A WC-Co-Cu-rare earth wear-resistant and corrosion-resistant coating material and its preparation method and use method

Abstract

The present invention provides a WC-Co-Cu-rare earth wear-resistant and corrosion-resistant coating material and a preparation method and a use method thereof. The wear-resistant and corrosion-resistant coating material is composed of the following mass percentages of substances: 75-80% tungsten carbide, 10-15% cobalt, 3-6% copper, 1-3% rare earth, 0.5-1.5% organic antioxidant, 0.5-2.0% adhesive, and the balance is nickel. The present invention enhances the bonding strength between the coating and the substrate by adding Cu elements and rare earth elements, inhibits the growth of tungsten carbide grains during precipitation, and improves the hardness of the alloy, wherein Cu has the dual effects of improving bonding strength and reducing porosity, and WC particles can be flattened and firmly bonded and filled into the pores of the coating during thermal spraying, thereby reducing the coating porosity; rare earth elements can inhibit the growth of tungsten carbide grains during precipitation, and improve the hardness of the coating; adding Ni elements can improve the corrosion resistance of the coating, and WC and Co act synergistically to form a mutually reinforcing WC-Co coating system with excellent wear resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of surface repair and strengthening of metal structural parts, and specifically relates to a WC-Co-Cu-rare earth wear-resistant and corrosion-resistant coating material and a preparation method and a use method thereof. Background Art

[0002] Wear-resistant cemented carbides are divided into the following categories according to their composition: (1) tungsten-cobalt cemented carbide (YG), which is mainly composed of WC-xCo and has the characteristics of high density, low expansion, high thermal conductivity, etc., but its wear resistance is average; (2) tungsten-cobalt-titanium cemented carbide (YT), which is mainly composed of WC-TiC-xCo. This type of alloy has high oxidation resistance and higher hardness and friction resistance than tungsten-cobalt alloys; (3) tungsten-cobalt-titanium (niobium) cemented carbide (YW), whose main components are one or a combination of TaC or NbC in addition to YT alloys. This type of alloy has good damage resistance and oxidation resistance under high temperature environment, but the raw materials and production prices are relatively expensive, and its application field is not wide; (4) titanium carbide-based alloy, which is mainly made of nickel or molybdenum alloy with TiC as the bonding phase sintered as the hard phase. When the carbon content of the alloy exceeds 94%, the hardness of this alloy is far higher than that of other types of alloys.

[0003] On December 15, 2020, the State Intellectual Property Office published an invention patent with publication number CN112080716A, and the patent name is a hydrophobic anti-corrosion coating material and its preparation method. This patent belongs to the field of thermal spraying technology. In principle, fluorine-containing materials and ceramic powders are used as modified raw materials, and thermal spraying technology is used to prepare one or two layers of anti-corrosion hydrophobic coatings on the metal surface. The application field of this patent is the field of marine corrosion protection. The main principle is to utilize the controllable morphology of the surface of the thermal spray coating organization, and the formation of a micro-nano protruding structure on the surface, and by doping a certain amount of low surface energy substances, the purpose of hydrophobicity is achieved, reducing the contact area between metal parts and liquid media in a corrosive environment, thereby increasing the service life of metal parts in a corrosive environment. In other words, the purpose is corrosion protection, but the impact resistance is poor. Summary of the invention

[0004] The purpose of the present invention is to provide a WC-Co-Cu-rare earth wear-resistant and corrosion-resistant coating material to overcome the above-mentioned technical problems existing in the prior art.

[0005] Another object of the present invention is to provide a method for preparing a WC-Co-Cu-rare earth wear-resistant and corrosion-resistant coating material, which can obtain a particle size that meets the wear-resistant and corrosion-resistant coating material requirements through ball milling and particle size screening.

[0006] Another object of the present invention is to provide a method for using a WC-Co-Cu-rare earth wear-resistant and corrosion-resistant coating material, which can significantly improve the wear resistance and corrosion resistance of the pipeline, extend the service life of the pipeline, and improve the safe operation capability of the pipeline through supersonic spraying technology.

[0007] To this end, the technical solution provided by the present invention is as follows:

[0008] A WC-Co-Cu-rare earth wear-resistant and corrosion-resistant coating material is composed of the following substances in percentage by mass: 75-80% tungsten carbide, 10-15% cobalt, 3-6% copper, 1-3% rare earth, 0.5-1.5% organic antioxidant, 0.5-2.0% adhesive, and the balance is nickel.

