Deoxiding of metals

Normatov, I., Shermatov, N. and Mirsaidov, U.M. (1990) About particularities of influence of atomic hydrogen on plazmochemical deoxidation of metal chlorides, Physics and Chemistry of materials processing, No. 3, 140-141. 

Discovered in 1997 at the Cambridge University by Farthing, Fray, and Chen (FFC) and developed in the industry from 2001, this recent process involves a molten salt electrolyzer with a cathodic basket containing metal oxides and a carbon anode [26]. The cell polarization promotes the deoxidation of metal oxides by... 

Copper and tin phosphides are used as deoxidants in the production of the respective metals, to increase the tensile strength and corrosion resistance in phosphor bronze [12767-50-9] and as components of brazing solders (see Solders and brazing alloys). Phosphor bronze is an alloy of copper and 1.25—11 wt % tin. As tin may be completely oxidized in a copper alloy in the form of stannic oxide, 0.03—0.35 wt % phosphoms is added to deoxidize the alloy. Phosphor copper [12643-19-5] is prepared by the addition of phosphoms to molten copper. Phosphor tin [66579-64-4] 2.5—3 wt % P, is made for the deoxidation of bronzes and German silver. 

In metallurgical practice, sodium uses include preparation of powdered metals removal of antimony, tin, and sulfur from lead modification of the stmcture of siHcon—aluminum alloys appHcation of diffusion alloy coatings to substrate metals (162,163) cleaning and desulfurizing alloy steels via NaH (164) nodularization of graphite in cast iron deoxidation of molten metals heat treatment and the coating of steel using aluminum or zinc. 

Calcium metal is produced in the United States by Pfizer Inc., Canaan, Coimecticut, and in Canada by Timminco Metals, Toronto, Ontario. In France it is produced by Pechiney ElectrometaHurgie. It is also produced in the Commonwealth of Independent States (CIS) and the People s RepubHc of China. Both Pfizer and Timminco supply the various grades in a variety of sizes and forms. In addition, Pfizer suppHes an 80% Ca—20% Mg alloy and a steel-clad calcium wire for use in deoxidation of steel and other metals. Timminco and Pfizer both supply ca 75% Ca—25% Al alloy for use in lead alloying. Timminco also suppHes a 70% Mg—30% Ca alloy for use in lead debismuthizing (18), and calcium particulate products, which are purchased by several companies for the manufacture of cored wire for use in the steel industry. 

The chemical reactivity of metallic Mg has been utilized in several ways. It is employed in the reduction step in the manufacture of Ti, in the deoxidation and desulfurization of steels and in the nodularization of cast iron. It has also been used for the preparation of photoengraving plates, in dry batteries, and as a sacrificial anode for cathodic protection of other metals. 

Neither Ca, Sr nor Ba metal has any structural integrity. The principal application of metallic Ca is as a reducing agent in the preparation of metals, such as Th and Zr. Like Mg, it can be used in the deoxidation and desulfurization of steels. Small quantities are used for alloying with Al and for the removal of Bi from Pb. Neither Sr nor Ba have any significant commercial uses. Barium is used to a limited extent as a getter to remove reactive gases from vacuum tubes. 

The most important apphcation of this metal is as control rod material for shielding in nuclear power reactors. Its thermal neutron absorption cross section is 46,000 bams. Other uses are in thermoelectric generating devices, as a thermoionic emitter, in yttrium-iron garnets in microwave filters to detect low intensity signals, as an activator in many phosphors, for deoxidation of molten titanium, and as a catalyst. Catalytic apphcations include decarboxylation of oxaloacetic acid conversion of ortho- to para-hydrogen and polymerization of ethylene. 

For removal of insoluble and/or water-immiscible inorganics by emulsification with detergent solutions For removal of ester and amide-based organics and inorganic salts by chemical hydrolysis with alkaline solutions For removal of metal ions from solutions and surfaces by chelation or complexation reactions For wetting and dispersion of soils with surfactants, suspension of soil residues in order to prevent resedimentation and recontamination on metal surface For removal of surface contaminations, rust scale, mill scale, and other bound moieties (including surface layers of metal itself) by chemical dissolution with acids or alkaline deoxidation with or without the application of an electric current... 

T aking into account the fact that deoxidation of solid metals is very difficult at low temperatures, it is usual to observe non-wetting contact angles for insoluble metal/metal systems. 

CNC POLYQUEST 80 is not readily attacked by peroxide bleaches. It inactivates the metallic ions and prevents deoxidation of the oxidizing agent. This lenghthens the life of the bleach baths. 0.1% to 0.25% CNC POLYQUEST 80 will add greatly to the efficiency of the bleach. 

Sodium does not form alloys with aluminum but is used to modify the grain structure of aluminum—silicon alloys and aluminum—copper alloys for improved machinability. Sodium—gold alloy is photoelectrically sensitive and may be used in photoelectric cells. A sodium—zinc alloy, containing 2 wt % sodium and 98 wt % zinc, is used to deoxidize other metals. 

Stabilized Zr02 has recently become a subject of interest as a solid electrolyte for fuel cells. Concentration cells with a solid electrolyte can be used for determining the concentration of oxygen in gaseous or liquid media at high temperatures. Solid electrolytes may also be used in the deoxidation of melted metals, removal of oxygen from gaseous mixtures, etc. 

Oberg, K.E., Eriedman, L.M., Boorstein, W.M. and Rapp, R.A. (1973) Electrochemical deoxidation of induction stirred copper melts. Metall. Trans., 4, 75-82. 

The reduction of zirconium tetrachloride in a carrier salt with sodium as a reducing agent may be examined next. Again, as described before, complete deoxidation of the bath before reduction is the essential condition for success, if ductile metal is wanted. Zirconium tetrachloride is soluble in sodium chloride or potassium chloride (48) and a salt with about 25% zirconium tetrachloride can be melted without excessive zirconium chloride losses. Such a bath can even be obtained from powdery commercial zirconium silicide and iron dichloride, which react when heated and deliver a stream of zirconium tetrachloride, contaminated with some titanium tetrachloride and silicon tetrachloride. The gas so produced can be condensed in a fused salt bath such as potassium chloride-sodium chloride, in which only the zirconium tetrachloride dissolves (47), To obtain a low oxide metal after reduction with sodium, the conditions for fluo salt deoxidation must be observed. This process of zirconium production has no special interest, except for obtaining powder for getter purposes. A carrier salt, which might introduce oxide, is not wanted, as the reaction itself liberates sodium chloride. 

Most metals when heated along with sulphur combine wuth it , but in many cases sulphates are obtained by the action of sulphur compounds on the oxides, or by the deoxidation of sulphates. 

A type of cored wire (q.v.) in which most of the core is of non-metallic, fluxing ingredients, although some iron powder, deoxidants and metallic alloying additions may also be present. Such a wire may give weld hydrogen levels (q.v.) ranging from very low to medium. 

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