Chemical Vapor Deposition and Atomic Layer Deposition of Coatings for Mechanical Applications
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JTTEE5 19:510–516 DOI: 10.1007/s11666-009-9364-8 1059-9630/$19.00 ASM International
Chemical Vapor Deposition and Atomic Layer Deposition of Coatings for Mechanical Applications G.L. Doll, B.A. Mensah, H. Mohseni, and T.W. Scharf (Submitted April 27, 2009; in revised form July 1, 2009) Chemical vapor deposition (CVD) of films and coatings involves the chemical reaction of gases on or near a substrate surface. This deposition method can produce coatings with tightly controlled dimensions and novel structures. Furthermore, the non-line-of-sight-deposition capability of CVD facilitates the coating of complex-shaped mechanical components. Atomic layer deposition (ALD) is also a chemical gas phase thin film deposition technique, but unlike CVD, it utilizes ‘‘self-limiting’’ surface adsorption reactions (chemisorption) to control the thickness of deposited films. This article provides an overview of CVD and ALD, discusses some of their fundamental and practical aspects, and examines their advantages and limitations versus other vapor processing techniques such as physical vapor deposition in regard to coatings for mechanical applications. Finally, site-specific cross-sectional transmission electron microscopy inside the wear track of an ALD ZnO/ZrO2 8 bilayers nanolaminate coating determined the mechanisms that control the friction and wear.
Keywords
atomic layer deposition, chemical vapor deposition, protective coatings, tribology
1. Introduction Chemical vapor deposition (CVD) is a process employing chemical reactions of gases near substrates for the purposes of depositing various materials. In a typical CVD process, the substrate is exposed to one or more volatile precursors, which react and/or decompose on the surface to produce the deposited material. Usually, volatile byproducts are also produced, which are removed by gas flow through the reaction chamber. CVD is a very versatile process used in the production of coatings, powders, fibers, and monolithic parts. It is possible to produce with CVD almost any metallic or nonmetallic element, including carbon and silicon, as well as compounds such as carbides, nitrides, borides, oxides, intermetallics, and many others. This article is an invited paper selected from presentations at the 2009 International Thermal Spray Conference and has been expanded from the original presentation. It is simultaneously published in Expanding Thermal Spray Performance to New Markets and Applications: Proceedings of the 2009 International Thermal Spray Conference, Las Vegas, NV, USA, May 4-7, 2009, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain Montavon, Ed., ASM International, Materials Park, OH, 2009. G.L. Doll, The Timken Technology Center, Canton, OH; and B.A. Mensah, H. Mohseni, and T.W. Scharf, The University of North Texas, Denton, TX. Contact e-mail: gary.doll@ timken.com.
510—Volume 19(1-2) January 2010
CVD is widely used in the semiconductor industry, as part of the semiconductor device fabrication process, to deposit vari
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