High Performance Automotive MaterialsLarry Paul - ThyssenKrupp
There is a great desire by the automotive industry to downsize engines and maintain performance. Currently a leading technology to accomplish this is the use of turbochargers. This has opened a market for some rather high temperature alloys in the automotive market.
First just a little about ThyssenKrupp. It is headquartered in Germany and is #2 in the world market for Ni Alloys. The company makes standard alloys, Superalloys, and Physical Property Alloys. It also is making Titanium Alloys. Product forms include forgings, plate, strip, bar and wire. Depending on product bottom pouring electric induction furnaces, vacuum induction furnaces and vacuum arc furnaces are employed.
Downsizing of automobile engines is a reality in much of the world which has very high emission standards. The US is way behind in this area. The terms Ecoflex and Ecotech are now programs of General Motors to deal with this issue. At present the turbocharger is the most widely accepted method of reducing engine impact while maintaining performance. The turbocharger uses exhaust gas to run a turbine which compresses incoming fuel. High temperature alloys are required for both blades and gaskets in the turbocharger due to the high temperatures involved. Alloys such as Nicrofer 5120, Alloy C283, Nicrofer 6025 HT, Alloy 602CA, and Nicrofer 6025 HT are finding use in such applications.
Another area requiring higher temperature is in spark plug wire. Nickle based wire such as 572, Nicrofer 7615 and NiAlSiY are proving useful in this application.
The exhaust system is now moving closer and closer to the engine in new designs, increasing the need for higher temperature materials. Specifically Lambda Probes (which checks oxygen levels for the engine's computer) require High Temperature alloy sheaths for protection. For this application alloys with high Cr and Al are used to obtain both high temperature functionality and high resistance to oxidation.
Bellows and Decouplers are required in connection with turbocharges to handle the high temperature exhaust gasses. These require alloys which are lean in Nickle, high in Chrome and Molybdenum to make them more resistant to chloride corrosion. Alloy 625 seems to have found a strong niche here.
Diesel injectors are now extremely fast acting using piezoelectric devices for activation. Since these devices are ceramic they need a very precise thermal expansion match such as specialty alloy 36 (64 Ni 36 Fe) to reduce stress on the piezo elements.
These are just a few examples of how High Temperature Superalloys and Specialty alloys are finding their way into the automotive market.