Zinc oxide technological applications

Despite of 150-year s history of vulcanization process, it is impossible to consider that fundamental and applied researches in direction of vulcanization systems perfection are completed. For today one of the ways of rubbers properties improvement is the synthesis and application of the new chemicals-additives, including, vulcanization active, that is connected, first of all, with reduction of global stocks of zinc ores as basic raw material for reception of traditional activator - zinc oxide. Besides, modem increase of industrial potential and the accumulation of big quantity wastes derivate the problems of ecological character, which require the emergency decision. Therefore creation of resourcesaving technologies of the new compounds reception from products of secondary raw material processing has paramount importance. 

Zinc oxide is a very old technological material. Already in the Bronze Age it was produced as a byproduct of copper ore smelting and used for healing of wounds. Early in history it was also used for the production of brass (Cu-Zn alloy). This was the major application of ZnO for many centuries before metallic zinc replaced the oxide [149]. With the start of the industrial age in the middle of the nineteenth century, ZnO was used in white paints (chinese white), in rubber for the activation of the vulcanization process and in porcelain enamels. In the following a number of existing and emerging electronic applications of ZnO are briefly described. 

Curatives. Consistent with dry type technology, metal oxides have three fimctions in a latex compound. Zinc oxide participates in the curing reaction. Zinc oxide is an effective acid scavenger. In applications where the substrate is not acidic, zinc oxide is not needed. Such substrates include chrysoltile asbestos gaskets or the hydraulic cement in elasticized concrete. 

The development of a methanol fuel processor prototype was described by Hdhlein et al. [556]. The methanol burner dedicated to this system has been described in Section 7.5. Later, a complete methanol reformer was developed by Wiese et al. [154]. It was operated at a S/C ratio of 1.5 and a pressure of 3.8 bar. The feed was evaporated and superheated to 280 °C. The reformer itself consisted of four pairs of concentric stainless steel tubes. In the annular gap between the tubes, steam was condensed at 65 bar and 280 °C for the heat supply, while the inner tube carried the copper/zinc oxide catalyst for steam reforming. The reformer response time to a load change from 40 to 100% was about 25 s, which was mainly attributed to the slow dynamics of the dosing pump. Because the dynamic behaviour of the reformer was too slow for an automotive drive system, which had been the target appUcation of the work, an additional gas storage system was considered. To improve the system dynamics, Peters et al. considered the application of microreactor technology for a subsequent improved fuel processor [569]. 

The so-called inverted structure is favorable for the application of practical printing technologies and to ensure long-term durability. A typical inverted device structure consists of indium tin oxide (ITO) as a cathode and zinc oxide (ZnO) as an electron transport layer, P3HT PCBM as a photoactive layer, PEDOT PSS as a hole transport layer and a silver anode, which are all printable. 

An application of thick-film printing technology for the fabrication of a Zn-Mn02 alkaline batteries [342] was also described. The mechanism of the capacity fade of rechargeable alkaline zinc-manganese cell was studied and discussed [343]. Zinc electrode with addition of several oxides (HgO, Sb203) for alkaline Zn-Mn02 cells [344] was also studied. 

Refs. [i] Habashi F (ed) (1998) Alloys, preparation, properties, applications. Wiley-VCH, Weinheim [ii] Matucha KH (1996) Structure and properties of nonferrous alloys. In Matucha KH (ed) Materials science and technology. A comprehensive treatment, vol 8. VCH, Weinheim [iii] Fleischer A, Lander J, (eds) (1971) Zinc-silver oxide batteries. Wiley, Chichester [iv] Hicks HG (1960) The radiochemistry of zinc. McGraw-Hill, New York [v] Linden D, Thomas BR (eds) (2002) Handbook of batteries, 3rd edn McGraw-Hill, New York [vi] Pauling L (1970) General chemistry, 3rd edn. Freeman, San Francisco [vii] Lide DR (ed) (2003-2004) Handbook of chemistry and physics, 84th edn. CRC Press, Boca Raton [viii] http //periodic.lanl.gov/elements/30.html... 

ZnO and CdO are wide bandgap semiconductors, and these materials may serve as transparent conducting oxides for photovoltaics and flat panel displays. ZnO may also have applications in blue and ultraviolet fight emitting devices and laser diodes. Thin films of zinc and cadmium chalcogenides also have many potential applications. The technological goals of these materials have been smnmarized in several recent... 

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