CS196635B1 - Metallic material based on iron-chromium alloy resistant against high temperature and corrosion by silicate melting,especially by fused basalt - Google Patents

Abstract

Refractory metal alloy, resisting corrosion in silicate melts, esp. in fused basalt, contains 60-98.9% Cr, 1-39.9% Fe and =0.1% C. The alloy is used in electric smelting plant, auxiliary heaters and silicate and basalt melting stock plant, including plant for fusing enamels and glass types in which colour is desirable or harmless. At the operating temps., e.g. =1450 degrees C in silicate melts and =1350 degrees C in air- and gas media, the alloys form a thin, protective Cr2O3 layer, which dissolves with difficulty in silicate melts and inhibits progressive oxidn. in gas media.

Description

The invention relates to a metal refractory material resistant to corrosion by silicate melts, in particular by melted basalt.

In melting glass and similar silicate materials, such as basalt, in addition to the refractory ceramic furnace lining, various devices or parts thereof, such as electrodes, pyrometers, stirrers, plungers, dispenser spouts, etc. are in contact with the melt. Their surface is more or less corroded by the melt at operating temperatures, which results in efforts to find materials that are as low as possible corroded by the melt while meeting other requirements for strength, electrical properties, coloring effects, etc.

With respect to electrodes, the beginnings of electrical smelting are associated with the use of graphite or iron electrodes, as disclosed, for example, in U.S. Pat. No. 1,820,247. Since graphite stains glass, other suitable materials have been sought and have recently been widely used. electrodes of molybdenum, such as disclosed in France Patent No. 1,397,385, or the use of molybdenum silicide according to France Patent No. 1,455,512 is also known.

Molybdenum electrodes are heavily corroded with glass containing a high content of polyvialent metal oxides, e.g. However, these electrodes are relatively expensive and are more suitable for lower melting temperatures. Molybdenum electrodes strongly corrode by the effect of basalt melts, and therefore, when the basalt melts, it remains in the graphite electrodes or is used according to the CS. No. 159 549 electrodes of refractory chromium-molybdenum steel containing 19 to 22% chromium, 36 to 40% nickel and 4.5 to

6.5% molybdenum. However, in the case of basalt melts, which have low infrared transmittance, local overheating above the carrying temperature occurs near the electrodes and the electrodes melt.

With respect to other devices or parts thereof, such as pyrometer housings, stirrers, plungers, spouts, etc. coming into contact with the melt, a wide variety of materials from which they are made, in particular various Al2O3-based ceramic materials, such as See, for example, U.S. Patent 3,711,267 or U.S. Pat. No. 148,949, and various metals or their alloys, ranging from platinum and tungsten to various types of refractory steels. Platinum and its alloys with rhodium and other metals such as iridium, palladium, titanium and the like, and tungsten are very expensive and are only used where 'high purity requirements' are required, especially when melting special optical and technical glasses and in the melting of glass in the single-stage production of glass fibers as disclosed in France Patent Nos. 2,159,605, 1,521,996 and 1,465,248 or in U.S. Patent 3,672,880 and DAS 1,194 585. It is also known to use a Ni-Cr metal alloy according to U.S. Patent No. 3,384,478. However, this material is only usable at lower melting temperatures of up to 135 ° C and is not suitable for parts that are not fully immersed in the melt. because in the gaseous environment above the melt it has an even lower resistance. · '

Swiss Patent No. 59,459 also discloses the use of an Fe-Cr alloy with a Cr content of 5 to 70% and optionally Si of up to 14% for the production of heat and acid-resistant articles. However, in experiments using similar alloys for silicate melt applications, it has been found that a mere addition of chromium in the alloy does not automatically guarantee the desired corrosion resistance of the silicate melt at high application temperatures up to 1450 ° C. Industrial alloys of this kind contain, practically, always a certain amount of carbon C, which according to the results of the tests affects the resistance of the alloy to corrosion by silicate melts at high temperature. Increasing the carbon C content of the alloy above the amount shown in the alloy of the invention results in a substantial decrease in the alloy's resistance to silicate melts.

SUMMARY OF THE INVENTION The present invention provides a metal material based on an alloy of Fe-Cr, resistant to high temperatures and corrosion by silicate melts, in particular fused basalt, containing 60 to 98.9% by weight, Cr and 1 to 39.9% by weight iron Fe wherein the carbon content of U does not exceed · 0.1% by weight.

Claims (1)

Iron-chromium-based metal material resistant to high temperatures and corrosion by silicate melts, in particular by molten wire, characterized in that: The materials according to the invention have a high corrosion resistance with silicate melts, in particular melted basalt, up to. temperature 1450 ° C and relatively high stability, in air and in gaseous environment, up to · · temperature 1350 ° C. On the surface of these materials, a surface layer of Cr 2 O 3 is formed at operating temperatures, which is hardly soluble in the silicate melt and prevents further oxidation in the gaseous environment. Exemplary Embodiments of the Invention: Example 1 In the electric heating of the basalt melt in the outlet trough, rod-shaped electrodes made of an alloy of 69.73 ° C / Cr, 0.025 ° C / Ca and 30.02% Fe were used in the side walls of the rod-shaped electrodes. The electrodes were inserted through the opposite side walls into the melt without cooling on their passage through the wall so that the end of the electrodes reached 20 mm into the melt and the electrodes in one side wall were connected in parallel and connected to one pole of the single phase pole source. After evaluation of the operation, the electrodes were removed from the furnace without apparent corrosion. Example 2 A plunger was made of the alloy of Example 1 and was immersed halfway through its length in a basalt melt in a spout. The space above the surface was heated by a gas burner to a temperature of 1350 ° C. At the end of operation, the entire plunger was also removed without apparent corrosion. The metal refractory material according to the invention is primarily intended for electric melting, electric heating and dosing of basalt and similar melts is possible. however, it can also be used in electrical melting, electric preheating and dosing of · other silicate melts, such as enamels and so on. Skel, in which a possible coloring of the melt is not a defect or is desired. OF THE INVENTION contains -60 to 98.9% by weight of Cr and 1 to 39.9% by weight of iron Fe, with a carbon content of C not exceeding 0.1 · ·%. wt.