is
faired in and then have a paddle made of flattened 1" copper tube wrapped
in cotton gauze and soaked in Citrisurf. I just swab the weld slowly for
about 5 minutes with the power supply delivering about 2 amps and get
similar results.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"Brent Philion" <brent_p@sympatico.ca> wrote in message
news:%qbBf.7638$ve.156110@news20.bellglobal.com...
Quote:
308 And it makes sense now

how Strong an acid?

Sulphuric?
Hydrochloric?
Acetic?

And what the proper name for the process so i can figure out what i need
ot buy to do it safely within a home shop



beav wrote:
On Sat, 21 Jan 2006 01:18:43 -0500, Brent Philion
brent_p@sympatico.ca> wrote:


Active Versus passive Stainless?

Whats the difference?



iron sites on active stainless can spot rust and act as corrosion
loci. the trick is to soak the 300 series stainless in hot strong
acid to dissolve out the iron hot spots.
And how do you flip them over between states?



soak the part in hot strong acid to repassivate



I've had stainless practive peices here rust on me after welding and it
didnt make sense to me as to the diff



what alloy of stainless? 400 series is hardly stainless. if it was
300 series, it needed to be soaked in acid.


Guy Fawkes wrote:

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

Back to top
Martin H. Eastburn
science forum beginner


Joined: 24 Nov 2005
Posts: 20

PostPosted: Tue Jan 24, 2006 3:09 am    Post subject: Re: O.T.- Chrome plating on salt water boat items?? Reply with quote

Quality Naval Bronze doesn't need cleaning. As I stated, it sat under salt water -
the ocean - rusting the iron bolts out - but the bronze is beautiful.

The special alloy props - monsters - a pair that exposed at low tide - were shinny.
I heard not long ago that one was dismounted for transport back to Germany.

So it really depends on the quality of bronze. Some require help - others don't.

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



beav wrote:
Quote:
On Fri, 20 Jan 2006 20:53:46 -0600, "Martin H. Eastburn"
lionslair@consolidated.net> wrote:


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



that's why brass and bronze have ben used on ships since time
immemorial. oh. yeah. and that's why swabbies have been polishing
and buffing it for just as long.
its durable, but it needs to be cleaned all the time....



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:

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==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----



----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----
Back to top
peter_dingemans@hotmail.c
science forum beginner


Joined: 24 Jan 2006
Posts: 1

PostPosted: Tue Jan 24, 2006 6:43 am    Post subject: Re: O.T.- Chrome plating on salt water boat items?? Reply with quote

As to the stainless corroding (usually in the HAZ?), it has to do with
the formation of chromium-carbides when temperature is high enough.
This reduces the amount of free chromium (in the HAZ), so corrision
resistance reduces. The common accepted 'threshold' for stainless is
12% free chromium, IIRC. The 'more' stainless your steel is, the more
chromium it will have.

BTW, this is all austenitic SS I'm talking about; don't know off-hand
about martensitic or ferritic SS.

Wasn't the passivating a form of heattreating? I know that SS could be
heattreated to reduce stress, but don't know if it would improve
corrosion resistance; it might if the chromium carbides get back into
solution?

Peter.
Back to top
Cliff
science forum beginner


Joined: 29 May 2005
Posts: 41

PostPosted: Tue Jan 24, 2006 9:38 am    Post subject: Re: O.T.- Chrome plating on salt water boat items?? Reply with quote

On Mon, 23 Jan 2006 17:30:44 -0500, "Glenn Ashmore" <gashmore@cox.net> wrote:

Quote:
I am using Citrisurf, a line of citric acid based passivating solutions on
my stainless welds. For basic passivating you just soak the part for a few
minutes but I have been doing some deep passivating using an adjustable DC
power supply. For smaller stuff I have a 5 gallon bucket and use a graphite
rod on the negative side. The result is not truly electropolishing because
my power supply is not that big and I don't use heat but it leaves a stain
free matt surface that buffs up very easily.

