Kernforschungsanlage Julich Gesellschaft MIT Beschrankter Haftung

Kernforschungsanlage Julich

Hartmut Luhleich

Francisco J Dias

Hubertus Nickel

Francesco Dias

Peter Pflaum

Marian Kampel

Erno Gyarmati

Ashok K Gupta

Rudolf Munzer

Arno Schirbach

Aristides Nauomidis

Aristides Naoumidis

Bernd D Struck

Willi Hannen

Aristidis Naoumidis

Ursula Paffen Nee Siebert

A method of making shaped bodies of silicon carbide, of graphite coated with silicon carbide or of a graphite-like material with a silicon carbide surface wherein a graphitic body is assembled from preformed parts in the desired shape and is immersed, under a chemically inert atmosphere, in a silicon melt and after penetration of the melt into gaps between abutting surfaces of the body and after reaction of the silicon with the graphite or the graphite-like material to form silicon carbide at the junctions, the body is removed from the melt and is cooled in a chemically inert atmosphere.

Method of making shaped bodies of silicon carbide or of graphite or

In order to provide enough permeability (air or liquid throughput) in a pus molded body of carbon made from a mixture of carbon powder and a binder, a first 'green' body (a body of the kind that has been fired heretofore, in its green state before firing) is broken up into small pieces with the help of a jaw crusher in a manner providing coarse particles and a fraction of uniform size (largest particle diameter not more than twice the smallest) in the overall range between 0.2 and 10 mm effective diameter is used to make a second green body of molded shape by placing it in a die and applying a pressure which may be light or heavier according to the desired degree of permeability. The second green body is then coked in vacuum or in an inert atmosphere at a temperature in the range between 600.degree. to 1000.degree. C. to produce a strong body through which gas and liquid may pass with a facility far exceeding what has been accomplished before with a body of comparable strength.

Method of producing porous carbon bodies of high permeability

A molded porous silicon carbide body in the shape of an armor plate, made by coking a mixture of carbon and silicon powder coated with an organic binder to which some silicon carbide powder may be added, and then rapidly raising the temperature to a level at which silicon carbide is formed, is impregnated so that its pores are filled with steel or a steel alloy to produce a plate that has the hardness and stiffness of silicon carbide and the toughness of metal. The plate has superior resistance to hollow or shaped explosive charges. The lower density provided by the silicon carbide favors its use in armored vehicles.

Method of producing composite armor plate bodies

A porous green-state body of carbon, with or without silicon carbide, made with a cokable binder, is crumbled to produce relatively coarse grains in the range from 0.2 to 10 mm and a fraction of the particles so produced with a much more limited range of grain size is then used to produce a second green-state body, which is then coked, siliconized if the silicon is not already provided in the making of the precursor body that was broken up, and converted into a silicon carbide body. If the siliconizing is done by immersion in a bath of molten silicon, the excess silicon is removed by vaporization or by boiling in sodium hydroxide solution.

Method of producing permeable, porous molded bodies of silicon carbide

Refractory parts or articles, even of very large dimensions, are made with starting material of carbon particles mixed with silicon particles in a predetermined ratio which is suspended in a solution of a binder, after which the suspension is squirted into a precipitating liquid to coat the particles with the binder, the solids then being separated and dried, molded under slight pressure, and coked (at 800.degree.-1,000.degree. C.), and then rapidly raised in temperature (to 1,400.degree.-1,600.degree. C.) for formation of silicon carbide throughout the article. It is useful to add powdered silicon carbide and mix it in before the coking step and, also, to hold the heated body at a temperature somewhat below 1,400.degree. C. long enough to remove temperature gradients within it, followed by rapid heating up to a carbide-forming temperature. The porous bodies thus formed can be heated to reduce porosity after the coking step by impregnation with a suspension of silicon powder in a resin, after which the body is again coked, or impregnation may be carried out on the completely fired body, with a liquid resin or a molten metal, after evacuation of the porous body and the application of pressure to the impregnating fluid.

Method of making thermal-shock resistant molded articles on the basis of

An anode for electrolytic oxidation of sulfur dioxide is made by coating an lectrode of a graphite-like carbon material with a layer of cokable organic material such as sugar, phenolic resin, and asphalt pitch, heating the coated electrode body in an inert atmosphere to a temperature of between 400.degree. to 800.degree. C. and thereafter heating the coated electrode to a temperature in the range of 1400.degree. to 2000.degree. C., so that the material is first coked on the graphite to produce a porous flow-through electrode body which, thereafter, is heated to a higher temperature, followed by cooling.

Method of producing an electrode usable as a flow-through anode

Silicon carbide body having pores filled with steel or steel alloys

A method of and an apparatus for the drying of articles, especially foodsfs, biological materials and other substances susceptible to cell damage with overheating, wherein the material is spread in a high-vacuum vessel directly adjacent a cooled condenser and is subjected to a vacuum by a pump capable of developing pressures as low as about 0.1 mbar. The chamber is evacuated until there is a noticeable formation of the condenser whereupon the connection between the pump and the chamber is closed and the product is heated to evaporate liquids but below a predetermined temperature (say a maximum of 50.degree. C.) while the condensate resulting from the evaporation is collected directly below the product and is discharged.

