KR-102964258-B1 - surface treatment method for reducing cavitation

Abstract

The present invention provides a surface treatment method for reducing cavitation, comprising: a first step in which the surface of a base material where cavitation occurs is cleaned and surface polished so as to improve durability and corrosion resistance; a second step in which a nanonitride layer is formed by depositing a base material on the surface of the base material, wherein the base material is placed inside a vacuum chamber provided for heating the base material, wherein nitrogen gas is injected into the vacuum chamber to generate nitrogen ions inside the vacuum chamber, the base material is heated to a first temperature and maintained for a first time, and then cooled to a second temperature lower than the first temperature; and a third step in which a corrosion-resistant composite powder containing chromium and titanium is applied to the surface of the nanonitride layer and then heated and cooled to perform a thermal diffusion surface treatment.

Inventors

• 방현배
• 문철근

Assignees

• (주)플로원

Dates

Publication Date

20260513

Application Date

20250915

Claims (5)

1. A first step in which the surface of the base material where cavitation occurs is cleaned and surface polished; A second step in which a nanonitride layer is deposited on the surface of the base material, wherein the base material is placed inside a vacuum chamber provided for heating the base material, wherein nitrogen gas is injected into the vacuum chamber to generate nitrogen ions inside the vacuum chamber, the base material is heated to a first temperature and maintained for a first time, and then cooled to a second temperature lower than the first temperature; and A surface treatment method for reducing cavitation comprising a third step in which a corrosion-resistant composite powder containing chromium and titanium is applied to the surface of the nanonitride layer, followed by heating and cooling to perform thermal diffusion surface treatment.
2. In Article 1, The above third step is The step of applying the above corrosion-resistant composite powder to the above nanonitride layer, and A step in which the inside of the vacuum chamber is heated until it reaches a third temperature, and at the same time, an inert gas containing argon is filled into the inside of the vacuum chamber, and A step of maintaining the substrate having the nanonitride layer formed thereon for a second time after heating it to the third temperature, and A surface treatment method for reducing cavitation, characterized by including the step of cooling the substrate on which the nanonitride layer is formed to a fourth temperature to form a thermal diffusion surface treatment layer.
3. In Article 2, A surface treatment method for reducing cavitation, characterized in that the corrosion-resistant composite powder comprises, based on the total weight of the corrosion-resistant composite powder, 9 to 47 weight% chromium, 0.7 to 3.5 weight% titanium, 0.1 to 1.5 weight% activator, and 49 to 89 weight% inactivator.
4. In Article 2, The third temperature is set to a temperature higher than the first temperature, and the fourth temperature is set to a temperature lower than the second temperature, wherein The above third temperature is set to 980~1,100℃, and The above fourth temperature is set to 290~310℃, and A surface treatment method for reducing cavitation, characterized in that the second time is set to 27 to 33 hours.
5. In Article 1, The above first temperature is set to 440~490℃, and The above second temperature is set to 59~90℃, and A surface treatment method for reducing cavitation, characterized in that the first time is set to 13 to 19 hours.

Description

Surface treatment method for reducing cavitation The present invention relates to a surface treatment method for reducing cavitation, and more specifically, to a surface treatment method for reducing cavitation in which durability and corrosion resistance are improved. In general, in devices used underwater, such as ships, cavitation occurs not only due to electrochemical corrosion caused by saltwater but also due to cavities formed by pressure differences naturally arising during the propulsion process, and the growth and activation of these cavities. Here, cavitation occurs because localized energy and shock waves exceeding 10,000 Kelvin (K) temperature cause the metal surface to instantaneously become an active state such as high temperature and ionization, and easily detach due to corrosion and aging. Consequently, there was a serious problem in which accelerated surface roughness due to cavitation and erosion, and the device surface from which corroded metal had detached, not only reduced output efficiency but also increased energy costs due to increased friction and torque with water. Furthermore, there was a problem where underwater noise caused by cavitation was generated, adversely affecting the marine ecosystem. Therefore, there is an urgent need to develop durable underwater devices that protect metal surfaces to improve energy efficiency and reduce underwater noise. FIG. 1 is a flowchart illustrating a surface treatment method for reducing cavitation according to an embodiment of the present invention. FIGS. 2 and FIGS. 3 are exemplary diagrams showing heating temperatures according to process steps in a surface treatment method for reducing cavitation according to an embodiment of the present invention. FIG. 4 is a cross-sectional view of a base material manufactured according to a surface treatment method for reducing cavitation according to an embodiment of the present invention. Hereinafter, a surface treatment method for reducing cavitation according to a preferred embodiment of the present invention will be described in detail with reference to the attached drawings. To clearly explain the present invention, parts unrelated to the explanation have been omitted from the drawings, and in the drawings, the width, length, thickness, etc. of the components may be exaggerated for convenience. FIG. 1 is a flowchart showing a surface treatment method for reducing cavitation according to an embodiment of the present invention, FIG. 2 and FIG. 3 are exemplary diagrams showing heating temperatures according to process steps in a surface treatment method for reducing cavitation according to an embodiment of the present invention, and FIG. 4 is a cross-sectional view of a base material manufactured according to a surface treatment method for reducing cavitation according to an embodiment of the present invention. As shown in FIG. 1, a surface treatment method for reducing cavitation according to an embodiment of the present invention comprises a first step (s10) in which the surface of a base material (10) where cavitation occurs is cleaned and surface polished; a second step (s20) in which the base material (10) is heated to a first temperature for a first time and then cooled to a second temperature lower than the first temperature to form a nanonitride layer (20) on the surface of the base material (10); and a third step (s30) in which a corrosion-resistant composite powder is applied to the surface of the nanonitride layer (20) and then heated and cooled to perform thermal diffusion surface treatment. Furthermore, it is preferable to understand the above base material (10) as the surface of the hull or turbine blade. In addition, the surface treatment method for reducing cavitation according to one embodiment of the present invention can be applied not only to the surface of the hull or turbine blade but also to the surface of ceramic-metal composites or metals and alloys to improve durability and surface strength. Furthermore, it can be applied not only to surfaces where cavitation occurs but also to general metal surfaces to improve durability and corrosion resistance. Here, the above-mentioned base material (10) may include a rotating body part to which a power shaft is connected in the central part when equipped as a rotor of a hull propulsion means, and a plurality of wing parts that extend radially in a circular direction on the outer surface of the rotating body part. Meanwhile, the surface of the base material (10) where cavitation occurs is cleaned and surface polished (s10). At this time, in one embodiment of the present invention, the case in which the base material (10) is provided as a stainless steel material is illustrated and described as an example. Of course, depending on the case, the base material (10) may be provided as a metal material other than stainless steel. In detail, the base material (10) may be provided with either S45C or SUS316 material. In this case, if the base ma