Refractory metals aluminum

Hoch M (1988) The critical point data of refractory metals, aluminum oxide and uranium dioxide using the Hoch- Arpshofen method. J Nucl Mater 152 289-294... 

Zarzycki G (1957) The critical point data of refractory metals, aluminum oxide and uranium dioxide using the Hoch- Arpshofen method. J Phys Radium 18 65A-69A. Study of molten salts by x- ray diffraction. II. Structure in the liquid state of the chlorides LiCl, NaCl, KCl, BaCl2, and of the fluoride Cap2. General considerations on the structure of molten halides (1958) J Phys Radium 19 13A-19A... 

Chlorination. In some instances, the extraction of a pure metal is more easily achieved from the chloride than from the oxide. Oxide ores and concentrates react at high temperature with chlorine gas to produce volatile chlorides of the metal. This reaction can be used for common nonferrous metals, but it is particularly useful for refractory metals like titanium (see Titanium and titanium alloys) and 2irconium (see Zirconium and zirconium compounds), and for reactive metals like aluminum. 

The nitrides reviewed here are those which are commonly produced by CVD. They are similar in many respects to the carbides reviewed in Ch. 9. They are hard and wear-resistant and have high melting points and good chemical resistance. They include several of the refractory-metal (interstitial) nitrides and three covalent nitrides those of aluminum, boron, and silicon. Most are important industrial materials and have a number of major applications in cutting and grinding tools, wear surfaces, semiconductors, and others. Their development is proceeding at a rapid pace and CVD is a major factor in their growth. 

The trend in CVD metallization is toward greater use of copper, and the refractory metals and their silicides in multilayered metallization designs, typically consisting of metal-silicide contacts, refractory-metal barriers, and copper or an aluminum alloy as the principal interconnect metal. Other metals deposited by CVD such as chromium, molybdenum, platinum, rhodium, and ruthenium are also actively considered for use as conductors. 

Aluminum and aluminum alloys Copper and copper alloys Rare-earth and rare-earth-like metals and alloys Low-melting metals and alloys Miscellaneous nonferrous metals and alloys Nickel and nickel alloys Precious metals and alloys Reactive and refractory metals and alloys... 

The aluminum reduction of a refractory metal oxide invariably yields a metal product containing significant amounts of residual aluminum and oxygen, represented usually as a metal-aluminum-oxygen alloy. When the metal contains aluminum in addition to oxygen, a number of reactions can occur during pyrovacuum treatments. These are ... 

After aluminum, the refractory metals and their silicides have been the subject of the most extensive efforts in metal etching (150-155). Because the fluorides and chlorides of the transition metals and silicon are volatile in the presence of ion bombardment, etch studies have been performed with nearly... 

In the present chapter, we will review the nature of plasma-enhanced CVD (PECVD) films for a variety of applications. We will look at dielectrics (silicon nitride, silicon dioxide), semiconductors (polysilicon, epi silicon) and metals (refractory metals, refractory metal silicides, aluminum). There are many other important films (i.e., amorphous silicon for solar cells and TiN for tool harden-... 

The next three chapters review the deposition of thermally-induced dielectric films (Chapter 3) and metallic conducting films (Chapter 4), as well as plasma-enhanced films of either type (Chapter 5). The many chemical systems employed to create these films are considered, and the nature of the resulting films is presented. Films studied are silicon dioxide, silicon nitride, polysilicon, epitaxial silicon, the refractory metal silicides, tungsten and aluminum. 

In this section we will show that air- and water-stable ionic liquids can be used for the electrodeposition of highly reactive elements which cannot be obtained from aqueous solutions, such as aluminum, magnesium and lithium, and also refractory metals such as tantalum and titanium. Although these liquids are no longer air-and water-stable when AICI3, TaFs, TiCU and others are dissolved, quite interesting results can be obtained in these liquids. 

Outside of these seemingly niche markets the main driving force for using non-aqueous electrolytes has been the desire to deposit refractory metals such as Ti, Al and W. These metals have numerous applications, especially in the aerospace industry, and at present they are deposited primarily by PVD and CVD techniques. The difficulty with using these metals is the affinity of the metals to form oxides. All of the metal chlorides hydrolyze rapidly with traces of moisture to yield HC1 gas and hence any potential process will have to be carried out in strict anhydrous conditions. Therefore the factor most seriously limiting the commercialization of aluminum deposition is the engineering of a practical plating cell. 

Aluminum. Aluminum, as A O, is a nuisance dust. There may be instances where elemental composition of the nuisance dustis desired therefore, Al is included in P CAM 173. Aluminum is difficult to dissolve in nitric acid and should be treated as a refractory metal. Since the nitrous oxide/acetylene flame is subject to many interferences, both 1000 ppm Cs and 1000 ppm La, a releasing agent, should be added to the final solution. 

They are normally cast in the form of brick and are sometimes bonded to assure stability. The outstanding property of these materials is their ability to act as insulators. The most important are fireclay (aluminum silicates), silica, high alumina (70-80% ALjOj), mullite (clay-sand), magnesite (chiefly MgO), dolomite (CaO-MgO), forsterite (MgO-sand), carbon, chrome ore-magnesite, zirconia, and silicon carbide. (2) Characterizing the ability to withstand extremely high temperature, e.g., tungsten and tantalum are refractory metals, clay is a refractory earth, ceramics are refractory mixtures. 

Use Metallurgical additive, high-temperature electrical conductor, refractory, cermet component, coatings resistant to attack by molten metals, aluminum manufacture, super alloys. 

Foils from refractory metals (Ti, Mo, W, etc.) of 20 to 500 pm in thickness were used for the cavitation study in melts of aluminum and its alloys. Specimens of the foil in stiff frames were situated into the melt under a radiator in such a way that the axis of the waveguide-radiating system passes through the plane of the frame... 

Metals are important resources and have a wide range of applications. Metals are often extracted from ores. Once the ore is mined, the metals must be extracted, usually by chemical or electrolytic reduction. Pyrometallurgy uses high temperatures to convert ore into raw metals, while hydrometalluigy employs aqueous chemistry for the same purpose. The methods used depend on the metal and their contaminants. Most metals are obtained by hydrometallurgical processes such as aqueous acids or alkalis are predominantly used to dissolve the metal oxides, sulfides, or silicates. Electrowinning and solvent extraction are frequently used to recover and concentrate the metals. A limited number of high-temperature molten salts have also been used for the recovery of refractory metals, such as titanium and aluminum, from their ores... 

J.W. Lee, and J.G. Duh, High-temperature MgO-C-Al refractories-metal reactions in high-aluminum-content alloy steels. J. Mater. Res. 18(8), 1950-1959 (2003). 

---