A method for enhancing the surface of aluminum alloy and its application in aluminum alloy products

Abstract

The present invention discloses a method for surface strengthening of aluminum alloy and its application in aluminum alloy products, comprising the following steps: (1) Mix Ni 60 alloy powder with an adhesive to obtain Ni 60 alloy coating, and coat it on the surface of the aluminum alloy. Use the laser surface alloying process to form a Ni 60 alloying zone with a preset morphological distribution on the surface of the aluminum alloy; (2) Mix the cladding material SiC-AlSi10Mg-Ni 60 with an adhesive to obtain a cladding coating, and coat it on the Ni 60 alloying zone. Use the laser cladding process to perform cladding treatment on the surface of the Ni 60 alloying zone to form a cladding zone; (3) Coat the above cladding coating on the surface of the aluminum alloy with the cladding zone, and use the laser cladding process to perform cladding treatment on the surface of the aluminum alloy to form a cladding layer. The present invention uses the laser alloying process combined with the laser cladding process to prepare a strengthening layer with an embedded structure on the surface of the aluminum alloy. The strengthening layer has a high bonding strength with the aluminum alloy matrix and can effectively improve the wear resistance of the aluminum alloy surface.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum alloy surface treatment, and in particular to a method for enhancing the surface of an aluminum alloy. Background Art

[0002] Aluminum alloy materials have become a highly-regarded lightweight material due to their advantages such as light weight, high specific strength and good formability. Among them, 7075 aluminum alloy has a wide range of uses in the fields of aviation, shipbuilding, etc. due to its compact structure, strong corrosion resistance and excellent processing performance. However, the surface hardness of 7075 aluminum alloy is low and its wear resistance is poor, which seriously restricts the application of 7075 aluminum alloy in the production of light-load transmission parts such as gears and cams. In order to increase the surface hardness of 7075 aluminum alloy and improve its wear resistance, the surface of 7075 aluminum alloy is currently strengthened by anodizing, surface plating or coating.

[0003] Compared with traditional surface strengthening technology, laser technology has a short processing cycle, fast cooling speed, and is easy to obtain fine-grained structure or produce new phases that cannot be obtained in equilibrium state. It can select zone melting and is easy to realize automation. Therefore, it has been widely used in surface strengthening in cast iron, stainless steel, titanium alloy, aluminum alloy and other fields. Among them, laser cladding is a method of adding cladding material to the surface of the substrate and using a high-energy-density laser beam to melt it together with a thin layer on the surface of the substrate. It can form a metallurgically bonded additive cladding layer on the surface of the base without reducing the performance of the substrate, so as to re-manufacture the parts with surface failure and improve the life of the workpiece. However, after large-area laser cladding, its organizational properties will change. The large difference between the mechanical properties of the cladding layer and the substrate can easily lead to large-area cracking or even shedding of the cladding layer under large load conditions, reducing its service life. In this regard, CN114150309A discloses an aluminum-based metal bionic surface containing a pinned structure strengthening layer, which uses a laser "melting-cladding" process to prepare a pinned structure strengthening layer with biomimetic skeleton characteristics on the aluminum-based surface, inhibiting the cracking and shedding of the cladding layer, and extending the service life of the laser repair / remanufacturing strengthening layer. However, in order to ensure the bonding strength between the strengthening layer and the aluminum base, and avoid problems such as cracking at the interface due to excessive differences in material properties, the difference in mechanical properties between the cladding material used in this method and the substrate cannot be too large. Therefore, the surface hardness and wear resistance of the aluminum alloy treated by this method cannot be greatly improved, and it is difficult to meet the application requirements of high-wear-resistant aluminum alloys. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for surface enhancement of aluminum alloy and its application in aluminum alloy products, which significantly improves the surface hardness and wear resistance of the aluminum alloy while effectively suppressing the problem of cracking and falling off of the cladding layer.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] A first aspect of the present invention provides a method for surface enhancement of an aluminum alloy, comprising the following steps:

