A coating for preventing marine biofouling and a preparation method thereof

Abstract

The present invention belongs to the field of new materials and surface engineering, and provides a coating for preventing marine biofouling and a preparation method thereof. The raw material for preparing the anti-fouling cladding layer of the present invention is Cu-Fe-Sn-Si-P alloy powder; the anti-fouling cladding layer forms a deironing layer due to electrochemical corrosion in a seawater environment, and Fe in the anti-fouling cladding layer will participate in the above process, and the Fe atoms include two parts: one part of Fe atoms and Cu atoms form a partially ordered segregated Cu-Fe-Sn-Si-P solid solution; the other part is Fe atoms in an Fe-rich precipitated phase; through the joint action of the above two parts of Fe atoms, a deironing layer with a copper-based solid solution as a skeleton and containing micro-channels with a diameter of 200 to 3000 nm is formed in the anti-fouling cladding layer along the thickness direction. The deironing layer with micro-channels significantly increases the contact area between the anti-fouling cladding layer and seawater, and has the functions of storing copper ions, promoting the shedding of surface corrosion products, and effectively preventing the attachment of marine organisms.

Description

Technical Field

[0001] The invention belongs to the technical field of new materials and surface engineering, and in particular relates to a coating for preventing marine biofouling and a preparation method thereof. Background Art

[0002] Ships and offshore installations operate in a complex and volatile marine environment, subject to the hazards of marine biofouling and requiring surface antifouling measures. Approximately 90% of global trade is conducted by sea, contributing nearly 3% of the world's carbon dioxide emissions. Marine biofouling on the hulls of large cargo ships can reduce fuel efficiency by approximately 50%.

[0003] In the 1950s, antifouling coatings based on organotin were invented. Their excellent antifouling properties gradually captured the global market. Since the 1980s, the primary antifouling coating used on ships worldwide has been TBT self-polishing antifouling coatings containing organotin. However, research has shown that TBT accumulates in organisms and is difficult to degrade, significantly impacting the reproduction and genetics of marine life. Since 2008, TBT self-polishing antifouling coatings have been gradually banned worldwide, and researchers have gradually shifted their focus to tin-free self-polishing antifouling coatings (TF-SPC), which contain toxic materials such as cuprous oxide. Research and development of the first generation of TF-SPC antifouling coatings began in the 1980s. These coatings primarily consist of a hydrolyzable base, low-toxic cuprous oxide, and an auxiliary agent. However, research has shown that the added auxiliary agent poses almost as harmful a threat to the ocean as organotin. The second generation of antifouling coatings is Wuxi self-polishing antifouling coatings. Its self-polishing is based on ion exchange to produce a hydrolyzable active surface layer, and inorganic fibers are added to the resin; this ensures the control of the polishing rate and enhances the bonding strength of the paint film.

[0004] After nearly 30 years of development, hydrated, hydrolyzed, and hybrid Wuxi self-polishing antifouling coatings have been commercially available both domestically and internationally. These coatings have a lifespan of three years, five years, and three to five years, respectively. However, they still have limitations. For example, zinc acrylate self-polishing antifouling coatings experience stagnant film thickness loss after 30 months, essentially losing their antifouling properties.

[0005] Researchers at the Smith Environmental Research Center in the United States have found through experimental studies that aged microplastics such as polystyrene (PS) and polyvinyl chloride (PVC) in organic coatings can act as carriers of heavy metal ions such as Cu and Zn and exist in the ocean for a long time, posing a serious threat to marine life and the environment.

[0006] In general, the limitations of existing self-polishing antifouling coatings are as follows:

[0007] (1) Since there is no water flow to polish the antifouling layer when the ship is stationary, the antifouling effect of the antifouling coating is poor when the ship is stopped for a long time;

[0008] (2) VOCs and other harmful substances (such as zinc oxide, diuron, etc.) contained in antifouling coatings have caused serious pollution to the environment;

[0009] (3) Microplastics released into the ocean by antifouling coatings are difficult to degrade naturally, posing a serious threat to marine life and the environment.

[0010] Copper alloys can release a certain concentration of copper ions during immersion in seawater and have excellent antifouling properties. By utilizing the toxicity of copper to fouling organisms and releasing copper ions through copper corrosion, the attachment of fouling organisms can be inhibited. At present, copper alloys have been widely used in seawater piping systems, propellers and other parts of ships. However, under the environment of marine salt spray corrosion and seawater corrosion, a relatively dense layer of corrosion products such as basic copper chloride, basic copper carbonate and other corrosion products will form and adhere to the surface of traditional copper alloys. The continuous deposition of these corrosion products leads to a significant decrease in the precipitation rate of copper ions, which seriously affects the antifouling effect. A large number of examples have shown that when ships are anchored for a long time, commonly used copper alloy propellers basically lose their antifouling ability. Photos of copper alloy propellers suffering from severe marine fouling can be seen in Figure 1 Domestic researchers conducted a 12-month live-sea test on eight traditional copper alloys in Zhanjiang Port and found that the surfaces of most traditional copper alloys were completely covered by marine organisms such as bryozoans and barnacles, essentially losing their antifouling capabilities, with the antifouling effectiveness lasting less than 12 months. Summary of the Invention

[0011] In view of this, the object of the present invention is to provide a coating for preventing marine biofouling and a preparation method thereof. The coating for preventing marine biofouling provided by the present invention can prevent marine biofouling in a long-term manner.

[0012] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0013] The present invention provides a coating for preventing fouling by marine organisms, comprising an antifouling cladding layer provided on a metal substrate;

[0014] The anti-fouling cladding layer is a metastable phase anti-fouling cladding layer;

[0015] The anti-fouling cladding layer includes a dispersed Fe-rich precipitate phase and a Cu-rich solid solution containing supersaturated Fe; the Cu-rich solid solution containing supersaturated Fe is a Cu-Fe-Sn-Si-P copper-based solid solution;

[0016] The raw material for preparing the anti-fouling cladding layer is Cu-Fe-Sn-Si-P alloy powder;

[0017] The Cu-Fe-Sn-Si-P alloy powder is prepared from raw materials having the following mass percentages:

[0018] Fe: 8-40%; Sn: 0.3-8%; Si: 0.1-0.5%; P: 0.1-0.5%; Cu: balance;

[0019] The metal matrix includes a steel matrix, a copper alloy matrix, a titanium alloy matrix and an aluminum alloy matrix.

[0020] Preferably, when the metal substrate is a steel substrate or an aluminum alloy substrate, a corrosion-resistant primer cladding layer is further provided between the metal substrate and the anti-fouling cladding layer;

[0021] The raw material for preparing the corrosion-resistant base cladding layer is Ni-Cr-Mo-Nb-Si alloy powder;

[0022] The Ni-Cr-Mo-Nb-Si alloy powder is prepared from raw materials comprising the following mass percentages:

[0023] Cr: 20-24%; Mo: 14-18%; Nb: 1-1.5%; Si: 0.5-1%; Ni: balance.

[0024] Preferably, the anti-fouling cladding layer has a thickness of 300 to 1000 μm; the corrosion-resistant base cladding layer has a thickness of 100 to 400 μm.

[0025] Preferably, the particle sizes of the Ni—Cr—Mo—Nb—Si alloy powder and the Cu—Fe—Sn—Si—P alloy powder are independently 200-400 meshes.

[0026] Preferably, the method for preparing the Cu-Fe-Sn-Si-P alloy powder comprises the following steps:

[0027] Cu, Fe, Sn, Si and P are mixed according to their mass percentages, and subjected to a first heating and melting process to obtain an anti-fouling alloy melt;

[0028] performing a first atomization powdering on the anti-fouling alloy melt to obtain the Cu-Fe-Sn-Si-P alloy powder;

[0029] The first heating and melting temperature is 1180-1450° C., and the holding time is 30-60 minutes;

[0030] The parameters of the first atomization powder making process include: the atomization medium is nitrogen, and the flow rate of the anti-fouling alloy melt is 0.5-1 kg / min.

