scandium

[blenkie1]

Interesting story about the different way boeing and airbus have gone about building their new aircraft. If you read the 2nd page it describes a metal I have never heard of, Scandium. Seemingly when mixed with Aluminium it makes it a lot easier to weld and also a lot stronger. Could do with some myself.

http://www.theregister.co.uk/2011/11/01/dreamline_airbus_rivet/

 

[ronan]

I never heard of it myself until a few years back smith and wesson started using it in the frames of their firearms for military and police use. Sounds like a good alloy.

 

[troppo]

Very interesting read, the author makes some good points regarding point to point flying when the airbus is limited in the airports it can realistically land at due to its size. Never heard of Scandium before myself but if its use in airframes is a success there will be the trickle down into the auto and engineering areas, more specialist welders, design modifications do to the change in structural use and of course the whole patent and use fight

 

[oz.]

Scandium is used in some well sought after bicycle frames. There is very little of it in the world so many frames which claim to contain scandium appears not to have any of the material at all.

As you know Alu needs more material to be as strong as steel, so when building aluminium structures you have to use more of the material to make it as strong. With bicycle frames many people know that steel frames are comfortable and soak up the bumps, an alu frame is really harsh as they have to increase the wall thickness.
They have to increase the wall thickness as too thin of a wall thickness will cause the welds to crack. Adding scandium into the mix changes how the material reacts to heat meaning that after welding it doesn't become brittle. Therefore you can reduce the wall thickness and reduce weight. A bike frame made of Alu+Sc is comfortable to ride

It has been used in bicycle frames for many years.

 

[hotrodder]

Scandium acts as a grain refiner improving mechanical properties in some alloys. I suspect the aerospace boys and girls definition of easier to weld is a bit different to ours, i think they're using friction stir welding to stick the wings together.

Easton's fabrication instructions for their scandium tubesets... http://www.eastoncycling.com/bike/wp-content/uploads/2010/04/fab_instructions-sc.pdf

 

[Engineer1964]

Apparently its only added in very small concentrations to the aluminium,

The addition of scandium to aluminium limits the excessive grain growth that occurs in the heat-affected zone of welded aluminium components. This has two beneficial effects: the precipitated Al3Sc forms smaller crystals than are formed in other aluminium alloys and the volume of precipitate-free zones that normally exist at the grain boundaries of age-hardening aluminium alloys is reduced. Both of these effects increase the usefulness of the alloy. However, titanium alloys, which are similar in lightness and strength, are cheaper and much more widely used.

The main application of scandium by weight is in aluminium-scandium alloys for minor aerospace industry components. These alloys contain between 0.1% and 0.5% of scandium. They were used in the Russian military aircraft, specifically the MiG-21 and MiG-29.

Some items of sports equipment, which rely on high performance materials, have been made with scandium-aluminium alloys, including baseball bats, and bicycle frames and components. Lacrosse sticks are also made with scandium-titanium alloys to take advantage of the strength of titanium. The American firearm manufacturing company Smith & Wesson produces revolvers with frames composed of scandium alloy and cylinders of titanium or carbon steel.

Approximately 20 kg (as Sc2O3) of scandium is used annually in the United States to make high-intensity discharge lamps. Scandium iodide, along with sodium iodide, when added to a modified form of mercury-vapor lamp, produces a form of metal halide lamp. This lamp is a white light source with high color rendering index that sufficiently resembles sunlight to allow good color-reproduction with TV cameras. About 80 kg of scandium is used in metal halide lamps/light bulbs globally per year. The first scandium-based metal halide lamps were patented by General Electric and initially made in North America, although they are now produced in all major industrialized countries. The radioactive isotope 46Sc is used in oil refineries as a tracing agent. Scandium triflate is a catalytic Lewis acid used in organic chemistry.

 

[Ed.]

They only use a small percentage of Scandium added to Aluminium to get a considerable increase in strength, which is just as well as it's about $1600/kg for almost pure Scandium Oxide.

 

[Ed.]

Interesting story about the different way boeing and airbus have gone about building their new aircraft. If you read the 2nd page it describes a metal I have never heard of, Scandium. Seemingly when mixed with Aluminium it makes it a lot easier to weld and also a lot stronger. Could do with some myself.

http://www.theregister.co.uk/2011/11/01/dreamline_airbus_rivet/

I don't think I would like to fly in the Boing, saw a story about how they built the Boeing plane and there was a lot of contoversy about using it where they did. As I recall, the entire section that holds up the wheels and the wings is made from a massive composite section of carbon fibre, apparently there were quite a few resignations in the company because they used it. Carbon fibre is good in some ways, it is light, strong and stiff with very little give, however it has a problem in that when it goes past it's strength it doesn't deform it just snaps in two. Which could possibly happen if the plane landed too hard, whereas aluminium will deform and will be visible on inspection. Carbon fibre on the other hand will not display any problem up to the point in which it snaps.

Apparently the resignations were in the engineering department which did the safety or design testing. They did not want it used and apparently quit in protest, at least this was the story I heard.

Either way I think I would prefer to be in a aluminium plane based on what I saw than the other. Just my preference.

 

[chunkolini]

Boeing wing being tested out
http://www.youtube.com/watch?v=WRf395ioJRY
Still dont like the idea of vehicles made of burned toast and glue.
Has this thread wondered a bit OT?

 

[PhillipM]

. Which could possibly happen if the plane landed too hard, whereas aluminium will deform and will be visible on inspection. Carbon fibre on the other hand will not display any problem up to the point in which it snaps.

If the plane landed that hard the landing gear would collapse and the wing tips would hit the floor.

 

[oz.]

Another thing I've remembered about the stuff - Easton bought most of the available material when the military decided to sell it's stock off. It's why you can pretty much guarantee that any frame not of an Easton tubeset doesn't actually contain any Sc.

 

[chunkolini]

Didnt an expose in MBUK describe Scandium alloys as being 'mostly Fu Fu dust thrown in the mix' Just looked on Fleabay loads of Scandium frames from about 200 quid.
Oz you are imagining that.

 

[Windy Miller]

If the plane landed that hard the landing gear would collapse and the wing tips would hit the floor.

Ah well, nothing to worry about then. Bring on the carbon fibre!

 

[chunkolini]

Weren't they looking at turbulence rather than hard landings.
Carbon Fibre? burned toast and glue.