摘要:
In an aluminium reduction cell including a cell lining and embedded therein at least one cathode current collector including a high temperature section comprising an electrically conducting refractory material such as titanium diboride, generally in conjunction with molten aluminium metal, corrosion is a problem. The invention provides a substance to protect the collector section. The substance may be a liquid impermeable layer e.g. particulate material impregnated with a molten fluoride-or chloride-containing salt mixture; for a getter such as particulate aluminium to react chemically with gaseous corrosive species. Combinations of these substances may be used, optionally in conjunction with a solid layer such as an alumina or aluminium metal tube.
摘要:
An aluminium reduction cell includes an anode 10, electrolyte 12, a cathode 14, a potlining 16 which may be of alumina and cathode current collectors embedded therein. The collectors include a section comprising a major proportion by volume of bodies 22, e.g. of titanium diboride or a TiB.sub.2 /Al cermet, joined or surrounded by aluminium, the section being so positioned that the aluminium is at least partly fluid when the cell is in operation. The bodies, which are preferably close-packed, may be cubic or cuboid or in the form of sheets or thin slabs arranged with their major faces parallel to one another and to the axis of the collector section. The collectors show good electrical conductivity together with satisfactory resistance to magnetic stirring and impact and transverse forces.
摘要:
In a process for refining Al or Mg a stream of relatively impure molten metal is passed along one face of a grille separator having interstices of the order of 0.1-1 cm in width. The interstices are filled with a molten salt electrolyte adapted to transport ions of the selected metal (Al or Mg) to a body of refined metal on the opposite side of the separator. The relatively impure metal is made in the anode and the refined metal is the cathode. Refined metal is progressively withdrawn from the cathode. The grille separator may be arranged substantially vertical or substantially horizontal, usually with slight inclination. Passages are preferably provided in the separator to allow escape of gas generated at a metal/electrolyte interface.
摘要:
A process and apparatus for melting metals that react rapidly with air at elevated temperatures to form a stable metal oxide and/or that contains a metal oxide prior to being exposed to elevated temperature, while reducing metal losses due to oxidation or the presence of the oxides. The process involves melting the metal in the presence of a molten metal salt metal salt mixture while electrolyzing metal oxide contained in the salt metal salt mixture to convert the oxide to elemental metal. The process requires an metal salt mixture which contains at least 25% by weight, and more preferably 100% by weight, of metal fluoride and which, for the metal being melted, has a composition which remains substantially unchanged during the electrolysis process. The fluoride improves oxide solubility in the metal salt mixture, making it possible to increase current densities without producing anode effects. The stable composition makes it possible to use the metal salt mixture for prolonged periods without change. The apparatus consists of a single vessel having an interior volume divided at least into a melting zone and an electrolysis zone by a heat-resistant partition which allows the metal salt mixture to be recirculated between those zones. The process and apparatus can be used for melting metals, metal matrix composites reinforced by metal oxides and metal foams stabilized by metal oxide particles.
摘要:
An aluminium reduction cell includes a potlining 16, which may be of alumina, with cathode current collectors 24, 32 embedded therein. The cell floor has an array of depressions 22 with at least one collector at the bottom of each depression. The depressions are filled with metal-wettable bodies 20, e.g. 5-20 mm diameter balls of titanium diboride, sized to prevent the entry of electrolyte or sludge. The depressions may be elongate in a direction perpendicular to the horizontal magnetic field in the cell.
摘要:
In an electrolytic reduction cell for the production of a molten metal by electrolysis of a molten electrolyte, the product metal collects on a cathodic carbon floor having embedded steel current collector bars for leading out the cathodic current. In order to reduce the wave motion of the metal due to interaction of horizontal currents in the product metal with the magnetic fields due to currents in conductors associated with the cell, electrically non-conductive barrier members are arranged on the floor of the cell transversely of horizontal currents in the product metal. Such barrier members have at least a surface layer of material resistant to product metal and extend upwardly from the cell floor to a height approximating to the normal maximum operating level of product metal.
摘要:
A method of sequentially sorting pieces of material in real-time into output bins where each piece has a composition defined by a plurality of control elements. Each piece is analyzed to determine the concentrations of each control element in the piece. The output bins are assigned target concentrations of the control elements that are defined by customer requirements. The method establishes a bin order used during composition checking to place each piece in a selected bin. The selected bin is the highest order bin that can accept a piece while retaining the actual concentration for each control element of the selected bin within the target concentration for each control element of the selected bin. To optimize the value of the input material to be sorted the bin order is established for each piece based on real-time sort parameters that can determine via global optimization of data from similar input material. Global optimization gives best blends of the known unique compositions and weights of the similar input material to maximize the aggregate value of the prescribed output compositions.
摘要:
The invention comprises a method of making self-supporting ceramic and ceramic composite structures by the oxidation reaction of a body of molten parent metal precursor with a vapor-phase oxidant to form an oxidation reaction product. This reaction or growth is continued to form a thick, self-supporting ceramic or ceramic composite body. The body is recovered and in a separate subsequent operation, at least a portion of a surface is coated with one or more materials in order to effect desired changes in the properties of the surface, e.g., hardness, corrosion resistance.
摘要:
The invention provides a method of removing inclusions from molten metal, particularly aluminum, by(a) contacting the molten metal with a medium which retains metal-non-wettable inclusions. The medium may be liquid such as a fused salt mixture; or solid such as a filter or metal-non-wettable ceramic materials or a bed of granules e.g. of tabular alumina,(b) passing the molten metal through a filter of metal-wettable material, e.g. a refractory hard metal such as titanium diboride. The metal-wettable filter attracts and holds metal wettable inclusions within itself, and may also prevent by surface tension the entry of fused salt droplets.
摘要:
A method for manufacture of Group IVB metal carbide ceramic composites is provided wherein a permeable mass of filler and carbon is contacted with a molten Group IVB metal. The molten metal is maintained in contact with the permeable mass for a sufficient period to infiltrate the permeable mass and to react the molten metal with the carbon source to form a Group IVB metal carbide composite. The permeable mass may comprise a Group IVB metal carbide, or other inert filler, or a combination of filler materials.