A seamless cored wire for preparing an Al-based composite coating with a high alumina content and a preparation method thereof

Abstract

The present invention relates to the technical field of material processing engineering, and specifically to a seamless cored wire for preparing an Al-based composite coating with a high alumina content and a preparation method thereof. The cored wire is obtained by wrapping a cored powder with an industrial pure aluminum tube and subjecting it to rotary forging. The cored powder includes aluminum alloy powder and Al2O3 ceramic powder, and the total content of the alumina ceramic powder in the cored powder is ≥ 30 wt%. By regulating the composition of the cored wire and combining with the rotary forging process, the present invention can prepare a cored wire with a high Al2O3 content. The cored wire has a smooth appearance, high density, and high heat conduction efficiency, and is particularly suitable for the preparation of an arc spraying coating with high wear resistance. The prepared coating has good bonding with the substrate, no obvious defects in the coating, uniform distribution of the ceramic phase, high deposition rate, and thus high hardness and good wear resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of material processing engineering, and in particular to a seamless powder core wire for preparing an Al-based composite coating with a high alumina content and a preparation method thereof. Background Art

[0002] The marine environment contains a large amount of salt and microorganisms, and is accompanied by the impact of waves, tides, and currents, which can easily cause corrosion and wear of offshore equipment and shorten the life of key operating components. In order to improve its reliability and service life, preparing protective coatings on the surface of equipment and key components is one of the effective solutions. Among them, pure Al coatings have low potential and can show good corrosion resistance, so Al-based materials have become ideal coating materials for protective coatings on the surface of offshore equipment. However, pure Al has low hardness and relatively poor wear resistance, which seriously affects the service life of Al-based coatings. Therefore, improving the wear resistance of pure Al coatings by adding ceramic phases is considered to be the main technical means. Traditional ceramic additive phases mainly include Al2O3, SiC and TiC. Among them, Al2O3 has good compatibility with the Al matrix and no interfacial reaction, and is widely used in the preparation of Al-based composite ceramic coatings.

[0003] Among material surface modification technologies, arc spraying boasts high spraying efficiency, good process controllability, simple operation, and environmental friendliness. It is widely used in the preparation of protective coatings on offshore equipment. Arc spraying utilizes an electric arc burning between two continuously fed metal wires to melt the metal. High-velocity airflow atomizes the molten metal, accelerating the atomized metal particles and spraying them onto the workpiece to form a coating. Therefore, the composition of the metal wire has a significant impact on the composition and performance of the coating.

[0004] At present, wires suitable for arc spraying technology to prepare Al / Al2O3 composite coatings are mostly prepared using a mature rolling and drawing process. However, due to the limitations of the rolling and drawing process characteristics, and in order to meet the requirements of arc spraying technology for wire quality and ensure the bonding strength of the coating, the volume content of the ceramic phase of the arc sprayed Al-based ceramic composite coating in the prior art is often low (generally less than 15%), resulting in its wear resistance and other properties still need to be further improved. For example, patent CN201810739750.9 discloses an aluminum-based B4C ceramic arc sprayed powder core wire. Although the content of ceramic powder in the powder core raw material is relatively high, due to the loss during the wire preparation and arc spraying process, the hardness and wear resistance of the obtained coating are still not good enough.

[0005] Therefore, how to further increase the ceramic phase content in arc-sprayed Al-based ceramic composite coatings, thereby improving the wear resistance and reliability of the coating, is a difficult problem that needs to be urgently solved in this field. Summary of the Invention

[0006] The object of the present invention is to provide a seamless cored wire for preparing an Al-based composite coating with a high alumina content and a preparation method thereof. Through the rotary forging technology, the content of Al2O3 in the cored wire, the formability and spraying processability of the wire are significantly improved, and the loss of Al2O3 in arc spraying is reduced, so as to increase the content of Al2O3 in the arc spraying coating and significantly improve the wear resistance of the coating.

[0007] To achieve the above object, the present invention provides a preparation method of a seamless cored wire, which is obtained by wrapping an industrial pure Al tube around a powder core and subjecting it to rotary forging. The powder core includes aluminum alloy powder and Al2O3 ceramic powder, and the total content of the alumina ceramic powder in the powder core is ≥30 wt%. It is mainly used for preparing a seamless cored wire with a high Al2O3 content. The cored wire has a smooth appearance, high density and high heat conduction efficiency, and is thus suitable for the preparation of an arc spraying coating with a high Al2O3 content.