[0009] The tungsten carbide has multiple particle sizes, which are 10nm~50nm, 0.1μm~0.5μm and 1.0μm~5.0μm.

[0010] The organic antioxidant is D-isoascorbic acid.

[0011] The adhesive is low carbon steel.

[0012] The mass percentages of 10nm~50nm, 0.1μm~0.5μm and 1.0μm~5.0μm tungsten carbide are 5~10%, 10~30% and 60~80% respectively.

[0013] A method for preparing a WC-Co-Cu-rare earth wear-resistant and corrosion-resistant coating material comprises the following steps:

[0014] Step 1) Add the formulated amounts of tungsten carbide, cobalt, copper, rare earth and nickel into a container in sequence and mix and stir evenly;

[0015] Step 2) adding a formulated amount of organic antioxidant, adhesive and a certain amount of water and mixing and stirring evenly;

[0016] Step 3) Place the mixture in a high-energy ball mill for ball milling for 20-25 hours, and then sieve the milled product to a particle size of 15-45 μm and then dry and granulate it to form a spherical mixture.

[0017] A method for using a WC-Co-Cu-rare earth wear-resistant and corrosion-resistant coating material, wherein a coating is formed on a metal by supersonic spraying, and the spraying distance is between 150 and 200 mm.

[0018] The beneficial effects of the present invention are:

[0019] The WC-Co-Cu-rare earth wear-resistant and corrosion-resistant coating material provided by the present invention enhances the bonding strength between the coating and the substrate, inhibits the growth of tungsten carbide grains during precipitation, and improves the hardness of the alloy by adding Cu elements and rare earth elements, wherein Cu has the dual functions of improving the bonding strength and reducing the porosity, and Cu has a low melting point and good fluidity, so WC particles can be flattened and firmly bonded during thermal spraying, and can also be filled into the pores of the coating, thereby reducing the porosity of the coating; the addition of rare earth elements can inhibit the growth of tungsten carbide grains during precipitation, thereby refining the grains and improving the hardness of the coating; and the addition of Ni elements can improve the corrosion resistance of the coating, and WC and Co act synergistically to form a mutually reinforcing WC-Co coating system, which has excellent wear resistance.

[0020] This wear-resistant and corrosion-resistant coating material is suitable for pipelines in high-velocity sand-containing natural gas gathering and transportation systems. Through supersonic spraying technology, WC-Co-Cu-rare earth wear-resistant and corrosion-resistant coatings are coated on the inner surfaces of pipelines and erosion-prone components, which can significantly improve the wear resistance and corrosion resistance of pipelines, extend the service life of pipelines, and improve the safe operation capability of pipelines.

[0021] Tungsten carbide adopts multi-level particle size, with large micron-sized particles playing a supporting role, submicron-sized medium-sized particles filling gaps, and nano-sized small-sized particles further filling the remaining gaps, which can improve the density of the thermal spray coating.

[0022] The following will provide further detailed description in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the erosion rate curve of the 20# substrate and the WC-Co-Cu-rare earth coating at different angles in the embodiment of the present invention;

[0024] Figure 2 is the erosion pit depth curve of the 20# substrate at different angles in the embodiment of the present invention;

[0025] Figure 3 is the erosion pit depth curve of WC-Co-Cu-rare earth coating at different angles;

[0026] Figure 4 This is a test curve of the bonding strength of the WC-Co-Cu-rare earth coating in an embodiment of the present invention;

[0027] Figure 5 This is a WC-Co-Cu-rare earth coating sample according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The following describes the implementation of the present invention through specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0029] The exemplary embodiments of the present invention are now described with reference to the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to disclose the present invention in detail and completely and to fully convey the scope of the present invention to those skilled in the art. The terms used in the exemplary embodiments shown in the accompanying drawings are not intended to limit the present invention.

[0030] Unless otherwise specified, the terms (including technical terms) used herein have the commonly understood meanings to those skilled in the art. In addition, it is understood that the terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0031] Aiming at the disadvantages of common tungsten-cobalt cemented carbide and existing coating materials in terms of general wear resistance, the present invention provides a WC-Co-Cu-rare earth wear-resistant and corrosion-resistant coating material, which is composed of the following substances in percentage by mass: 75-80% tungsten carbide, 10-15% cobalt, 3-6% copper, 1-3% rare earth, 0.5-1.5% organic antioxidant, 0.5-2.0% adhesive, and the balance is nickel.

