Iron-free low-melting nickel-based alloy coating and method for producing same

Abstract

The present application relates to a low melting point nickel-based alloy coating without iron element and a preparation method thereof, which is prepared by taking nickel powder as main powder and adding various alloy powders and pure element powders, wherein B4C powder and Si powder are respectively taken as B source and Si source, and the mass percentages of the two are respectively 3.63-4.96% and 3.88-5.13%. In the present application, the preparation process of the nickel-based alloy coating mainly includes mixing of various powders, pretreatment of the base material and coating preparation, and the preparation of the high-density nickel-based alloy coating is realized under lower surfacing current and laser power by using the violent reaction characteristics of B4C powder and Si powder with Ni and other metals; the melting point of the coating mixed powder is 921.5-926.9℃. The prepared coating has a porosity of only 0.39-0.91%, a good metallurgical bonding between the coating and the base material, and the hard phases M7(B,C)3 and M 23 (B,C)6 are uniformly distributed in the coating area, the hardness of the coating is 57.3-61.4HRC, and the corrosion resistance is higher than that of the nickel-based alloy coating containing iron element, so the coating has high corrosion resistance and high wear resistance.

Description

Technical Field

[0001] This invention belongs to the field of nickel-based composite materials, and relates to a coating of a composite material with no iron element, low melting point, and high wear resistance, and its preparation method. Technical Background

[0002] Nickel-based composite coatings possess excellent comprehensive properties, including good corrosion resistance, oxidation resistance, high hardness, excellent wear resistance, and good impact toughness. They are commonly used in applications requiring high temperature resistance, corrosion resistance, and especially high friction and wear resistance. The main coating preparation methods include welding, thermal spraying, and laser cladding. The raw material powders used to prepare these nickel-based coatings are mostly pre-alloyed powders, with boron (B) primarily sourced from iron-boron powder and pure boron powder. When using iron-boron powder to introduce B, there are issues such as easy oxidation of the raw material powder and excessively high levels of Fe. Excessive Fe in the coating leads to the formation of brittle Fe-containing compounds, which is detrimental to the coating's hardness and wear resistance, and also reduces its corrosion resistance. When using pure boron powder to introduce B, the high chemical reactivity and toxicity of high-purity boron powder pose certain risks in industrial production, and its raw material price is also high. Furthermore, laser cladding, plasma welding, and other similar methods typically operate at high temperatures. This can lead to significant temperature differences between the substrate and the coating, potentially causing cracking and other defects. Additionally, these methods result in high energy consumption, hindering energy conservation. Therefore, it is necessary to improve the raw material sources for nickel-based self-fluxing powders and appropriately lower the powder's melting point to minimize energy consumption and prevent coating cracking.

[0003] B4C is a chemically stable and safe source of boron (B), offering a low-cost alternative. Using B4C to introduce boron avoids the problem of excessively high Fe content associated with iron-boron powder. Furthermore, B4C, as a boron source, reacts strongly with Group IV, V, and VI transition metals at relatively low temperatures, significantly reducing the melting temperature. This prevents high-temperature damage to the coating substrate and mitigates issues such as substrate deformation, coating cracking, and weak coating adhesion caused by thermal stress. Summary of the Invention

[0004] The purpose of this invention is to provide an iron-free, low-melting-point nickel-based alloy coating and its preparation method. The coating uses Ni, B4C, Si, Cr, Mo, Cu and other powders as raw materials, and designs the powder ratio and coating preparation process. It provides an iron-free nickel-based alloy coating with high wear resistance and a low preparation temperature, and its preparation method overcomes the shortcomings of iron-containing nickel-based coatings, such as low corrosion resistance, easy cracking and low bonding strength.

[0005] To achieve the above objectives, the technical solution provided by this invention is as follows:

[0006] The nickel-based alloy coating powder is composed of a mixture of nickel powder, chromium powder, molybdenum powder, copper powder, boron carbide powder, and silicon powder. The mass percentages of the raw material powders used are: Ni: 64.19–67.55%; Cr, Mo, and Cu: 22–25%, wherein the mass ratio of Cr, Mo, and Cu is 5:1:1; B4C: 3.63–4.96%; Si: 3.88–5.13%. After mixing and drying, the powder is used for coating preparation. The coating process includes welding, cladding, and spraying.

[0007] The melting point range of the prepared mixed powder is 921.5–926.9 °C; the resulting iron-free nickel-based coating exhibits a self-corrosion current density of 1.084–4.179 × 10⁻⁶ °C in a 3.5 wt.% sodium chloride solution. -7 A×cm -2 The self-corrosion current density of the nickel-based alloy coating containing iron is 3.834 × 10⁻⁶. -6 A×cm -2 The corrosion resistance of the obtained coating is better than that of the nickel-based alloy coating containing iron. The hardness of the obtained coating is 57.3 to 61.4 HRC. If the wear resistance of 42CrMo quenched and tempered steel is defined as 1, then the relative wear resistance of the nickel-based alloy coating is 3.51 to 5.19. The obtained coating has the characteristics of high hardness, high wear resistance and low preparation temperature.

[0008] The preparation method of the iron-free low-melting-point nickel-based alloy coating with the above properties includes the following steps:

[0009] (1) Powder mixing: Prepare B4C powder, Si powder, Cr powder, Mo powder, Cu powder and Ni powder according to the required proportions; weigh the powder and mix it; dry and sieve the mixed powder; the powder mixing methods include planetary ball milling, vibratory ball milling, V-type mixing and drum mixing.