[0031] Preferably, the method for preparing the Ni-Cr-Mo-Nb-Si alloy powder comprises the following steps:

[0032] Mixing Ni, Cr, Mo, Nb and Si according to their mass percentages, and performing a second heating and melting process to obtain a base alloy melt;

[0033] The base alloy melt is subjected to a second atomization powdering to obtain the Ni-Cr-Mo-Nb-Si alloy powder;

[0034] The temperature of the second heating and melting is 1400-1600° C., and the holding time is 30-60 minutes;

[0035] The parameters of the second atomization powder making process include: the atomizing medium is nitrogen, and the flow rate of the base alloy melt is 0.5-1 kg / min.

[0036] The present invention also provides a method for preparing the coating for preventing marine biofouling as described in the above technical solution, comprising the following steps:

[0037] Pre-treating a metal substrate to obtain a pre-treated substrate; the metal substrate includes a steel substrate, a copper alloy substrate, a titanium alloy substrate and an aluminum alloy substrate;

[0038] An antifouling cladding layer is prepared on the pretreated substrate by a first laser cladding process to obtain the coating for preventing fouling by marine organisms.

[0039] Preferably, the parameters of the first laser cladding include: powder feeding rate of 0.8-2 kg / h, laser power of 2-6 kW, relative movement speed of laser spot and workpiece of 10-25 cm / s, flow rate of shielding gas of 15-20 L / min, and laser head stepping distance of 0.5-0.8 mm.

[0040] Preferably, when the metal substrate is a steel substrate and an aluminum alloy substrate, it also includes preparing a corrosion-resistant base cladding layer; the preparation method of the corrosion-resistant base cladding layer is a second laser cladding; the parameters of the second laser cladding include: powder feeding rate of 0.8~2kg / h, laser power of 2~6kW, relative movement speed of laser spot and workpiece of 10~25cm / s, flow rate of shielding gas of 15~20L / min, and laser head stepping distance of 0.5~0.8mm.

[0041] Preferably, the pretreatment includes removing the oxide layer, cleaning and drying in sequence; the method for removing the oxide layer includes sandblasting or electric grinding wheel grinding; and the cleaning agent includes acetone.

[0042] The present invention provides a coating for preventing fouling by marine organisms, comprising an antifouling cladding layer provided on a metal substrate; the antifouling cladding layer is a metastable phase antifouling cladding layer; the antifouling cladding layer comprises a dispersed Fe-rich precipitate phase and a Cu-rich solid solution containing supersaturated Fe; the Cu-rich solid solution containing supersaturated Fe is a Cu-Fe-Sn-Si-P copper-based solid solution; the raw material for preparing the antifouling cladding layer is Cu-Fe-Sn-Si-P alloy powder; the Cu-Fe-Sn-Si-P alloy powder is prepared from raw materials comprising the following mass percentages: Fe: 8-40%; Sn: 0.3-8%; Si: 0.1-0.5%; P: 0.1-0.5%; Cu: balance; the metal substrate comprises a steel substrate, a copper alloy substrate, a titanium alloy substrate and an aluminum alloy substrate.

[0043] Beneficial effects:

[0044] According to phase diagrams and experimental results, under equilibrium conditions, the solid solubility of Cu and Fe in each other is very low. At 1050°C, the solid solubility of Fe in Cu is only 3.5%, and at 635°C, the solid solubility drops to 0.15%. At 1477°C, the solid solubility of Cu in Fe is 8.5%, and below 650°C, the solid solubility is only 0.35%. To address this problem, the present invention utilizes a rapid solidification method to prepare a metastable anti-fouling cladding layer, resulting in the anti-fouling cladding layer comprising a Cu-rich solid solution containing supersaturated Fe and an iron-rich precipitate phase; the Cu-rich solid solution containing supersaturated Fe is a Cu-Fe-Sn-Si-P copper-based solid solution. By utilizing the electrochemical corrosion effect of natural seawater on the anti-fouling cladding layer, a de-ironization layer containing microchannels with diameters of approximately 200 to 3000 nm is formed along the thickness of the anti-fouling cladding layer, with a copper-based solid solution as the framework. The deironing layer with microchannels significantly increases the contact area between the anti-fouling cladding layer and seawater, and the microchannels have the function of storing copper ions; through the combined action of alloying and microchannels, the bonding strength between the corrosion products and the anti-fouling cladding layer is effectively reduced, making the corrosion products on the surface of the cladding layer loose and containing a large number of holes and cracks; at a certain flow rate, these loose corrosion products containing a large number of holes and cracks can peel off by themselves, thereby achieving a self-polishing effect and achieving the purpose of long-term prevention of marine organism attachment.

[0045] The key point of the present invention is to use a metastable antifouling coating to form a de-ironization layer in a seawater environment. The Fe atoms involved in the reaction are composed of two parts: (1) a part of the Fe atoms and Cu atoms form a partially ordered segregated Cu-Fe-Sn-Si-P solid solution; according to the standard electrode potential table of commonly used electrode reactions, (Fe 2+ / Fe) and (Cu 2+ The standard electrode potentials of Cu and E 0 Cu=0.34V(vs SHE); E 0 Fe =-0.45V (vs SHE); therefore, in a seawater environment, due to the higher chemical activity of Fe atoms, they can preferentially react to form iron oxides; the reaction starts from the surface, and the iron atoms in contact with seawater preferentially react and form vacancies at the corresponding positions. The Cu atoms around the vacancies are no longer bound by Fe atoms, and are affected by the force to diffuse, agglomerate, and grow; since the microchannels formed by corrosion are quite narrow and long, it can be assumed that the solution in the microchannel is stationary, and there is no material exchange with the external solution, but there is a closed system for energy exchange. Since there is no material exchange between the microchannel and the outside world, the microchannel is an oxygen-deficient corrosion environment. The front end of the microchannel is a microenvironment with a lower pH. Under the action of the voltage potential in the microchannel, iron cations diffuse outward toward the microchannel mouth, and eventually form iron oxides at the microchannel mouth. Some Fe atoms undergo hydrolysis reactions in the corrosion pits. According to existing literature, the main product is γ-FeOOH. Affected by Cl - Due to the influence of pH value in the micro-area at the mouth of the micro-channel, γ-FeOOH will be further converted into Fe(OH)Cl in the micro-channel. As a result, most of the loose corrosion products formed are deposited on the surface of the cladding layer, while a small amount of corrosion products are deposited inside the micro-channel. Affected by the potential drop inside the corrosion pit and the change of pH value, the micro-channel gradually spreads and grows inside the anti-fouling cladding layer. Since the Fe atom segregation area has a certain randomness, a large number of curved micro-channels similar to earthworm holes (with a diameter of 200 to 3000 nm) connected to the surface of the anti-fouling cladding layer are gradually formed; (2) Another part of the reaction is the Fe atoms in the Fe-rich precipitate phase; if the Fe-rich precipitate phase is exposed on the surface of the cladding layer, Fe directly reacts with seawater to generate iron corrosion products, which dissolve into seawater to form corrosion channels. For the Fe-rich precipitate phase inside the cladding layer, when the microchannels are connected to the Fe-rich precipitate phase, the Fe-rich precipitate phase comes into contact with seawater, and after dealloying, corrosion holes connected to the microchannels are formed (holes with a shape basically the same as that of the Fe-rich precipitate phase). The micropores also become part of the microchannels (the cross-sectional diameter of this area is larger than the diameter of other areas without Fe-rich precipitates). The formation process of its corrosion products is similar to that in (1). Through the combined action of the above two parts of Fe atoms, a microchannel de-ironification layer with a copper-based solid solution as the skeleton and a depth that increases with time is formed in the cladding layer along the thickness direction. Due to the segregation of iron elements at the microscale, the microchannels may also bifurcate as the length increases.

[0046] Experiments show that when the antifouling cladding layer is placed in static artificial seawater, the thickness h of the de-ironization layer is exponentially related to the time t, and approximately satisfies h(t) = At m Relationship, in the above formula, A, m are constants, 0 <m<1。

[0047] Assuming the thickness of the anti-fouling cladding layer is H, the time required for the anti-fouling cladding layer to be iron-free is The time required for the anti-fouling cladding layer to lose iron can be determined based on experimental results. For example, when the iron content is in the range of 10-40% and H = 500 μm, the time required for the anti-fouling cladding layer to lose iron in static seawater is 100-140 days.