That buffing probably removes or scratches ....
--
Cliff
Back to top
Cliff
science forum beginner


Joined: 29 May 2005
Posts: 41

PostPosted: Tue Jan 24, 2006 9:48 am    Post subject: Re: O.T.- Chrome plating on salt water boat items?? Reply with quote

On Mon, 23 Jan 2006 21:09:35 -0600, "Martin H. Eastburn"
<lionslair@consolidated.net> wrote:

Quote:
Quality Naval Bronze doesn't need cleaning. As I stated, it sat under salt water -
the ocean - rusting the iron bolts out - but the bronze is beautiful.

The special alloy props - monsters - a pair that exposed at low tide - were shinny.
I heard not long ago that one was dismounted for transport back to Germany.

So it really depends on the quality of bronze. Some require help - others don't.

Copper is an anti-fouling agent.
Quite toxic to much marine life.
Which is why it's often used (or was?) in marine paints .... (NOT for use on
Aluminum).
--
Cliff
Back to top
Glenn Ashmore
science forum beginner


Joined: 23 Jan 2006
Posts: 13

PostPosted: Tue Jan 24, 2006 3:17 pm    Post subject: Re: O.T.- Chrome plating on salt water boat items?? Reply with quote

<peter_dingemans@hotmail.com> wrote

Quote:
Wasn't the passivating a form of heattreating? I know that SS could be
heattreated to reduce stress, but don't know if it would improve
corrosion resistance; it might if the chromium carbides get back into
solution?

"Passivation" has two definitions. The first is the spontaneous formation
of a chromium oxide skin which protects the iron from corrosion. The second
is the process of treating the surface of stainless with a mild acid to
remove free iron molecules so the first definition can happen.

Actually you need to passivate after heat treating. Heat, especially
welding temps, makes the molecules in the alloy separate to a degree leaving
free iron molecules on the surface. A mild acid passivating bath removes
the free iron and exposes the chromium below it to oxygen to form the
protective chromium oxide skin. .


--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com
Back to top
beav
science forum addict


Joined: 18 Oct 2005
Posts: 63

PostPosted: Tue Jan 24, 2006 3:27 pm    Post subject: Re: O.T.- Chrome plating on salt water boat items?? Reply with quote

On Mon, 23 Jan 2006 21:09:35 -0600, "Martin H. Eastburn"
<lionslair@consolidated.net> wrote:

Quote:
Quality Naval Bronze doesn't need cleaning. As I stated, it sat under salt water -
the ocean - rusting the iron bolts out - but the bronze is beautiful.

sounds like the iron galvanically protected the bronze.
Quote:

The special alloy props - monsters - a pair that exposed at low tide - were shinny.
I heard not long ago that one was dismounted for transport back to Germany.

So it really depends on the quality of bronze. Some require help - others don't.

Martin

i was thinking more about brass and bronze that on the deck that would
see salt spray and gets spots of tarnish that need to be cared for...
Quote:

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



beav wrote:
On Fri, 20 Jan 2006 20:53:46 -0600, "Martin H. Eastburn"
lionslair@consolidated.net> wrote:


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



that's why brass and bronze have ben used on ships since time
immemorial. oh. yeah. and that's why swabbies have been polishing
and buffing it for just as long.
its durable, but it needs to be cleaned all the time....



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:

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==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----



----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----
Back to top
beav
science forum addict


Joined: 18 Oct 2005
Posts: 63

PostPosted: Tue Jan 24, 2006 3:35 pm    Post subject: Re: O.T.- Chrome plating on salt water boat items?? Reply with quote

On Mon, 23 Jan 2006 17:30:44 -0500, "Glenn Ashmore" <gashmore@cox.net>
wrote:

Quote:
I am using Citrisurf, a line of citric acid based passivating solutions on
my stainless welds. For basic passivating you just soak the part for a few
minutes but I have been doing some deep passivating using an adjustable DC
power supply. For smaller stuff I have a 5 gallon bucket and use a graphite
rod on the negative side.

hmmm! i'd seen a new mil std for using citric acid, but i'd never
tried it out.

we'd use straight up HNO3 (i can't recall the baume..) with a pinch of
HCl, and let the part soak for 20 minutes.
once rinsed, we'd spray a dilute KMnO4 solution on the part. any dark
spots that we could visually spot would indicate that the part wasn't
done and it would go back into the passivating solution.

the dark spots are active Fe locations that haven't been dissolved
out.

at that conc of HNO3, very few parts would need to be retreated.