[0008] The present invention prepares a seamless cored wire containing Al2O3 ceramic powder by rotary forging, which can reduce the loss during the processing, significantly increase the content of Al2O3 ceramic powder in the cored wire, and at the same time improve the formability and spraying processability of the cored wire. When used for arc spraying, it can reduce the loss during the spraying process, thereby increasing the content of the Al2O3 ceramic phase in the coating. The bonding compactness and uniformity of each phase in the coating are also improved. Therefore, the cored wire provided by the present invention has good practicability and broad application prospects.

[0009] Further, the mass content of the Al2O3 ceramic powder in the powder core is 30-80%, such as 33%, 35%, 38%, 45%, 49%, 55%, 60%, 65%, 75%, etc., and preferably 49-69%. Although the Al2O3 ceramic powder can improve the wear resistance of the coating, when its content is too high, it is not conducive to the improvement of the coating bonding strength. Therefore, it is necessary to ensure the content of the aluminum alloy powder at the same time, so as to utilize the melting and bonding effect of the aluminum alloy powder during the arc spraying process to improve the formability of the coating and the bonding strength with the substrate. The present invention controls the content of the Al2O3 ceramic powder in the powder core, and then controls the content of Al2O3 in the arc spraying coating and the formability of the coating, so as to ensure the wear resistance and bonding strength of the coating.

[0010] Further, the filling rate of the cored wire is 45-60 wt%, and preferably 50-55 wt%. The filling rate refers to the mass content of the powder core in the cored wire. The present invention can realize the preparation of a cored wire with a high filling rate through rotary forging processing, and the loss of the powder core during the rotary forging process is small.

[0011] Further, the particle size of the Al2O3 ceramic powder is 10 μm - 75 μm, and the particle size of the aluminum alloy powder is 10 μm - 75 μm. Preferably, the particle size of the Al2O3 ceramic powder is 10 μm - 45 μm, and the particle size of the aluminum alloy powder is 10 μm - 45 μm.

[0012] Further, the selected aluminum alloy powder is an aluminum alloy powder with an aluminum content of 85 - 95 wt%, and the aluminum content is preferably 88 - 92 wt%.

[0013] In some embodiments, the selected aluminum alloy powder is AlSi10Mg alloy powder.

[0014] Further, the industrial pure Al tube is a seamless aluminum tube. Preferably, the inner diameter of the seamless Al tube is 8.0 - 13.0 mm, and the outer diameter is 10.0 - 15.0 mm. In some embodiments, the industrial pure Al tube is an Al tube with a purity greater than 99.9%, such as a 1060 half-hard Al tube with a purity greater than 99.9%.

[0015] Further, the feeding speed of the rotary forging is 4 - 10 m / min, and the number of passes of the rotary forging is 4 - 11 times.

[0016] Preferably, the total deformation of the cored wire compared to the outer skin is 70 - 97%, preferably 80 - 97%. Specifically, the total deformation = (the cross-sectional area of the initial wire - the cross-sectional area of the final wire) / the cross-sectional area of the initial wire.

[0017] Further, the sealed seamless aluminum tube is subjected to the rotary forging treatment 4 - 8 times in a mold. The inner diameter of the mold is smaller than the outer diameter of the seamless aluminum tube, and the difference in the inner diameter of the mold between adjacent passes is 0.5 - 2 mm.

[0018] In some specific embodiments, the method for preparing the cored wire includes:

[0019] Mix different contents of AlSi10Mg powder and Al2O3 powder evenly by mechanical means, and then put them into a drying oven for drying. Seal one end of a 1060 half-hard seamless Al tube, load the mixed powder into the prepared Al tube, and use ultrasonic vibration to fully fill the powder. After sealing, perform rotary forging treatment with a special rotary forging fixture. After completion, replace it with a rotary forging die with a finer aperture for forging processing until a sized cored wire is obtained.

[0020] The present invention innovatively proposes to prepare Al / Al2O3 cored wire by rotary forging processing. It mainly improves the formability of the finished wire, the spraying processability of the wire, and the performance of the sprayed coating by regulating the composition of the cored wire and combining with the rotary forging process, adjusting the number of forging passes and the single-pass downward pressure.

[0021] To achieve the above object, the present invention further provides a seamless cored wire obtained by the preparation method of the cored wire described in any one of the above.

[0022] Furthermore, to achieve the above object, the present invention further provides a high-Al2O3 content Al-based composite coating obtained by arc spraying using the seamless cored wire described in any one of the above.

[0023] Furthermore, before spraying, the substrate is sandblasted to roughen its surface. The above-mentioned cored wire is selected to form a coating on the substrate. The specific process parameters of arc spraying are: voltage: 30 - 40V, current: 100 - 200A, spraying pressure: 0.5 - 0.7MPa, spraying distance: 150 - 200mm.