[0048] According to the above analysis, the service process of the anti-fouling cladding layer can be divided into two stages:

[0049] The first stage is the iron removal stage of the anti-fouling cladding layer, and the second stage is the copper ion seepage stage with a stable iron removal layer thickness after iron removal. For the second stage, assuming that the copper ion seepage rate remains unchanged, the annual consumption rate of the anti-fouling cladding layer can be estimated. Assume that the copper content of the anti-fouling cladding layer before immersion in seawater is C, and the copper ion steady-state release rate is M (unit: μg·cm -2 ·d -1 ), then the thickness reduction rate of the anti-fouling cladding layer is approximately calculated based on experimental and theoretical analysis.

[0050] The thickness of the antifouling coating can be designed according to the required antifouling effect. For example, if the thickness of the antifouling layer is H = 500 μm, then when M = 40 μg·cm -2 ·d -1 When C=70%, h=24.3μm; the antifouling period can be approximately calculated as T2=20.6 years.

[0051] According to the above analysis, the time of the second stage of stable copper ion seepage is much longer than the time required for the formation of the deironing layer.

[0052] The micro-pipeline layer has the following functions:

[0053] (1) In the first stage of the formation of the deironing layer, although the iron in the antifouling cladding layer is corroded before the copper, which reduces the copper ion release rate per unit area of ​​the antifouling cladding layer, when a large number of microchannels in contact with seawater are formed, the contact area between the antifouling cladding layer and the seawater is significantly increased. Assuming that there are n microchannels with circular cross sections per unit area of ​​the antifouling cladding layer, the average diameter of the microchannel cross section is d, and the length is L, then the actual contact area between the cladding layer per unit surface area and the seawater is (1+πndL); since the length of the microchannel increases with time, the contact area between the antifouling cladding layer per unit area and the seawater also increases with time. When the thickness of the deironing layer reaches the thickness of the antifouling cladding layer, the first stage of deironing is completed and enters the second stable release stage.

[0054] (2) The microchannel is a long and narrow blind hole with a length much larger than its diameter. Therefore, it can be approximately assumed that even under dynamic conditions, the seawater in the microchannel is in a static state. The copper ion concentration in the microchannel is higher than the copper ion concentration outside the microchannel. Therefore, there is only diffusion of copper ions from the inside of the microchannel to the outside of the outlet. In this way, the copper ion concentration in the seawater in the microchannel can be kept at a high level. That is, the microchannel has the function of storing copper ions, thereby storing some copper ions in the anti-fouling cladding layer. When marine organisms adhere to the surface of the anti-fouling cladding layer, the high concentration of copper ions released by the microchannel can effectively inhibit the growth of marine organisms (see Figure 2 ).

[0055] After the microchannels are formed, the copper on the inner wall of the microchannels that is in contact with seawater will also undergo electrochemical corrosion. Since the seawater in the microchannels is in a static state, the dissolved oxygen and OH in the seawater in the microchannels - 、HCO3 - The concentration decreases continuously with the increase of reaction time, which is beneficial to inhibiting the formation of basic copper carbonate and basic copper chloride on the inner surface of the microchannel. Assuming that the microchannel continuously releases copper ions from the outlet into the seawater at a certain rate (non-constant rate), through theoretical analysis, it can be found that the pore size of the microchannel increases with time, and the pore size of the area near the microchannel outlet increases at the fastest rate over time. According to the existing electrochemical corrosion theory, it can be found that the copper ion concentration in the area near the microchannel outlet in seawater is significantly higher than the copper ion concentration in the area without microchannels at the same vertical coordinate. The copper ion concentration distribution in the area near the microchannel is as follows: Figure 3 As shown, the copper ion concentration is Figure 3 The depth of the color is proportional to the color.

[0056] (3) By adding the alloying effect of Sn, Si and P elements, the bonding strength between the corrosion products and the anti-fouling cladding layer can be reduced, making the corrosion products on the surface of the cladding layer loose and containing cracks. Through the truncation effect at the outlet of the micro-pipeline, the corrosion products on the surface of the anti-fouling cladding layer produce a large number of 200 to 3000 μm holes; at a certain flow rate, these loose surface corrosion products containing holes and cracks can peel off by themselves, thereby achieving a self-polishing effect.

[0057] The coating for preventing marine biofouling of the present invention can be used for various structural parts working in harsh marine environments, such as the outer plates below the waterline of ships, propellers, sonar domes, seawater piping systems, steel structures of offshore drilling platforms in contact with seawater, and steel structures of offshore wind turbines in contact with seawater.

[0058] The present invention also provides a method for preparing a coating that prevents marine biofouling as described in the above technical solution, comprising the following steps: pre-treating a metal substrate to obtain a pre-treated substrate; the metal substrate includes a steel substrate, a copper alloy substrate, a titanium alloy substrate, and an aluminum alloy substrate; preparing an anti-fouling cladding layer on the pre-treated substrate by a first laser cladding to obtain the coating that prevents marine biofouling. The preparation method of the present invention prepares an anti-fouling cladding layer by laser cladding, so that the anti-fouling cladding layer and the metal substrate are metallurgically bonded, and the bonding strength can reach more than 30 times that of the anti-fouling coating. The anti-fouling cladding layer can work for a long time in harsh environments such as high stress, temperature changes, and alternating dry and wet corrosion, avoiding the shortcomings caused by the low bonding strength of coatings and thermal spray coatings, and has the advantages of long-lasting and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 A photo of a copper alloy propeller severely damaged by marine organisms;

[0060] Figure 2 Schematic diagram of the anti-fouling mechanism of the micro-channel anti-fouling cladding layer in seawater environment. Figure 2 In the figure, 1 is the substrate, 2 is the Cu-rich matrix phase of the anti-fouling cladding layer, 3 is the Fe-rich precipitated phase of the anti-fouling cladding layer, 4 is the hole formed by the corrosion of the Fe-rich precipitated phase during seawater immersion, 5 is the microchannel formed in the anti-fouling cladding layer during seawater immersion, 6 is the marine fouling organism (barnacle) attached to the surface of the anti-fouling cladding layer with microchannels, and 7 is the corrosion product generated on the surface of the anti-fouling cladding layer;

[0061] Figure 3 This is a schematic diagram of the copper ion concentration distribution in seawater near the micro-channel. Figure 3 In the figure, the copper ion concentration is proportional to the depth of the color. 8 is the surface of the anti-fouling cladding layer, and 9 is the micro-pipeline;

[0062] Figure 4 This is a schematic diagram of rudder blade cladding in Example 1. Figure 4 In the figure, 10 is the upper surface of the rudder blade, 11, 12, 13 are the weld areas, 14 is the side steel plate of the rudder blade, and 15 is the bottom plate of the lower end of the rudder blade;

[0063] Figure 5 This is a photo of the rudder blade after cladding is completed in Example 1;

[0064] Figure 6 This is the copper ion release rate curve of the anti-marine biofouling coating prepared in Example 2 after being immersed in a simulated seawater environment for one month;

[0065] Figure 7 This is a photo of the propeller hub cap after cladding is completed in Example 3;

[0066] Figure 8This is a cross-sectional scanning electron microscope photograph of the anti-fouling cladding layer prepared in Example 2. Figure 8 Among them, 16 is the Fe-rich precipitation phase, and 17 is the Cu-rich matrix phase;

[0067] Figure 9 For Figure 8 The results of the surface scan analysis of the 16 areas in the middle, Figure 9 Among them, 18 is the distribution result of Cu element, and 19 is the distribution result of Fe element;

[0068] Figure 10 This is a scanning electron microscope image of the microchannels formed in the antifouling cladding layer in Example 2 after immersion in a simulated seawater environment for 2 months;

[0069] Figure 11 This is the line scan result of the cross section of the anti-fouling cladding layer in Example 2 after immersion in a simulated seawater environment for 2 months. Figure 11 In the figure, 20 is the element content curve of Cu, and 21 is the element content curve of Fe;

