AVS 49th International Symposium
    Thin Films Tuesday Sessions
       Session TF-TuM

Paper TF-TuM10
Synthesis and Characterization of Nanolayered TiB@sub 2@/TiC Coatings for Possible Elevated Temperature Applications

Tuesday, November 5, 2002, 11:20 am, Room C-101

Session: Mechanical Properties of Thin Films
Presenter: K.W. Lee, Northwestern University
Authors: K.W. Lee, Northwestern University
Y.-W. Chung, Northwestern University
L. Keer, Northwestern University
E. Ehmann, Northwestern University
Correspondent: Click to Email
Multilayered coatings composed of 3 nm TiB@sub 2@ and various individual layer thicknesses of TiC were synthesized using non-reactive dual-cathode magnetron sputtering techniques with substrate rotation on silicon (001), M2 steel and WC cutting inserts. The two coating materials were chosen for their high hardnesses, melting temperatures, and immiscibility. The goal of the research is to synthesize hard and chemically stable coatings that provide wear protection at high contact pressures and temperatures. Under appropriate deposition conditions, we obtained coatings with TiB@sub 2@(001) preferred orientation. Room-temperature hardness of these coatings approaches 60 GPa, far exceeding the rule-of-mixture value. High-resolution transmission electron microscopy and low-angle x-ray diffraction studies confirmed that the layer structure of these coatings was preserved after one-hour annealing in argon at 1000C. Scanning electron microscopy shows that coatings were rapidly oxidized at 800C in 25% oxygen/argon environment. Wear and durability tests on coated M2 steels and C6 WC cutting inserts demonstrated the improved room temperature tribological performance of these coatings under unlubricated conditions compared with standard coatings such as TiN. Actual dry machining on coated C3 WC cutting inserts was performed. Scanning electron microscopy and white-light interferometry were used to evaluate durability of these coatings before and after machining. These results will be presented and discussed in terms of the coating's potential in dry machining and high-temperature tribological applications.