[0024] Preferably, the volume content of Al2O3 in the high-Al2O3 content Al-based composite coating is 20% - 50%;

[0025] More preferably, the volume content of Al2O3 in the high-Al2O3 content Al-based composite coating is 30% - 40%.

[0026] On the one hand, the present invention ensures a high content of Al2O3 in the cored wire through rotary swaging processing. On the other hand, through the appropriate formulation design of the present invention, under rotary swaging processing, the formability and spraying processability of the wire are improved, so that the content of Al2O3 in the coating obtained by arc spraying can preferably reach more than 30%. The present invention utilizes the four-way compressive stress state and pulse loading mode provided by the rotary swaging process to gradually compact the cored powder during rotary swaging, thereby achieving close contact between the powders. The high-density cored wire has a high heat conduction efficiency, which ensures that the cored powder can achieve a good metallurgical reaction with the Al material of the pipe wall during the transient process of arc combustion; at the same time, the full melting of the metal powder can also better coat the Al2O3 particles for flight and deposition to reduce the probability of its rebound and splash, and finally increase the content of the high-melting-point ceramic phase in the coating. In addition, the high-concentration Al2O3 particles continuously compact the coating during spraying, further enhancing the bonding strength between the coating and the substrate.

[0027] Furthermore, the HV 0.1 Vickers hardness of the high-Al2O3 content Al-based composite coating is greater than 400, preferably 440 - 500, and more preferably 450 - 480. The bonding strength between the high-Al2O3 content Al-based composite coating obtained by the present invention and the substrate can reach more than 21MPa, preferably more than 23MPa.

[0028] The beneficial effects of the present invention are as follows:

[0029] 1. The seamless cored wire provided by the present invention is obtained by regulating the composition of the cored wire and combining with the rotary forging process, and a cored wire with a high Al2O3 content is prepared, which can be used to prepare a high wear-resistant coating by arc spraying.

[0030] 2. The seamless cored wire prepared by the present invention has a higher density and wire formability than the wire obtained by rolling and drawing with the same composition content.

[0031] 3. The Al-based ceramic composite coating prepared by the present invention has good formability, and the volume content of the Al2O3 ceramic phase can reach up to 34.5% and is evenly distributed. The bonding strength of the coating is higher than 21 MPa, and the hardness reaches 400 HV 0.1 or more. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0033] Figure 1 It is a cross-sectional metallographic photograph of the cored wire prepared in Example 6.

[0034] Figure 2 It is a cross-sectional metallographic photograph of the cored wire prepared in Comparative Example 4.

[0035] Figure 3 It is a coating morphology diagram of the cored wire in Example 6. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] To make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below. Obviously, the described embodiments are some embodiments of the present invention, rather than all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0037] The same parts in the following embodiments are described as follows:

[0038] 1. Preparation of seamless cored wire:

[0039] Weigh according to the powder ratio described in each of the following embodiments, mechanically mix evenly and fill into a 1060 semi-hard Al tube. Use ultrasonic vibration to make the powder fully filled. After sealing, perform rotary forging treatment with a special rotary forging fixture. After completion, replace with a rotary forging die with a finer aperture for forging processing until a cored wire with a diameter of 3.0 mm is obtained.

[0040] 2. Preparation of the coating:

[0041] The coating is prepared by arc spraying technology. The specific process parameters of arc spraying are: voltage 36V, current 150A, spraying pressure: 0.5MPa, spraying distance: 150mm.

[0042] Example 1

[0043] By mass percentage, the powder core formula is: 200g of AlSi10Mg powder and 192g of Al2O3 powder; the outer diameter of the Al tube is 10.0mm and the inner diameter is 8.0mm. During the rotary forging process, the feeding speed is 8m / min, the number of rotary forging passes is 4, and the total deformation of the core wire is 91.0%.

[0044] Example 2

[0045] By mass percentage, the powder core formula is: 200g of AlSi10Mg powder and 192g of Al2O3 powder; the outer diameter of the Al tube is 11.0mm and the inner diameter is 9.0mm. During the rotary forging process, the feeding speed is 6m / min, the number of rotary forging passes is 5, and the total deformation of the core wire is 92.6%.

[0046] Example 3

[0047] By mass percentage, the powder core formula is: 200g of AlSi10Mg powder and 192g of Al2O3 powder; the outer diameter of the Al tube is 15.0mm and the inner diameter is 13.0mm. During the rotary forging process, the feeding speed is 8m / min, the number of rotary forging passes is 7, and the total deformation of the core wire is 96.0%.

