Lead compounds, coatings industry

Catalysts were expensive, however, so the petroleum industry did not solve the problem of cheap, lead-free, knock-free gasoline until the 1970s, after General Motors adopted the catalytic converter. Lead compounds inactivate the catalysts, and sophisticated catalytic cracking techniques had to be developed to replace the fuel additive. Ironically, an even more difficult job was finding a substitute for the protective coating that tetraethyl lead formed on exhaust valve seats not even newly developed, extremely hard materials prevent wear and tear on them as well as tetraethyl lead did. 

Solder -antimony m [ANTIMONY AND ANTIMONY ALLOYS] (Vol 3) -arsenic m [ARSENIC AND ARSENIC ALLOYS] (Vol 3) -lead m [LEAD COMPOUNDS - INDUSTRIAL TOXICOLOGY] (Vol 15) -masks as electronics coatings [ELECTRONICS, COATINGS] (Vol 9) -as metallic coatings [METALLIC COATINGS - SURVEY] (Vol 16) -thin films of [IHIN FILMS - FILM FORMATION TECHNIQUES] (Vol 23) -tin alloys as [TIN AND TIN ALLOYS] (Vol 24) -use of selenium m [SELENIUMAND SELENIUM COMPOUNDS] (Vol 21)... 

Tetravalent silicon is the only structural feature in all silicon sources in nature, e.g. the silicates and silica even elemental silicon exhibits tetravalency. Tetravalent silicon is considered to be an ana-logon to its group 14 homologue carbon and in fact there are a lot of similarities in the chemistry of both elements. Furthermore, silicon is tetravalent in all industrially used compounds, e.g. silanes, polymers, ceramics, and fumed silica. Also the reactions of subvalent and / or low coordinated silicon compounds normally lead back to tetravalent silicon species. It is therefore not surprising that more than 90% of the relevant literature deals with tetravalent silicon. The following examples illustrate why "ordinary" tetravalent silicon is still an attractive field for research activities Simple and small tetravalent silicon compounds - sometimes very difficult to synthesize - are used by theoreticians and preparative chemists as model compounds for a deeper insight into structural features and the study of the reactivity influenced by different substituents on the silicon center. As an example for industrial applications, the chemical vapor decomposition (CVD) of appropriate silicon precursors to produce thin ceramic coatings on various substrates may be mentioned. 

In alkaline electrolyzers, Ni is the only elemental cathode that can be used. It is generally considered as a fairly good electrocatalyst, but in facts it exhibits two shortcomings (i) its activity decreases with time [cf. the AVtterm in Equation (7.16)] especially under conditions of intermittent electrolysis and (ii) shutdown of industrial cells (for maintenance) leads to Ni dissolution at the cathode since this electrode is driven to more positive potentials by short-circuit with the anode. These shortcomings can be alleviated if Ni cathodes are activated, that is, if they are coated with a thin layer of more active and more stable materials. Activation has been attempted with a variety of materials from sulfides to oxides, from alloys to intermetallic compounds. 

Hot-melt extrusion is one of the most widely applied processing techniques in the plastics industry. Joseph Brama invented the extrusion process for the manufacturing of lead pipes at the end of the eighteenth century. However, hot-melt extrusion was not applied in the plastics industry until the mid-nineteenth century, when it was first introduced into a wire insulation polymer coating process. Today, hot-melt extrusion is not only widely applied in the production of polymeric articles but also in polymer production and compounding. Currently, more than half of all plastic products, including plastic bags, sheets, and pipes, are manufactured by this process. ... 

Lead and its compounds are widely used throughout industry. They are found in lead acid storage batteries, paints, sheet metal, bearings, solder, piping, and ammunition. Lead arsenate is used in insecticides and herbicides. Lead chromate is used as a yellow pigment in paints, rubber, plastics, and ceramic coatings. House paints must have less than 0.05% lead. 

---