[0010] (2) Substrate pretreatment: Clean and wash the substrate surface; dry the cleaned substrate; preheat the substrate at 200-350℃ for 5-8 hours; substrate types include carbon steel and structural steel;

[0011] (3) Coating preparation: The uniformly mixed powder is loaded into the powder feeding device and the preheated substrate is coated to obtain a nickel-based alloy coating; Argon, nitrogen or hydrogen is used as a protective gas when preparing the coating; The coating preparation methods include welding, cladding and spraying; After the coating is prepared, it is air-cooled to room temperature.

[0012] The three steps for preparing the nickel-based alloy coating described above are explained in detail below:

[0013] Step (1): Taking the preparation of 10 kg of nickel-based alloy coating powder as an example, the specific steps for preparing 10 kg of nickel-based mixed powder are as follows:

[0014] Preliminary mixing: Place 363–496 g of boron carbide (B4C) powder, 388–513 g of silicon (Si) powder, 1584–1800 g of chromium (Cr) powder, 308–350 g of molybdenum (Mo) powder, and 308–350 g of copper (Cu) powder together in a container and perform preliminary stirring and grinding for 20 minutes. Add the powder to a ball mill jar, add grinding balls at a ball-to-powder ratio of 0.8–1.1, and add anhydrous ethanol at a ratio of 10–30 ml / 100 g powder. First, perform preliminary stirring and mixing of the powder, grinding balls, and anhydrous ethanol for about 5 minutes, then place the ball mill jar in a ball mill to begin ball milling. The ball milling methods include planetary ball milling and vibratory ball milling.

[0015] Among them, the planetary ball mill for mixing has a revolution speed of 200-300 r / min, and rotates alternately clockwise and counterclockwise, with a single rotation time of 30 min; or the vibratory ball mill for mixing has a swing frequency of 200-300 times / min, with a tank amplitude of 30-40 mm in the up-down direction and a tank amplitude of 10-15 mm in the front-back and left-right directions;

[0016] After ball milling for 7–10 hours, the ball mill jar is opened and placed in a vacuum drying oven for 7–10 hours. The dried powder is then sieved to separate the powder from the milling balls, resulting in a uniformly mixed powder. This initial mixing process is to ensure that the boron carbide powder and silicon powder are fully mixed and distributed in the gaps between other metal powders. Powder mixing: 6419–6755 g of nickel (Ni) powder is added to the initially mixed powder and placed in a roller or V-shaped drum for mixing. The mixing speed is set to 16–20 r / min, and the mixing time is 10–14 hours. After mixing, the powder is removed and placed in a vacuum drying oven for 2–4 hours. The dried powder is then sieved to obtain a dry, uniformly mixed powder with good flowability.

[0017] Step (2): The pretreatment of the matrix material is as follows:

[0018] The substrate is treated by grinding with steel wool, grinding with a grinding wheel, or sandblasting to remove the oxide film on the surface; after treatment, the substrate material is further cleaned with ethanol or propanol, and the residual cleaning agent on the surface is dried after cleaning; the substrate material is placed in a heat treatment device and preheated at 200-350℃ for 5-8 hours.

[0019] The base materials used include carbon steel and alloy steel.

[0020] Step (3): The specific steps for preparing a nickel-based alloy coating on the substrate material using the dried mixed powder are as follows:

[0021] The dried mixed powder is loaded into a powder feeding device, and the preheated substrate material is transferred to the working area; the coating is prepared by means of plasma welding or laser cladding.

[0022] The plasma cladding process includes the following parameters: torch height of 8–9 mm, torch swing amplitude of 10–12 mm, swing speed of 1800–2000 mm / min, and torch movement speed of 10–12 mm / min; powder feeding device rotation speed of 70–80 rpm, powder gas flow rate of 3–5 L / min, ion gas flow rate of 1.5–2 L / min, and shielding gas flow rate of 10–12 L / min; shielding gases include argon, nitrogen, and helium; welding current of 75–80 A; and laser cladding with a laser power of 100 A. The laser beam strength ranges from 0 to 1500 W, with a spot diameter of 1.5 to 2.5 mm and a scanning speed of 200 to 400 m / min. The multi-pass overlap rate is 40 to 50%. The synchronous powder feeding rate is 27.6 g / min to 31.2 g / min, and the shielding gas flow rate is 7 to 10 L / min. The shielding gases include argon, nitrogen, and helium. The spraying methods include flame spraying, oxy-acetylene flame powder spraying, oxy-acetylene flame welding, high-velocity flamingo (HVOF) spraying, arc spraying, plasma spraying, atmospheric plasma spraying, and low-pressure plasma spraying.

[0023] After the coating is prepared, it is air-cooled to room temperature to obtain a nickel-based alloy coating.

[0024] In the above coating preparation process, a high-density nickel-based coating with good bonding and a porosity of only 0.39% to 0.91% was achieved using relatively low welding current and laser power. Compared with iron-containing nickel-based coatings, the nickel-based coating prepared by this invention has the following advantages:

[0025] (1) Under the condition that the content of B element is high, the content of Fe element in the nickel-based alloy coating material is not increased too much, which improves the corrosion resistance of the coating.