Vacuum-drying method and apparatus

A heat-coalescible graphitic aggregate for making graphite molds, graphite uel elements or moderating elements for nuclear reactors, and so on, is made by first forming a suspension of carbon particles in an alkaline solution of phenolformaldehyde. The suspension is then mixed together with acidulated water, the latter being heated to 40.degree. to 70.degree. C. to accelerate the reaction, with violent mixing, as in a jet device, causing a skin of insoluble phenolformaldehyde to be applied as a coating to each of the particles in suspension, which particles readily settle out and are soon separated by decanting and filtration, after which the composite solid is dried and the aqueous liquid is neutralized before being discarded.

Process for making a starting material for the manufacture of artificial

In order to prevent a protective carbide layer on a graphitic molded arti from splitting off under thermal stress, an external carbide layer is provided on a graphitic molded article having a graded content of silicon or zirconium (in the carbide state) that increases from near zero at the interior boundary of the layer to about 50 atomic percent at the exterior. Such a layer is produced either by dipping the graphitic molded article into melted silicon, dipping it into a succession of suspensions of carbon and either silicon or zirconium, with a greater silicon or zirconium content in each successive dip, the suspensions also including a binder resin, or by applying layers of a paste of carbon and either silicon or zirconium, also with some resin, each successive layer having a higher silicon or zirconium content. In the case of the successive dipping into suspensions, the article is dried after each dip and then heated to harden the binder, and in the case of application of successive paste layers, the binder is likewise hardened each time. In each case, the treatment terminates with heating to a coking temperature, followed by a rapid rise of temperature to a value at which silicon carbide or zirconium carbide will be formed, followed by cooling to room temperature.

Graphitic molded article with corrosion-resistant surface layer stable

In order to prevent a protective carbide layer on a graphitic molded article from splitting off under thermal stress, an external carbide layer is provided on a graphitic molded article having a graded content of silicon or zirconium (in the carbide state) that increases from near zero at the interior boundary of the layer to about 50 atomic percent at the exterior. Such a layer is produced either by dipping the graphitic molded article into melted silicon, dipping it into a succession of suspensions of carbon and either silicon or zirconium, with a greater silicon or zirconium content in each successive dip, the suspensions also including a binder resin, or by applying layers of a paste of carbon and either silicon or zirconium, also with some resin, each successive layer having a higher silicon or zirconium content. In the case of the successive dipping into suspensions, the article is dried after each dip and then heated to harden the binder, and in the case of application of successive paste layers, the binder is likewise hardened each time. In each case, the treatment terminates with heating to a coking temperature, followed by a rapid rise of temperature to a value at which silicon carbide or zirconium carbide will be formed, followed by cooling to room temperature.

Making temperature-stable protectively coated graphite molded body

In the production of shaped silicon-carbide bodies, especially tubes which onsist predominantly of silicon carbide throughout their thickness for use in nuclear-reactor technology, a carbon-containing preform (body of the desired shape) is contacted with elemental silicon powder at a temperature of 1400.degree. C. to 1500.degree. C. and the silicon-contacted carbon-containing body is thereafter treated at a temperature of 1800.degree. C. to 2000.degree. C. to transform at least the major part of the carbon into silicon carbide.

Method of producing shaped silicon-carbide bodies

A suspension of novolac resin is first produced by dissolving phenol in an queous formaldehyde solution and the addition of an acid catalyst, followed by heating and refluxing. The hot novolac suspension is diluted with water and then converted into a solution by the addition of alkali hydroxide solution bringing the pH value to the range from 10 to 13. While the solution is still hot, particles of some form of carbon are suspended therein by mixing, vibration, or other agitation and the suspension is fed at 60.degree. C. into acidulated water of a temperature of about 50.degree. C., with the flow of acidulated water and suspension adjusted for a volume ratio of, respectively, 8:1. The resin is thereby precipitated on the surface of the particles and the particles are filtered, washed, and dried to produce a material made up of fine grains, evenly coated with binder, which are useful for making graphitic molds for casting metal.

Method of producing resin solution and a suspension of particles therein

Shaped graphitic or graphite-like carbonaceous bodies are produced by forming binder-coated particles of a carbonaceous filler in a slurry, shaping the slurry or paste of the particles to the desired configuration, drying and cokefying the shaped body. The system is suitable for the production of graphitic structures for use in high-temperature gas-cooled nuclear reactors, as casting molds and the like. The present invention starts with the assumption that binder-coated filler particles are available, the particles having been coated uniformly (e.g. as described in our application Ser. No. 267,480).

Method of making shaped carbonaceous bodies

Shaped graphitic or graphite-like carbonaceous bodies are produced by forming binder-coated particles of a carbonaceous filler in a slurry, shaping the slurry or paste of the particles to the desired configuration, drying and cokefying the shaped body. The system is suitable for the production of graphitic structures for use in high-temperature gas-cooled nuclear reactors, as casting molds and the like. The present invention starts with the assumption that binder-coated filler particles are available, the particles having been coated uniformly (e.g. as described in U.S. Pat. No. 4,009,143.

Growing community of inventors

Duren, Germany

Hartmut Luhleich