Plasma enhanced aerosol–gel method: a new way of preparing ceramic coatings

Abstract

The sol-gel process is widely used for the production of powders, coatings and bulk materials. However, being a wet-chemical technique, it has certain limitations related to properties of aqueous colloidal solution, especially when applied as a coating. The most frequently used methods, such as dip-and spin-coating, are difficult to apply onto more complex substrates. In these cases, the aerosol-gel deposition method can be regarded as the solution of this problem. In the present article, a novel plasma enhanced aerosol-gel method of coatings production is presented. A novelty of this method is based on an integration of the aerosol-gel deposition of thin films and their low temperature plasma treatment. Owing to the above, all stages of the coatings production processsubstrate preparation, film deposition, and its plasma treatment, can be carried out in a single reactor. The design and operational scheme of such device is presented in this work. Using this device, thin coatings were first deposited on substrates and then plasma treated. The effect of deposition and plasma discharge conditions on morphology and chemical structure of the films has been studied. It was found that plasma treatment had a substantial influence on all the examined properties of the aerosol-gel deposited coatings.

Alumina Thin Films

“…Thus, droplet sizes and velocities can be chosen independently from each other. Recently, a home-built apparatus enabling coating production by the plasma-enhanced aerosol-gel method and using an aqueous alumina sol was described (Pietrzyk et al 2013a, b). This work clearly demonstrated the potential of this technique.…”

“…• Ultrasonic cleaning with acetone, isopropanol, ethanol, or special detergents (Truyen et al 2006) • Polishing of metals to obtain a smooth and definite surface allowing, e.g., detailed studies of diffusion of ions from substrates into the alumina coating (e.g., Velez and Quinson 2000) • Grinding (e.g., Wang and Zeng 2010), shot peening (Ruhi et al 2006), or sand blasting (Zhu et al 2006) of metals to yield a surface with defined roughness which could support the adhesion of the coating • Roughening by treatment with hot nitric acid (Singh et al 2015a) • The anodic oxidation of aluminum (Zemanová et al 1996) • Plasma etching leading to activation and cleaning of the metallic substrate surfaces (Pandey et al 2012;Pietrzyk et al 2013a, b), thus obtaining an excellent wetting by aqueous sols • Phosphating which could improve the adhesion of alumina layers on steel (Ruhi et al 2006) • Preoxidation to create a surface with a grainy morphology which is beneficial for the adhesion of the alumina coating (Cebollada and Garcia-Bordejé 2009) Deposition of Sols…”

Zirconia coatings deposited by novel plasma‐enhanced aerosol–gel method

“…The thermal treatment (annealing) was carried out in air at the temperature of 500 °C for 15 min. More details of the manufacturing process have been described elsewhere .…”

“…As can be seen, much effort is put into development of effective, versatile, and inexpensive methods of producing oxide coatings on various types of substrates. This paper presents the results of investigations on zirconium oxide (ZrO 2 ) coatings, manufactured using an unconventional and very comprehensive technique: plasmaenhanced aerosol-gel method [16]. Aerosol-gel deposition is an alteration of the typical sol-gel process and consists of wet aerosol generation and its deposition on the surface of substrates, leading to the formation of coating [17,18].…”

Frictional Behaviour of Composite Anodized Layers on Aluminium Alloys

“…There are many methods of producing anodized layers on aluminium alloys, from methods based on acid baths, through sol-gel technologies [ 9 , 10 ] to methods using high electrolytic treatment potentials, causing the presence of plasma (plasma electrolytic oxidation — PEO) or micro-arc discharges (micro arc oxidation — MAO) [ 11 , 12 , 13 , 14 , 15 , 16 ].…”