CS254220B1 - Protective layer, in particular continuous steel casting plate - Google Patents

Abstract

The essence of the solution is that the protective layer, in particular a continuous casting crystallizer plate of a steel based on a metal layer and a working layer sprayed with a plasma torch into a thickness of 0.2 to 3.0 millimeters using silicon powder. zirconium oxide or zirconium oxide powder doped with calcium oxide in an amount of 5% by weight or titanium dioxide doped aluminum oxide in an amount of 3% by weight, has a metal interlayer applied by an electric arc of 0.1 to 0.3 mm nickel alumides, from 4 to 20% by weight of aluminum and 80 to 96% by weight of nickel.

Description

4 254220

BACKGROUND OF THE INVENTION The present invention relates to a protective layer, a copper or crystalline cast iron crystallizer, based on a medium or an alloy and solves the problem of increasing their resistance to abrasion and reducing the occurrence of external cracks on the cast.

Crystallizers for continuous o-cell casting are media-based, alloys with silver, chromium, nickel or zirconium, with a surface hardness of 70-130HV. The purpose of the crystallizer is to provide a rapid heat dissipation from the surface of the cast steel surface to the center and thereby to crystallize it with a continuous continuous strip. The solidifying surface desiccated in the presence of the oxide residues, the casting powder and the high temperature treatment causes an intensive abrasion of the plate mainly in the lower third of the crystallizer.

Since this wear is not uniform, no further slab extension is possible, so as to attain a roughness of 1.5 to 3 mm, the succession is discontinued and the crystallizer has to be processed to the flood plain, which is only possible with minimal safety bearing horizons. This causes excessive consumption of the crystallizer material. In addition, an uncluttered inner flat crystallizer, in this process, a portion of the diffusing surface of the surface, the hot slab, and the surface of the surface. when lowering the melting temperature, it cools and flows along the grain boundaries in the slab, creating the effect of so-called spherical cracks in the steel, resulting in the rolling of rolling stock.

Several ways are known to prevent premature wear of the crystallizers and their impact on the quality of the brams. When galvanizing the surface of the working wall of the bleeder with nickel having a hardness of up to 200 HV and a coating thickness of 1 to 4 mm, only a relatively low abrasion resistance is achieved, while the high processing costs associated with the ecological problems of the liquidation of the galvanic bath worn.

In this diffusion alignment of the workpieces in a powder mixture of iron, alumina and ammonium chloride by sintering, the temperature is 860 to 900 ° C. a relatively thin layer of hardness up to 330 HVm is formed. but also low-resistance and deformation of the boards in speculation. Protective coatings for components of ferrous or non-ferrous metals are known for base-ceramic materials, for example, aluminum oxide, zirconium oxide and silicon silicon dioxide. AO No. 171 063 or. AO No. 204,331. The spraying of the oxidic materials applied to the copper itself has poor adhesion and low heat shock resistance. Attempts to use these materials have been unsuccessful because of the lack of material and application to the basic material.

The above-mentioned drawbacks are eliminated and the present invention is solved by a protective layer on the crystallisers of the medium or its alloys for the aforementioned purpose. The essence of this is that under the working layer of 0.2 to 3.0 mm, the plasma torch is sprayed with materials based on zirconium silicate, or oxide zirconium oxide doped with calcium oxide at 5%, or alumina doped with oxide. titanium dioxide in the amount of 3%, the metal interlayer formed according to the invention having a thickness of 0.1 to 0.3 mm is deposited with an electric arc of Nikelalumide powder having a composition of 4 to 20% by weight. % aluminum and 80 to 96 wt. nickel. The advantages of the protective layer of the present invention are that the combination of coating formation provides at least 2 to 2.4 times the lifetime of the crystallizer plates at an equivalent thermal conductivity across the entire crystallizer and substantially reducing diffusion. the material of the slab casting, the stress reduction in the corners and, to a lesser extent, the possibility of surface protection for low loads.

