Method for densifying the surface of wear-resistant Mo2NiB2-based cermet coating

Abstract

The present application relates to the technical field of surface protection, and particularly relates to a surface densification treatment method of an anti-abrasion Mo2NiB2-based cermet coating. The surface densification treatment method of the anti-abrasion Mo2NiB2-based cermet coating comprises: preheating: simultaneously preheating a base material and a Mo2NiB2-based cermet coating to 150-300 DEG C, and adopting inert gas protection during the preheating process; B powder cladding: performing laser cladding of B powder on the surface of the Mo2NiB2-based cermet coating in an inert gas environment to form a densification layer, wherein the laser cladding temperature is 600-800 DEG C. The surface densification treatment method of the anti-abrasion Mo2NiB2-based cermet coating provided by the present application has low porosity and good anti-abrasion performance.

Description

Technical Field

[0001] This invention relates to the field of surface protection technology, and more specifically, to a method for densifying the surface of a wear-resistant Mo2NiB2-based cermet coating. Background Technology

[0002] Mo2NiB2-based cermets have broad application prospects in wear-resistant and corrosion-resistant fields, such as high-hardness, wear-resistant and corrosion-resistant cutting tools, drill bits, and mining machinery. Compared with traditional Wo-WC cemented carbides, Mo2NiB2-based cermets have a significant cost-performance advantage and are commonly used as laser cladding coatings, exhibiting good bonding with steel substrates.

[0003] However, while existing Mo2NiB2-based cermet coatings exhibit good wear resistance, their high porosity can impair their wear resistance. Summary of the Invention

[0004] The purpose of this invention is to provide a method for densifying the surface of a wear-resistant Mo2NiB2-based cermet coating, so as to alleviate the technical problem of high porosity in existing Mo2NiB2-based cermet coatings.

[0005] The method for densifying the surface of a wear-resistant Mo2NiB2-based cermet coating provided by the present invention is characterized by comprising: Preheating: The substrate and the Mo2NiB2-based cermet coating are preheated to 150-300°C simultaneously, with inert gas protection during the preheating process; B powder cladding: In an inert gas environment, B powder is laser cladding is performed on the surface of the Mo2NiB2-based metal ceramic coating to form a densified layer, wherein the laser cladding temperature is 600-800℃.

[0006] Preferably, as one possible implementation, after the B powder is clad, the method further includes: Cooling: Cover the cladding surface with borax, cool to room temperature, and then remove the borax.

[0007] Preferably, as one possible implementation, the B powder cladding step includes: placing B powder into the powder feeder of a laser cladding equipment, then sealing and filling it with inert gas, and cladding the surface of the Mo2NiB2-based metal ceramic coating with the B powder, wherein the laser cladding parameters include: laser power 0.5-1.5kW, powder feed rate 15-20g / min, cladding speed 50-100mm / min, and inert gas flow rate 10-20ml / min.

[0008] Preferably, as one possible implementation, the cladding process is repeated 3 to 5 times according to the B powder cladding steps, and the surface temperature of the Mo2NiB2-based metal ceramic coating is 150 to 300°C before each cladding.

[0009] Preferably, as one possible implementation, the thickness of the densification layer ranges from 50 to 250 μm.

[0010] Preferably, as one possible implementation, the particle size of the B powder is 300-500 μm and the purity is 99% or higher.

[0011] Preferably, as one possible implementation, before the preheating, the method further includes: Cleaning: The surface of the Mo2NiB2-based metal ceramic coating that has been fused onto the substrate is cleaned until the surface of the Mo2NiB2-based metal ceramic coating exhibits a metallic luster.

[0012] Preferably, as one possible implementation, anhydrous ethanol is used for cleaning in the cleaning step.

[0013] Preferably, as one possible implementation, the inert gas is argon.

