Zicral Alloy Use in Climbing Equipment

[catbirdseat]

REI has a pair of Simonds Crampons on sale at present. The ad on their website mentions that they are made of an alloy called Zicral. Some investigation on the web revealed that this is a type of zirconium-aluminum alloy for which there are claims of greater strength than conventional alloys.

 

Zicral has been used in bicycle crank sets, frames and spoke, also in baseball bats. It is used in the Petzl Spirit carabiner for which is claimed a 9.5 kN open gate strength. This extra ~2 kN strength over conventional carabiners presumably comes by virtue of the stronger alloy.

 

Further reading brought me to a site on caving in France in which it was mentioned that Zicral carabiners were subject to accelerated corrosion when left fixed in the cave. But it wasn't exactly clear from reading it that conventional biners wouldn't have also corroded under similar conditions of constant immersion.

 

Zicral carabiners used for the usual climbing purposes are not usually in contact with water for extended periods, so it is probably not an issue, but it might pay to rinse your Spirit biners periodically if you get sweat on them, which is true of any carabiner for that matter.

 

I was curious as to whether any of you have access to metalurgical data on the properties of Zicral or have any other info on this alloy. Is it harder, for example? Greater hardness means crampons would stay sharper longer.

[Dru]

Zicral is not Zirconium but zinc, chromoly and aluminum according to my 15 year old Simond Zicral biners. which have never broken by the way

[catbirdseat]

The zinc would explain the greater corrosion.

[Dru]

Yeah because as everyone knows, zinc is the component of stainless steel which renders it stainless, so therefore it corrodes MUCH faster.

[fenderfour]

Zircal is another fancy name for aluminum alloy. Would it have caught your eye if they called it 6065-T6? I doubt it. Most aluminum alloys are more than 95% aluminum with stuff like manganese, nickel, copper, and silicon thrown in for flavor.

 

It's odd that Simond would mention Chromoly Steel in their alloy. It's an alloy made up of Iron, Carbon, Nickel, Chromium, and Molybdenum.

[catbirdseat]

No, you are wrong there. Stainless steel is commonly composed of primarily iron, chromium and nickel with other minor components. Zinc is very low on the electromotive series. Brass, which has zinc and copper in it, is much less resistant to corrosion than either pure copper or bronze (copper and tin).

[fenderfour]

Found something - LINKAGE

 

Zinc, Aluminum, and Magnesium

 

The site implies that it's 7075 Aluminum. Nothing special.

 

And here's som info on 7000 series aluminum LINKAGE #2

[catbirdseat]

So it's basically aircraft aluminum.

 

While zinc is high in the electromotive series, aluminum is even higher. Corrosion resistance is also related to adhesion force of the oxide.

[ketch]

Yes it is an aircraft aluminum. I have not crossed paths with the trade name of Zicral but 7075 I have worked with. It is a heat treatable alloy. I don't know what process the manufactures are using but they would like it as it forms easy and them can be hardened after the fact. It is higher in resistance to stress cracks than many of the more common alloys.

 

I would expect it to work well for crampons (if they worked that hard) as the manufacture could control the durability in the solution treatment process.

[JoshK]

[catbirdseat]

Hey, what better place to get in touch with one's Inner Nerd than the Gear Critic?

[snoboy]

Yeah because as everyone knows, zinc is the component of stainless steel which renders it stainless, so therefore it corrodes MUCH faster.

 

Actually it's what galvanized hardware is coated in. That too corrodes very quickly.

[Dru]

zinc is just another name for chromium, you can't fool me

[catbirdseat]

Yeah because as everyone knows, zinc is the component of stainless steel which renders it stainless, so therefore it corrodes MUCH faster.

Actually it's what galvanized hardware is coated in. That too corrodes very quickly.

The zinc coating is there to protect the steel it coats. It has a higher oxidation potential than iron and therefore acts as a sort of sacrificial anode.

 

They used to coat cans with tin. The tin provided a non-corroding barrier. The only problem is if the slightest nick penetrated the layer, the steel would corrode at the expense of the tin, because unlike zinc, tin is more "noble" than iron, that is iron has the higher oxidation potential.

 

So today "tin cans" are coated with epoxy not tin.