[0026] (2) In this nickel-based alloy coating, the hard phases M7(B,C)3 and M 23 (B,C)6 is evenly distributed in the coating area, which plays a strengthening role and improves the hardness and wear resistance of the coating; a good metallurgical bond is formed between the substrate and the coating; no subsequent heat treatment is required, and the coating is free from cracks and other defects.

[0027] (3) The hardness of the nickel-based alloy coating reaches a relatively high level of 57.3 to 61.4 HRC. If the wear resistance of 42CrMo quenched and tempered steel is defined as 1, then the relative wear resistance of the nickel-based alloy coating prepared by the present invention reaches 3.51 to 5.19, which has the characteristics of high hardness and high wear resistance.

[0028] (4) The nickel-based alloy coating produced by the present invention has the advantages of simple preparation process, simple equipment, low energy consumption and low cost. Attached Figure Description

[0029] Figure 1 Example 1: XRD diffraction pattern of nickel-based alloy coating;

[0030] Figure 2 Example 1: Scanning electron microscope image of the cross-section of the nickel-based alloy coating;

[0031] Figure 3 Example 1: Tafel curves of nickel-based alloy coatings and iron-containing nickel-based alloy coatings in 3.5 wt.% sodium chloride solution. Detailed Implementation

[0032] Example 1

[0033] 1. Powder Mixing: Weigh out 4.96% B4C powder, 3.88% Si powder, 18% Cr powder, 3.50% Mo powder, and 3.50% Cu powder according to the mass ratio and add them to a mortar. Perform preliminary stirring and grinding for 20 minutes. Then, add the preliminarily mixed powder to a ball mill jar, add cemented carbide balls at a ball-to-powder ratio of 0.9:1, and add anhydrous ethanol at a ratio of 25 ml / 100 g powder. First, perform preliminary stirring and mixing of the powder, grinding balls, and anhydrous ethanol for about 5 minutes. Then, place the ball mill jar in a planetary ball mill to begin ball milling. The rotation speed is 300 r / min, alternating between clockwise and counterclockwise rotations, with a single rotation time of 30 minutes. After ball milling for 8 hours, open the ball mill jar and place it in a vacuum chamber. The powder was dried in an empty drying oven for 9 hours. The dried powder was then passed through an 80-mesh sieve to separate the powder from the grinding balls, resulting in a pre-mixed powder. Ni powder at a mass ratio of 64.19% was added to the pre-mixed powder and then added to a drum mixer for powder mixing. The mixing speed was set to 16 r / min and the mixing time was 14 hours. After mixing, the powder was removed and placed in a vacuum drying oven for 4 hours. The dried powder was then passed through a 100-mesh sieve to obtain a dry, uniformly mixed powder with good flowability. The melting point of the prepared mixed powder was 921.5℃.

[0034] 2. Matrix pretreatment: The 42CrMo matrix was polished with steel wool to remove the oxide film on the surface; after treatment, the matrix material was further cleaned with ethanol, and the residual cleaning agent on the surface was dried after cleaning; the matrix material was placed in a box furnace and preheated at 240℃ for 6 hours.

[0035] 3. Coating Preparation: The dried mixed powder is loaded into the powder feeding device, and the preheated substrate material is transferred to the working area; the coating is prepared by plasma welding; the spray gun height during welding is 8 mm, the welding gun swing amplitude is 12 mm, the swing speed is 1800 mm / min, and the welding gun moving speed is 10 mm / min; the powder feeding speed of the powder feeding device is 70 rpm, the powder feeding gas flow rate is 5 L / min, the ion gas flow rate is 1.5 L / min, and the shielding gas flow rate is 10 L / min; the shielding gas is argon; the welding current is 75 A; after the coating preparation is completed, it is air-cooled to room temperature to obtain a nickel-based alloy coating.

[0036] The nickel-based alloy coating prepared by the above method consists of the following phases: γ-Ni, M7(B,C)3, M... 23 (B,C)6. Figure 1 The XRD diffraction pattern of the coating indicates that the nickel-based alloy coating is composed of the aforementioned phases. In this nickel-based alloy coating, the hard phases M7(B,C)3 and M... 23 (B,C)6 is relatively evenly distributed in the nickel-based coating area. Figure 2 Here is a scanning electron microscope image of the cross-section of the coating, from Figure 2 The black blocky phase M7(B,C)3 and the white blocky phase M can be seen in the image. 23 (B,C)6, and M7(B,C)3, M 23 (B,C)6 is relatively uniformly distributed in the nickel matrix, while M7(B,C)3 occupies a larger volume fraction in the coating area, among which M 23 (B,C)6 is more concentrated near the matrix. Figure 3 The Tafel curves for the nickel-based alloy coating and the iron-containing nickel-based alloy coating in a 3.5 wt.% sodium chloride solution show that the self-corrosion current density of the iron-free nickel-based coating is 1.774 × 10⁻⁶. -7 A×cm -2 The self-corrosion current density of the nickel-based alloy coating containing iron is 3.834 × 10⁻⁶. -6 A×cm -2The iron-free nickel-based coating prepared by this invention exhibits superior corrosion resistance compared to iron-containing nickel-based alloy coatings. This nickel-based alloy coating has a porosity of 0.91% and a hardness of 57.3 HRC. Based on volumetric wear rate calculations, if the wear resistance of 42CrMo quenched and tempered steel is defined as 1, then the relative wear resistance of this nickel-based alloy coating reaches 3.51, demonstrating high hardness and high wear resistance.