[0070] Figure 12 This is a low-magnification scanning electron microscope photograph of the cross section of the anti-fouling cladding layer with micro-channels in Example 2 after immersion in a simulated seawater environment for 2 months. Figure 12 In the figure, 22-27 are micro-area scanning areas at different positions;

[0071] Figure 13 This is a surface morphology of the anti-fouling cladding layer in Example 2 after being immersed in a simulated seawater environment for 2 months. DETAILED DESCRIPTION

[0072] The present invention provides a coating for preventing fouling by marine organisms, comprising an antifouling cladding layer provided on a metal substrate;

[0073] The anti-fouling cladding layer is a metastable phase anti-fouling cladding layer;

[0074] The anti-fouling cladding layer includes a dispersed Fe-rich precipitate phase and a Cu-rich solid solution containing supersaturated Fe; the Cu-rich solid solution containing supersaturated Fe is a Cu-Fe-Sn-Si-P copper-based solid solution;

[0075] The raw material for preparing the anti-fouling cladding layer is Cu-Fe-Sn-Si-P alloy powder;

[0076] The Cu-Fe-Sn-Si-P alloy powder is prepared from raw materials having the following mass percentages:

[0077] Fe: 8-40%; Sn: 0.3-8%; Si: 0.1-0.5%; P: 0.1-0.5%; Cu: balance;

[0078] The metal matrix includes a steel matrix, a copper alloy matrix, a titanium alloy matrix and an aluminum alloy matrix.

[0079] In the present invention, unless otherwise specified, the raw materials used in the present invention are preferably commercially available products.

[0080] The coating for preventing fouling by marine organisms provided by the present invention includes an antifouling cladding layer provided on a metal substrate. In the present invention, the metal substrate includes a steel substrate, a copper alloy substrate, a titanium alloy substrate, and an aluminum alloy substrate. In the present invention, the antifouling cladding layer is a metastable phase antifouling cladding layer. In the present invention, the antifouling cladding layer includes a dispersed Fe-rich precipitate phase and a Cu-rich solid solution containing supersaturated Fe; the Cu-rich solid solution containing supersaturated Fe is a Cu-Fe-Sn-Si-P copper-based solid solution. In the present invention, the particle diameter of the Fe-rich precipitate phase is preferably 200 to 1000 nm.

[0081] In the present invention, the thickness of the anti-fouling cladding layer is preferably 300 to 1000 μm, more preferably 400 to 900 μm, and even more preferably 500 to 800 μm. In the present invention, the raw material for preparing the anti-fouling cladding layer is Cu-Fe-Sn-Si-P alloy powder; the particle size of the Cu-Fe-Sn-Si-P alloy powder is preferably 200 to 400 mesh.

[0082] In the present invention, the Cu-Fe-Sn-Si-P alloy powder is prepared from raw materials comprising the following mass percentages: Fe: 8-40%; Sn: 0.3-8%; Si: 0.1-0.5%; P: 0.1-0.5%; and Cu: the balance.

[0083] In the present invention, the raw materials of the Cu-Fe-Sn-Si-P alloy powder include Fe in an amount of 8-40% by mass, preferably 10-40%, and more preferably 15-35%. In the present invention, the role of the Fe element is: (1) it has a lower electrode potential and higher chemical activity, can be preferentially dissolved, and helps to form a de-ironized micro-channel layer and micro-pores in the anti-fouling cladding layer; (2) the micro-channels formed after de-ironization can cause the corrosion products on the surface of the anti-fouling cladding layer to produce a large number of pore defects, which helps to peel off the corrosion products and achieve a self-polishing effect. If the Fe content in the anti-fouling cladding layer is too low, the volume fraction of the micro-channels formed in the anti-fouling cladding layer is also low, and the purpose of significantly better anti-fouling performance than flat copper alloys cannot be achieved. Although a high iron content is conducive to the formation of a larger volume fraction of micro-channels in the anti-fouling cladding layer, if the Fe content in the anti-fouling cladding layer is too high, it will lead to an increase in the annual thinning rate of the anti-fouling cladding layer thickness and a decrease in the anti-fouling effect. Therefore, based on the experiments, an optimized range of Fe mass percentage of 8 to 40% is proposed.

[0084] In the present invention, the raw materials of the Cu-Fe-Sn-Si-P alloy powder include Sn in an amount of 0.3 to 8% by weight, preferably 3 to 7%, and more preferably 4 to 6%. In the present invention, the role of Sn is to promote the formation of stratified corrosion products of different components on the surface of the copper alloy cladding layer, and to cause a large number of microcracks in the corrosion products through the internal stress generated between the corrosion products of different components, thereby preventing the copper ion release rate from rapidly decreasing due to the thickening of the corrosion products.

[0085] In the present invention, the raw material of the Cu-Fe-Sn-Si-P alloy powder includes Si in an amount of 0.1-0.5% by mass, preferably 0.2-0.4% by mass, and more preferably 0.35% by mass.

[0086] In the present invention, the raw material of the Cu-Fe-Sn-Si-P alloy powder includes 0.1-0.5% by mass of P, preferably 0.15-0.3%, and more preferably 0.25%.

[0087] In the present invention, the raw materials of the Cu-Fe-Sn-Si-P alloy powder include a balance of Cu. In the present invention, Cu is an essential element for improving the antifouling performance of the antifouling cladding layer in seawater, and can provide copper ions to kill marine organisms. In addition, when the antifouling cladding layer is prepared by laser cladding, Cu can cause the supersaturated Fe in the melt to precipitate during solidification, thereby forming a dispersed Fe-rich phase and a Cu-rich matrix phase. At room temperature, Cu and Fe have different crystal structures and cannot form an infinite solid solution. The solid solubility of Fe in Cu is very small. In the process of preparing the anti-fouling cladding layer, the powder material is first heated to a temperature above the melting point by the laser beam. When the laser beam is removed, the molten pool cools down rapidly and solidifies rapidly. Due to the low solubility of Fe in Cu, part of Fe precipitates during the solidification process, forming a dispersed non-stable Fe-rich phase (the Fe-rich phase is a Fe-Cu-Sn-Si-P solid solution with high Fe content and low Cu content) and a non-stable Cu-rich phase (Cu-Fe-Sn-Si-P solid solution containing supersaturated Fe).

[0088] In the present invention, Fe is added to the alloy powder. Some of the Fe atoms form a non-equilibrium, partially ordered, segregated Cu-Fe-Sn-Si-P solid solution with Cu atoms, while another portion of the Fe atoms form a non-stable Fe-rich precipitate phase. The addition of Si and P reduces the metal oxide content in the cladding layer, improves the fluidity of the alloy melt in the cladding pool, and promotes the formation of relatively loose corrosion products containing cracks on the surface of the anti-fouling cladding layer.

[0089] In the present invention, the method for preparing the Cu-Fe-Sn-Si-P alloy powder preferably comprises the following steps:

[0090] Cu, Fe, Sn, Si and P are mixed according to their mass percentages, and subjected to a first heating and melting process to obtain an anti-fouling alloy melt;

[0091] The anti-fouling alloy melt is subjected to a first atomization powdering process to obtain the Cu-Fe-Sn-Si-P alloy powder.

[0092] The present invention mixes Cu, Fe, Sn, Si, and P in percentage by mass and performs a first heating and melting process to obtain an antifouling alloy melt. In the present invention, the mixing of Cu, Fe, Sn, Si, and P in percentage by mass and the first heating and melting process preferably include: first heating and melting Cu, and then adding Fe, Sn, Si, and P after Cu is completely melted, and then performing the first heating and melting process. In the present invention, the temperature of the first heating and melting process is preferably 1180-1450°C, more preferably 1200-1400°C, and even more preferably 1250-1350°C; the holding time is preferably 30-60 minutes, more preferably 40-50 minutes.

