Northwestern University researchers have shown that the hardness of transition metal nitrides can be increased substantially by depositing them in the form of superlattices with alternating thin layers of different nitrides. This invention consists of alternating layers of NbN and TiN, each only a few nm thick which are repeated approximately 1000 times to form a coating several microns thick. The rate of deposition is the same as TiN coatings. This opens up many applications to parts which cannot withstand high temperatures. In addition to cutting tools and machine parts, this film also has applications with ball bearings and roller bearings, as well as any metal parts which are subject to failure due to stress fatigue.
Stress is induced in the film as the film is grown.
Thus, some of the stress applied to the metal part is absorbed by the coating. Very good results have been achieved with this application, and work has shown that many more cycles are necessary to initiate fatigue in coated parts than with uncoated parts. Patent applications have been filed and Northwestern is seeking commercial partners with the resources and interest in order to achieve the full potential for this technology.