[0007] S1: Ni 60 Alloy powder is mixed with a binder to obtain Ni 60 The alloy coating is applied on the surface of the aluminum alloy, and a Ni with a preset morphological distribution is formed on the surface of the aluminum alloy by laser surface alloying process. 60 Alloying zone;

[0008] S2: The cladding material SiC-AlSi10Mg-Ni 60 The cladding coating is mixed with a binder and coated on the Ni 60 In the alloying area, laser cladding process is used to 60 The surface of the alloying zone is clad in the Ni 60 A cladding zone is formed above the alloying zone;

[0009] S3: coating the cladding coating prepared in S2 on the surface of the aluminum alloy, performing cladding treatment on the surface of the aluminum alloy using a laser cladding process, and forming a cladding layer on the surface of the aluminum alloy;

[0010] The Ni 60 The alloying zone, the cladding zone and the cladding layer constitute a strengthening layer, and the strengthening layer is used for strengthening the surface of the aluminum alloy.

[0011] Furthermore, the aluminum alloy is 7075 aluminum alloy.

[0012] Furthermore, in S1, the surface of the aluminum alloy is first polished to increase the surface roughness to Ra 3.9-6.5, and then Ni is coated on the surface of the aluminum alloy according to a preset pattern. 60 Alloy coating: By increasing the surface roughness of aluminum alloy, the absorption rate of aluminum alloy to laser is improved.

[0013] Further, in S1, the Ni 60 The alloy coating is prepared as follows: Ni 60 Alloy powder is added to the binder and mixed evenly to obtain Ni 60 Alloy coating.

[0014] Further, in S1, the Ni 60 The thickness of the alloy powder coated on the surface of the aluminum alloy is 300-400 μm, for example, 400 μm.

[0015] Further, in S1, the Ni with a preset morphological distribution is formed on the surface of the aluminum alloy by adjusting the laser processing path. 60The alloying zone, the preset shape is one or more of point shape, strip shape, and mesh shape.

[0016] Furthermore, when the preset shape is a dot shape, the dot shape Ni 60 Alloying zones are equally spaced on the surface of the aluminum alloy, and adjacent Ni 60 The interval between the alloying zones is 720 μm to 799 μm.

[0017] Furthermore, when the preset shape is a strip, the strip Ni 60 Alloying zones are equally spaced and parallel on the surface of the aluminum alloy, and adjacent Ni 60 The interval between alloying zones is 1931 μm to 1972 μm.

[0018] Furthermore, when the preset shape is a mesh, the mesh Ni 60 The alloying zone consists of two groups of interlaced Ni strips. 60 Alloying zone composition, each group of strip Ni 60 Each Ni in the alloying zone 60 The alloying zones are equally spaced and parallel on the surface of the aluminum alloy, and the adjacent Ni 60 The interval between alloying zones is 1396 μm to 1524 μm.

[0019] Furthermore, in S1, the process parameters of the laser surface alloying process are: laser processing current 85A~120A, pulse width 2ms~5ms, frequency 5hz~15hz, scanning speed 15mm / min~30mm / min, and defocus amount -3mm.

[0020] Further, in S1, the Ni 60 The alloying zone is embedded in the aluminum alloy, and the Ni 60 The depth h1 of the alloyed zone is preferably 339 μm to 521 μm.

[0021] Further, in S2, the cladding material SiC-AlSi10Mg-Ni 60 The composite material is composed of the following components in percentage by weight: 15 wt% to 35 wt% SiC, 25 wt% AlSi10Mg and 40 wt% to 60 wt% Ni. 60 ; For example, 15wt% SiC, 25wt% AlSi10Mg and 60wt% Ni 60 , 20wt% SiC, 25wt% AlSi10Mg and 55wt% Ni 60 , 30wt% SiC, 25wt% AlSi10Mg and 45wt% Ni 60 .