[0014] Preferably, as one possible implementation, after the B powder is clad, the method further includes: Polishing: Polish the surface of the Mo2NiB2-based cermet coating until the surface of the Mo2NiB2-based cermet coating exhibits a metallic luster.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides a method for densifying the surface of a wear-resistant Mo2NiB2-based cermet coating. This method involves laser cladding boron powder onto the surface of the Mo2NiB2-based cermet coating, causing the boron powder to be fused into the surface pores of the coating, thus filling the pores and reducing the porosity of the coating. This densification process improves the oxidation resistance of the Mo2NiB2-based cermet coating at high temperatures. Simultaneously, boron powder can react with oxygen at a certain temperature to generate B2O3. When the Mo2NiB2-based cermet coating with boron powder is used in a high-temperature environment, the B2O3 generated by the oxidation of the boron powder melts into a liquid state. The liquid B2O3 has good fluidity, which further densifies the surface of the Mo2NiB2-based cermet coating.

[0016] Therefore, the surface densification treatment method for the wear-resistant Mo2NiB2-based cermet coating provided by this invention results in a densified Mo2NiB2-based cermet coating with low porosity and good wear resistance. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0018] Figure 1 A schematic diagram of the structure of an undensified Mo2NiB2-based cermet coating surface; Figure 2 This is a schematic diagram of the structure of the densified Mo2NiB2-based metal ceramic coating surface obtained in Embodiment 1 of the present invention. Detailed Implementation

[0019] This invention uses laser cladding to clad B powder onto a Mo2NiB2-based cermet coating, thereby achieving surface densification of the Mo2NiB2-based cermet coating and reducing its porosity.

[0020] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings.

[0022] This invention provides a method for densifying the surface of a wear-resistant Mo2NiB2-based cermet coating, comprising: Preheating: The substrate and the Mo2NiB2-based cermet coating are simultaneously preheated to 150–300°C. An inert gas is used for protection during preheating to prevent oxidation. The preheating temperature is preferably 170–280°C, more preferably 200–250°C, and even more preferably 220–230°C.

[0023] Boron powder cladding: Boron powder is laser-clad onto the surface of a Mo2NiB2-based cermet coating in an inert gas environment to form a densified layer. The laser cladding temperature is 600–800℃. Because the laser cladding process is carried out in an inert gas environment, the Boron powder will not undergo oxidation even at high temperatures. The laser cladding temperature is preferably 630–770℃, more preferably 660–740℃, even more preferably 680–720℃, and even more preferably 690–710℃.

[0024] The densification method for the wear-resistant Mo2NiB2-based cermet coating surface provided in this embodiment involves laser cladding boron powder onto the surface of the Mo2NiB2-based cermet coating. This cladding fills the pores of the Mo2NiB2-based cermet coating, reducing its porosity and achieving densification. This improves the oxidation resistance of the Mo2NiB2-based cermet coating at high temperatures. Simultaneously, boron powder reacts with oxygen at a certain temperature to generate B2O3. When the Mo2NiB2-based cermet coating with boron powder is used in a high-temperature environment, the B2O3 generated by the oxidation of the boron powder melts into a liquid state. The liquid B2O3 has good fluidity, further densifying the surface of the Mo2NiB2-based cermet coating.

[0025] Therefore, the surface densification treatment method for the wear-resistant Mo2NiB2-based cermet coating provided in this embodiment results in a densified Mo2NiB2-based cermet coating with low porosity and good wear resistance.

[0026] After completing the B powder cladding, a cooling step can be added: cover the cladding surface with borax to keep the cladding surface warm and allow it to cool down slowly, thereby further improving the density of the Mo2NiB2-based metal ceramic coating surface. After cooling to room temperature, the borax can be removed.

[0027] The steps of the above-mentioned B powder cladding can specifically include: placing B powder into the powder feeder of the laser cladding equipment, then sealing and filling it with inert gas, so as to achieve B powder cladding on the surface of the Mo2NiB2-based metal ceramic coating in an inert gas environment. The laser cladding parameters include laser power of 0.5-1.5kW, powder feeding rate of 15-20g / min, cladding speed of 50-100mm / min, and inert gas flow rate of 10-20ml / min. The laser power is preferably 0.7–1.3 kW, more preferably 0.8–1.2 kW, and even more preferably 1–1.1 kW; the powder feeding rate is preferably 16–19 g / min, and even more preferably 17–18 g / min; the cladding speed is preferably 60–90 mm / min, more preferably 70–85 mm / min, and even more preferably 75–80 mm / min; the inert gas flow rate is preferably 12–18 ml / min, more preferably 13–16 ml / min, and even more preferably 14–15 ml / min.