[0048] Example 4

[0049] By mass percentage, the powder core formula is: 160g of AlSi10Mg powder and 230g of Al2O3 powder; the outer diameter of the Al tube is 10.0mm and the inner diameter is 8.0mm. During the rotary forging process, the feeding speed is 6m / min, the number of rotary forging passes is 4, and the total deformation of the core wire is 91.0%.

[0050] Example 5

[0051] By mass percentage, the powder core formula is: 160g of AlSi10Mg powder and 230g of Al2O3 powder; the outer diameter of the Al tube is 11.0mm and the inner diameter is 9.0mm. During the rotary forging process, the feeding speed is 6m / min, the number of rotary forging passes is 5, and the total deformation of the core wire is 92.6%.

[0052] Example 6

[0053] In terms of mass percentage, the powder core formula is: 160 g of AlSi10Mg powder and 230 g of Al2O3 powder; the outer diameter of the Al tube is 15.0 mm and the inner diameter is 13.0 mm. During the rotary swaging process, the feeding speed is 8 m / min, the number of rotary swaging passes is 7, and the total deformation of the core wire is 96.0%.

[0054] Figure 1 It is the cross-sectional metallographic photo of the powder core wire prepared in Example 6, and it can be seen that the uniformity and density are good. Figure 3 It is the obtained coating morphology diagram.

[0055] Example 7

[0056] In terms of mass percentage, the powder core formula is: 120 g of AlSi10Mg powder and 265 g of Al2O3 powder; the outer diameter of the Al tube is 10.0 mm and the inner diameter is 8.0 mm. During the rotary swaging process, the feeding speed is 6 m / min, the number of rotary swaging passes is 4, and the total deformation of the core wire is 91%.

[0057] Example 8

[0058] In terms of mass percentage, the powder core formula is: 120 g of AlSi10Mg powder and 265 g of Al2O3 powder; the outer diameter of the Al tube is 11.0 mm and the inner diameter is 9.0 mm. During the rotary swaging process, the feeding speed is 6 m / min, the number of rotary swaging passes is 5, and the total deformation of the core wire is 92.6%.

[0059] Example 9

[0060] In terms of mass percentage, the powder core formula is: 120 g of AlSi10Mg powder and 265 g of Al2O3 powder; the outer diameter of the Al tube is 15.0 mm and the inner diameter is 13.0 mm. During the rotary swaging process, the feeding speed is 6 m / min, the number of rotary swaging passes is 7, and the total deformation of the core wire is 96%.

[0061] Example 10

[0062] In terms of mass percentage, the powder core formula is: 220 g of AlSi10Mg powder and 180 g of Al2O3 powder; the outer diameter of the Al tube is 15.0 mm and the inner diameter is 13.0 mm. During the rotary swaging process, the feeding speed is 8 m / min, the number of rotary swaging passes is 7, and the total deformation of the core wire is 96.0%.

[0063] Example 11

[0064] In terms of mass percentage, the powder core formula is: 250 g of AlSi10Mg powder and 150 g of Al2O3 powder; the outer diameter of the Al tube is 15.0 mm and the inner diameter is 13.0 mm. During the rotary swaging process, the feeding speed is 8 m / min, the number of rotary swaging passes is 7, and the total deformation of the core wire is 96.0%.

[0065] Example 12

[0066] By mass percentage, the powder core formula is: 270 g of AlSi10Mg powder and 135 g of Al2O3 powder; the outer diameter of the Al tube is 15.0 mm and the inner diameter is 13.0 mm. During the rotary swaging process, the feeding speed is 8 m / min, the number of passes of rotary forging is 7, and the total deformation amount of the core wire is 96.0%.

[0067] Comparative Example 1

[0068] By mass percentage, the powder core formula is: 400 g of AlSi10Mg powder and 45 g of Al2O3 powder; the outer diameter of the Al tube is 10.0 mm and the inner diameter is 8.0 mm. During the rotary swaging process, the feeding speed is 6 m / min, the number of passes of rotary forging is 4, and the total deformation amount of the core wire is 91%.

[0069] Comparative Example 2

[0070] By mass percentage, the powder core formula is: 350 g of AlSi10Mg powder and 85 g of Al2O3 powder; the outer diameter of the Al tube is 11.0 mm and the inner diameter is 9.0 mm. During the rotary swaging process, the feeding speed is 6 m / min, the number of passes of rotary forging is 5, and the total deformation amount of the core wire is 92.6%.

[0071] Comparative Example 3

[0072] By mass percentage, the powder core formula is: 300 g of AlSi10Mg powder and 125 g of Al2O3 powder; the outer diameter of the Al tube is 15.0 mm and the inner diameter is 13.0 mm. During the rotary swaging process, the feeding speed is 6 m / min, the number of passes of rotary forging is 7, and the total deformation amount of the core wire is 96%.