[0022] Further, in S2, the cladding material is SiC-AlSi10Mg-Ni 60 The cladding coating is prepared as follows: the corresponding powder samples are weighed according to the distribution ratio of each component in the cladding material, the cladding powder is evenly mixed by a mechanical method to obtain the cladding powder, the cladding powder is added to the adhesive, and the mixture is evenly mixed to obtain the cladding coating.

[0023] Furthermore, in S2, the adhesive is preferably a sodium silicate adhesive.

[0024] Furthermore, in S2, the thickness of the cladding coating applied on the surface of the Ni60 alloying zone is preferably 400 μm to 700 μm.

[0025] Furthermore, in S2, the process parameters of the laser cladding process are: laser processing current 85A~120A, pulse width 4ms~6ms, frequency 4hz~6hz, scanning speed 30mm / min, and defocus amount -5mm.

[0026] Further, in S2, the cladding zone is embedded in the aluminum alloy, and the depth h2 of the cladding zone is preferably 123 μm to 334 μm.

[0027] Furthermore, in S3, the thickness of the cladding coating applied on the surface of the aluminum alloy is preferably 400 μm to 700 μm.

[0028] Furthermore, in S3, the process parameters of the laser cladding process are: laser processing current 85A~120A, pulse width 4ms~6ms, frequency 4hz~6hz, scanning speed 30mm / min, overlap rate 10%~30%, and defocus amount -5mm.

[0029] Furthermore, in S3, the thickness H of the cladding layer is preferably 123 μm to 334 μm.

[0030] Further, in S3, the Ni 60 The sum of the depth of the alloying zone and the depth of the cladding zone is H1, and the thickness H of the cladding layer is more preferably 0.27H1 to 0.29H1. When the thickness of the cladding layer is too low, less than 0.27 times the depth of the nickel-based deep melting unit body, the stress borne by the nickel-based deep melting unit body during use is too high, and the strengthening layer will wear out quickly; when the thickness H of the cladding layer is greater than 0.29H1, the strengthening layer is easy to fall off under the action of large stress. Therefore, the height of the cladding layer needs to be controlled within a suitable range to match the depth of the nickel-based deep melting unit body, so as to ensure the bonding strength between the strengthening layer and the aluminum alloy while improving the wear resistance of the strengthening layer.

[0031] Furthermore, in S1 to S3, the laser alloying process and the laser cladding process are both performed under the protection of an inert gas.

[0032] The second aspect of the present invention provides an aluminum alloy product treated by the method of the first aspect.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. The present invention adopts a combined process of laser alloying and laser cladding to prepare a nickel-based bionic strengthening layer with a pinning-like structure on the surface of an aluminum alloy. First, a Ni alloying zone is prepared on the surface of the aluminum alloy by a laser alloying process. On the one hand, the grains of the alloying zone are refined, thereby increasing the hardness of the alloying zone. At the same time, Ni reacts with the aluminum alloy to generate aluminum-nickel intermetallic compounds. Such hard intermetallic compounds play a role of second phase strengthening, further increasing the hardness of the alloying zone. Then, a single-pass laser cladding is performed on the above-mentioned Ni alloying zone to form a cladding zone. The cladding zone is combined with the Ni alloying zone to obtain a dual-material nickel-based deep-melting unit body. Then, a high-strength cladding layer is prepared on the surface of the aluminum alloy having the nickel-based deep-melting unit body. Under the action of the laser, the SiC in the cladding coating reacts with the aluminum alloy matrix to generate a hard and brittle phase Al 4 C 3 , so that the hardness of the cladding layer is further improved. Through the optimization of the above structure and strengthening layer materials (alloy zone, cladding zone and cladding layer), the dual-zone nickel-based deep melting unit prepared by the present invention plays a better role in carrying and strengthening the structure, effectively improving the bonding strength between the strengthening layer and the aluminum alloy substrate, avoiding the problem of easy cracking at the bonding interface due to the large difference in mechanical properties between the strengthening layer and the substrate material, and under the premise of effectively suppressing the problem of easy cracking and falling off of the cladding layer, significantly improving the surface hardness and wear resistance of the aluminum alloy.

