metal reactions

[rusty69bus]

could we have a list of metals which react to each other when used together...?

for example
black iron and brass promotes corrosion

 

[madkayaker]

copper and aluminium increased corrosion

 

[English Steve]

All of them do to some extent! There is a chart showing the different materials and their reaction with each other - I'll have a Google and see if I can find it.

Edit - Found one here. It's not the chart I was thinking of and doesn't give much information but is a start.

 

[MrFluffy]

It depends on how far apart they are on the galvanic table how much they react.
They basically form little tiny batteries, and the atoms flow from one plate to another, better electrodes make more voltage make more atoms flowing hence more corrosion. Also you need a electrolyte which is why we try to paint things to keep the electrolyte from coming into contact with the surfaces, salt water is more corrosive than plain (salty water is a good electrolyte/conductor) or we fit sacrificial anodes to ships etc.
http://www.auf.asn.au/scratchbuilder/galvanic_table.html

 

[TechnicAl]

There is also a phenomenon known as LME Liquid Metal Embrittlement. The most common reaction is Silicon and Zinc in steel. Molten zinc will react with silicon in steel, effectively leaching out the silicon leaving a matrix of zinc which is weak and leads to embrittlement. It is most common in Galvanising baths when the liquid zinc eats into the steel unless its a special low silicon grade.
It works to advantage when you want to galvanise. Higher Si will give you a thicker layer of zinc.

 

[English Steve]

Higher Si will give you a thicker layer of zinc.

Hence the different thickness of galv over a weld compared to the parent metal around it. (Someone cleverer than me said that on here previously )

 

[TechnicAl]

Thats right but it depends on the weld metal (and the plate). MIG with CO2 will be lower Si than MIG with Argon CO2. Some sticks give considerably lower Si than others.

 

[rusty69bus]

just a small silly question....how does gavinised steel and silicon adhesive react???

 

[Wozzaaah]

Rusty, that is a small silly question , it's silicon not silicone which is added to steel .

 

[Drains]

Ok then Woz, for the sake of those of us too ignorant to know (), what's the difference between silicon and silicone?

Hactually chap, it's a genuine question. Can't believe it's never occurred to me before!



Just looked up silicone on Wikipedia. Handy stuff! More than just a bathroom sealant, that's for sure.

 

[snowcat]

I'm guess you've figured it now Si, but silicone, is a compound of several elements Oxygen being one (I think) silicon is just an element, (Si) ............

 

[hareng]

what's the difference between silicon and silicone

One we used to wear at school with a big D on it, the other women use to pump up their best assets.
Am i right sir?

 

[Hitch]

Silica, silicone, silicon...
Manganese, Magnesium....

Often confused

 

[Paul.]

silicon is an element, silicones are compounds of several elements, such as hydrogen, carbon and others to make polymers, as used in adhesives, sealers, surface coatings etc.

Silica is a mineral, an oxide of silicon. manganese and magnesium are elements.

 

[homer]

When connecting to different types of metals together (other than welding) use a dialectic coupling.

 

[Drains]

Now then. Good replies on the silicon/silicone thing. I was well aware of what they were, but really what I wondered was why silicone got it's name. It is so similar you'd expect it to be a derivative of silicon, which it's not... so why, particularly as (I'd imagine), silicone would have been named well after silicon had been identified as an element.

 

[Archie]

I'm pretty sure they're called Silicones because the common thing to all of them is a Silicon based structure. Here we go. Shamelessly plagiarised

Silicones are synthetic polymers and are not therefore found naturally. They have a linear, repeating silicon-oxygen backbone akin to silica. However, organic groups attached directly to the silicon atoms by carbon-silicon bonds prevent formation of the three-dimensional network found in silica. These types of compound are also known as polyorganosiloxanes. Certain organic groups can be used to link two or more of these silicon-oxygen backbones and the nature and extent of this crosslinking enables a wide variety of products to be manufactured. The most important materials used in medical implants are fluids, gels and rubbers (elastomers) whose physical and chemical properties include, amongst others, a high degree of chemical inertness, thermal stability and resistance to oxidation.

 

[Drains]

Gosh Archie, arn't you clever!

 

[madkayaker]

Ive got a mate who uses the sealant gun for every thing Ive seen him glue a fuse board to a shipping cabin before today!

 

[zardoz]

Ive got a mate who uses the sealant gun for every thing Ive seen him glue a fuse board to a shipping cabin before today!

I suppose what really matters is what he's got in the sealent gun.