DD202899A1 - METHOD FOR PRODUCING A GLOSSY CONTAINMENT ON OXYDABLE MATERIAL, IN PARTICULAR MOLYBDAENE - Google Patents

Abstract

The invention relates to a method for producing a glassy coating on oxidizable material, in particular molybdenum for electrodes or similar components, primarily in glass melting plants. It is the object of the invention with little effort to protect against the oxidation of high-temperature materials, largely independent of the shape of the components. The object is achieved by applying to the component a first layer of a glass powder-water mixture and, after drying, applying a second layer consisting of water glass and the glass powder in a ratio of 1: 1 to 1: 2. Depending on d. Application temperature consists of the glass powder of a type of glass or glasses of different softening temperature.

Description

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Title of the invention

Process for producing a glassy coating on oxidizable material, in particular molybdenum

Field of application of the invention

The invention relates to a method for producing a glassy coating on oxidizable material, in particular molybdenum for electrodes or similar components, primarily in glass melting plants.

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Characteristic of the known technical solutions

The use of high temperature materials such as tungsten, tantalum and especially molybdenum in the glass industry, for example for electrodes, thermowells, stirrers and bubblers or in the chemical industry, is fraught with the lachteil that these materials are destroyed far below their temperature of use in air by oxidation , The parts of such devices that do not dip, for example, in molten glass, must be protected from the ingress of oxygen. "This is known to be done by means of inert gas, sheaths, for example, with precious metals, the material's own. Protective layers such as molybdenum disilicide or cooling below the temperature at which damaging oxidation occurs

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From an unpublished EOrschungsbericht a method is known to cover electrodes or protective tubes made of molybdenum with a Glasschutzschioht · Here, the glass to be glazed electrode is inserted into a glass tube of suitable glass type and dimension closed on one side, this closed and evacuated · By heating in an oven, the glass softens and forms a tight protective layer.

The disadvantages of this method are that its implementation requires a high expenditure on equipment J , is energy-intensive, a suitable glass tube closed on one side of certain dimensions must be present and only rod or tubular parts can be provided with the protective layer · Cracks in the protective layer remove the protective effect and are not repairable.

Object of the invention

It is the object of the invention to considerably reduce the expense of producing a protective layer of glass on molybdenum or similar material and to be largely independent of the interior of the device to be protected.

Explanation of the essence of the invention

It is an object of the present invention to provide, in a convenient process, molybdenum or similar oxydation-sensitive high temperature material devices, a protective layer of glass or vitreous material which keeps the heated material permanently against entry of air or immersion in a protective medium, e.g. Glass, preserved from oxidation.

The task is solved by layering. Applying glass powder by wet route to the object to be protected. A first layer consists of a glass. -Qualc powder-water mixture of suitable consistency. After drying, a second layer consisting of water glass and glass powder is applied in a ratio of 1: 1 to 1: 2. Depending on the application temperature, the glass powder consists of a GlaSart or glasses of different softening temperature ·

The advantage of the method is above all in its simple practicability. The protective layer is sufficiently strong to be able to handle the protected devices, does not crack when heated by sufficient plasticity and forms: especially when the glass powder consists of glasses of different softening temperature a dense layer even at temperatures that cause harmful oxidation,

embodiment

The process is explained by means of the protection of a molybdenum electrode for the heating of a glass feeder by means of Joule heat. The electrode provided with protective layer is inserted into the feeder through the side wall and heated with this to about 900 ° C. by means of gas heating, before the glass melter that covers the electrode and partially fills in the itor guide bore. In the glass, the protective layer is removed · The power supply via the electrode is ensured unhindered.

A glass powder of the following composition is used:

softening

in ⁰ C: 420 440 555 570

Proportion of glasses. - .... ,

in% by volume: 16.7 .16.7 16.7 16.7 33.2

The glasses were selected exclusively according to their softening point, without consideration of other properties.

Without pretreatment of the surface, the paste-like glass powder-water mixture is spread on the machined electrode and dried at temperatures up to about 100 ° C.

The mixture of waterglass and the glass powder in a ratio of 1: 1.5 is spread on this layer, so that after drying at temperatures up to about 150 ° C. a total of a solid layer of thickness 3 to 6 mm results.

Claims (2)

claim 1β A method for producing a glassy coating on oxidizable material, in particular molybdenum for electrodes or similar components, mainly in glass melting plants, characterized in that applied to the component to be protected against oxidation, a first layer of a glass powder-water mixture of suitable consistency and dried and after drying, applying a second layer of waterglass and the glass powder in a ratio of 1: 1 to 1: 2, 2 »Method according to item 1, characterized in that the glass powder consists of a type of glass or glasses of different softening temperature.