[0032] Among them, tungsten carbide has multiple levels of particle sizes, namely 10nm~50nm, 0.1μm~0.5μm and 1.0μm~5.0μm.

[0033] The organic antioxidant is D-isoascorbic acid (CAS No. 89-65-6, molecular formula C6H8O6, alias: isoascorbic acid, erythrosonic acid, isovitamin C), which is easily soluble in water (soluble range of about 30%) and alcohol. It has strong reducing properties and gradually changes color (blackens) when exposed to light or heated. It has strong stability in a dry state, but will quickly decompose when exposed to air in an aqueous solution. It has a water solubility of 1g / 10mL, is soluble in water, alcohol and pyridine, is quite soluble in propanol, and slightly soluble in glycerol. Its chemical properties are very similar to ascorbic acid and have the same strong reducing effect.

[0034] The bonding agent is mild steel.

[0035] The mass percentages of 10nm~50nm, 0.1μm~0.5μm and 1.0μm~5.0μm tungsten carbide are 5-10%, 10-30% and 60-80% respectively.

[0036] Embodiment 1:

[0037] The present embodiment provides a WC-Co-Cu-rare earth wear-resistant and corrosion-resistant coating material, which is composed of the following substances in the following mass percentages: 75% tungsten carbide, 12% cobalt, 4% copper, 1.5% rare earth, 0.5% organic antioxidant, 1% adhesive, and 6% nickel.

[0038] In this embodiment, 100 g of wear-resistant and corrosion-resistant coating material powder is taken as an example, and the raw materials are weighed according to the following mass: 75 g of tungsten carbide (WC); 12 g of cobalt (Co); 4 g of copper (Cu); 1.5 g of rare earth; 0.5 g of organic antioxidant; 1.0 g of binder; and 6.0 g of nickel (Ni).

[0039] Preparation process:

[0040] Step 1) Add the formulated amounts of tungsten carbide, cobalt, copper, rare earth and nickel into a container in sequence and mix and stir evenly;

[0041] Step 2) adding a formulated amount of organic antioxidant, adhesive and a certain amount of water and mixing and stirring evenly;

[0042] Step 3) Place the mixture in a high-energy ball mill for ball milling for 20-25 hours, and then sieve the milled product to a particle size of 15-45 μm and then dry and granulate it to form a spherical mixture.

[0043] To prepare 100g of wear-resistant and corrosion-resistant coating material, 30ml of water is needed.

[0044] In this embodiment, 10nm~50nm nano-grade WC7.5g, 0.1μm~0.5μm submicron-grade WC15g, 1.0μm~5.0μm micron-grade WC52.5g.

[0045] Principle of the invention:

[0046] The invention enhances the bonding strength between the coating and the substrate by adding Cu element and rare earth element, inhibits the growth of tungsten carbide grains during precipitation, and improves the hardness of the alloy. Cu has the dual functions of improving the bonding strength and reducing the porosity. Since Cu has a low melting point and good fluidity, WC particles can be flattened and firmly bonded during thermal spraying, and can also be filled into the pores of the coating to reduce the porosity of the coating. The bonding force between the prepared WC-Co-Cu-rare earth coating and the substrate reaches more than 200N. The addition of the rare earth element can inhibit the growth of tungsten carbide grains during precipitation, refine the grains, and improve the hardness of the coating. At the same time, the addition of the Ni element can improve the corrosion resistance of the coating. WC and Co act synergistically to form a mutually reinforcing WC-Co coating system, which has excellent wear resistance. The main component of the organic antioxidant is D-isoascorbic acid, with the molecular formula C6H8O6, which prevents the oxidation of various metal powders. The main component of the adhesive is low-carbon steel, which mixes tungsten carbide mixtures of different particle sizes and other metal powders to reduce the porosity of the coating.

[0047] The hardness of the WC-Co-Cu-rare earth coating prepared by the invention reaches 2000 HV.