[0037] Example 2

[0038] 1. Powder Mixing: Weigh out 4.96% B4C powder, 3.88% Si powder, 18% Cr powder, 3.50% Mo powder, and 3.50% Cu powder by mass and add them to a mortar. Perform preliminary stirring and grinding for 20 minutes. Then, add the preliminarily mixed powder to a ball mill jar, add cemented carbide balls at a 1:1 ball-to-powder ratio, and add anhydrous ethanol at a ratio of 30 ml / 100 g powder. First, perform preliminary stirring and mixing of the powder, grinding balls, and anhydrous ethanol for about 5 minutes. Then, place the ball mill jar in a planetary ball mill to begin ball milling. The rotation speed is 200 r / min, alternating between clockwise and counterclockwise rotations, with each rotation lasting 30 minutes. After ball milling for 10 hours, open the ball mill jar and place it under vacuum. The powder was dried in a drying oven for 10 hours, and then passed through an 80-mesh sieve to separate the powder from the ball milling balls, resulting in a pre-mixed powder. Ni powder at a mass ratio of 64.19% was added to the pre-mixed powder and then added to a V-type mixer for powder mixing. The mixing speed was set to 20 r / min and the mixing time was 10 hours. After mixing, the powder was removed and placed in a vacuum drying oven for 3 hours. The dried powder was then passed through a 100-mesh sieve to obtain a dry, uniformly mixed powder with good flowability. The melting point of the prepared mixed powder was 921.5℃.

[0039] 2. Substrate pretreatment: The Q235 substrate is treated with a sandblasting machine to remove the oxide film on the surface; after treatment, the substrate material is further cleaned with propanol, and the residual cleaning agent on the surface is dried after cleaning; the substrate material is placed in a box furnace and preheated at 300℃ for 5 hours.

[0040] 3. Coating Preparation: The dried mixed powder is loaded into the powder feeding device, and the preheated substrate material is transferred to the working area; the coating is prepared by plasma welding; the spray gun height is 9 mm, the welding gun swing amplitude is 10 mm, the swing speed is 2000 mm / min, and the welding gun moving speed is 12 mm / min; the powder feeding speed of the powder feeding device is 80 rpm, the powder feeding gas flow rate is 3 L / min, the ion gas flow rate is 2.5 L / min, and the shielding gas flow rate is 12 L / min; the shielding gas is nitrogen; the welding current is 85 A; after the coating preparation is completed, it is air-cooled to room temperature to obtain a nickel-based alloy coating.

[0041] The nickel-based alloy coating prepared by the above method consists of the following phases: γ-Ni, M7(B,C)3, M... 23 (B,C)6. In this nickel-based alloy coating, the hard phases M7(B,C)3 and M 23 (B,C)6 is relatively uniformly distributed in the nickel-based coating area. M7(B,C)3 has a larger volume fraction in the coating area. 23 (B,C)6 is relatively concentrated near the substrate. The self-corrosion current density of this iron-free nickel-based coating is 1.084 × 10⁻⁶. -6 A×cm -2 The self-corrosion current density of the nickel-based alloy coating containing iron is 3.834 × 10⁻⁶. -6 A×cm -2 The iron-free nickel-based coating prepared by this invention exhibits superior corrosion resistance compared to iron-containing nickel-based alloy coatings. This nickel-based alloy coating has a porosity of 0.87% and a hardness of 60.3 HRC. Based on volumetric wear rate calculations, if the wear resistance of 42CrMo quenched and tempered steel is defined as 1, the relative wear resistance of this nickel-based alloy coating reaches 4.75, demonstrating high hardness and high wear resistance.

[0042] Example 3

[0043] 1. Powder Mixing: Weigh out 3.63% B4C powder, 5.13% Si powder, 15.84% Cr powder, 3.08% Mo powder, and 3.08% Cu powder according to the mass ratio and add them to a mortar. Perform preliminary stirring and grinding for 20 minutes. Then, add the preliminarily mixed powder to a ball mill jar, add cemented carbide balls at a ball-to-powder ratio of 0.8:1, and add anhydrous ethanol at a ratio of 10 ml / 100 g powder. First, perform preliminary stirring and mixing of the powder, grinding balls, and anhydrous ethanol for about 5 minutes. Then, place the ball mill jar in a vibratory ball mill to begin ball milling. The vibration frequency is 300 times / min, the vertical amplitude of the jar is 40 mm, and the horizontal and vertical amplitudes are 15 mm. After ball milling for 7 hours, open the jar and place it in a suitable container. The powder was dried in a vacuum drying oven for 7 hours, and then passed through an 80-mesh sieve to separate the powder from the grinding balls, resulting in a pre-mixed powder. Ni powder at a mass ratio of 67.55% was added to the pre-mixed powder and then added to a V-type mixer for powder mixing. The mixing speed was set to 19 r / min and the mixing time was 11 hours. After mixing, the powder was removed and placed in a vacuum drying oven for 4 hours. The dried powder was then passed through a 100-mesh sieve to obtain a dry, uniformly mixed powder with good flowability. The melting point of the prepared mixed powder was 926.9℃.