[0035] 2. Parts made of aluminum alloy may suffer from uneven wear due to uneven force in some special applications (such as drill pipes), resulting in dimensional changes and affecting precision. Based on this, the present invention arranges a strengthening layer with dot-shaped, strip-shaped or grid-shaped nickel-based deep-melting units on the surface of the aluminum alloy to form a soft and hard structure with the matrix to better relieve stress concentration. At the same time, the hardness and wear resistance of the strengthening layer can be adjusted according to the distribution morphology of the nickel-based deep-melting units, thereby accurately repairing aluminum alloy parts and improving the uniformity of wear on various parts of the parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a partial cross-sectional schematic diagram of a 7075 aluminum alloy having a nickel-based bionic strengthening layer with a pinning-like structure prepared by the present invention, wherein ① is a nickel-based deep melting unit body, and ② is a cladding layer;

[0037] Figure 2 A local structural entity diagram of a 7075 aluminum alloy having a nickel-based bionic strengthening layer with a pinning-like structure prepared in Example 1;

[0038] Figure 3 A schematic diagram of the structure of a 7075 aluminum alloy with a nickel-based bionic strengthening layer prepared by the present invention;

[0039] Figure 4 The laser cladding structure of the 7075 aluminum alloy surface with a nickel-based bionic strengthening layer having a pinning-like structure prepared in Example 1;

[0040] Figure 5 This is the XRD pattern of the nickel-based bionic strengthening layer with a pinning-like structure prepared in Example 1;

[0041] Figure 6 The laser alloying structure of the 7075 aluminum alloy surface having a nickel-based bionic strengthening layer with a pinning-like structure prepared in Example 1;

[0042] Figure 7 The laser alloy-cladding structure of the 7075 aluminum alloy surface with a nickel-based bionic strengthening layer having a pinning-like structure prepared in Example 1;

[0043] Figure 8 The microhardness distribution diagram of the nickel-based bionic strengthening layer prepared in Examples 1 to 3 in the width direction of the molten pool;

[0044] Fig. 9 Schematic diagrams of the structures of nickel-based deep-melting units with different morphological distributions in Examples 1 to 3, where a is a strip distribution, b is a grid distribution, and c is a point distribution. DETAILED DESCRIPTION

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0046] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0047] Example 1

[0048] This embodiment provides a method for preparing a nickel-based bionic strengthening layer for surface enhancement of 7075 aluminum alloy, and the specific operations are as follows:

[0049] (1) The surface of 7075 aluminum alloy was polished with sandpaper to increase the surface roughness Ra = 4.5 and increase the laser absorption rate of the substrate; 60 Alloy powder was added to liquid sodium silicate binder to prepare Ni 60 alloy coating, and coated on the substrate surface, the coating thickness is 400μm; under the protection of argon atmosphere, Ni is prepared by high energy density laser alloying process 60 Alloying zone. The alloying zone is distributed on the surface of the 7075 aluminum alloy substrate with a certain spacing, and the processing path is adjusted to make it distributed in strips on the substrate surface. The laser processing parameters are: laser processing current 120A, pulse width 5ms, frequency 5hz, scanning speed 30mm / min, defocus amount -3mm;

[0050] (2) Ni with a mass fraction of 60wt% 60 The granular powders of 15 wt% SiC and 25 wt% AlSi10Mg were fully mixed by mechanical method, and the mixed metal ceramic powders were put into liquid sodium silicate binder to prepare the cladding coating, which was pre-coated on Ni 60 Alloying area, coating thickness is 700μm; laser cladding process is used on Ni 60 The surface of the alloying zone is clad to obtain the cladding zone, and the cladding zone is 60 The alloying zone forms a double-material nickel-based deep melting unit body. It is distributed on the surface of the 7075 aluminum alloy substrate at the same spacing as the alloying zone, and a strip-shaped bionic skeleton is formed on the substrate surface by adjusting the processing path. The laser cladding processing parameter range is: laser processing current 120A, pulse width 5ms, frequency 5hz, scanning speed 30mm / min, defocus amount -5mm, and argon protection throughout the process;

[0051] (3) The cladding coating prepared in step (2) is coated on the surface of the aluminum-based substrate of the nickel-based deep-melting unit body, and the coating thickness is 700 μm; under the protection of an argon atmosphere, a high-strength cladding layer is prepared on its surface by a laser cladding process, and the laser cladding processing parameter range is as follows: laser processing current 120A, pulse width 5ms, frequency 5Hz, scanning speed 30mm / min, overlap rate 10%, defocus amount -5mm, and argon protection throughout the process.

