RU2466864C1 - Method to produce protective-decorative coating on concrete items - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: method to produce protective-decorative coatings on concrete items includes formation of a protective layer, supply of aluminium or copper into a plasma burner, their melting, plasma sputtering and monitoring of finished items quality. Prior to plasma sputtering on the face surface of the specified items a microroughened layer of heat resistant concrete is formed, which includes an aluminous cement with a filler from fractions of ground chamotte of 0.315-1.25 mm with thickness of 2-3 mcm. Plasma sputtering is carried out at the plasmatron capacity of 8.5 kW and speed of plasma burner movement on the face surface equal to 0.25 m/s.

EFFECT: invention makes it possible to increase strength of adhesion between a protective-decorative coating and a base, to eliminate dehydration of a surface layer on concrete items.

2 tbl, 2 ex

Description

The invention relates to the field of protective and decorative coatings on concrete products and can be used in the building materials industry.

A known method of obtaining a protective and decorative coating on concrete products, which consists in plasma spraying on the front surface of metals [1] [Fedosov SV, Akulova MV Plasma metallization of concrete: monograph - M.: Publishing house ASV, 2003 - 120 p.].

The disadvantage of this method is the high energy intensity of the process and the low adhesion strength of the protective and decorative coating due to the dehydration of cement stone in the surface layer of concrete products.

The closest technical solution is the method of obtaining a protective and decorative coating, which consists in the plasma spraying of copper or aluminum onto a previously expanded “face down” protective expanded clay layer [2] [Krokhin VP, Immortal BC, Burlakov NM, Popov V .AND. Plasma decorative surface treatment of building materials. - M .: NII, BTISM, - 1980, p.125-129].

The disadvantage of this method is the high energy intensity of the process (10.5-16.0 kW), low quality of the protective layer due to flowing cement dough during molding "face down", low adhesive strength of the protective and decorative coating due to dehydration of cement stone [2].

The aim of the proposed method is to improve the quality of the final product, the adhesion of the protective and decorative layer to the base, reducing energy consumption and, as a result, obtaining high-quality competitive products.

This goal is achieved by the fact that in the proposed method of obtaining a protective and decorative coating before plasma spraying on the front surface of concrete products, a layer of heat-resistant concrete is formed, and plasma spraying is performed at a plasma torch power of 8.5 kW and a plasma torch travel speed on the front surface of 0.25 m / s

Distinctive features of the proposed method is the elimination of the processes of dehydration of cement stone in the surface layer of concrete products due to the pre-formed layer of heat-resistant concrete with a filler from the fractions of ground fireclay 0.315-1.25 mm and, as a result, an increase in the adhesion strength of the protective and decorative coating to the base when subsequent plasma spraying of copper and aluminum.

When molding a layer of heat-resistant concrete 2.0-3.0 μm with a filler of ground fireclay 0.315-1.25 mm, a micro-rough surface is formed on the front surface of concrete products, which provides strong mechanical adhesion of the sprayed coating to the base.

Copper and aluminum in the form of a powder or wire were used as the starting material to achieve this goal. The proposed method provides for the separate use of copper and aluminum both in the form of a wire and in the form of a powder.

In the known method, the protective layer is a mixture of granules of expanded clay 1.25-2.5 mm with cement dough based on Portland cement. In plasma spraying of aluminum or copper due to significant thermal shock as a result of dehydration of cement stone, a partial softening of the protective layer occurs. This leads to a decrease in the adhesion strength of the protective and decorative coating to the base. It is the value of adhesion to the base that determines the durability and quality of the concrete product.

In the proposed method, in order to eliminate the effects of thermal shock and dehydration of cement stone in the surface layer before plasma spraying of aluminum and copper on the surface of concrete products, a micro-rough layer of heat-resistant concrete with a filler of ground fireclay with a granule size of 0.315-1.25 mm is formed. This allows, in comparison with the known method, to spray at lower values of the power of the plasma torch and significantly reduce energy consumption. High temperatures of plasma (about 8000-1000K) and molten aluminum or copper do not cause dehydration processes in the protective layer of heat-resistant concrete. The micro-rough surface of the protective layer additionally provides high mechanical adhesion of molten aluminum or copper to the base.

The inventive step of the proposed method is confirmed by the fact that the elimination of the effects of thermal shock and dehydration of cement stone due to the formation of a micro-rough layer of heat-resistant concrete with ground chamotte filler allows not only to obtain a high-quality concrete product with high adhesion strength to the base, but also to reduce energy costs.

The analysis of known methods for producing protective and decorative coatings on concrete products allows us to conclude that the claimed invention meets the criterion of "novelty."

The optimal conditions for obtaining a protective and decorative coating, experimentally obtained, are the power of the plasma torch 8.5 kW at a speed of passage of the plasma torch of 0.25 m / s (table 1).