[0093] After obtaining the anti-fouling alloy melt, the present invention performs a first atomization pulverization on the anti-fouling alloy melt to obtain the Cu-Fe-Sn-Si-P alloy powder. In the present invention, the parameters of the first atomization pulverization include: the atomizing medium is preferably nitrogen; the flow rate of the anti-fouling alloy melt is preferably 0.5 to 1 kg / min, more preferably 0.6 to 0.9 kg / min, and even more preferably 0.7 to 0.8 kg / min.

[0094] After the first atomization powdering, the present invention preferably further comprises screening. The present invention does not specifically limit the parameters of the screening, as long as the Cu-Fe-Sn-Si-P alloy powder of the target particle size can be obtained.

[0095] Figure 2 Schematic diagram of the anti-fouling mechanism of the micro-channel anti-fouling cladding layer in seawater environment. Figure 2 The antifouling cladding layer is characterized by a Cu-rich matrix phase and a dispersed Fe-rich precipitate phase. During seawater immersion, a de-ironified layer with a thickness of 350μm and numerous microchannels forms along the thickness of the antifouling cladding layer. Due to the alloying effect between the microchannels and elements such as Fe, Sn, Si, and P, the corrosion products formed on the surface of the antifouling cladding layer, such as basic copper chloride, basic copper carbonate, tin oxide, and cuprous oxide, become loose and stratified, with numerous cracks and pores. These corrosion products have low bonding strength and easily peel off due to shear stress at low water velocities, achieving a self-polishing effect. This solves the problem of significantly reduced copper ion leakage due to the thickening of dense corrosion products. Marine organisms attached to the antifouling cladding layer are more easily killed by the higher concentration of copper ions stored in the microchannels, thereby reducing the attachment of marine organisms to the antifouling cladding layer and achieving long-term antifouling effects.

[0096] In the present invention, when the metal substrate is a steel substrate or an aluminum alloy substrate, a corrosion-resistant primer cladding layer is preferably provided between the metal substrate and the anti-fouling cladding layer. In the present invention, the thickness of the corrosion-resistant primer cladding layer is preferably 100 to 400 μm.

[0097] In the present invention, the raw material for preparing the corrosion-resistant base cladding layer is preferably Ni-Cr-Mo-Nb-Si alloy powder; the particle size of the Ni-Cr-Mo-Nb-Si alloy powder is preferably 200-400 meshes.

[0098] In the present invention, the Ni-Cr-Mo-Nb-Si alloy powder is prepared from raw materials comprising the following mass percentages: Cr: 20-24%; Mo: 14-18%; Nb: 1-1.5%; Si: 0.5-1%; and Ni: the balance.

[0099] In the present invention, the raw material of the Ni—Cr—Mo—Nb—Si alloy powder includes 20 to 24% by mass of Cr, preferably 21 to 23% by mass, and more preferably 22% by mass.

[0100] In the present invention, the raw material of the Ni—Cr—Mo—Nb—Si alloy powder includes 14-18% by mass of Mo, preferably 15-17%, and more preferably 16% by mass.

[0101] In the present invention, the raw material of the Ni—Cr—Mo—Nb—Si alloy powder includes 1 to 1.5% by mass of Nb, preferably 1.1 to 1.4%, and more preferably 1.2 to 1.3%.

[0102] In the present invention, the raw material of the Ni—Cr—Mo—Nb—Si alloy powder includes Si in an amount of 0.5 to 1% by mass, preferably 0.6 to 0.9%, and more preferably 0.7 to 0.8% by mass.

[0103] In the present invention, the raw material of the Ni—Cr—Mo—Nb—Si alloy powder includes a balance of Ni.

[0104] In the present invention, the method for preparing the Ni-Cr-Mo-Nb-Si alloy powder preferably comprises the following steps:

[0105] Mixing Ni, Cr, Mo, Nb and Si according to their mass percentages, and performing a second heating and melting process to obtain a base alloy melt;

[0106] The base alloy melt is subjected to a second atomization powdering process to obtain the Ni-Cr-Mo-Nb-Si alloy powder.

[0107] In the present invention, Ni, Cr, Mo, Nb, and Si are mixed according to their mass percentages and subjected to a second heating and melting process to obtain a base alloy melt. In the present invention, the temperature of the second heating and melting process is preferably 1400-1600°C, more preferably 1450-1550°C, and more preferably 1500°C; the holding time is preferably 30-60 minutes, more preferably 40-50 minutes.

[0108] After obtaining the base alloy melt, the present invention subjects the base alloy melt to a second atomization pulverization to obtain the Ni-Cr-Mo-Nb-Si alloy powder. In the present invention, the parameters of the second atomization pulverization include: the atomizing medium is preferably nitrogen, the flow rate of the base alloy melt is preferably 0.5 to 1 kg / min, more preferably 0.6 to 0.9 kg / min, and more preferably 0.7 to 0.8 kg / min. After the second atomization pulverization, the present invention preferably further includes screening. The present invention does not specifically limit the parameters of the screening, as long as the Ni-Cr-Mo-Nb-Si alloy powder of the target particle size can be obtained.

[0109] The present invention also provides a method for preparing the coating for preventing marine biofouling as described in the above technical solution, comprising the following steps:

[0110] Pre-treating a metal substrate to obtain a pre-treated substrate; the metal substrate includes a steel substrate, a copper alloy substrate, a titanium alloy substrate and an aluminum alloy substrate;

[0111] An antifouling cladding layer is prepared on the pretreated substrate by a first laser cladding process to obtain the coating for preventing fouling by marine organisms.

[0112] The present invention pre-treats the metal substrate to obtain a pre-treated substrate. In the present invention, the metal substrate includes a steel substrate, a copper alloy substrate, a titanium alloy substrate or an aluminum alloy substrate.

[0113] In the present invention, the pretreatment preferably includes sequentially removing the oxide layer, cleaning, and drying. In the present invention, the method for removing the oxide layer preferably includes sandblasting or electric grinding. The present invention does not impose any specific restrictions on the operation of the sandblasting or electric grinding method, as long as the oxide layer on the surface of the metal substrate can be removed. In the present invention, the cleaning agent preferably includes acetone. The present invention does not impose any specific restrictions on the drying method, as long as drying is possible.

[0114] After obtaining the pretreated substrate, the present invention prepares an antifouling cladding layer on the pretreated substrate through a first laser cladding to obtain the coating for preventing fouling by marine organisms.

[0115] In the present invention, the parameters of the first laser cladding include: the powder feeding rate is preferably 0.8 to 2 kg / h, more preferably 1.0 to 1.5 kg / h; the laser power is preferably 2 to 6 kW, more preferably 3 to 5 kW, and more preferably 4 kW; the relative movement speed of the laser spot and the workpiece is preferably 10 to 25 cm / s, more preferably 15 to 20 cm / s; the flow rate of the shielding gas is preferably 15 to 20 L / min, more preferably 16 to 19 L / min, and more preferably 17 to 18 L / min; the shielding gas preferably includes argon or nitrogen; the laser head stepping distance is preferably 0.5 to 0.8 mm, more preferably 0.6 to 0.7 mm.

[0116] After the anti-fouling cladding layer is prepared, the present invention preferably further comprises polishing. The present invention does not impose any specific limitation on the polishing operation, as long as the surface of the anti-fouling cladding layer can be polished to a bright finish.

[0117] In the present invention, when the metal substrate is a steel substrate and an aluminum alloy substrate, it is preferably further included to prepare a corrosion-resistant base cladding layer. In the present invention, the method for preparing the corrosion-resistant base cladding layer is preferably a second laser cladding, and the parameters of the second laser cladding include: the powder feeding rate is preferably 0.8 to 2 kg / h, more preferably 1.0 to 1.5 kg / h; the laser power is preferably 2 to 6 kW, more preferably 3 to 5 kW, more preferably 4 kW; the relative motion speed between the laser spot and the workpiece is preferably 10 to 25 cm / s, more preferably 15 to 20 cm / s; the flow rate of the shielding gas is preferably 15 to 20 L / min, more preferably 16 to 19 L / min, more preferably 17 to 18 L / min; the shielding gas preferably includes argon or nitrogen; the laser head stepping distance is preferably 0.5 to 0.8 mm, more preferably 0.6 to 0.7 mm.