[0073] The following comparative examples use the rolling and drawing process to prepare powder core wire:[[]]

[0074] Comparative Example 4

[0075] By mass percentage, the powder core formula is: 250 g of AlSi10Mg powder and 165 g of Al2O3 powder. Use 1060 semi-hard Al strip as the outer skin, roll the Al strip into a U shape with the opening upward, then evenly feed the mixed powder into the U-shaped Al strip, and gradually close the Al strip using rollers so that the joint is in a lap form without powder leakage. Use a wire drawing die to gradually reduce the diameter by drawing, and finally the diameter of the wire is about 3.0 mm.[[]]

[0076] As Figure 2 shown, it can be seen that the powder core distribution uniformity in Comparative Example 4 is not good.[[]]

[0077] Comparative Example 5

[0078] In terms of mass percentage, the powder core formula is: 200 g of AlSi10Mg powder and 195 g of Al2O3 powder. Use 1060 semi-hard Al strip as the outer skin, roll the Al strip into a U shape with the opening facing up, then evenly feed the mixed powder into the U-shaped Al strip, and gradually close the Al strip using rollers so that the joint is in a lap joint form without powder leakage. Use a wire drawing die to gradually reduce the diameter by drawing, and finally the diameter of the wire is about 3.0 mm.

[0079] The test results of the powder core wire filling rate and the hardness, Al2O3 content, and bonding strength of the corresponding coatings for Examples 1-12 and Comparative Examples 1-5 are shown in Table 1.

[0080] Table 1 Test results of the structural parameters and coating properties of the examples and comparative examples

[0081]

[0082]

[0083] As can be seen from Examples 1-12 in Table 1, ensuring a relatively high Al2O3 content in the powder core can obtain a coating with a hardness above 400 HV 0.1 and a bonding strength with the substrate higher than 21 MPa. It can be seen that the present invention does not affect its bonding strength due to too high an Al2O3 content, indicating that the spraying processability of the powder core wire obtained by this process is good. As can be seen from Comparative Examples 1 and 2, when the Al2O3 content in the powder core is too low, the hardness is significantly reduced. As can be seen from Comparative Examples 3-5, using the wire drawing process, even if the Al2O3 content in the raw materials is increased, the Al2O3 content in the coating cannot be increased. For example, as can be seen from Comparative Example 2 and Comparative Example 5, when ensuring the same Al2O3 content in the coating, using the method of the present invention can significantly reduce the Al2O3 content in the raw materials, indicating that the processability of the present invention is good and helps to reduce costs.

[0084] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing examples, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing examples, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various examples of the present invention.

Claims

1. A method for preparing a seamless cored wire, characterized in that, It is obtained by wrapping a powder core with an industrial pure aluminum tube and subjecting it to rotary forging. The powder core includes AlSi10Mg alloy powder and Al2O3 ceramic powder, and the total content of alumina ceramic powder in the powder core is 48.98 - 70 wt%. The filling rate of the powder core wire is 50.9 - 52.2 wt%. The particle size of the Al2O3 ceramic powder is 10 μm - 45 μm, and the particle size of the AlSi10Mg alloy powder is 10 μm - 45 μm. The volume content of Al2O3 in the Al-based composite coating obtained from the powder core wire is 30% - 40%.

2. The preparation method of the seamless cored wire according to claim 1, characterized in that, The inner diameter of the industrial pure aluminum tube is 8.0 - 13.0 mm, and the outer diameter is 10.0 - 15.0 mm.

3. The preparation method of the seamless cored wire according to claim 2, characterized in that, The industrial pure aluminum tube is an Al tube with a purity greater than 99.9%.

4. The preparation method of the seamless cored wire according to any one of claims 1-3, characterized in that, The feeding speed of the rotary forging is 4 - 10 m / min, and the number of passes of the rotary forging is 4 - 11 times.

5. The preparation method of the seamless cored wire according to any one of claims 1-3, characterized in that, The total deformation amount of the powder core wire is 80 - 97%.

6. A seamless cored wire, characterized in that, It is obtained by using the preparation method described in any one of claims 1 - 5.

7. An Al-based composite coating with a high Al2O3 content, characterized in that, The coating is obtained by arc spraying of a seamless powder core wire obtained by using the preparation method described in any one of claims 1 - 5.

8. The high-Al2O3 content Al-based composite coating according to claim 7, wherein The hardness of the Al-based composite coating is greater than 400 HV 0.1 .

9. The high-Al2O3-content Al-based composite coating according to claim 8, wherein The hardness of the Al-based composite coating is 440-500 HV 0.1 .

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