KR-102964293-B1 - Arc Spraying Gun with Laval type nozzle to supply auxiliary gas

Abstract

The present invention relates to an arc spray gun equipped with a Laval-type nozzle that supplies an auxiliary gas capable of extending the lifespan of parts with severe erosion and deterioration, such as water wall tubes, superheater tubes, and reheater tubes inside a boiler, by applying a durable coating mixed with high-hardness carbides. The main configuration of the present invention is an arc spray gun equipped with a laval-type nozzle to which auxiliary gas is supplied, wherein the laval-type nozzle is characterized as a single-stage laval-type nozzle comprising: a body part (10) that narrows toward the exit direction, which is opened in the shape of a truncated cone of inlet/outlet, and injects primary gas from the center toward the exit direction; a pair of wire guides (20) that guide a wire (30) while being positioned to converge toward the front end of the body part (10) on both sides inside the body part (10); a primary diffusion extension part (40) that has a truncated cone shape of inlet/outlet (widening from the front end toward the rear end), with the front end connected to the exit of the body part (10) and the rear end extending outward; and a secondary gas injection part (50) formed to penetrate the outer surface of the body part (10) of inlet/outlet narrow and injects secondary gas into the body part.

Inventors

• 김병두

Assignees

• (주)한국코팅

Dates

Publication Date

20260513

Application Date

20251118

Claims (4)

1. In an arc spray gun equipped with a Laval-type nozzle supplied with auxiliary gas, A laval nozzle is, A single-stage laval-type nozzle comprising: a body part (10) that narrows toward the outlet direction, which is opened in the shape of a truncated cone with an inlet/outlet narrowness, and injects primary gas from the center toward the outlet direction; a pair of wire guides (20) positioned to converge toward the front end of the body part (10) on both sides inside the body part (10) and guiding a wire (30); a primary diffusion extension part (40) that has a truncated cone shape with an inlet/outlet narrowness (a shape that widens from the front end toward the rear end), with the front end connected to the outlet of the body part (10) and the rear end extending outward; and a secondary gas injection part (50) formed to penetrate the outer surface of the body part (10) with an inlet/outlet narrowness and injects secondary gas into the body part. An arc spray gun equipped with a Laval-type nozzle to which auxiliary gas is supplied, characterized by including a two-stage Laval-type nozzle comprising a truncated cone-shaped second diffusion extension part (60) with a front end (61) of the light input/output narrowing connected to the rear end of the first diffusion extension part (40) and a rear end (62) of the light input/output narrowing, and a third gas injection part (70) formed to penetrate the outer surface of the first diffusion extension part (40) and injecting third gas into the interior of the first diffusion extension part (60).
2. An arc spray gun with a Laval-type nozzle attached for supplying auxiliary gas, characterized in that, in claim 1, the secondary gas injection part (50) comprises a plurality of gas injection holes (51) formed to penetrate the body part (10) vertically, and a gas supply port (52) that surrounds the gas injection holes (51) on the outer surface of the body part and supplies secondary gas to each gas injection hole (51) when it flows in.
3. delete
4. An arc spray gun with a Laval-type nozzle for supplying auxiliary gas, characterized in that, in claim 1, the third gas injection part (70) further comprises a plurality of gas injection holes (71) formed to horizontally penetrate the first diffusion extension part (40), and a gas supply port (72) that surrounds the gas injection holes (71) on the outer surface of the first diffusion extension part (40) and supplies the third gas to each gas injection hole (71) when the gas is introduced.

Description

Arc Spraying Gun with Laval type nozzle to supply auxiliary gas The present invention relates to an arc spray gun equipped with a Laval-type nozzle that supplies an auxiliary gas capable of extending the lifespan of parts with severe erosion and deterioration, such as water wall tubes, superheater tubes, and reheater tubes inside a boiler, by applying a durable coating mixed with high-hardness carbides. Since thermal power plants and specialized industrial equipment are continuously exposed to extreme environments such as high temperature, high pressure, wear, and corrosion, technical reinforcement to enhance durability is essential. To this end, technologies for forming wear-resistant and corrosion-resistant coatings on the surfaces of these parts are being applied; among the various coating techniques, electric arc spraying is used in most sites, considering field applicability and productivity. Arc spraying technology, widely used in the field, is a method in which positive and negative voltages are applied to two metal wires, and the wire tips are converged to a single point to melt the wires using arc heat, after which a coating layer is formed on the surface of the base material by spraying it with high-speed compressed air. Although this method can be effectively applied to high-temperature and corrosive environments, it presents several problems due to insufficient kinetic energy of the coating material melted by arc heat. These include poor bonding between the base material and the coating, weak bonding between internal particles, the formation of pores and microcracks within the coating, and reduced thermal conductivity and corrosion resistance resulting from increased oxides. Additionally, uneven wear occurs due to the non-uniform distribution of reinforcing particles. Overseas examples include U.S. published patents US4075376A and US5294462A, which present a fusion process following flame spraying and amorphous arc spraying technology using nitrogen gas, respectively. However, the high-temperature process of flame spraying is unsuitable for on-site power plant applications, and amorphous arc spraying inevitably suffers from insufficient high-temperature hardness and heat resistance. Additionally, although research on plasma-assisted arc spraying technology and the addition of reinforcing particles has been conducted, these technologies have not been utilized due to limitations such as equipment costs and reduced meltability caused by excessive reinforcing particle content. Therefore, there is an urgent need for the development of new coating materials and high-performance arc spraying technology that are suitable for field application and can exhibit excellent performance even in high-temperature and high-wear environments. In conventional arc spraying technology, there have been concerns regarding durability limitations due to insufficient bonding strength with the substrate surface caused by incomplete melting and low-speed flight of molten coating droplets, insufficient bonding strength between particles within the coating layer, occurrence of excessive pores and hair cracks, uneven distribution of hardness due to the uneven distribution of reinforcing particles, and insufficient corrosion resistance due to reduced density, as well as concerns regarding reduced boiler efficiency caused by reduced thermal conductivity resulting from excessive pores, hair cracks, and oxides. Fundamentally resolving these issues has emerged as an important technical challenge. Accordingly, the inventor of the present invention has provided a new technical means to fundamentally solve problems that have persisted until now by overcoming the performance limitations and application technical constraints of existing coating materials. Figure 1 is a cross-sectional view of a conventional arc spray gun nozzle. FIG. 2 is a cross-sectional view of a first arc spray gun Laval-type nozzle for forming a coating layer of a thermal power plant facility according to the present invention. FIG. 3 is a cross-sectional view of a second arc spray gun Laval-type nozzle for forming a coating layer of a thermal power plant facility according to the present invention. FIG. 4 is a cross-sectional photograph of the coating layer of Comparative Example 1 of the present invention. FIG. 5 is a cross-sectional photograph of the coating layer of Example 5 according to the present invention. FIG. 6 is a cross-sectional photograph of the coating layer of Example 8 according to the present invention. Hereinafter, an arc spray gun equipped with a Laval-type nozzle supplied with auxiliary gas according to the present invention will be described in detail. The present invention uses an arc spray gun equipped with a laval nozzle as shown in FIG. 2 and FIG. 3 to perform a coating layer by applying a film material manufactured in the form of a circular cored wire, which overcomes the performance limitations of a conventional arc spray gun nozzle as