RU1813796C - Process for repairing damaged glass-enamel coatings - Google Patents

Abstract

SUMMARY OF THE INVENTION: a method of repairing a damaged glass enamel coating consists in the fact that after preparing the area to be repaired, a layer of titanium is applied with a thickness of 0.3-0.7 mm by electric arc spraying with compressed air, additionally enriched with oxygen (5-8 vol.%), After whereby the layer is impregnated with tetra-furfurylxylan at a flow rate of 150-180 g / cm and subsequent heat treatment of the entire coating at 250-300 ° C.

Description

The invention relates to the production of coatings and can be used in the chemical, biochemical and food industries for the repair of glass enamel coatings.

An object of the invention is to prevent cracking of intact glass-enamel coatings.

The goal is achieved in that the method of repairing damaged glass-enamel coatings involves obtaining on the damaged section of the coating a mixture of a refractory metal with its oxide by thermal spraying and then impregnating it with a fluid polymer. The coating is obtained with a thickness of 0.3-0.7 mm by electric arc spraying of titanium using air enriched with oxygen of 5-8 vol.%, And the impregnation is carried out using tetrafurfurylsilane as a fluid

polymer with a flow rate of 150-180 r / m, followed by heat treatment for 0.25-0.3 hours

During electric arc spraying of titanium with compressed air, it partially oxidizes to TiOa. Small particles consisting of nucleus-Ti and the shell of TiOa fall on the sprayed surface.

The melting points Ti 1820 ± 100 ° C and TiOa 1820 ± 25 ° are the same. This causes the particle to reach the surface in a liquid state. As a result, particles that have fallen on the metal are fused with it, and particles that have fallen on the enamel melt it (melting point, acid-resistant enamels 8bO-880 ° C). The resulting coating as a result does not have a clear phase boundary (main coating / sprayed coating). The resulting coating is monolithic.

The diameter of the sprayed particles is 40-120 microns. When enriching the air kis00

s xi

SO

about

the thickness of the oxide film reaches 1 μm. When the oxygen content is more than 100%, the complete combustion of titanium to TiOa begins and the adhesion to the metal deteriorates sharply.

As a result of spraying, a composite coating is formed on the surface of the metal and glass enamel, consisting of a metal (titanium) matrix and a second phase, titanium oxide. The matrix gives good adhesion to the metal, the second phase - hardness, wear resistance, chemical resistance. The outer surface of the coating is almost completely formed from TU2 molecules. TI02 is practically insoluble in water, in dilute solutions of acids and alkalis.

Coatings obtained by electric arc spraying have a porosity in the range of 8-15%.

In order to obtain an impermeable protective coating, the sprayed coating having a porous structure is impregnated with a furyl silicate resin, which is a product of the transesterification of tetraethoxysilane with furfuryl alcohol and is technical tetrafurf.uryl xylan. Tetrafurfurylxylan (TFS) complies with TU-05-2P-1268-81. During the heat treatment of TFS, the organic part of tetrafurfurylxylan is destroyed. The degradation products are a sealing filler of the resulting silicate film, which significantly reduces its porosity.

When using electric arc metallization with air, the temperature on the sprayed surface does not exceed 700 ° C. therefore, no cracking of the glass enamel occurs, and particles of the sprayed material are melted into the metal.

Example. The surface of the defective area of the glass enamel coating is cleaned of corrosion products using a grinding machine. The edges of the durable glass-enamel coating are polished with a grinder. Defective place and cleaned enamel degrease. Coating of titanium is carried out on a KDM-2 apparatus at a current magnitude of I 360-350 A and a voltage of U 25-28 V. The spraying distance is ISO 250 mm. The main glass-enamel coating is covered by spraying 15-20 mm. The thickness of the coating is 0.3-0.5 mm.

Spraying is carried out by a stream of compressed air at a pressure of 0.5-0.7 MPa. The air is enriched with oxygen (58 vol.%).

In electrometallizers, an arc is excited between two titanium wires,

isolated from one another and located at an acute angle. These wires are melted, and then the metal is atomized and blown out by compressed air. The wire is fed into the melting zone.

a turbine operating on compressed air enriched with oxygen.

The resulting coating is impregnated with tetrafurfurylxilane (TFS) using a spray gun and heat treated with

200-280 ° C for 0.3 hours

The condition of the glass-enamel coating around the repaired area was determined using color inspection according to TU6-15-06M-6-86.

On samples repaired by the proposed method, color flaw detection showed no cracking of the main glass-enamel coating.

On samples repaired by

Claims (1)

the prototype, when using color inspection, a network of cracks is visible in the area adjacent to the repaired area. SUMMARY OF THE INVENTION A method for repairing damaged glass-enamel coatings, comprising producing a mixture of a refractory metal with its oxide by gas-thermal spraying on a damaged section of a coating and then impregnating it with a flowable polymer, characterized in that, in order to prevent cracking of the intact main coating, a thick coating is obtained on the damaged section 0.3-0.7 mm by electric arc sputtering of titanium using air enriched with oxygen of 5-8 vol.%, and the impregnation is carried out using tetrafurfurylxilane as a liquid flowing polymer with a flow rate of 150-180 g / m followed by heat treatment at 250-300 ° C for 0.25-0.3 hours