[0044] 2. Matrix pretreatment: The 65Mn matrix was treated with a grinding wheel to remove the oxide film on the surface; after treatment, the matrix material was further cleaned with ethanol, and the residual cleaning agent on the surface was dried after cleaning; the matrix material was placed in a muffle furnace and preheated at 200℃ for 7 hours.

[0045] 3. Coating Preparation: The dried mixed powder is loaded into the powder feeding device, and the preheated substrate material is transferred to the working area; the coating is prepared by plasma welding; the spray gun height during welding is 8 mm, the welding gun swing amplitude is 11 mm, the swing speed is 1900 mm / min, and the welding gun moving speed is 11 mm / min; the powder feeding speed of the powder feeding device is 75 rpm, the powder feeding gas flow rate is 4 L / min, the ion gas flow rate is 2.0 L / min, and the shielding gas flow rate is 11 L / min; the shielding gas is helium; the welding current is 80 A; after the coating preparation is completed, it is air-cooled to room temperature to obtain a nickel-based alloy coating.

[0046] The nickel-based alloy coating prepared by the above method consists of the following phases: γ-Ni, M7(B,C)3, M... 23 (B,C)6. In this nickel-based alloy coating, the hard phases M7(B,C)3 and M 23 (B,C)6 is relatively uniformly distributed in the nickel-based coating area. M7(B,C)3 has a larger volume fraction in the coating area, while M 23 The volume fraction of (B,C)6 is relatively low. The self-corrosion current density of this iron-free nickel-based coating is 3.427 × 10⁻⁶. -7 A×cm -2 The self-corrosion current density of the nickel-based alloy coating containing iron is 3.834 × 10⁻⁶. -6 A×cm -2 The iron-free nickel-based coating prepared by this invention exhibits superior corrosion resistance compared to iron-containing nickel-based alloy coatings. This nickel-based alloy coating has a porosity of 0.76% and a hardness of 59.7 HRC. Based on volumetric wear rate calculations, if the wear resistance of 42CrMo quenched and tempered steel is defined as 1, the relative wear resistance of this nickel-based alloy coating reaches 3.96, demonstrating high hardness and high wear resistance.

[0047] Example 4

[0048] 1. Powder Mixing: Weigh out 4.96% B4C powder, 3.88% Si powder, 18% Cr powder, 3.50% Mo powder, and 3.50% Cu powder by mass and add them to a mortar. Perform preliminary stirring and grinding for 20 minutes. Then, add the preliminarily mixed powder to a ball mill jar, add cemented carbide balls at a ball-to-powder ratio of 0.9:1, and add anhydrous ethanol at a ratio of 20 ml / 100 g powder. First, perform preliminary stirring and mixing of the powder, grinding balls, and anhydrous ethanol for about 5 minutes. Then, place the ball mill jar in a vibratory ball mill to begin ball milling. The vibration frequency is 200 times / min, the vertical amplitude of the jar is 30 mm, and the horizontal and vertical amplitudes are 15 mm. After ball milling for 8 hours, open the jar and place it in a suitable container. The powder was dried in a vacuum drying oven for 8 hours, and then passed through an 80-mesh sieve to separate the powder from the grinding balls, resulting in a pre-mixed powder. Ni powder at a mass ratio of 64.19% was added to the pre-mixed powder and then added to a drum mixer for powder mixing. The mixing speed was set to 17 r / min and the mixing time was 12 hours. After mixing, the powder was removed and placed in a vacuum drying oven for 2 hours. The dried powder was then passed through a 100-mesh sieve to obtain a dry, uniformly mixed powder with good flowability. The melting point of the prepared mixed powder was 921.5℃.

[0049] 2. Matrix pretreatment: The 55Mn2 matrix was treated with a grinding wheel to remove the oxide film on the surface; after treatment, the matrix material was further cleaned with ethanol, and the residual cleaning agent on the surface was dried after cleaning; the matrix material was placed in a pit furnace and preheated at 280℃ for 8 hours.

[0050] 3. Coating preparation: The dried mixed powder is loaded into the powder feeding device, and the preheated substrate material is transferred to the working area; the coating is prepared by laser cladding; the laser power is 1000W, the laser spot diameter is 1.5mm, the laser scanning speed is 400m / min, and the multi-pass overlap rate is 50%; the synchronous powder feeding rate is 27.6g / min, the protective gas flow rate is 7L / min; the protective gas is helium; after the coating is prepared, it is air-cooled to room temperature to obtain a nickel-based alloy coating.

[0051] The nickel-based alloy coating prepared by the above method consists of the following phases: γ-Ni, M7(B,C)3, M... 23 (B,C)6. In this nickel-based alloy coating, the hard phases M7(B,C)3 and M 23 (B,C)6 is relatively evenly distributed in the nickel-based coating area. M7(B,C)3 has a larger volume fraction in the coating area and mostly exhibits an elongated shape. 23 (B,C)6 is more abundant in the region near the substrate. The self-corrosion current density of this iron-free nickel-based coating is 2.391 × 10⁻⁶.-7 A×cm -2 The self-corrosion current density of the nickel-based alloy coating containing iron is 3.834 × 10⁻⁶. -6 A×cm -2 The iron-free nickel-based coating prepared by this invention exhibits superior corrosion resistance compared to iron-containing nickel-based alloy coatings. This nickel-based alloy coating has a porosity of 0.82% and a hardness of 59.4 HRC. Based on volumetric wear rate calculations, if the wear resistance of 42CrMo quenched and tempered steel is defined as 1, the relative wear resistance of this nickel-based alloy coating reaches 3.85, demonstrating high hardness and high wear resistance.