[0118] After the preparation of the corrosion-resistant primer cladding layer, the present invention preferably further comprises grinding; the grinding is preferably performed by an electric cloth grinding wheel; the present invention does not specifically limit the grinding operation, as long as the surface of the corrosion-resistant primer cladding layer can be polished to a bright finish.

[0119] The coating for preventing marine biofouling and the preparation method thereof provided by the present invention are described in detail below with reference to the following examples, but they should not be construed as limiting the scope of protection of the present invention.

[0120] Example 1: Preparation of a coating on the surface of a rudder blade to prevent marine biofouling

[0121] The assembled rudder blade made of Q345 is selected as the substrate to be clad. The edge of the curved surface to be clad is a trapezoid with an upper bottom of 850mm, a lower bottom of 1250mm and a height of 1430mm. Figure 4 shown.

[0122] 1. Powder composition and preparation

[0123] 1. Alloy powder composition

[0124] (1) Raw materials for preparing Ni-Cr-Mo-Nb-Si alloy powder:

[0125] Cr: 22wt.%; Mo: 15wt.%; Nb: 1wt.%; Si: 0.5wt.%; Ni: balance, and the purity of the above-prepared raw materials is ≥99.9%.

[0126] (2) Raw materials for the preparation of Cu-Fe-Sn-Si-P alloy powder:

[0127] Fe: 30wt.%; Sn: 2wt.%; Si: 0.5wt.%; P: 0.2wt.%; Cu: balance, and the purity of the above-mentioned raw materials is ≥99.9%.

[0128] 2. Alloy powder preparation method

[0129] (1) Preparation of Ni-Cr-Mo-Nb-Si-P alloy powder

[0130] Ni, Cr, Mo, Nb and Si are placed in a vacuum medium frequency induction furnace according to the mass fractions of 1 (1) and heated to melt at 1450°C, and kept at this temperature for 50 minutes to obtain a base alloy melt;

[0131] The obtained base alloy melt was poured into a crucible of an atomizing rapid condensation device, and the device was used to atomize and pulverize to obtain alloy powder; the atomizing medium was nitrogen, and the flow rate of the base alloy melt was 0.5 kg / min;

[0132] The obtained alloy powder is sieved to obtain Ni-Cr-Mo-Nb-Si alloy powder with a particle size of 200-400 meshes.

[0133] (2) Preparation of Cu-Fe-Sn-Si-P alloy powder

[0134] Fe, Sn, Si, Cu and P were weighed according to the mass fractions of (2) in 1, and metal Cu was first added and placed in a vacuum medium frequency induction furnace to be heated and melted at 1400°C. After Cu was completely melted, Fe, Sn, Si and P were added, and the molten alloy liquid was kept at 1400°C for 50 minutes to obtain an antifouling alloy melt;

[0135] The obtained antifouling alloy melt was poured into a crucible of an atomizing rapid condensation device, and the device was used for atomization and powdering to obtain alloy powder; the atomizing medium was nitrogen, and the flow rate of the antifouling alloy melt was 0.7 kg / min.

[0136] The alloy powder is sieved to obtain Cu-Fe-Sn-Si-P alloy powder with a particle size of 200-400 meshes.

[0137] 2. Cladding layer preparation process

[0138] Laser cladding is a relatively mature process. This example uses a high-speed laser cladding system with coaxial powder feeding to prepare the rudder blade. The cladding system mainly includes: a 3.3kW fiber laser, a water cooling system, a coaxial powder feeding system, a gas shielding system, a complex curved surface cladding workbench with a robotic arm to control the movement of the laser head, and a control system. The specific steps for preparing the cladding layer are as follows:

[0139] 1. Preparation of corrosion-resistant base cladding layer

[0140] (1) Use an electric grinding wheel to remove rust from the surface of the Q345 steel plate of the rudder blade, and use acetone to clean and remove oil stains. Fix the rudder blade to be clad after surface treatment on the cladding workbench;

[0141] (2) Ni-Cr-Mo-Nb-Si alloy powder with a particle size of 200-400 mesh was loaded into the powder storage container of a pneumatic powder feeder. A corrosion-resistant base cladding layer was prepared using a laser head motion and overlapping cladding method. The main overlapping cladding parameters were: powder feed rate of 0.8 kg / h, laser power of 2.5 kW, relative motion speed of the laser spot and the workpiece of 18 cm / s, protective gas (argon) flow rate of 15 L / min, and laser head step distance of 0.7 mm. The resulting corrosion-resistant base cladding layer had an average thickness of 300 μm.

[0142] 2. Preparation of anti-fouling cladding layer

[0143] (1) using an electric cloth grinding wheel to polish the surface of the corrosion-resistant primer cladding layer prepared in step 1 until smooth;

[0144] (2) The Cu-Fe-Sn-Si-P alloy powder was loaded into the powder storage container of the pneumatic powder feeder, and the anti-fouling cladding layer was prepared on the surface of the corrosion-resistant base cladding layer prepared in step 1 by using the laser head movement and overlapping cladding method; the main parameters of the overlapping cladding were: powder feeding amount of 1 kg / h, laser power of 2.6 kW, relative movement speed of the laser spot and the workpiece of 15 cm / s, flow rate of the protective gas argon of 15 L / min, and laser head step distance of 0.6 mm, forming an anti-fouling cladding layer with an average thickness of 700 μm.

[0145] (3) After the cladding is completed, the surface of the rudder blade is polished with an electric cloth grinding wheel, and then the surface of the cladding layer is polished flat with an angle grinder. After polishing, the rudder blade is clad as shown in the figure below. Figure 5 shown; from Figure 5It can be seen that the cladding layer on the surface of the sample has a good morphology and is free of defects such as cracks and holes.

[0146] Example 2: Preparation of a coating for preventing marine biofouling on an A32 steel plate of a ship hull below the waterline. An A32 steel plate was selected as the substrate to be clad, and the size of the steel plate was: 16000 mm×2000 mm×12 mm.

[0147] 1. Powder composition and preparation

[0148] 1. Alloy powder composition

[0149] (1) Raw materials for preparing Ni-Cr-Mo-Nb-Si alloy powder:

[0150] Cr: 24wt.%; Mo: 17wt.%; Nb: 1.2wt.%; Si: 0.6wt.%; Ni: balance, and the purity of the above-mentioned raw materials is ≥99.9%.

[0151] (2) Raw materials for the preparation of Cu-Fe-Sn-Si-P alloy powder:

[0152] Fe: 16wt.%; Sn: 5wt.%; Si: 0.3wt.%; P: 0.4wt.%; Cu: balance, and the purity of the above-mentioned raw materials is ≥99.9%.

[0153] 2. Alloy powder preparation method

[0154] (1) Preparation of Ni-Cr-Mo-Nb-Si alloy powder

[0155] Ni, Cr, Mo, Nb and Si are placed in a vacuum medium frequency induction furnace according to the mass fractions of (1) and heated to 1500°C for melting, and kept at this temperature for 50 minutes to obtain a base alloy melt;

[0156] The obtained base alloy melt was poured into a crucible of an atomizing and rapid condensing device, and the device was used to atomize and pulverize to obtain alloy powder; the atomizing medium was nitrogen, and the flow rate of the base alloy melt was 0.6 kg / min;

[0157] The obtained alloy powder is sieved to obtain Ni-Cr-Mo-Nb-Si alloy powder with a particle size of 200-400 meshes.

[0158] (2) Preparation of Cu-Fe-Sn-Si-P alloy powder

[0159] Fe, Sn, Si, P and Cu were weighed according to the mass fractions of (2) in 1, and metallic Cu was first added into a vacuum medium frequency induction furnace and heated to melt at 1380°C. After Cu was completely melted, Fe, Sn, Si and P were added, and the molten alloy liquid was kept at 1380°C for 50 minutes to obtain an antifouling alloy melt;

[0160] The anti-fouling alloy melt obtained was poured into a crucible of an atomizing rapid condensation device, and the device was used to atomize and pulverize the alloy powder; the atomizing medium was nitrogen, and the flow rate of the anti-fouling alloy melt was 0.6 kg / min;

[0161] The alloy powder is sieved to obtain Cu-Fe-Sn-Si-P alloy powder with a particle size in the range of 200-400 meshes.

