Durability thinning

In this paper we are concerned with the adhesive systems beneath thick rubber adherends. Unlike the technology for the paint industry, where the science of qualification testing for durable thin coatings has produced paints with 10, possibly 20 years life... 

The first decision in choosing a synthetic method for a PPV material is the way in which the material will be processed (Scheme 7.8). The precursor routes will enable the preparation of solvent-resistant and more durable thin films of PPV. This is particularly desirable if a multilayer device structure is required for the application. When choosing different precursor methods, it is important to assess the criteria of the application. Most precursor methods involve a thermal elimination step to convert the precursor polymer to the PPV material. Sul-fonium precursors require higher-temperature elimination compared to sulfinyl precursors. This makes the sulfinyl route compatible with deposition on plastic substrates. Another factor to consider in precursor methods is the nature of the elimination byproducts. Sulfonium precursors convert to PPV with elimination of acids, such as HCl or HBr, which has been shown to be detrimental to device performance. Xanthate and dithiocarbamate routes involve the elimination of amine and CO2 and CS2, respectively. 

Several processes currently exist that produce a thin-walled part with a fabric-covered surface. These processes, however, are limited by cost, low production volmnes, and durability of the part. A new process is described here that produces a high-quality and durable, thin-walled part using low-cost mass production techniques. 

Rhenium may be electroplated from solutions of ReO in sulfuric acid. To obtain a durable rhenium plate it is desirable to deposit the metal in thin layers, annealing at high temperature after each layer is appHed. 

Zinc or aluminum metal spray Sprayed metal coatings are porous and should be sealed after application by applying a sealer coat (i.e. a thin coat such as an etch primer) or a thinned version of the final coating system. Oil-based systems should not be used. Metal spray coatings can have excellent durability without overcoating with paint and, particularly for aggressive conditions it is preferable to leave them with sealer only. 

The biggest challenge to produce an ultra-thin (about 1 nm) overcoat is to make the coating free of pin-holes while maintaining the durability and tribological properties. In an HDD system, pin-holes can cause much more contaminants from all sources, such as outgas compounds from polymeric foam components, pressure sensitive adhesives, ionic residues from improperly cleaned components and ambient pollutants, which can be detrimental to the tribology and durability of the HDD. Therefore, efforts have been made mainly on the improvement of carbon film [4-7]. 

Sinha, S. K., Kawaguchi, M., Kato, T. et al., "Wear Durability Studies of Ultra-Thin Perfluoropolyether Lubricant on Magnetic Hard Disks, Tribol. Int., Vol. 36,2003, pp. 217-225. 

With respect to pH sensitivity and an adequate speed of response (time constant r = RC where R is the resistance of the measuring circuit and C the capacitance of the electrode), a certain degree of superficial swelling is needed however, the gel layer thus formed should remain thin in order to minimize the solubility of the glass and to guarantee sufficient durability of the electrode. In this respect lithium barium silicates offer an attractive compromise32. 

H. Suzuki, A. Hiratsuka, S. Sasaki, and I. Karu, Problems associated with the thin-film Ag AgCl reference electrode and a novel structure with improved durability. Sens. Actuators B. 46, 104-113 (1998). 

Although considerable research has been conducted with Pd-alloy foils, tubes, and thinner composite membranes, long-term durability and stability need to be further demonstrated, especially in the fuel reforming or WGS operating conditions, for acceptance of this technology in a commercial sector. Furthermore, mass-scale and cost-effective production of industrial-scale Pd-alloy thin-film composite membranes need to be demonstrated to be competitive in the hydrogen production and purification market. 

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