[0052] The surface after laser alloying and cladding is mechanically polished to achieve a roughness that is actually used in industry.

[0053] In this embodiment, a nickel-based bionic strengthening layer is prepared on the surface of the aluminum alloy, wherein the nickel-based deep melting units are distributed on the surface of the aluminum alloy in parallel and at equal intervals in strips (such as Fig. 9 As shown in Figure a, the width of each nickel-based deep melting unit is 899 μm, and the spacing between adjacent nickel-based deep melting units is 1931 μm.60 The depth of the alloying zone is 521 μm, the depth of the cladding zone is 186 μm, and the thickness of the cladding layer is 186 μm.

[0054] Figure 2 The figure is a solid picture of the local structure of the strengthening layer prepared in this embodiment. As can be seen from the figure, the molten pool morphology of the strengthening layer is a pinned structure, and there are no obvious defects such as cracks and voids.

[0055] Figure 4 The microstructure of the laser cladding structure on the aluminum alloy surface is shown in Figure 2. Figure 5 ) shows that the prepared cladding layer is composed of Al, CrC, Al 3 Ni 2 、Al 4 C 3 、Al 4 SiC 4 and Cr 3 Ni 2 CSi composite material layer, that is, there is a large amount of Al on the surface of the cladding layer 3 Ni 2 、Al 4 C 3 Intermetallic compounds, which constitute the strengthening phase of the cladding layer, can effectively improve the hardness of the surface of 7075 aluminum alloy.

[0056] Figure 6 This is the microstructure diagram of the junction of the Ni alloying zone and the aluminum alloy. It can be seen from the figure that the grains in the alloying zone are obviously refined, but there are fewer reinforcing phases.

[0057] Figure 7 This is the microstructure diagram of the junction of the Ni alloying zone and the cladding zone. A clear dividing line can be observed in the figure, which also shows that there is a big difference in the degree of grain refinement between laser cladding and laser alloying.

[0058] Example 2

[0059] This embodiment provides a method for preparing a nickel-based bionic strengthening layer for surface enhancement of 7075 aluminum alloy. The difference from Embodiment 1 is that the nickel-based deep melting units prepared in this embodiment are distributed in a network shape on the surface of the aluminum alloy. The specific operation is as follows:

[0060] (1) The surface of 7075 aluminum alloy was polished with sandpaper to increase the surface roughness Ra = 4.5 and increase the laser absorption rate of the substrate; 60 Alloy powder was added to liquid sodium silicate binder to prepare Ni 60 alloy coating, and coated on the substrate surface, the coating thickness is 400μm; under the protection of argon atmosphere, Ni is prepared by high energy density laser alloying process 60Alloying zone. The alloying zone is distributed on the surface of the 7075 aluminum alloy substrate with a certain spacing, and the processing path is adjusted to make it distributed in a mesh on the substrate surface. The laser processing parameters are: laser processing current 120A, pulse width 5ms, frequency 5hz, scanning speed 30mm / min, defocus amount -3mm;