Table 1 Optimal parameters of plasma spraying and quality indicators of concrete products No. p / p Power of plasma torch, kW The consumption of plasma-forming gas, m ³ / h The speed of the plasma torch, m / s Product quality The adhesion strength of the coating, MPa The presence of porosity in the coating one 4,5 twenty 0.10 1,03 porous 0.15 1.21 porous 0.20 1.35 porous 0.25 1.42 porous 0.30 1.36 porous 2 6.5 twenty 0.10 1.29 non-porous 0.15 1.47 non-porous 0.20 1.55 porous 0.25 1,61 porous 0.30 1,56 porous 3 8.5 * twenty 0.10 1.49 non-porous 0.15 1,61 non-porous 0.20 1.75 non-porous 0.25 * 1.80 * non-porous 0.30 1.72 porous four 10.5 twenty 0.10 1.27 non-porous 0.15 1.32 non-porous 0.20 1.41 non-porous 0.25 1,54 non-porous 0.30 1.42 porous * - optimal spraying mode

The use of chamotte granules larger than 1.25 mm leads to a large overspending of the metal to create a uniform layer. The use of granules of less than 0.315 mm does not allow to create a micro-rough surface and significantly reduces the adhesion strength of the coating to the base, according to experimental data - 0.8-1.2 MPa.

Comparative data of quality indicators, technological parameters and operations of the proposed and known methods are presented in table.2.

table 2 Quality indicators of protective and decorative coatings on concrete products No. p / p Indicators Unit. The known method [2] The proposed method one. Process flow Forming concrete products with a protective expanded clay layer "face down" The formation of a layer of heat-resistant concrete on the front surface of concrete products ↓ ↓ Supply of aluminum or copper to a plasma torch Supply of aluminum or copper to a plasma torch ↓ ↓ Melting aluminum or copper in a plasma torch Plasma spraying of aluminum or copper on the front surface of concrete products ↓ Plasma spraying of aluminum or copper on the front surface of concrete products ↓ Quality control ↓ Quality control 2. Energy consumption (plasma torch power) KW 10,5-16 8.5 (30 × 0.35 = 10.5) (32 × 0.5 = 16) 3. Plasma torch GN-5R GN-5R four. Plasma gas flow rate l / min 25-30 twenty 5. The distance from the nozzle of the plasma torch to the surface of the product mm 240-250 200 6. Grip strength MPa ** 1.8 7. Argon pressure MPa 0.27-0.29
(2.7-2.9 kgf / cm ² ) 0.25

Continuation of Table 2 one 2 3 four 5 8. Spraying speed m / s - 0.25 Material: 9. a) aluminum wire ⌀ 2.5 2.5 b) copper wire ⌀ 1,5 1,5 10. The composition of the protective layer Portland cement, expanded clay Alumina cement, chamotte eleven. Protective layer thickness mm 4-5 2-3 Granule size mm 12. - expanded clay 1.2-2.5 - - chamotte - 0.315-1.25 ** - in the prototype was not determined (according to own research (0.4-0.8 MPa)).

Example

Obtaining protective and decorative coatings on concrete products.

To obtain a protective and decorative coating, a concrete product (prototype) was used 2.76 × 3.18 m.

Pre-prepared a mixture for the intermediate layer. As a mixture for the formation of a layer of heat-resistant concrete used:

- alumina cement according to GOST 969 - 20-30%

- filler: chamotte with a granule size of 0.315-1.25 mm according to GOST 23037 - 70-80%.

The mixture was averaged and shut with water. An aqueous solution of the mixture was applied to the surface of the panel with a roller in automatic mode or with a P-G8 industrial spray gun. At the same time, a microrough layer of heat-resistant concrete with a thickness of 2-3 mm was formed.

A GN-5r plasma torch with a drive of an electric arc plasma torch UPU-8M was installed on an industrial conveyor. The electric drive made it possible to perform reciprocating movements with the GN-5r burner at a speed of 0.1-0.3 m / s. A ⌀ 1.5 mm copper wire was automatically fed into the plasma torch. A molten stream of metal particles was sprayed onto the panel in 30 passes. The speed of passage of the plasma torch GN-5p was 0.25 m / s.

The plasma torch operation parameters were as follows: operating voltage 30 V, current 283 A. Argon served as the plasma-forming gas, the flow rate of which was 20 l / min.

After plasma deposition of copper, quality control was performed.

An example of quality control.

The porosity of the coatings was determined by the "spot" method. After plasma spraying with optimal parameters of the plasma torch, the protective and decorative coating was non-porous.

Monitoring the adhesion of a protective-decorative coating to the base is a destructive method. In this regard, to determine the adhesion strength, 5 samples were prepared from concrete 60 × 60 × 60 mm in size and copper was sprayed using the indicated technology.

Five metal rods with a length of 150 mm and an area of 1 cm ^{2 were} glued to the front surface of five samples with epoxy. After polymerization of the epoxy resin for 24 hours, we proceeded to determine the adhesion strength of the coating to the base on a tensile testing machine R-0.5.

Samples with metal rods were fixed in special clamps of the tensile testing machine. After uniform loading, the protective-decorative coating peeled off.

Adhesion strength was determined as the arithmetic average of five measurements:

Claims (1)

A method for producing protective and decorative coatings on concrete products, including forming a protective layer, supplying aluminum or copper to a plasma torch, melting them, plasma spraying and quality control of finished products, characterized in that a micro-rough layer is formed on the front surface of said products before plasma spraying heat-resistant concrete, including alumina cement with a filler of fractions of ground fireclay 0.315-1.25 mm, 2-3 microns thick, and plasma spraying is carried out with a plasma torch power of 8.5 kW and the speed of passage of the plasma torch along the front surface of 0.25 m / s.