[0162] 2. Cladding layer preparation process

[0163] A32 steel plate samples were prepared using a coaxial powder feeding high-speed laser cladding system. The cladding system mainly includes: a 4kW fiber laser, a water cooling system, a coaxial powder feeding system, a gas shielding system, a flat cladding workbench, and a control system. The laser is a laser light source that is focused by a lens and radiated onto the surface of the substrate material. The water cooling system provides cooling water of appropriate temperature to the laser box to prevent the box from overheating. The flat workbench is used to fix the steel plate. The gas shielding system can prevent oxidation during the cladding process. The coaxial powder feeding high-speed laser cladding system has the advantages of high powder utilization and low dilution rate. The specific steps for preparing the cladding layer are as follows:

[0164] 1. Preparation of corrosion-resistant base cladding layer

[0165] (1) Use an electric grinding wheel to grind the surface of the fixed steel plate until it is smooth and free of tiny holes, remove oxides and other impurities on the surface of the sample, and then use acetone solution to clean the surface of the sample to remove oil stains.

[0166] (2) Ni-Cr-Mo-Nb-Si alloy powder with a particle size of 200-400 mesh was loaded into the powder storage container of a pneumatic powder feeder, and a corrosion-resistant base cladding layer was prepared by laser head stepping motion and overlapping cladding. The main overlapping cladding parameters were: powder feeding rate of 1.2 kg / h, laser power of 2.6 kW, relative motion speed of laser spot and workpiece of 25 cm / s, flow rate of shielding gas argon of 15 L / min, and laser head stepping distance of 0.5 mm. The corrosion-resistant base cladding layer with an average thickness of 300 μm was formed.

[0167] 2. Preparation of anti-fouling cladding layer

[0168] (1) using an angle grinder to clean the surface of the corrosion-resistant primer cladding layer prepared in step 1;

[0169] (2) The Cu-Fe-Sn-Si-P alloy powder was loaded into the powder storage container of the pneumatic powder feeder, and the anti-fouling cladding layer was prepared on the surface of the corrosion-resistant base cladding layer prepared in step 1 by using the laser head stepping motion and overlapping cladding method; the main parameters of the corrosion-resistant base cladding layer were as follows: powder feeding amount of 1.2 kg / h, laser power of 3 kW, relative motion speed of laser spot and workpiece of 20 cm / s, flow rate of protective gas argon of 15 L / min, laser head stepping distance of 0.7 mm, and an anti-fouling cladding layer with an average thickness of 500 μm was formed.

[0170] The copper ion permeation rate of the anti-fouling cladding layer is calculated according to the national standard "GB / T 6824-2008". The copper ion permeation rate is calculated from the copper ion concentration. The formula used is as follows:

[0171]

[0172] Where:

[0173] R—Copper ion leakage rate (μg·cm -2 ·d -1 );

[0174] ρ V —Cu ion concentration in exudate (μg·L -1 );

[0175] F—Correction factor for exudate sample, F=1.01

[0176] ρ B —Cu ion concentration in artificial seawater blank solution (μg·L -1 );

[0177] V—volume of simulated seawater solution in the seepage tank (1.4 L);

[0178] t—immersion time of cladding layer sample in the seepage tank (1h);

[0179] A—Exposed surface area of ​​sample (cm 2 );

[0180] Existing studies have shown that for smooth flat surfaces, the ion release rate can reach 40 μg·cm -2 ·d -1 When the water is thick, it can protect most marine organisms such as barnacles, algae, hydra, jellyfish, etc.

[0181] Figure 6 This is the copper ion release rate curve of the anti-marine biofouling coating prepared in Example 2 after being immersed in a simulated seawater environment for one month; Figure 6It can be seen that the copper ion release rate is relatively high at the beginning of immersion, then decreases and gradually stabilizes with time, and all release rate results are greater than 40 μg·cm -2 ·d -1 .

[0182] Example 3: Preparation of a coating to prevent marine biofouling on a propeller boss cap

[0183] The propeller hub cap is made of corrosion-resistant copper alloy, so only the anti-fouling cladding layer is prepared on its surface. The propeller hub cap is selected as the base material to be clad. The hub cap is conical in shape with a bottom radius of 8 cm and a height of 18 cm.

[0184] 1. Powder composition and preparation

[0185] 1. Alloy powder composition

[0186] Raw materials for preparation of Cu-Fe-Sn-Si-P alloy powder:

[0187] Fe: 20wt.%; Sn: 4wt.%; Si: 0.5wt.%; P: 0.5wt.%; Cu: balance, and the purity of the above-mentioned raw materials is ≥99.9%.

[0188] 2. Alloy powder preparation method

[0189] Fe, Sn, Si, P and Cu were weighed at a mass fraction of 1, and metallic Cu was first added to a vacuum medium-frequency induction furnace and heated to melt at 1440°C. After Cu was completely melted, Fe, Sn, Si and P were added, and the molten alloy was kept at 1440°C for 50 minutes to obtain an antifouling alloy melt.

[0190] The anti-fouling alloy melt obtained was poured into a crucible of an atomizing rapid condensation device, and the device was used to atomize and pulverize the alloy powder; the atomizing medium was nitrogen, and the flow rate of the anti-fouling alloy melt was 0.8 kg / min;

[0191] The obtained alloy powder is sieved to obtain Cu-Fe-Sn-Si-P alloy powder with a particle size of 200-400 meshes.

[0192] 2. Cladding layer preparation process

[0193] The propeller hub cap sample was fabricated using a high-speed laser cladding system with coaxial powder feeding. The cladding system primarily includes a 3kW high-speed fiber laser, a water cooling system, a coaxial powder feeding system, a gas shielding system, a complex-shaped component cladding workbench, and a control system.

[0194] The specific steps for preparing the anti-fouling cladding layer are as follows:

[0195] 1. First, use a three-way chuck to fix the propeller hub cap on a rotatable laser cladding workbench and rotate it slowly. Use an electric grinding wheel to remove the oxide on the surface of the propeller hub cap, and then use acetone solution to clean the surface of the sample to remove oil stains.

[0196] 2. The Cu-Fe-Sn-Si-P alloy powder was loaded into the powder storage container of the pneumatic powder feeder, and an anti-fouling cladding layer was prepared on the surface of the propeller hub cap by rotating the propeller hub cap, stepping the laser head, and overlapping cladding. The main cladding parameters were: powder feeding rate of 1 kg / h, laser power of 2.6 kW, relative motion speed of the laser spot and the workpiece of 15 cm / s, flow rate of the protective gas argon of 15 L / min, and stepping distance of the laser head of 0.6 mm, forming an anti-fouling cladding layer with an average thickness of 600 μm.

[0197] 3. Other subsequent processing process description

[0198] After the cladding is completed, the propeller hub cap surface is polished with an electric cloth grinding wheel. After polishing, the propeller hub cap is clad as shown in the figure below. Figure 7 shown; from Figure 7 It can be seen that the cladding layer on the surface of the sample has a good morphology and is free of defects such as cracks and holes.

[0199] Figure 8 This is a cross-sectional scanning electron microscope photograph of the anti-fouling cladding layer prepared in Example 2; Figure 8 It can be seen that the anti-fouling cladding layer consists of Fe-rich precipitated phase 16 and Cu-rich matrix phase 17.

[0200] Figure 9 For Figure 8 The results of the surface scanning analysis of the 16 areas (only the Cu and Fe contents were analyzed) are as follows: Figure 9 It can be seen that the Fe element is concentrated in area 16, while the Cu element is mainly distributed in area 17.

[0201] Table 1 is Figure 8 Energy spectrum analysis results of region 16.

[0202] Table 1 Figure 8 Energy spectrum analysis results of the middle area 16 (only Cu and Fe content are analyzed)

[0203] element Cu Fe Mass fraction of each element (wt.%) 32.0 68.0

[0204] It can be seen from Table 1 that the mass fraction of Fe is 68.0% and the mass fraction of Cu is 32.0%.