[0061] (2) Ni with a mass fraction of 60wt% 60 The granular powders of 15 wt% SiC and 25 wt% AlSi10Mg were fully mixed by mechanical method, and the mixed metal ceramic powders were put into liquid sodium silicate binder to prepare the cladding coating, which was pre-coated on Ni 60 Alloying area, coating thickness is 700μm; laser cladding process is used on Ni 60 The surface of the alloying zone is clad to obtain the cladding zone, and the cladding zone is 60 The alloying zone forms a nickel-based deep melting unit of dual materials. It is distributed on the surface of the 7075 aluminum alloy substrate at the same spacing as the alloying zone, and a mesh bionic skeleton is formed on the substrate surface by adjusting the processing path. The laser cladding processing parameter range is: laser processing current 120A, pulse width 5ms, frequency 5hz, scanning speed 30mm / min, defocus amount -5mm;

[0062] (3) The cladding coating prepared in step (2) is coated on the surface of the aluminum-based substrate of the nickel-based deep-melting unit body, and the coating thickness is 700 μm; under the protection of an argon atmosphere, a high-strength cladding layer is prepared on its surface by a laser cladding process, and the laser cladding processing parameter range is as follows: laser processing current 120A, pulse width 5ms, frequency 5Hz, scanning speed 30mm / min, overlap rate 10%, and defocus amount -5mm.

[0063] The surface after the laser "alloying-cladding" is mechanically polished to achieve a roughness suitable for actual industrial use.

[0064] In this embodiment, a nickel-based bionic strengthening layer is prepared on the surface of the aluminum alloy, wherein the nickel-based deep melting units are distributed in a network shape on the surface of the aluminum alloy (such as Fig. 9 As shown in Figure b, the mesh Ni 60 The alloying zone consists of two groups of mutually perpendicular strip-shaped Ni 60 Alloying zone composition, each group of strip Ni 60 Each Ni in the alloying zone 60 The alloying zones are evenly spaced and parallel on the aluminum alloy surface), the width of each nickel-based deep melting unit is 738μm, and the spacing between adjacent nickel-based deep melting units is 3mm. 60 The depth of the alloying zone is 508 μm, the depth of the cladding zone is 142 μm, and the thickness of the cladding layer is 142 μm.

[0065] Example 3

[0066] This embodiment provides a method for preparing a nickel-based bionic strengthening layer for surface enhancement of 7075 aluminum alloy. The difference from Embodiment 1 is that the nickel-based deep melting unit bodies prepared in this embodiment are distributed in a dotted manner on the surface of the aluminum alloy. The specific operation is as follows:

[0067] (1) The surface of 7075 aluminum alloy was polished with sandpaper to increase the surface roughness Ra = 4.5 and increase the laser absorption rate of the substrate; 60 Alloy powder was added to liquid sodium silicate binder to prepare Ni 60 alloy coating, and coated on the substrate surface, the coating thickness is 400μm; under the protection of argon atmosphere, Ni is prepared by high energy density laser alloying process 60 Alloying zone. The alloying zone is distributed on the surface of the 7075 aluminum alloy substrate with a certain spacing, and the processing path is adjusted to make it distributed in a dotted manner on the substrate surface. The laser processing parameters are: laser processing current 120A, pulse width 5ms, frequency 5hz, scanning speed 30mm / min, defocus amount -3mm;

[0068] (2) Ni with a mass fraction of 60wt% 60 The granular powders of 15 wt% SiC and 25 wt% AlSi10Mg were fully mixed by mechanical method, and the mixed metal ceramic powders were put into liquid sodium silicate binder to prepare the cladding coating, which was pre-coated on Ni 60 Alloying area, coating thickness is 700μm; laser cladding process is used on Ni 60 The surface of the alloying zone is clad to obtain the cladding zone, and the cladding zone is 60 The alloying zone forms a nickel-based deep melting unit of dual materials. It is distributed on the surface of the 7075 aluminum alloy substrate at the same spacing as the alloying zone, and a dot-shaped bionic skeleton is formed on the substrate surface by adjusting the processing path. The laser cladding processing parameter range is: laser processing current 120A, pulse width 5ms, frequency 5hz, scanning speed 30mm / min, defocus amount -5mm;

[0069] (3) The cladding coating prepared in step (2) is coated on the surface of the aluminum-based substrate of the nickel-based deep-melting unit body, and the coating thickness is 700 μm; under the protection of an argon atmosphere, a high-strength cladding layer is prepared on its surface by a laser cladding process, and the laser cladding processing parameter range is as follows: laser processing current 120A, pulse width 5ms, frequency 5Hz, scanning speed 30mm / min, overlap rate 10%, and defocus amount -5mm.