[0052] Example 5

[0053] 1. Powder Mixing: Weigh out 3.63% B4C powder, 5.13% Si powder, 15.84% Cr powder, 3.08% Mo powder, and 3.08% Cu powder according to the mass ratio and add them to a mortar. Perform preliminary stirring and grinding for 20 minutes. Then, add the preliminarily mixed powder to a ball mill jar, add cemented carbide balls at a ball-to-powder ratio of 0.8:1, and add anhydrous ethanol at a ratio of 10 ml / 100 g powder. First, perform preliminary stirring and mixing of the powder, grinding balls, and anhydrous ethanol for about 5 minutes. Then, place the ball mill jar in a planetary ball mill to begin ball milling. The rotation speed is 260 r / min, alternating between clockwise and counterclockwise rotations, with a single rotation time of 30 minutes. After ball milling for 9 hours, open the ball mill jar and place it in a vacuum chamber. The powder was dried in an empty drying oven for 8 hours. The dried powder was then passed through an 80-mesh sieve to separate the powder from the grinding balls, resulting in a pre-mixed powder. Ni powder at a mass ratio of 67.55% was added to the pre-mixed powder and then added to a drum mixer for powder mixing. The mixing speed was set to 16 r / min and the mixing time was 12 hours. After mixing, the powder was removed and placed in a vacuum drying oven for 3 hours. The dried powder was then passed through a 100-mesh sieve to obtain a dry, uniformly mixed powder with good flowability. The melting point of the prepared mixed powder was 926.9℃.

[0054] 2. Matrix pretreatment: The 8CrMoV matrix was treated with a sandblasting machine to remove the oxide film on the surface; after treatment, the matrix material was further cleaned with propanol, and the residual cleaning agent on the surface was dried after cleaning; the matrix material was placed in a salt bath furnace and preheated at 350℃ for 6 hours.

[0055] 3. Coating preparation: The dried mixed powder is loaded into the powder feeding device, and the preheated substrate material is transferred to the working area; the coating is prepared by laser cladding; the laser power is 1500W, the laser spot diameter is 2.5mm, the laser scanning speed is 340m / min, and the multi-pass overlap rate is 45%; the synchronous powder feeding rate is 20.4g / min, the protective gas flow rate is 10L / min, and the protective gas is argon; after the coating is prepared, it is air-cooled to room temperature to obtain a nickel-based alloy coating.

[0056] The nickel-based alloy coating prepared by the above method consists of the following phases: γ-Ni, M7(B,C)3, M... 23 (B,C)6. In this nickel-based alloy coating, the hard phases M7(B,C)3 and M 23 (B,C)6 is relatively evenly distributed in the nickel-based coating area. M7(B,C)3 has a larger volume fraction in the coating area and mostly exhibits an elongated shape. 23 (B,C)6 has a relatively low volume fraction. The self-corrosion current density of this iron-free nickel-based coating is 4.179 × 10⁻⁶. -7 A×cm -2 The self-corrosion current density of the nickel-based alloy coating containing iron is 3.834 × 10⁻⁶. -6 A×cm -2 The iron-free nickel-based coating prepared by this invention exhibits superior corrosion resistance compared to iron-containing nickel-based alloy coatings. This nickel-based alloy coating has a porosity of 0.39% and a hardness of 60.1 HRC. Based on volumetric wear rate calculations, if the wear resistance of 42CrMo quenched and tempered steel is defined as 1, the relative wear resistance of this nickel-based alloy coating reaches 4.17, demonstrating high hardness and high wear resistance.

[0057] Example 6

[0058] 1. Powder Mixing: Weigh out 4.96% B4C powder, 3.88% Si powder, 18% Cr powder, 3.50% Mo powder, and 3.50% Cu powder according to the mass ratio and add them to a mortar. Perform preliminary stirring and grinding for 20 minutes. Then, add the preliminarily mixed powder to a ball mill jar, add cemented carbide balls at a 1:1 ball-to-powder ratio, and add anhydrous ethanol at a ratio of 15 ml / 100 g powder. First, perform preliminary stirring and mixing of the powder, grinding balls, and anhydrous ethanol for about 5 minutes. Then, place the ball mill jar in a vibratory ball mill to begin ball milling. The vibration frequency is 270 times / min, the vertical amplitude of the jar is 35 mm, and the horizontal and vertical amplitudes are 10 mm. After ball milling for 7 hours, open the jar and place it in a vibratory ball mill. The powder was dried in a vacuum drying oven for 7 hours, and then passed through an 80-mesh sieve to separate the powder from the grinding balls, resulting in a pre-mixed powder. Ni powder at a mass ratio of 64.19% was added to the pre-mixed powder and then added to a V-type mixer for powder mixing. The mixing speed was set to 18 r / min and the mixing time was 10 hours. After mixing, the powder was removed and placed in a vacuum drying oven for 2 hours. The dried powder was then passed through a 100-mesh sieve to obtain a dry, uniformly mixed powder with good flowability. The melting point of the prepared mixed powder was 921.5℃.

