SU1663056A1 - Method of producing composite coats - Google Patents

Abstract

The invention relates to the electrochemical deposition of multilayer composite coatings on products and can be used to protect products operating in aggressive environments, such as oil wells. The purpose of the invention is to increase the corrosion-mechanical resistance of products. The method of obtaining composite coatings on products includes the sequential electrochemical deposition of layers of nickel, nickel with particles of titanium carbide and boron, nickel and nickel with particles of silicon nitride with a ratio of the thickness of the layers of nickel and nickel with particles 1: (1-5) and equal thickness of the layers homogeneous in structure. The method makes it possible to increase the corrosion-mechanical resistance of products by a factor of 2–3 compared with the known method of applying composite coatings to nickel-particles of titanium carbide and boron. 2 tab.

Description

The invention relates to the electrochemical deposition of multilayer composite coatings on products and can be used to protect products operating in aggressive environments, such as oil wells.

The purpose of the invention is to increase the corrosion and mechanical resistance of products.

The proposed method for producing composite coatings will include sequential electrochemical deposition of layers of nickel, nickel with titanium carbide and boron particles, nickel with silicon nitride particles with a ratio of 1: (1-5) layers of nickel and nickel and uniform thickness of the layers.

Nickel plating electrolytes are prepared for the implementation of the method. Nickel chloride and boric acid are dissolved in separate tanks in water heated to 50-60 ° C. Both solutions are combined, the preliminary and main baths are filled with the resulting solution. Then, the mixture of titanium carbide powders and boron powders and powder is diluted into a creamy state in separate containers with the resulting solution.

silicon nitride. The resulting gruel from a mixture of powdered carbide titanium and iodine is added to the pre-bath, and the gruel from silicon nitride powder is added to the main bath,

The coating process is as follows.

Depending on the required coating thickness, electrodeposition is carried out at a current density of A / dm, the same for both baths. First, the parts to be coated are placed in a pre-bath. The first 10-15 minutes the process of electroplating is carried out in a calm bath. Since the first 10-15 min process goes in a calm bath,

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This is followed by the precipitation of pure nickel with a layer of 1–5 μm, and then the deposition of nickel with particles of the solid phase during electrolyte sparging. After applying the precoat, the parts are washed in water and transferred to the main bath, where the electroplating process is carried out similarly to the process in a pre-bath.

The deposition time of nickel layers is 10-15 minutes. The deposition time of nickel layers with particles of solid phases is 15-45 minutes, which ensures the formation of coatings with the required ratio of layer thicknesses. The proposed method can produce high quality coatings up to 100 microns thick. In order to increase the adhesion of the coating to the surface of the part, it is necessary to agglomerate the coating preferably in vacuum at 900 - 950 ° C with a dwell time of 20 - 40 minutes.

When titanium and boron carbide particles are present together in the coating, an increase in the corrosion resistance of the resulting coating is observed, which occurs due to the inhibition of the said particles in the preliminary coating layer, and due to the physicochemical nature of the particles themselves a layer of silicon nitride particles deposited on a layer of particles of titanium carbide and boron. Nickel layers provide adhesion of the entire coating to the surface of the product and adhesion between the composite layers. With this combination of solid particles and layers in the coating, a significant increase in wear resistance is observed when exposed to high sliding speed and specific load. During sintering, diffusion saturation of the base metal and the sintering of particles of the solid phase and nickel occurs with nickel. The result is a dense, pore-free coating characterized by high wear resistance and adhesion to the base metal,

The compositions used electrolytes and electrolysis modes are given in table 1.

After coating, parts of 1-4 batches were heat treated at 950 ° C for 25 minutes.

The thickness of the obtained coating was determined with a micrometer of the type MK 0-25 (GOST 6507-78) by measuring the cleavage of the small surface of the coating of the sample under study.

Hardness was determined by the Vickers method using a PMT-3 type microhardness meter.

The study of corrosion-mechanical resistance was carried out on the installation of friction and wear of the UT1 / 1-1 type;

conditions are created in which parts of a submerged electric motor are operating in an oil well, i.e. The specific load on the sample was 90 kg / cm2, the sliding speed was 8 m / s, and the surrounding atmosphere was a salt-acetic-copper fog at 50 ° C and a humidity of 96%. Tests on the installation were carried out continuously for 2 shifts (16 h).

Corrosion has also been determined

resistance to the residence time of a part in a vessel with a mixture of hydrochloric and sulfuric acids. Extracting parts in a vessel is 2 shifts (16 hours).

The adhesion of the coating to the base metal was determined by bending the specimen through 180 ° until fracture.

The properties of the coatings are given in table 2. As can be seen from the data of Table 2, the proposed method makes it possible to increase the corrosion-mechanical resistance of products several times in comparison with the prototype.

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Claims (1)

Invention Formula The method of obtaining composite coatings, including electrochemical deposition of a layer of nickel with particles of titanium carbide and boron on the products and subsequent thermal processing, characterized in that. that, in order to increase the corrosion-mechanical resistance of products, a nickel layer is preliminarily electrochemically deposited on them, and after applying a layer Nickel with particles of titanium carbide and boron successively electrochemically deposit a layer of nickel and nickel with particles of silicon nitride at a ratio of the thickness of the layers of nickel and nickel with particles of 1: (1–5) and equality between the thickness of the homogeneous layers. Sample Coating properties Common 40 40 40 40 40 50 50 ten 7 five four 3.4 i Vickers hardness, HV Corrosion and mechanical resistance, h Corrosion resistance in a mixture of acids, h Adhesion ten 13 15 sixteen 16.6 50 ten 7 five four 3.4 10 13 15 16 16.6 1: 1 1: 2 1: 3 1: 4 1: 5 430 438 445 452 460 380 400 32 32 32 32 32 five 7 32 32 32 32 32 6 five Wes ki Without either Without either No ki No ki No ki Without either exfoliation of the layer of the layer of the aivotel aivaot the layer of the layer., from from with about 1L from