Chemical Vapor Deposition and Atomic Layer Deposition of Coatings for Mechanical Applications

Abstract

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/ZrO 2 8 bilayers nanolaminate coating determined the mechanisms that control the friction and wear.

Friction mechanism of zinc oxide films prepared by atomic layer deposition

“…The existence of this layer has been reported in a previous study. 23 They attributed this layer to be ZnO film 15 which is transformed from nanocrystal structure to amorphous structure. The transformation process may be the continuous decreasing the grain size to amorphous structure.…”

Reaction factorization for the dynamic analysis of atomic layer deposition kinetics

“…Photovoltaic applications include surface passivation layers on crystalline-Si cells Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/ces (Werner et al, 2011), as well as buffer and barrier layers in CIGS cells (Pimenoff, 2012;Holmqvist, 2013). ALD also finds use in numerous other applications such as nanostructured self-cleaning surfaces (Ng et al, 2008), protective coatings for spacecraft surfaces (Cooper et al, 2008) and glass displays (Pimenoff, 2012), as well as solid lubricant oxides used in various devices including MEMS (Kim et al, 2009) and automotive components (Doll et al, 2009). ALD modeling work falls into two main categories: empirical methods which require fitting parameters based on experiments (such as Holmqvist et al, 2012Holmqvist et al, , 2013, and first principles (or ab initio) methods which do not.…”

Role of atomic layer deposited solid lubricants in the sliding wear reduction of carbon–carbon composites at room and higher temperatures

“…Atomic layer deposition (ALD), which is a variant of the CVD technique, provides extremely conformal coatings of elements, binary and ternary compounds along with desired uniform thickness and conformality [8][9][10]. Processing of nanocomposite and nanolaminate coatings where each phase or layer has a specific contribution to the entire coating are additional attributes of the ALD technique.…”