[0070] The surface after the laser "alloying-cladding" is mechanically polished to achieve a roughness suitable for actual industrial use.

[0071] In this embodiment, a nickel-based bionic strengthening layer is prepared on the surface of the aluminum alloy, wherein the nickel-based deep melting units are distributed in a dotted manner on the surface of the aluminum alloy (such as Fig. 9 As shown in Figure c, the width of each nickel-based deep melting unit body is 441μm, and the spacing between adjacent nickel-based deep melting units is 720μm. 60 The depth of the alloying zone is 339 μm, the depth of the cladding zone is 123 μm, and the thickness of the cladding layer is 123 μm.

[0072] Comparative Example 1

[0073] This comparative example provides a method for preparing an aluminum-based strengthening layer for surface enhancement of 7075 aluminum alloy. The difference from Example 2 is that a laser melting process is used instead of a laser alloying process. The specific operation is as follows:

[0074] (1) The surface of 7075 aluminum alloy was polished with sandpaper to increase the surface roughness Ra = 4.5 and increase the laser absorption rate of the substrate; under the protection of argon atmosphere, the laser melting process was used to irradiate the surface of 7075 aluminum alloy to prepare the molten zone. The molten zone is distributed on the surface of 7075 aluminum alloy substrate with a certain spacing, and the processing path is adjusted to make it distributed in a mesh on the surface of the substrate. The laser processing parameters are: laser processing current 120A, pulse width 5ms, frequency 5hz, scanning speed 30mm / min, defocus amount -3mm;

[0075] (2) Ni with a mass fraction of 60wt% 60 , 15%wt% SiC and 25wt% AlSi10Mg granular powders are fully mixed by mechanical method, and the mixed metal ceramic powders are placed in liquid sodium silicate adhesive to prepare cladding coatings, which are pre-coated on the molten area with a coating thickness of 700μm; laser cladding process is used to clad the surface of the molten area to obtain a cladding area, and a deep melting unit is formed with the molten area. It is distributed on the surface of the 7075 aluminum alloy substrate at the same spacing as the molten area, and a mesh bionic skeleton is formed on the surface of the substrate by adjusting the processing path. The laser cladding processing parameter range is: laser processing current 120A, pulse width 5ms, frequency 5hz, scanning speed 30mm / min, defocus amount -5mm;

[0076] (3) The cladding coating prepared in step (2) is coated on the surface of the aluminum-based substrate of the nickel-based deep-melting unit body, and the coating thickness is 700 μm; under the protection of an argon atmosphere, a high-strength cladding layer is prepared on its surface by a laser cladding process, and the laser cladding processing parameter range is as follows: laser processing current 120A, pulse width 5ms, frequency 5Hz, scanning speed 30mm / min, overlap rate 10%, and defocus amount -5mm.

[0077] The surface after the laser "melting-cladding" is mechanically polished to achieve a roughness that is actually used in industry.

[0078] In this comparative example, an aluminum-based bionic strengthening layer is prepared on the surface of the aluminum alloy, wherein deep-melting units are distributed in a network pattern on the surface of the aluminum alloy, the width of each deep-melting unit is 738 μm, the spacing between adjacent strips of deep-melting units is 3 mm, the depth of the fusion zone is 470 μm, the depth of the cladding zone is 156 μm, and the thickness of the cladding layer is 156 μm.