[0028] In the B-powder cladding step, the laser cladding parameters also include: a defocusing amount of 18-22 mm, preferably 19-21 mm, and more preferably 20 mm.

[0029] Repeat the above B powder cladding steps 3 to 5 times. Before each cladding, ensure that the surface temperature of the Mo2NiB2-based cermet coating is 150 to 300°C, preferably 180 to 280°C, more preferably 200 to 250°C, and even more preferably 220 to 230°C. In this way, a dense layer of moderate thickness can be formed on the surface of the Mo2NiB2-based cermet coating, which can achieve a better densification effect and is not easy to crack.

[0030] After several cladding processes with B powder, the thickness of the dense layer on the surface of the Mo2NiB2-based cermet coating is 50–250 μm, preferably 90–200 μm, more preferably 120–170 μm, and even more preferably 140–150 μm.

[0031] In fact, the thicker the Mo2NiB2-based cermet coating, the more times the B powder cladding step needs to be repeated, and correspondingly, the thickness of the dense layer will also be thicker. That is, the thickness of the dense layer is positively correlated with the thickness of the Mo2NiB2-based cermet coating.

[0032] Specifically, B powder with a particle size of 300–500 μm and a purity of 99% or higher can be selected. The particle size of the B powder is preferably 330–470 μm, more preferably 360–450 μm, and even more preferably 400–420 μm.

[0033] Preferably, before the preheating step described above, a cleaning step can be performed: the surface of the Mo2NiB2-based cermet coating fused onto the substrate surface is cleaned until the surface of the Mo2NiB2-based cermet coating exhibits a metallic luster, thus obtaining a better dense layer. Specifically, anhydrous ethanol can be used to clean the surface of the Mo2NiB2-based cermet coating fused onto the substrate surface, which has a better cleaning effect and lower cleaning cost.

[0034] Argon can be used as the inert gas in the densification process.

[0035] After completing the B powder cladding step, a polishing step can be performed: polish the surface of the Mo2NiB2-based cermet coating until it exhibits a metallic luster, making the surface smoother. Specifically, sandpaper can be used to polish the surface of the Mo2NiB2-based cermet coating.

[0036] The beneficial effects of the surface densification treatment method for wear-resistant Mo2NiB2-based cermet coatings provided in this embodiment of the invention are: The surface densification treatment method for wear-resistant Mo2NiB2-based cermet coatings provided by this invention reduces the porosity of the densified Mo2NiB2-based cermet coating from approximately 35% to below 5% (measured using the water displacement method), thereby improving the high-temperature oxidation resistance of the Mo2NiB2-based cermet coating by more than 100%. This invention utilizes the fact that boron powder can react with oxygen at a certain temperature to generate B2O3. When operating in a high-temperature environment, the molten liquid B2O3 exhibits good fluidity, resulting in a denser surface for the Mo2NiB2-based cermet coating, which has significant engineering application value.

