Cobalt and Cobalt Alloys

Cobalt and cobalt alloys are non-ferrous metals with high strength and toughness, excellent corrosion and oxidation resistance, and high-temperature strength. A cobalt alloy is a ferromagnetic, non-ferrous composite that contains cobalt, a metallic element with a higher melting point than nickel or iron alloys. Consequently, cobalt and cobalt alloys can absorb stress to a higher absolute temperature than other metals. Cobalt and cobalt alloys also provide excellent thermal fatigue resistance and can be welded or used in electroplating. Metals with high chromium content are used in gas-turbine atmospheres because of resistance to corrosion at high temperatures. In addition to cobalt-base alloys, other commonly used turbine metals include aluminum alloys, stainless steels, high strength steels, nickel base alloys, and titanium alloys.

Selecting cobalt and cobalt alloys requires an understanding of chemical compositions and characteristics Cobalt (Co) is a lustrous, silvery-blue, hard metal found in cobaltite, smaltite, and erythrite minerals. Chromium (Cr) is a blue-white, hard metal found mainly in ore chromites. Chromium is used to harden steel and in the manufacture of stainless steels and steel alloys. Molybdenum (Mo) is a silver-white metal that is relatively soft in its pure form. The main source of molybdenum is ore molybdenite. Typically, molybdenum (moly) is used as an alloying agent to increase the hardness and toughness of quenched, tempered steels. Molybdenum is also used in some nickel-based alloys that are heat-resistant and corrosion-resistant to chemical solutions. Cobalt chrome moly or Co-Cr-Mo is a cobalt alloy that provides increased hardenability and toughness. Co-Cr-Mo can resist abrasion and corrosion, and is often used in hip and knee replacement systems.

Cobalt and cobalt alloys meet the compositional standards of the Unified Numbering System (UNS), a specification established by the American Society for Testing and Materials (ASTM), the Society of Automotive Engineers (SAE), and metal trade associations such as the American Iron and Steel Institute (AISI) and the Aluminum Association (AA). The UNS assigns metals and alloys a lettered prefix and a five-digit number. Other standards for cobalt and cobalt alloys include European Norm (EN) and U.S. military specifications (MIL-SPEC). QQ and QQS prefixes are used to designate specific MIL-SPEC metals.

• Cobalt-based Superalloys
  Cobalt-based super alloys are non-ferrous magnetic alloys with high strength and toughness, excellent corrosion and oxidation resistance, and high temperature strength – all key qualities for a...
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• Magnetostriction: Basic Physical Elements
  Magnetostriction is a phenomenon only found in ferromagnetic materials such as iron, nickel, cobalt and their alloys. The magnetostrictive principle is based on certain agnetomechanical properties of...
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• Alloy Steel
  Steels that contain specified amounts of alloying elements -- other than carbon and the commonly accepted amounts of manganese, copper, silicon, sulfur, and phosphorus -- are known as alloy steels....
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