[0048] The WC-Co-Cu-rare earth wear-resistant and corrosion-resistant coating of the present invention adopts tungsten carbide as a mixture, and the size of the mixture is a multi-level particle size structure, and the multi-level particle sizes are 10nm-50nm, 0.1μm-0.5μm and 1.0μm-5.0μm, respectively, and the proportions of the multiple particle sizes are: nano-level tungsten carbide accounts for 5%-10%, submicron-level tungsten carbide accounts for 10%-30%, and micron-level tungsten carbide accounts for 60%-80%. The micron-level large-size particle size plays a supporting role, the submicron-level medium-size particle size fills the gap, and the nano-level small-size particle size further fills the remaining gap, which can significantly improve the compactness of the thermal spray coating.

[0049] Embodiment 2:

[0050] The present embodiment provides a WC-Co-Cu-rare earth wear-resistant and corrosion-resistant coating material, which is composed of the following substances in the following mass percentages: 76.5% tungsten carbide, 12.5% ​​cobalt, 4.6% copper, 1.5% rare earth, 0.5% organic antioxidant, 1.0% adhesive, and 3.4% nickel.

[0051] In this embodiment, 100 g of wear-resistant and corrosion-resistant coating material powder is taken as an example, and the raw materials are weighed according to the following mass: 76.5 g of tungsten carbide (WC); 12.5 g of cobalt (Co); 4.6 g of copper (Cu); 1.5 g of rare earth; 0.5 g of organic antioxidant; 1.0 g of binder; and 3.4 g of nickel (Ni).

[0052] The preparation process is the same as that of Example 1.

[0053] In this embodiment, 10nm~50nm nano-grade WC 7.65g, 0.1μm~0.5μm submicron-grade WC 15.3g, 1.0μm~5.0μm micron-grade WC 53.55g.

[0054] Among them, rare earth is a metal extracted from rare earth ore containing lanthanum, cerium, praseodymium, neodymium and a small amount of samarium, europium and gadolinium mixed oxides produced by molten salt electrolysis. The addition of rare earth elements can inhibit the growth of tungsten carbide grains during precipitation, play a role in refining grains, and improve the hardness of the coating. Ni can improve the strength of steel, has a higher corrosion resistance to acids and alkalis, and makes the coating have a certain degree of corrosion resistance.

[0055] Embodiment 3:

[0056] The present embodiment provides a WC-Co-Cu-rare earth wear-resistant and corrosion-resistant coating material, which is composed of the following substances in the following mass percentages: 80% tungsten carbide, 11% cobalt, 5% copper, 1% rare earth, 0.5% organic antioxidant, 1.0% adhesive, and 1.5% nickel.

[0057] In this embodiment, 100g of wear-resistant and corrosion-resistant coating material powder is taken as an example, and the raw materials are weighed according to the following mass: 80g of tungsten carbide (WC); 11g of cobalt (Co); 5g of copper (Cu); 1g of rare earth; 0.5g of organic antioxidant; 1.0g of binder; and 1.5g of nickel (Ni).

[0058] The preparation process is the same as that of Example 1.

[0059] In this embodiment, 10nm~50nm nano-grade WC8g, 0.1μm~0.5μm submicron-grade WC17.5g, 1.0μm~5.0μm micron-grade WC54.5g.

[0060] Embodiment 4:

[0061] This embodiment provides a method for using a WC-Co-Cu-rare earth wear-resistant and corrosion-resistant coating material, which uses supersonic spraying to form a coating on a metal, with a spraying distance between 150 and 200 mm.

[0062] The spray gun type used is DJ2700. The parameters used are: the fuel gas is propane, the pressure is 1.2MPa, the flow rate is 43L / min, the secondary gas is oxygen, the pressure is 0.8MPa, the flow rate is 43L / min; the carrier gas is argon or nitrogen, the pressure is 0.8MPa, and the flow rate is 45L / min.

[0063] The present invention belongs to the technical field of surface repair and strengthening of metal structural parts, and is particularly suitable for pipelines of high-velocity sand-containing natural gas gathering and transportation systems. By using supersonic spraying technology, WC-Co-Cu-rare earth wear-resistant and corrosion-resistant coatings are coated on the inner surfaces of pipelines and easily eroded components, which can significantly improve the wear resistance and corrosion resistance of the pipeline, extend the service life of the pipeline, and improve the safe operation capability of the pipeline.

[0064] The WC-Co-Cu-rare earth coating sample of the present invention is shown in FIG. Figure 5 The Vickers hardness of the WC-Co-Cu-rare earth coating was measured and found to be 2000 HV.