[0037] To further illustrate the present invention, the surface densification treatment method for wear-resistant Mo2NiB2-based cermet coatings provided by the present invention will be described in more detail below with reference to the accompanying drawings and embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0038] Example 1 Step 1: Clean the surface of the Mo2NiB2-based cermet coating (approximately 1-2 mm) that has been fused onto the surface of Q235 steel with anhydrous ethanol until a metallic luster appears on the surface. Step 2: Preheat the substrate and the Mo2NiB2-based cermet coating to 150°C simultaneously, with argon gas protection during the preheating process. Step 3: Place B powder with a particle size of 300μm and a purity of 99% into the powder feeder of the laser cladding equipment, then seal and fill with argon gas. The laser cladding parameters are: laser power 0.5kW; powder feed rate 15g / min; defocusing amount 20mm; cladding speed 50mm / min; argon gas flow rate 10ml / min. Clamping B powder is performed on the surface of the Mo2NiB2-based cermet coating at a cladding temperature of approximately 600℃. Step 4: Perform three cladding passes as in Step 3. Before each cladding pass, ensure the surface temperature of the coating is 150°C. The dense layer formed on the surface of the Mo2NiB2-based cermet coating reaches 50μm. Step 5: After the cladding is completed, quickly cover the cladding surface with borax, allow it to cool naturally to room temperature, and then remove the borax. Step 6: Use sandpaper to polish the coating surface until it shows a metallic luster.

[0039] Figure 1 The surface structure of the undensified wear-resistant Mo2NiB2-based cermet coating is shown, and it can be seen that the surface of the undensified wear-resistant Mo2NiB2-based cermet coating has obvious pores. Figure 2 The diagram illustrates the surface densification treatment method for the wear-resistant Mo2NiB2-based cermet coating in Example 1, and the resulting surface structure of the densified Mo2NiB2-based cermet coating. It can be seen that the surface of the densified wear-resistant Mo2NiB2-based cermet coating has no obvious pores.

[0040] Using the surface densification treatment method of the wear-resistant Mo2NiB2-based cermet coating in Example 1, the porosity of the resulting densified Mo2NiB2-based cermet coating was reduced from about 35% to about 7% (using the drainage method), which is very effective. After high-temperature friction and wear at 850℃ (2 hours), the volume loss was reduced by more than half (see Table 1).

[0041] Table 1

[0042] Example 2 Step 1: Clean the surface of the Mo2NiB2-based cermet coating (approximately 2-4 mm) that has been fused onto the surface of Q235 steel with anhydrous ethanol until a metallic luster appears on the surface. Step 2: Preheat the substrate and the Mo2NiB2-based cermet coating to 300°C simultaneously, with argon gas protection during the preheating process. Step 3: Place B powder with a particle size of 500μm and a purity of 99.5% into the powder feeder of the laser cladding equipment, then seal and fill with argon gas. The laser cladding parameters are: laser power 1.5kW; powder feed rate 20g / min; defocusing amount 20mm; cladding speed 100mm / min; protective argon gas flow rate 20ml / min. Clamping B powder onto the surface of the Mo2NiB2-based cermet coating ensures that the cladding temperature is between 600-800℃.

[0043] Step 4: Perform 5 cladding passes as in Step 3; ensure the coating surface temperature is 300℃ before each cladding pass, and form a dense layer of 250μm on the surface of the Mo2NiB2-based cermet coating. Step 5: After the cladding is completed, quickly cover the cladding surface with borax, allow it to cool naturally to room temperature, and then remove the borax.

[0044] Step 6: Use sandpaper to polish the coating surface until it shows a metallic luster.

[0045] Using the surface densification treatment method of the wear-resistant Mo2NiB2-based cermet coating in Example 2, the porosity of the obtained Mo2NiB2-based cermet coating was reduced from about 35% to about 4.6% (using the drainage method). After high-temperature friction and wear at 850℃ (2 hours), the volume loss was reduced by more than half (see Table 2).

[0046] Table 2

[0047] Example 3 Step 1: Clean the surface of the Mo2NiB2-based cermet coating (approximately 1-3 mm) that has been fused onto the carbon steel surface with anhydrous ethanol until a metallic luster appears on the surface. Step 2: Preheat the substrate and the Mo2NiB2-based cermet coating to 200°C simultaneously, with argon gas protection during the preheating process. Step 3: Place B powder with a particle size of 400μm and a purity of 99% into the powder feeder of the laser cladding equipment, then seal and fill with argon gas. The laser cladding parameters are: laser power 1kW; powder feed rate 18g / min; defocusing amount 20mm; cladding speed 75mm / min; argon gas flow rate 15ml / min. Clamping the coating surface with B powder at a cladding temperature of 600-800℃. Step 4: Perform four cladding passes as in Step 3. Before each cladding pass, ensure the coating surface temperature is 200℃. The dense layer formed on the surface of the Mo2NiB2-based cermet coating reaches 120μm. Step 5: After the cladding is completed, quickly cover the cladding surface with borax, allow it to cool naturally to room temperature, and then remove the borax. Step 6: Use sandpaper to polish the coating surface until it shows a metallic luster.