[0059] 2. Substrate pretreatment: The 45 steel substrate is treated with a sandblasting machine to remove the oxide film on the surface; after treatment, the substrate material is further cleaned with ethanol, and the residual cleaning agent on the surface is dried after cleaning; the substrate material is placed in a vertical furnace and preheated at 200℃ for 7 hours.

[0060] 3. Coating preparation: The dried mixed powder is loaded into the powder feeding device, and the preheated substrate material is transferred to the working area; the coating is prepared by laser cladding; the laser power is 1250W, the laser spot diameter is 2.0mm, the laser scanning speed is 200m / min, and the multi-pass overlap rate is 40%; the synchronous powder feeding rate is 31.2g / min, the protective gas flow rate is 9L / min, and the protective gas is nitrogen; after the coating is prepared, it is air-cooled to room temperature to obtain a nickel-based alloy coating.

[0061] The nickel-based alloy coating prepared by the above method consists of the following phases: γ-Ni, M7(B,C)3, M... 23 (B,C)6. In this nickel-based alloy coating, the hard phases M7(B,C)3 and M 23 (B,C)6 is relatively evenly distributed in the nickel-based coating area. M7(B,C)3 has a larger volume fraction in the coating area and mostly exhibits an elongated shape. 23 (B,C)6 has a low volume fraction. The self-corrosion current density of this iron-free nickel-based coating is 1.673 × 10⁻⁶. -7 A×cm-2 The self-corrosion current density of the nickel-based alloy coating containing iron is 3.834 × 10⁻⁶. -6 A×cm -2 The iron-free nickel-based coating prepared by this invention exhibits superior corrosion resistance compared to iron-containing nickel-based alloy coatings. This nickel-based alloy coating has a porosity of 0.64% and a hardness of 64.3 HRC. Based on volumetric wear rate calculations, if the wear resistance of 42CrMo quenched and tempered steel is defined as 1, the relative wear resistance of this nickel-based alloy coating reaches 5.19, demonstrating high hardness and high wear resistance.

[0062] The friction test and relative wear resistance calculation in the above embodiments are explained as follows:

[0063] The friction test used a ball-disc friction method, and the coated sample was cut into pieces with a diameter of 30 mm and a height of 5 mm.

[0064] The test was conducted on a cylindrical grinding ball. The grinding ball was a silicon nitride ceramic ball with a diameter of 6 mm. The rotation diameter was 6 mm, the load was 30 N, the rotation speed was 300 r / min, the test time was 60 min, and the sampling frequency was 1 Hz during the test. The mass of the sample was measured before and after the friction test. The volume wear rate of the friction sample was calculated according to formula (1), and the relative wear resistance of the nickel-based alloy coating was calculated according to formula (2) based on the obtained volume wear rate.

[0065]

[0066]

[0067] In equation (1), W represents the volumetric wear rate (mm). 3 / (N×m)), m1 and m2 are the masses (g) of the sample before and after the friction test, respectively, and ρ is the density of the sample (g / cm³). 3 F is the load (N), L is the sliding distance (m); in equation (2), β is the relative wear resistance of the nickel-based alloy coating, and W is the volumetric wear rate of the nickel-based alloy coating (mm). 3 / (N×m)), W0 is the volumetric wear rate (mm) of 42CrMo quenched and tempered steel. 3 / (N×m)).

Claims

1. A low-melting-point nickel-based alloy coating free of iron, characterized in that: The coating powder is a mixture of nickel powder, chromium powder, molybdenum powder, copper powder, boron carbide powder, and silicon powder. The mass percentages of the raw material powders used are: Ni: 64.19 ~ 67.55%; Cr, Mo, and Cu: 22 ~ 25%, with the mass ratio of Cr, Mo, and Cu being 5:1:1; B4C: 3.63 ~ 4.96%; Si: 3.88 ~ 5.13%. After mixing and drying, the powder is used for coating preparation. The coating process includes welding, cladding, and spraying. The melting point range of the prepared mixed powder is 921.5 ~ 926.9 ℃. The resulting iron-free nickel-based coating exhibits a self-corrosion current density of 1.084 ~ 4.179 × 10⁻⁶ in a 3.5 wt.% sodium chloride solution. -7 A×cm -2 The self-corrosion current density of the nickel-based alloy coating containing iron is 3.834 × 10⁻⁶. -6 A×cm -2 The resulting coating exhibits superior corrosion resistance compared to nickel-based alloy coatings containing iron elements; the hardness of the resulting coating is 57.3~61.4 HRC. If the wear resistance of 42CrMo quenched and tempered steel is defined as 1, then the relative wear resistance of the nickel-based alloy coating is 3.51~5.19; the resulting coating has the characteristics of high hardness, high wear resistance, and low preparation temperature.

2. The iron-free, low-melting-point nickel-based alloy coating as described in claim 1, characterized in that: The specific mixing and drying process is as follows: Prepare B4C powder, Si powder, Cr powder, Mo powder, Cu powder, and Ni powder according to the required proportions; add anhydrous ethanol to the weighed powder at a ratio of 10~30 ml / 100 g powder; the powder mixing methods include planetary ball milling, vibratory ball milling, V-type mixing, and drum mixing; after mixing, remove the powder; place the powder in a vacuum drying oven and dry for 2~4 hours; the dried powder is then sieved to obtain a dry, uniformly mixed powder with good flowability.

