Over 2/3 of all molybdenum is used in alloys. Molybdenum use soared during World War I, when demand for tungsten (Wolfram) made tungsten scarce and high-strength steels were at a premium. Molybdenum is used to this day in high-strength alloys and in high-temperature steels. Special molybdenum-containing alloys, such as the Hastelloys, are notably heat-resistant and corrosion-resistant. Molybdenum is used in oil pipelines, aircraft and missile parts, and in filaments. Molybdenum finds use as a catalyst in the petroleum industry, especially in catalysts for removing organic sulfurs from petroleum products. Mo-99 is used in the nuclear isotope industry. Molybdenum oranges are pigments ranging from red-yellow to a bright red orange and used in paints, inks, plastics, and rubber compounds. Molybdenum disulfide is a good lubricant, especially at high temperatures. Molybdenum is also used in some electronic applications, as the conductive metal layers in thin-film transistors (TFTs).