Conductive coating deposition

In a more recent work, Michalik and Rohwerder (2005) stndied the self-healing effect in defected PPy conducting coatings deposited on gold, using the scarming Kelvin probe technique. They concluded that, in thick (1 pm) PPy films doped with tosylate anions, the transport of small cations is fast and responsible for polymer reduction and delamination. According to this study, the cationic transport... 

Another growing apphcation that overlaps the electrically functional area is the use of transparent conductive coatings or tin oxide, indium—tin oxide, and similar materials in photovoltaic solar ceUs and various optic electronic apphcations (see Photovoltaic cells). These coatings are deposited by PVD techniques as weU as by spray pyrolysis, which is a CVD process. 

Deposition of thin films is used to change the surface properties of the base material, the substrate. For example, optical properties such as transmission or reflection of lenses and other glass products, can be adjusted by applying suitable coating layer systems. Metal coatings on plastic web produce conductive coatings for film capacitors. Polymer layers on metals enhance the corrosion resistance of the substrate. 

The electroforming process is used for the production of single or low numbers of cavities, as opposed to others requiring many cavities. The process deposits metal on a master in a plating bath. Many proprietary processes exist. The master can be constructed of such materials as plastic, reinforced plastic, plaster, or concrete that is coated with silver to provide a conductive coating. The coated master is placed in a plating tank and nickel or nickel-cobalt is deposited to the desired thickness of up to about 0.64 cm (0.25 in.). With this method, a hardness of up to 46 RC is obtainable. To reinforce the nickel shell it is backed up with different materials (copper, plastic, etc.) to meet different applications. A sufficient thickness of copper allows for machining a flat surface to enable the cavity to be mounted into a cavity pocket. 

Highly conductive coatings (i.e., all metals and most semiconductors) must, of course, be electrically insulated from IDT electrodes in order to prevent shorting this is not a concern with the planar electrodes of TSM quartz resonators. This is readily accomplished by either deposition using a line-of-sight technique. 

Fig. 11 SEM cross-section of a CCVD-deposited LSM conductive coating, showing the open columnar structure over a dense YSZ layer on a sapphire substrate.

Taylor et al.8 were the first to report an electrochemical method for preparation of MEAs for PEMFCs. In their technique, Pt was electrochemically reduced and deposited at the electrode membrane interface, where it was actually utilized as an electrocatalyst. Nation, which is an ion exchange polymer membrane, is first coated on a noncatalyzed carbon support. The Nafion-coated carbon support is then immersed into a commercial acidic Pt plating solution for electrodeposition. Application of a cathodic potential results in diffusion of platinum cations through the active Nation layer. The migrated platinum species are reduced and form Pt particle at the electrode/membrane interface only on the sites which are both electronically and ionically conductive. The deposition of Pt particles merely at the electrode/membrane interface maximizes the Pt utilization. The Pt particles of 2-3.5 nm and a Pt loading of less than 0.05 mg cm-2 were obtained employing this technique.8 The limitation of this method is the difficulty of the diffusion of platinum... 

Significant variants exist electrostatic charge patterns may be transferred instead of powders, charged colloids dispersed in dielectric liquids may be used as developers, images may be formed directly on photo-conductive coated paper or even by the deposition of electrically photosensitive particles (3.). We shall return to some of these alternatives later--after describing the roles of interfaces in conventional dry transfer xerography. 

Irregular surface coatings such as discontinuous oxide coatings, deposits of more noble metals (e g., copper on iron), and deposits of conducting materials, such as graphite, resulting from fabrication processes... 

Exploratory studies were conducted to deposit coatings consisting of CaTi2Zr2 (P04)6 and Ca Zr4(P04)6 (Reisel, 1996) as well as CaTiZr3(P04)6 (Schneider, Heimann and Berger, 1998, 2001 Heimann, 2006b). 

A comparative study of biological stability and osteoconductivity of hydroxyapatite coatings deposited by pulsed laser deposition (PLD) and APS was conducted... 

Chemically deposited non stoichiometric cuprous sulfide films (Cui.gS) have been used as conducting layers as reported by Grozdanov et al. [50]. The films, deposited at 40 °C, present a resistivity of 2.10 Q.cm. In addition they present optical transmission values between 50 and 70% in the visible range for a 0.12 pm thick film. These properties have been used for ohmic contacts to ferroelectric films and transparent conducting coatings on polymers. These films can also be used as chemical sensors for Cu + ions. Note that due to the low deposition temperature polymer substrates can be used [61]. 

Most of the transparent conductive coatings are produced by vacuum evaporation and sputtering. Other techniques are hot spraying and chemical vapour deposition, as manufactured by Corning, Pittsburgh Plate Glass (PPG) and others [162]. 

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