The sprayed metal interlayer on the roughened surface of the thatch has a good adhesion of the base copper material to form solid chemical bonds at the tops of the roughness of the roughened thatch, allowing the bonding of the ceramic layer, in particular of aluminum oxide, titanium or zirconium, to be further thermally conductive. wherein the interlayer decreases the level of internal stresses that would otherwise result from a significant difference in the coefficient of expansion of the medium and the ramic substances. The adhesion of such a coating is between 4.2 and 6.0 MPa, and after 15 casting cycles, its adhesion is 3.7 MPa, the microhardness of the particles does not change with temperature and it ranges from 780 to 1200 HVm. Examples of the invention: Example 1

The main plate of the crystallizer, fixed on a cooling flange of 1510 x 1700 mm, weighing 960 kg, has the required geometric shape, is degreased with trichlorethylene. It is then roughened by means of a pneumatic jet, for example a corundum with a particle size of 0.9 mm. The O-blasted surface has a minimum roughness of Ra = 6 μΐη. The pre-treated flat surface was sprayed with a radius of 1.6 mm, with a 4.5 wt. aluminum, nickel residue, 0.15-0.20 mm thick. Spray parameters: 200 A current, 28 V voltage, 150 mm spray distance, 0.3 MPa air pressure. A 1.2 mm thick zirconium oxide layer coated with 5% by weight of zirconium oxide is sprayed onto this sublayer with a plasma torch. calcium oxide. Plasma Spray Meters: 420 A Current,

Claims (1)

2 5 4 2 5 340 V, cutting distance 270 mm, powder delivery 18 kg. h '1, powder inlet diameter 5 mm, burner mouth distance 20 mm, angle of inclination 75 °. The spraying surface is abraded with a diamond wheel for roughness R2 = 1.6 urn, with a thickness of 0.9 mm. EXAMPLE 2 A lateral plate of a crystallizer fixed to a cooling flange of 1000 x 200 mm is turned to a prescribed geometry, degreased with trichlorethylene. Then it is blasted with a pneumatic jet, e.g., corundum, with a grain size of 0.9 mm. Blasted surface has at least roughness Ra - 6. The nickel-alumina intermediate layer is sprayed with a 1.6 mm diameter drill with a 4.5 wt. aluminum, nickel residue, 0.2 to 0.3 mm thick. Spreading parameters: current 200 A, voltage 28 V, distance 150m. A 1.2 mm thick alumina doped with 3 wt.% Alumina is sprayed onto this sublayer with a plasma torch. titanium dioxide. Plasma parameterization and processing are as in Example 1. EXAMPLE 3 A crystallizer side plate mounted on a cooling flange of 1000 x 200 mm, planed to a prescribed geometry, is degreased with trichlorethylene. The roughening, spraying of the metallic interlayer is the same as in Example 1. In this layer, a 1.2 mm thick zirconium silicate working layer is sprayed with a plasma torch. Spray parameters: 460 A current, 130 V voltage, 160 mm distance, 7 kg powder delivery. Im1, shielding gas 75% Ar; 25% H2. After spraying, the surface is abraded with a diamond disk for a roughness of Ra = 1.6 µm, with a thickness of 0.7 mm. The invention can be used in the workplace in the industry in addition to the treatment of crystallizers and in the treatment of other heat-stressing components such as welders and the like. PRED Μ ET A protective layer, in particular a continuous steel casting plate made of a base medium or its alloys, consisting of a metallic interlayer and a working layer sprayed with a plasma torch of 0.2 to 3.0 mm of zirconium silicate powder or oxi powder EXAMPLE 1 5% by weight of zirconium doped with oxides of oxides. or titanium dioxide doped alumina in an amount of 3% by weight, characterized in that the intermediate layer is deposited by an electric arc on a ridge of 0.1 to 0.3 mm by weight from a 4 to 20% w / w material. % aluminum and 80 to 96 wt. nickel.