References
—http://www.eng.fsu.edu/~castral
—http://www.enginebuildermag.com/Article/1171/valve_selection_hot_valve_materials_for_hot_engines.aspx
—https://supportcentral.ge.com/products/sup_products.asp?prod_id=184232
—http://www.machinerylubrication.com/Read/775/reciprocating-compressor
—http://www.machinerylubrication.com/Read/1348/acid-lubricant-piston-rods
—http://www.electro-coatings.com/hard-chrome-wear-resistance.php
—http://www.prepol.com/Perlast.html
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