3. The method for preparing an iron-free low-melting-point nickel-based alloy coating as described in claim 1, characterized in that: Includes the following steps: (1) Powder mixing: Prepare B4C powder, Si powder, Cr powder, Mo powder, Cu powder and Ni powder according to the required proportions; weigh the powder and mix it; dry and sieve the mixed powder; the powder mixing methods include planetary ball milling, vibratory ball milling, V-type mixing and drum mixing. (2) Substrate pretreatment: Clean and wash the substrate surface; dry the cleaned substrate; preheat the substrate at 200~350 ℃ for 5~8 h; the substrate type is carbon steel; (3) Coating preparation: The uniformly mixed powder is loaded into the powder feeding device and the preheated substrate is coated to obtain a nickel-based alloy coating; Argon, nitrogen or helium is used as a protective gas when preparing the coating; The coating preparation methods include welding, cladding and spraying. After coating preparation, air cool to room temperature.

4. The method for preparing an iron-free low-melting-point nickel-based alloy coating as described in claim 3, characterized in that: The powder mixing in step (1) is carried out in the following specific steps: Preliminary mixing: Weigh the boron carbide (B4C) powder, silicon (Si) powder, chromium (Cr) powder, molybdenum (Mo) powder, and copper (Cu) powder together in a container and perform preliminary stirring and grinding for 20 minutes. Add the powder to a ball mill jar, add grinding balls at a ball-to-powder ratio of 0.8-1.1, and add anhydrous ethanol at a ratio of 10-30 ml / 100 g powder. First, perform preliminary stirring and mixing of the powder, grinding balls, and anhydrous ethanol for about 5 minutes, then place the ball mill jar in a ball mill to begin ball milling. Ball milling methods include planetary ball milling and vibratory ball milling. For planetary ball milling, the mill's revolution speed is 200-300 r / min, rotating alternately clockwise and counterclockwise, with a single rotation time of 30 minutes. Alternatively, for vibratory ball milling, the oscillation frequency is 200-300 times / min, the vertical jar amplitude is 30-40 mm, and the horizontal and vertical jar amplitudes are 10-10 mm. 15 mm; After ball milling and mixing for 7 to 10 hours, the ball mill jar is opened and placed in a vacuum drying oven for 7 to 10 hours. The dried powder is then sieved to separate the powder from the ball milling balls, resulting in a uniformly mixed powder. The above preliminary mixing process is to fully mix the boron carbide powder and silicon powder so that they are distributed in the gaps between other metal powder particles. Powder mixing: Add the weighed nickel (Ni) powder to the pre-mixed powder and put it into a roller or V-shaped drum for powder mixing; set the powder mixing speed to 16~20 r / min and the mixing time to 10~14h; after the mixing is completed, take out the powder; put the powder into a vacuum drying oven to dry for 2~4h, and sieve the dried powder to obtain a dry, uniformly mixed powder with good flowability.

5. The method for preparing an iron-free low-melting-point nickel-based alloy coating as described in claim 3, characterized in that: The matrix pretreatment described in step (2) is as follows: The substrate is treated by grinding with steel wool, grinding with a grinding wheel, or sandblasting to remove the oxide film on the surface; after treatment, the substrate material is further cleaned with ethanol or propanol, and the surface is dried to remove any residual cleaning agent; the substrate material is then placed in a heat treatment device and preheated at 200~350 ℃ for 5~8 h; the substrate type used is carbon steel.

6. The method for preparing an iron-free low-melting-point nickel-based alloy coating as described in claim 3, characterized in that: The coating preparation described in step (3) is as follows: The dried mixed powder is loaded into a powder feeding device, and the preheated substrate material is transferred to the working area; the coating is prepared by means of plasma welding, laser cladding or spraying. The plasma welding process includes a spray gun height of 8-9 mm, a welding gun swing amplitude of 10-12 mm, a swing speed of 1800-2000 mm / min, and a welding gun movement speed of 10-12 mm / min. The powder feeding device operates at a speed of 70-80 rpm, a powder feeding gas flow rate of 3-5 L / min, an ion gas flow rate of 1.5-2 L / min, and a shielding gas flow rate of 10-12 L / min. The shielding gas is argon, nitrogen, or helium. The welding current is 75-80 A. During laser cladding, the laser power is 1000~1500 W, the laser spot diameter is 1.5~2.5 mm, the laser scanning speed is 200~400 m / min, and the multi-pass overlap rate is 40~50%; the synchronous powder feeding rate is 27.6 g / min~31.2 g / min, and the protective gas flow rate is 7~10 L / min; the protective gas is argon, nitrogen, or helium. Spraying includes oxyacetylene flame spraying, high-velocity oxygen flame spraying (HVOF), arc spraying, atmospheric plasma spraying, and low-pressure plasma spraying; After the coating is prepared, it is air-cooled to room temperature to obtain a nickel-based alloy coating; during the coating preparation process; Because the melting point of the coating powder is low, ranging from 921.5 to 926.9 °C, the above coating process uses current, power, or temperature that are lower than commonly used process requirements. By using lower welding current, laser power, or spraying temperature, a highly dense nickel-based coating with good bonding and a porosity of only 0.39 to 0.91% is achieved.

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