[0065] Performance Test:

[0066] 1) Solid particle erosion resistance test:

[0067] Under the same erosion conditions (sand content 100g / min, wind speed 20m / s, time 5min), the 20# substrate sample, the samples obtained by spraying the WC-Co-Cu-rare earth coating prepared in the three groups of examples 1 to 3 onto the 20# substrate, and the samples obtained by spraying the comparative example (nickel-based alloy coating) onto the 20# substrate were experimentally evaluated at five erosion angles of 20°, 30°, 50°, 70°, and 90°. The results are shown in Figure 1 , Figure 2 and Figure 3 shown.

[0068] The test results show that at the above five angles, the erosion rate and erosion pit depth of the WC-Co-Cu-rare earth coating in the three groups of embodiments are much smaller than those of the 20# substrate (i.e., 20 steel), and are also better than those of the nickel-based alloy coating. It is calculated that the uniform erosion resistance of the WC-Co-Cu-rare earth coating is about 6 times that of the 20# substrate, and the local erosion resistance is about 20 times that of the 20# substrate.

[0069] 2) Corrosion resistance test:

[0070] Under the test conditions of temperature 60°C, CO2 partial pressure 0.25MPa, flow rate 2.5m / s, and mineralization 25000mg / L, the corrosion rates of 20# substrate (no coating on the surface), samples obtained by spraying WC-Co-Cu-rare earth coatings prepared in three groups of examples 1 to 3 onto 20# substrate, and comparative sample (obtained by spraying nickel-based alloy coating onto 20# substrate) were tested, and the spraying thickness was the same as 120μm. The test results are shown in Table 1.

[0071] The test results show that the corrosion rate of the 20# substrate sprayed with the WC-Co-Cu-rare earth coating in the three groups of embodiments is much lower than the corrosion rate of the 20# substrate, and its corrosion resistance is about 35 times that of the 20# substrate without the coating, and the corrosion resistance is 1.76 times that of the sprayed comparative sample.

[0072] Table 1 Corrosion rate of 20# substrate and WC-Co-Cu-rare earth coating

[0073]

[0074] 3) Adhesion evaluation. Acoustic emission was used to measure the bonding strength between the WC-Co-Cu-rare earth coating and the substrate. The measurement data is shown in the figure. Figure 4 It can be seen that the bonding force of the WC-Co-Cu-rare earth coating is above 200N, where the vertical lines in the figure represent noise signals and the horizontal curves represent roughness.

[0075] The above examples are merely illustrative of the present invention and do not constitute a limitation on the protection scope of the present invention. All designs that are the same or similar to the present invention fall within the protection scope of the present invention.

Claims

1. A WC-Co-Cu-rare earth wear-resistant and corrosion-resistant coating material, characterized in that: It is composed of the following substances in percentage by mass: tungsten carbide 75-80%, cobalt 10-15%, copper 3-6%, rare earth 1-3%, organic antioxidant 0.5-1.5%, adhesive 0.5-2.0%, and the balance is nickel; The tungsten carbide has multiple particle sizes, which are 10nm~50nm, 0.1μm~0.5μm and 1.0μm~5.0μm respectively; the mass percentages of 10nm~50nm, 0.1μm~0.5μm and 1.0μm~5.0μm tungsten carbide are 5~10%, 10~30% and 60~80% respectively.

2. The WC-Co-Cu-rare earth wear-resistant and corrosion-resistant coating material according to claim 1, characterized in that: The organic antioxidant is isoascorbic acid.

3. The WC-Co-Cu-rare earth wear-resistant and corrosion-resistant coating material according to claim 1, characterized in that: The adhesive is low carbon steel with a carbon content of less than 0.25%.

4. The method for preparing a WC-Co-Cu-rare earth wear-resistant and corrosion-resistant coating material according to claim 1, characterized in that: The following steps are involved: Step 1) Add the formulated amounts of tungsten carbide, cobalt, copper, rare earth and nickel into a container in sequence and mix and stir evenly; Step 2) adding a formulated amount of organic antioxidant, adhesive and a certain amount of water and mixing and stirring evenly; Step 3) Place the mixture in a high-energy ball mill for ball milling for 20-25 hours, and then sieve the milled product to a particle size of 15-45 μm and then dry and granulate it to form a spherical mixture.

5. The method for using the WC-Co-Cu-rare earth wear-resistant and corrosion-resistant coating material according to claim 1, characterized in that: The coating is formed on the metal by supersonic spraying, and the spraying distance is between 150 and 200 mm.

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