Originally Posted by George K Lee
So do many engine manufacturers use something else?
It's a new story to me, but high-temperature turbine production has been accelerating steadily for decades, and you'd have thought it would have been a flagged issue.
It is true, rhenium has been used to add both temperature capability and improve high temperature strength in turbine airfoils for decades. But as events would have it, the availability of rhenium was an issue and worrisome but always available and manageable.
First it was used in petroleum cracking towers, those used to produce unleaded gasoline. It replaced 10% of the platinum catalyst at one tenth the cost of the platinum it replaced. That usage didn't affect the aircraft engine turbine market in the long run as the petroleum folks found a way to clean and reuse the rhenium after it ran through a cracking tower's catalyst total life cycle.
P&W were the first to use a substantial amount of rhenium in their proprietary high temperature alloys for turbine blades. However, that amount dropped off as their commercial engine business went down when GE's commercial business increased. GE entered the rhenium usage marketplace with the F110 engine competing against P&W's F100 engine. Then after settling a patent dispute with P&W, GE began to use it in commercial engines as well. The availability of rhenium remained acceptable because the price of copper rose and copper production increased as well as the supply of rhenium which mainly comes from a molybdenum producer in Chile but some from the US producer as well. Both GE and P&W maintained reserves in case the copper market changed. A typical high temperature superalloy contains 3% rhenium.
Then Rolls Royce entered the rhenium market on their newer commercial and military engine alloys. Everything was okay in the beginning because the Chinese were buying copper and molybdenum in huge quantities enhancing the availability of rhenium. Then a problem occurred, the Chinese copper and molybdenum market slowed and it became apparent there may not be enough rhenium available for all the new turbine airfoil production, excluding Russia from the picture. So what is the solution?
Develop new superalloys that have the same capability as rhenium containing alloys which do not contain rhenium or have a reduced rhenium content. I know of one engine producer that has done this with some success. Also, reclamation programs have been established with engine customers to reclaim used parts and recover the rhenium through remelting the recovered parts back into alloy for new rhenium alloy part manufacturing.
There is a lot at play when the material is a byproduct of a byproduct as is the case with rhenium.