Titanium possesses properties and characteristics which are extremely important to design engineers in a wide variety of fields, as it is basically immune to corrosion by salt water or marine atmospheres. It also offers a high degree of resistance to a broad range of acids, alkalis, natural waters and industrial chemicals.
The combination of high strength and low density results in exceptionally favorable strength-to-weight ratios for titanium-based alloys, superior to almost all other metals and vital in such diverse applications as aircraft, space vehicles, and surgical implants.
Superior Strength-to-Weight RatiosThe densities of titanium-based alloys range between .160 lb/in3 (4.43 gm/cm3) and .175 lb/in3 (4.85 gm/cm3). Yield strengths range from 25,000 psi (172 MPa) commercially pure (CP) Grade 1 to above 200,000 psi (1380 MPa) for heat treated beta alloys.
Titanium is immune to corrosion that often results from exposure to salt water or marine atmospheres. It also offers a high degree of resistance to a broad range of acids, alkalis, natural waters and industrial chemicals. Titanium offers exceptional resistance to erosion, cavitation or impingement. Titanium is greater than twenty times more resistant to erosion than standard copper-nickel alloys. Titanium and titanium alloys have proven to be technically superior, highly reliable and cost-effective in a wide variety of chemical, industrial, marine and aerospace applications. Titanium is utilized in many critical services due to its unique set of properties.
States of Titanium
Titanium can exist in two crystal forms: alpha which has a hexagonal close-packed crystal structure, and beta which has a body-centered cubic structure. In unalloyed titanium, the alpha phase is stable at all temperatures up to 1620°F. (880°C.) where it transforms to the beta phase. This temperature is known as the beta transus temperature. The beta phase is stable from 1620°F. (880°C.) to the melting point.
Discovery of Titanium
Titanium was discovered by William Gregor in 1791. It was first isolated and named after the powerful "Titans" of Greco-Roman mythology. Titanium is commonly associated with jet engines and airframes, but recent media attention has focused on fittings for prosthetic devices and artificial hearts.
To produce titanium, the basic ore (usually rutile (Ti02)) is converted to sponge in two distinct steps. First, Ti02, is mixed with coke or tar and charged in a chlorinator. Heat is applied and chlorine gas is passed through the charge. The titanium ore reacts with the chlorine to form TiCl4, titanium tetrachloride, and the oxygen is removed as C0 and C02. The resultant crude TiCl4, produced is a colorless liquid and is purified by continues fractional distillation. It is then reacted with either magnesium or sodium under an inert atmosphere. This results in metallic titanium sponge, and either magnesium or sodium chloride which is reprocessed and recycled.
Melting is the second step. Titanium is converted from sponge to ingot by first blending crushed sponge with the desired alloying elements to insure uniformity of composition, and then pressing into briquettes, which are welded together to form an electrode. The electrode is melted in a consumable electrode vacuum arc furnace where an arc is struck between the electrode and a layer of titanium in a water-cooled copper crucible. The molten titanium on the outer surface solidifies on contact with the cold wall, forming a shell or skull to contain the molten pool. The ingot is not poured, but solidifies under vacuum in the melting furnace. To insure homogeneity of the final ingot, a second or sometimes a third melting operation is applied.
Applications of Titanium
Titanium and its alloys have proven to be technically superior and cost-effective materials of constrLlction for a wide variety of aerospace, industrial, marine and commercial applications. In North America, approximately 70% of the titanium consumed is utilized for aerospace applications.
In the Industrial & aerospace industry, titanium is currently being utilized in: Gas Turbine Engines, Heat Transfer, DSA-Dimensional Stable Anodes, Desalination, Extraction of Electrowinning of Metals, Medical, Hydrocarbon Pressing, Marine Applications, Chemical Processing, Steam Turbines, Automotive, Airframes, Space Structures, FGD (Flue Gas Desulfurization), Nuclear Waste Storage, etc.
Recently, there has been a great deal of interest in titanium jewelry, as it possesses great strength, resistance to corrosion, and is highly bio-compatible. Some examples of titanium jewelry that have become very popular recently are: titanium engagement rings, titanium wedding bands, titanium earrings, and mens titanium rings. There are a number of prominent skilled jewelry designers working with this highly desirable metal to produce beautifully crafted jewelry.