Metal Products: Markets and Applications

Special Metals are used in different industrial applications like pyrotechnics, metallurgy, getter, hydrogen generation, as drying agent, for the battery industry and in organic synthesis.

Pyrotechnics

In powdered form, titanium and zirconium are corrosion-resistant to a remarkable degree and, in contrast to other commercial metal powders, they are also stable for long periods of time when kept under regular storage conditions. Coupled with this stability is a high degree of chemical reactivity at a slightly elevated temperature. Combustion in air is rapid, and accompanied by the evolution of much heat and light. In mixture with an oxidizing agent (e.g. KClO4, Ba(ClO4)2) titanium and zirconium form a very reliable composition that ignites easily and produces a high energy output, along with the discharge of numerous hot particles. Such behavior makes titanium and zirconium powders very useful as fuel in initiation elements. Titanium and zirconium constitute a heat source for squibs and ignition devices in a variety of uses, including automotive airbag igniters and inflators.

In some pyrotechnic applications titanium and zirconium are introduced in the shape of their respective hydrides, TiH2 and ZrH2.

A Zr/Ni alloy is used as a fuel in delay compositions because of its slow and reliable burning characteristics. In addition, compositions containing Zr/Ni alloys and an oxidizing agent react without producing gas.

Metallurgy

Albemarle's metal products are most suitable for special alloying purposes. The addition of zirconium or ZrH2 to steel alloys will improve the high temperature stability of such alloys, whereas an admixture of barium metal will increase the strength of Pb alloys. Barium metal has deoxidizing and reducing properties as well; these properties are exploited in the metal-refining industry. Titanium metal powder is employed as a raw material for the production of Ti parts by metal-injection molding. Titanium has an influence on magnetic hysteresis. Our titanium metal powders and TiH2 powders are therefore used in the production of AlNiCo magnets. Ti metal powder is also utilized as a deoxidizing agent in powder metallurgy, for reactive solders and brazes (e.g. joining of glass or ceramics to metals).

Besides serving alloying purposes, Ti/Cu alloys are also useful for covering non-metals with a metallization coating.

At high temperatures, calcium hydride reduces refractory oxides to the metals.

Getter

Getters are widely used as pumps in high-vacuum systems and tubes and for the purification of gases. Getters are classified in two categories:

Evaporable getters

Evaporable getters are used in order to create and maintain a high vacuum in cathode ray tubes (CRTs) for television sets and computer monitors. Other current applications of evaporable getters include low pressure discharge lamps and fluorescent displays. Our barium is particularly well suited as evaporable getter material because it has a low vapor pressure at the working temperatures of the CRTs, low pressure discharge lamps, and fluorescent displays. Barium is very reactive towards undesired gases, such as oxygen, nitrogen, hydrogen, carbon dioxide, water vapor, even removing residues of inert gases by inclusion.

Non-evaporable getters

Non-evaporable getters are primarily used for incandescent lamps, high-pressure discharge lamps, metal-halide lamps, and other industrial applications. These getters are also used to maintain the necessary vacuum in metal-vacuum applications. When heated, metal powders such as titanium and zirconium, are capable of directly absorbing gaseous impurities present within evacuated or inert gas volumes, without prior evaporation.

Battery Industry

The main advantage for the use of lithium metal in batteries is its high electrochemical potential of -3.024 V, combined with its low equivalent weight. Hence, it has a high electrochemical equivalent of 3.86 Ah/g. The gravimetric energy density of lithium batteries is up to 5 times higher than that of alkaline batteries. Other important advantages of lithium batteries consist in their low self-discharge rates of about 1% per year, and wide ringe of working-temperatures from -60 °C to +100 °C. Conventional alkaline batteries do not work in extremely low-temperature applications.

Organic Synthesis

The partial reduction of benzene derivatives to 1,4-cyclohexadienes as the main products in the presence of a proton source is known as Birch reduction. Usually alcohols (EtOH, tert.-BuOH), amines, H2O, or NH4Cl are used as proton sources. Electron-withdrawing substituents enhance the reaction, and the presence of alcohols is therefore not always necessary as compared to substrates with electron-releasing substituents. The use of lithium in the partial reduction of benzene derivatives is preferred in case of less reactive systems. More powerful but less selective reductions of aromatic systems can be done with lithium in primary amines as solvents (Benkeser reaction). Due to the higher solvation of lithium, the amines most commonly used are ethylamine and ethylenediamine. The higher reactivity can be explained by the higher reaction temperatures compared to liquid ammonia. Another advantage is also the better solubility of many organic compounds in amines relative to ammonia. Reductions with sodium dissolved in amines are not feasible due to the very low solubility of sodium in these solvents.