[0048] Using the surface densification treatment method of the wear-resistant Mo2NiB2-based cermet coating in Example 3, the porosity of the obtained Mo2NiB2-based cermet coating was reduced from about 35% to about 5.0% (using the drainage method). After high-temperature friction and wear at 850℃ (2 hours), the volume loss was reduced by more than half (see Table 3).

[0049] Table 3

[0050] In summary, the surface densification treatment method for wear-resistant Mo2NiB2-based cermet coatings provided by this invention results in a densified Mo2NiB2-based cermet coating with low porosity and good wear resistance.

[0051] Finally, it should be noted that, in this document, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0052] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to the embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for densifying the surface of a wear-resistant Mo2NiB2-based cermet coating, characterized in that, include: Preheating: The substrate and the Mo2NiB2-based cermet coating are preheated simultaneously to 150–300°C, with inert gas protection used during the preheating process; B powder cladding: In an inert gas environment, B powder is laser-clad onto the surface of the Mo2NiB2-based metal ceramic coating to form a densified layer, wherein the laser cladding temperature is 600-800℃.

2. The method for densifying the surface of the wear-resistant Mo2NiB2-based cermet coating according to claim 1, characterized in that, After the B powder is clad, the method further includes: Cooling: Cover the cladding surface with borax, cool to room temperature, and then remove the borax.

3. The method for densifying the surface of the wear-resistant Mo2NiB2-based cermet coating according to claim 1, characterized in that, The B powder cladding step includes: placing B powder into the powder feeder of the laser cladding equipment, then sealing and filling it with inert gas, and cladding the surface of the Mo2NiB2-based metal ceramic coating with the B powder. The laser cladding parameters include: laser power 0.5-1.5kW, powder feed rate 15-20g / min, cladding speed 50-100mm / min, and inert gas flow rate 10-20ml / min.

4. The method for densifying the surface of the wear-resistant Mo2NiB2-based cermet coating according to claim 1, characterized in that, Repeat the B powder cladding process 3 to 5 times, and before each cladding, the surface temperature of the Mo2NiB2-based metal ceramic coating is 150 to 300°C.

5. The method for densifying the surface of the wear-resistant Mo2NiB2-based cermet coating according to claim 1, characterized in that, The thickness of the densification layer ranges from 50 to 250 μm.

6. The method for densifying the surface of the wear-resistant Mo2NiB2-based cermet coating according to claim 1, characterized in that, The particle size of the B powder is 300-500 μm, and the purity is above 99%.

7. The method for densifying the surface of the wear-resistant Mo2NiB2-based cermet coating according to claim 1, characterized in that, Prior to the preheating, the method further includes: Cleaning: The surface of the Mo2NiB2-based metal ceramic coating that has been fused onto the substrate is cleaned until the surface of the Mo2NiB2-based metal ceramic coating exhibits a metallic luster.

8. The method for densifying the surface of the wear-resistant Mo2NiB2-based cermet coating according to claim 7, characterized in that, In the cleaning step, anhydrous ethanol is used for cleaning.

9. The method for densifying the surface of the wear-resistant Mo2NiB2-based cermet coating according to claim 1, characterized in that, The inert gas is argon.

10. The method for densifying the surface of the wear-resistant Mo2NiB2-based cermet coating according to any one of claims 1-9, characterized in that, After the B powder is clad, the method further includes: Polishing: Polish the surface of the Mo2NiB2-based cermet coating until the surface of the Mo2NiB2-based cermet coating exhibits a metallic luster.

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