Known for low density, high strength, corrosion resistance and conductive properties, titanium metal and titanium alloys are up to 45% lighter than steel of comparable strength and twice as strong as aluminum, copper or brass. These benefits are weighed against the cost and difficulty of acquiring and processing this extremely hard substance. The forming of foils, however, is a pre-process that adds ductility to the long list of desirable attributes of the materials and renders titanium easily fabricated. This allows the use of titanium foil in such diverse fields as machine building, aerospace, aircraft, shipping, transit, automotive, sport, medical and power generation.
Foil is used both in the creation of final products as well as in finishing as it is easily molded and adheres to pre-existing forms for added protection, strength and resistance to corrosive materials and environmental wear. Generally available in rolled coils, many manufacturers prefer to buy titanium in this stock form as it is regulated and allows for predictable shipping and processing requirements. Common processes used to create titanium foils include continuous cast stripping, rolling and pressing of cast ingots.
The production of titanium foil necessitates the extraction of titanium from mineral deposits, most often utilizing the Kroll Method. This involves forming titanium tetrachloride through fractional distillation. The substance is then reduced to useable metallic titanium using magnesium. The resulting highly porous yield is referred to as a sponge. Foils are formed when this sponge, or bulk, is melted and then pressed, rolled and cut into predetermined or customized titanium sheets which are sold by the square inch or square foot. Used in such varied applications as capacitor and converter foils, camera shutters, and wind screens, foils offer a wide range of thickness.
Titanium can be pressed as thin as 0.001″. Thicker foils can be up to 0.009″ thick, but thicker qualifies as a sheet or titanium plate rather than a foil. Titanium foils are produced using either raw materials provided by the customer or using the mills own resources. Some mills will not manufacture foils from outside titanium sources without grade certification and mechanical property testing to ensure that they are outfitted with the proper equipment. Titanium grade is a significant consideration for manufacturers as processing high purity titanium is extremely energy intensive and ductility varies among the many grades.