Ceskoslovenska Akademie Ved

Vysoka Skola Chemicko-technologicka

Petr Kroupa

Karel Zverina

Josef Szabo

Miloslav Bartuska

Antonin Cieslar

Veslav Maroszczyk

Valter Bohm

Borivoj Pospisil

Denek Tluchor

Jaromir Polidor

The present invention relates to the foundry industry and solves the problem of extended service life of valve closure gate assemblies for foundry ladles. The valve closure gate assembly of the present invention comprises two mutually slidable heat-resistant gates furnished with a protecting layer of an oxide refractory material and having flow-through rings made from an oxide refractory material disposed in the openings of the gates. The respective upper and lower surfaces of the rings are coated with a layer of refractory material.

Valve closure gate assembly for foundry ladles

Method of and apparatus for stabilizing a plasma stream by the use of two different stabilization liquids. The plasma arc is stabilized in the discharge chamber by a whirl of a first stabilization liquid containing at least one element chosen from the group consisting of carbon and nitrogen, and the plasma arc is stabilized in the stabilization channel by a second stabilization liquid differing in its boiling point from the first stabilization liquid. Between the discharge chamber of the burner and the stabilization channel there is provided a transition space from which there lead outlets for the stabilization liquids. In the transition space there may be place an orifice plate dividing said space into two sub-spaces. From the stabilization channel upstream of the front nozzle of the burner there may be provided an outlet for the second stabilization liquid, which is disposed in the stabilization channel. In accordance with the invention the stabilization system of the plasma burner of torque is divided into two comparatively independent circuits.

Method of and apparatus for stabilization of low-temperature plasma of

The present invention relates to a method of producing self-supporting constructional elements by plasma-spraying onto a removable core. Recently, there is in widespread use the method of producing constructional elements, especially of heat-resistant elements of rotary shape, by plasma-spraying of ceramic oxides onto a removable core. Existing problems in the art are caused by the slow removal of an intermediate layer, which separates the deposited constructional element material from the core, in suitable solvents, and the necessary neutralization of the produced constructional element. These disadvantages are overcome by the method of the present invention characterized in that a core is preheated to a temperature in the range of from about 200.degree. C. to about 650.degree. C., a metallic or non-metallic intermediate layer having a thickness of about 0.1 to about 2 millimeters is deposited on the core by plasma-spraying. Afterwards, there are deposited by plasma-spraying the required layers on the intermediate layer; the required layers being of a heat-resistant ceramic oxide and forming the self-supporting constructional element. Thereafter, the core is cooled, the intermediate layer is separated from the material of the self-supporting constructional element, and the constructional element is removed from the core. The method according to the present invention takes advantage of the thermal expansion of different materials and considerably speeds-up the production. It has special utility for the production of hollow bodies having a cylindrical or nearly cylindrical shape.

Method of producing self-supporting constructional elements

Spray-coating materials having a high heat-resistance and thermal conductivity for the surface protection of materials. The spray-coating material consists of 8-35 wt. % magnesium oxide MgO or calcium oxide CaO, 2-10 wt. % of beryllium oxide BeO and 55-90 wt. % of aluminum oxide Al.sub.2 O.sub.3, zirconium dioxide ZrO.sub.2, silicon dioxide SiO.sub.2, chromic oxide Cr.sub.2 O.sub.3 and titanium dioxide TiO.sub.2. The spray-coating material of the invention can be employed to advantage, for example, in the chemical industry and in metallurgy.

Spray-coating material

There is disclosed a material for hot or plasma spraying, especially a material based on oxide ceramics, and a process for the production thereof. The composition of the invention is a mixture of powdered oxides containing at least two fundamental oxides with high melting point, and at least one glass-forming oxide the melting point of which is lower. The invention also includes a process for the production of such composition by the melting and agglomeration of individual components in the oxidizing medium of a plasma stream, including the special treatment of the starting components.

Material for plasma spraying and method of making same

Process of radial stabilization and homogenization of a plasma stream and a liquid stabilized plasma burner for the realization of such process. The arc is stabilized by its passage through several orifice plates, stabilized by a whirl or eddy of cooling liquid, then passes through a nozzle and is bent toward the peripheral surface of a rotatable anode lying out of the main outlet plasma stream issuing from the nozzle. The liquid stabilized burner has a rod cathode placed in the arc chamber, the cathode being progressively fed into the arc chamber to from an arc therewithin.

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Prague, Czechia

Petr Kroupa