[0205] Table 2 is Figure 8 Energy spectrum analysis results of region 17.

[0206] Table 2 Figure 8Energy spectrum analysis results of the middle area 17 (only Cu and Fe content are analyzed)

[0207] element Cu Fe Mass fraction of each element (wt.%) 93.8 6.2

[0208] It can be seen from Table 2 that the mass fraction of Fe is 6.2% and the mass fraction of Cu is 93.8%.

[0209] Figure 10 is a scanning electron microscope image of the micro-channels formed in the anti-fouling cladding layer in Example 2 after immersion in a simulated seawater environment for 2 months; Figure 10 It can be seen that the pore size is larger at the top of the anti-fouling cladding layer, and then gradually decreases with the increase of the depth of the anti-fouling cladding layer. The diameter of the microchannel is in the range of 200 to 3000 nm.

[0210] Figure 11 The line scan results of the cross section of the antifouling cladding layer in Example 2 after immersion in a simulated seawater environment for 2 months are shown. Figure 11 It can be seen that after two months of immersion, the Fe content in the anti-fouling cladding layer within a range of about 350 μm in the thickness direction decreased significantly, while the Cu content increased, indicating that a de-ironization layer with a depth of about 350 μm was formed in the anti-fouling cladding layer along the thickness direction.

[0211] Figure 12 This is a scanning electron microscope photograph of a cross section of the anti-fouling cladding layer with microchannels in Example 2 at low magnification after immersion in a simulated seawater environment for 2 months.

[0212] Table 3 shows the Figure 12 Micro-area energy spectrum analysis results of the middle 22-27 area.

[0213] Table 3 Figure 12 Energy spectrum analysis results of area 22-27 (only analyzed Cu, Fe, O, and Cl content)

[0214] area Distance from the surface (μm) Cu (wt.%) Fe (wt.%) O (wt.%) Cl (wt.%) 22 0 76.9 9.4 10.1 3.6 23 60.35 94.0 4.8 0.6 0.6 24 115.60 92.2 4.9 2.1 0.9 25 190.34 94.7 4.3 0.5 0.5 26 256.78 90.7 7.1 0.9 1.4 27 354.31 84.5 11.6 3.3 0.6

[0215] Table 3 shows that the Fe content in the deironing layer containing micro-pipes has significantly decreased, reaching a minimum of 4.3%. Analysis shows that the residual iron in the deironing layer consists of iron corrosion products and a small amount of unreacted iron. The increase in Fe content at the top of the deironing layer is due to the formation of Fe corrosion products on the surface of the anti-fouling cladding layer.

[0216] Figure 13 The surface morphology of the antifouling cladding layer in Example 2 after being immersed in a simulated seawater environment for 2 months is shown in FIG. Figure 13 It can be seen that there are a large number of micropores on the surface of the anti-fouling cladding layer (i.e., at the outlet of the micro-pipeline).

[0217] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A coating for preventing marine biofouling, characterized in that: It includes an antifouling cladding layer provided on a metal substrate; The anti-fouling cladding layer is a metastable phase anti-fouling cladding layer; The anti-fouling cladding layer includes a dispersed Fe-rich precipitate phase and a Cu-rich solid solution containing supersaturated Fe; the Cu-rich solid solution containing supersaturated Fe is a Cu-Fe-Sn-Si-P copper-based solid solution; The raw material for preparing the anti-fouling cladding layer is Cu-Fe-Sn-Si-P alloy powder; The Cu-Fe-Sn-Si-P alloy powder is prepared from raw materials having the following mass percentages: Fe: 8~40%; Sn: 0.3~8%; Si: 0.1~0.5%; P: 0.1~0.5%; Cu: balance; The metal matrix includes a steel matrix, a copper alloy matrix, a titanium alloy matrix and an aluminum alloy matrix; The anti-fouling cladding layer is prepared by first laser cladding; the parameters of the first laser cladding include: powder feeding rate of 0.8 to 2 kg / h, laser power of 2 to 6 kW, relative movement speed of the laser spot and the workpiece of 10 to 25 cm / s, flow rate of the shielding gas of 15 to 20 L / min, and laser head stepping distance of 0.5 to 0.8 mm.

2. The anti-marine biofouling coating according to claim 1, characterized in that: When the metal substrate is a steel substrate or an aluminum alloy substrate, a corrosion-resistant primer cladding layer is further provided between the metal substrate and the anti-fouling cladding layer; The raw material for preparing the corrosion-resistant base cladding layer is Ni-Cr-Mo-Nb-Si alloy powder; The Ni-Cr-Mo-Nb-Si alloy powder is prepared from raw materials comprising the following mass percentages: Cr: 20-24%; Mo: 14-18%; Nb: 1-1.5%; Si: 0.5-1%; Ni: balance.

3. The anti-marine biofouling coating according to claim 2, characterized in that: The thickness of the anti-fouling cladding layer is 300 to 1000 μm; the thickness of the corrosion-resistant base cladding layer is 100 to 400 μm.

4. The anti-marine biofouling coating according to claim 2, characterized in that: The particle sizes of the Ni-Cr-Mo-Nb-Si alloy powder and the Cu-Fe-Sn-Si-P alloy powder are independently 200-400 meshes.

5. The anti-marine biofouling coating according to claim 1 or 4, characterized in that: The preparation method of the Cu-Fe-Sn-Si-P alloy powder comprises the following steps: Cu, Fe, Sn, Si and P are mixed according to their mass percentages, and subjected to a first heating and melting process to obtain an anti-fouling alloy melt; performing a first atomization powdering on the anti-fouling alloy melt to obtain the Cu-Fe-Sn-Si-P alloy powder; The first heating and melting temperature is 1180-1450° C., and the holding time is 30-60 min; The parameters of the first atomization powder making process include: the atomization medium is nitrogen, and the flow rate of the anti-fouling alloy melt is 0.5-1 kg / min.

6. The anti-marine biofouling coating according to claim 2 or 4, characterized in that: The preparation method of the Ni-Cr-Mo-Nb-Si alloy powder comprises the following steps: Mixing Ni, Cr, Mo, Nb and Si according to their mass percentages, and performing a second heating and melting process to obtain a base alloy melt; The base alloy melt is subjected to a second atomization powdering to obtain the Ni-Cr-Mo-Nb-Si alloy powder; The temperature of the second heating and melting is 1400-1600° C., and the holding time is 30-60 min; The parameters of the second atomization powder making process include: the atomizing medium is nitrogen, and the flow rate of the base alloy melt is 0.5-1 kg / min.

7. The method for preparing a coating for preventing marine biofouling according to any one of claims 1 to 6, characterized in that: The following steps are involved: Pre-treating a metal substrate to obtain a pre-treated substrate; the metal substrate includes a steel substrate, a copper alloy substrate, a titanium alloy substrate and an aluminum alloy substrate; preparing an antifouling cladding layer on the pretreated substrate by a first laser cladding to obtain the coating for preventing fouling by marine organisms; The parameters of the first laser cladding include: powder feeding rate of 0.8-2 kg / h, laser power of 2-6 kW, relative movement speed of laser spot and workpiece of 10-25 cm / s, flow rate of shielding gas of 15-20 L / min, and laser head step distance of 0.5-0.8 mm.

8. The preparation method according to claim 7, characterized in that When the metal substrate is a steel substrate and an aluminum alloy substrate, it also includes preparing a corrosion-resistant base cladding layer; the preparation method of the corrosion-resistant base cladding layer is second laser cladding; the parameters of the second laser cladding include: powder feeding rate of 0.8~2kg / h, laser power of 2~6kW, relative movement speed of laser spot and workpiece of 10~25cm / s, flow rate of protective gas of 15~20L / min, and laser head step distance of 0.5~0.8mm.

9. The preparation method according to claim 7, characterized in that The pretreatment includes removing the oxide layer, cleaning and drying in sequence; the method for removing the oxide layer includes sandblasting or electric grinding wheel grinding; the cleaning agent includes acetone.

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