Quote:
The result is not truly electropolishing because
my power supply is not that big and I don't use heat but it leaves a stain
free matt surface that buffs up very easily.


electropolishing and passivating aren't the same thing.

Quote:
Good test for your welding
ability too. When you grind down a weld the pits often get smeared over.
10 minutes in the Citrisurf at max amps will reveal any voids.


hmmm! again... very neat.

Quote:

For big stuff like the welds on the bow pulpit I grind until the weld is
faired in and then have a paddle made of flattened 1" copper tube wrapped
in cotton gauze and soaked in Citrisurf. I just swab the weld slowly for
about 5 minutes with the power supply delivering about 2 amps and get
similar results.


brush passivating. even neater.

thanks. i learned something new today!
Back to top
Glenn Ashmore
science forum beginner


Joined: 23 Jan 2006
Posts: 13

PostPosted: Tue Jan 24, 2006 3:59 pm    Post subject: Re: O.T.- Chrome plating on salt water boat items?? Reply with quote

Having spent two summers as a deck hand on an old classic 80' Herreshoff
yawl I can definitely state that bronze DOES need cleaning. That boat had
10 bronze Dorade vents, 52 bronze hinges and latches and a bronze bow
fitting. And I had to polish every D#*%^! one of them once a week!

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"Martin H. Eastburn" <lionslair@consolidated.net> wrote in message
news:1138072363_13827@sp6iad.superfeed.net...
Quote:
Quality Naval Bronze doesn't need cleaning. As I stated, it sat under
salt water -
the ocean - rusting the iron bolts out - but the bronze is beautiful.

The special alloy props - monsters - a pair that exposed at low tide -
were shinny.
I heard not long ago that one was dismounted for transport back to
Germany.

So it really depends on the quality of bronze. Some require help - others
don't.

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



beav wrote:
On Fri, 20 Jan 2006 20:53:46 -0600, "Martin H. Eastburn"
lionslair@consolidated.net> wrote:


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



that's why brass and bronze have ben used on ships since time
immemorial. oh. yeah. and that's why swabbies have been polishing
and buffing it for just as long.
its durable, but it needs to be cleaned all the time....



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:

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==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+
Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption
=----



----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet
News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+
Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption
=----
Back to top
Google

Back to top
Display posts from previous:   
Post new topic   Reply to topic Page 3 of 6 [78 Posts] Goto page:  Previous  1, 2, 3, 4, 5, 6 Next
View previous topic :: View next topic
The time now is Thu Dec 14, 2017 12:34 am | All times are GMT
Forum index » Science and Technology » Chem » Coatings
Jump to:  

Similar Topics
Topic Author Forum Replies Last Post
No new posts Estimating the ammount of water relased by burning petrol Jan Kalin Chem 7 Wed Jul 19, 2006 11:26 am
No new posts Fuzzy Inference System (FIS) Based Decision-Making Algori... amizo1@gmail.com Mechanics 0 Fri Jul 14, 2006 7:26 pm
No new posts O-18 Water, surplus Clay Herzog Chem 2 Wed Jul 12, 2006 1:39 pm
No new posts de-ionised water = distilled water = eau déminéralisée ? beerismygas Chem 17 Tue Jul 11, 2006 6:29 pm
No new posts Improvements to my building based on group consensus. anilcool@gmail.com Math 9 Sun Jul 09, 2006 12:02 am

Copyright © 2004-2005 DeniX Solutions SRL
Other DeniX Solutions sites: Electronics forum |  Medicine forum |  Unix/Linux blog |  Unix/Linux documentation |  Unix/Linux forums  |  send newsletters
 


Powered by phpBB © 2001, 2005 phpBB Group
[ Time: 0.0678s ][ Queries: 16 (0.0058s) ][ GZIP on - Debug on ]