Novel Composite Coatings With 3D Coating Architectures for Tribological Applications Fabricated Using Semiconductor Patt
- PDF / 327,040 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 79 Downloads / 202 Views
Y3.9.1
NOVEL COMPOSITE COATINGS WITH 3D COATING ARCHITECTURES FOR TRIBOLOGICAL APPLICATIONS FABRICATED USING SEMICONDUCTOR PATTERNING PROCESSES James E. Krzanowski and Jose L. Endrino, Mechanical Engineering Department, University of New Hampshire, Durham, NH, 03824, and Karl Hirschman, Semiconductor and Microsystems Fabrication Laboratory, Rochester Institute of Technology, Rochester, NY 14623 ABSTRACT Composite coatings consisting of hard compounds and soft solid lubricant phases have been actively investigated as tribological coatings for reducing friction while improving wear resistance. In most cases structural modifications in these coatings have been achieved by either natural phase separation or sequential layer deposition. In this study, we explore the concept of creating a three-dimensional structure in a tribological composite coating by using well-established semiconductor patterning methods. Using photolithography, we have patterned the substrate surface with a regular array of micronsize islands. The substrate was then coated with various metal and carbide coatings, including Cr and TiC, using sputter deposition. The substrates were sonicated in a solvent to remove the photoresist islands leaving an array of holes. MoS2 was then deposited onto the substrates. A pin-on-disk friction and wear test was conducted on a TiC/MoS2 sample to examine the effects of these islands on wear morphology. The results showed that the MoS2-filled holes can act as lubricant reservoirs, and the areas of the sample coated with TiC/MoS2 provided better wear protection than areas coated with only MoS2. INTRODUCTION Composite coatings have the potential to provide new functional capabilities and a broader range of applications for thin film technologies. In our laboratory we have investigated nano-composite coatings consisting of a hard phase (a carbide, i.e., TiC, WC, HfC or SiC) and a soft lubricant phase, namely silver [1,2]. These coatings have exhibited good frictional behavior in vacuum environments in comparison to carbide coatings alone. Microstructural investigations of these coatings demonstrated the presence of two separate phases, the carbide and silver, which is possible due to the immiscibility of these phases. Other studies have examined thin films combining carbides and sulfides [3], and in some cases soft metals as well [4], for the purpose of providing low friction in multiple environments. However, in these coatings natural phase separation must occur, or the result may simply be an amorphous structure. Another route to obtaining separate phases is to deposit multilayers. However, this can lead to an “onion skin” effect where the hard layers peel away from the soft interlayers. Even if the layers remain intact, the geometry of multilayers is not optimal for tribological applications since alternating hard/soft layers will be uncovered during wear.
Y3.9.2
A more promising approach would be to artificially fabricate a structure with the soft lubricant phase embedded in a hard matrix. Voevodin and Zabinski
Data Loading...