[0079] Comparative Example 2

[0080] This comparative example provides a preparation method for a nickel-based bionic strengthening layer for surface enhancement of 7075 aluminum alloy. The difference from Example 2 is that the original cladding material is replaced with a 82wt% Ni 60 , 15wt%SiC and 3wt%CeO 2 The cladding materials are composed of the following specific operations:

[0081] (1) The surface of 7075 aluminum alloy was polished with sandpaper to increase the surface roughness Ra = 4.5 and increase the laser absorption rate of the substrate; 60 Alloy powder was added to liquid sodium silicate binder to prepare Ni 60 alloy coating, and coated on the substrate surface, the coating thickness is 400μm; under the protection of argon atmosphere, Ni is prepared by high energy density laser alloying process 60 Alloying zone. The alloying zone is distributed on the surface of the 7075 aluminum alloy substrate with a certain spacing, and the processing path is adjusted to make it distributed in a mesh on the substrate surface. The laser processing parameters are: laser processing current 120A, pulse width 5ms, frequency 5hz, scanning speed 30mm / min, defocus amount -3mm;

[0082] (2) Ni with a mass fraction of 82wt% 60 , 15wt%SiC and 3wt%CeO 2 The granular powder is fully mixed by mechanical method, and the mixed metal ceramic powder is put into liquid sodium silicate binder to prepare the cladding coating, which is pre-coated on Ni 60 Alloying area, coating thickness is 700μm; laser cladding process is used on Ni 60 The surface of the alloying zone is clad to obtain the cladding zone, and the cladding zone is 60 The alloying zone forms a nickel-based deep melting unit of dual materials. It is distributed on the surface of the 7075 aluminum alloy substrate at the same spacing as the alloying zone, and a mesh bionic skeleton is formed on the substrate surface by adjusting the processing path. The laser cladding processing parameter range is: laser processing current 120A, pulse width 5ms, frequency 5hz, scanning speed 30mm / min, defocus amount -5mm;

[0083] (3) The cladding coating prepared in step (2) is coated on the surface of the aluminum-based substrate of the nickel-based deep-melting unit body, and the coating thickness is 700 μm; under the protection of an argon atmosphere, a high-strength cladding layer is prepared on its surface by a laser cladding process, and the laser cladding processing parameter range is as follows: laser processing current 120A, pulse width 5ms, frequency 5Hz, scanning speed 30mm / min, overlap rate 10%, and defocus amount -5mm.

[0084] The surface after the laser "alloying-cladding" is mechanically polished to achieve a roughness suitable for actual industrial use.

[0085] In this comparative example, the nickel-based bionic strengthening layer prepared on the aluminum alloy surface, wherein the nickel-based deep melting unit body is distributed on the aluminum alloy surface in a network, the width of each nickel-based deep melting unit body is 594 μm, the spacing between adjacent strip-shaped nickel-based deep melting unit bodies is 3 mm, and the nickel-based deep melting unit body is 1.5 mm thick. 60 The depth of the alloying zone is 318 μm, the depth of the cladding zone is 169 μm, and the thickness of the cladding layer is 169 μm.

[0086] Comparative Example 3

[0087] This comparative example provides a method for preparing a nickel-based bionic strengthening layer for surface enhancement of 7075 aluminum alloy. The difference from Example 2 is that the nickel-based bionic strengthening layer is prepared by alloying and single-pass cladding. The specific operation is as follows:

[0088] (1) The surface of 7075 aluminum alloy was polished with sandpaper to increase the surface roughness Ra = 4.5 and increase the laser absorption rate of the substrate; 60 Alloy powder was added to liquid sodium silicate binder to prepare Ni 60 alloy coating, and coated on the substrate surface, the coating thickness is 400μm; under the protection of argon atmosphere, Ni is prepared by high energy density laser alloying process 60 Alloying zone. The alloying zone is distributed on the surface of the 7075 aluminum alloy substrate with a certain spacing, and the processing path is adjusted to make it distributed in a mesh on the substrate surface. The laser processing parameters are: laser processing current 120A, pulse width 5ms, frequency 5hz, scanning speed 30mm / min, defocus amount -3mm;

[0089] (2) Ni with a mass fraction of 60wt% 60 The granular powders of 15 wt% SiC and 25 wt% AlSi10Mg were fully mixed by mechanical method, and the mixed metal ceramic powders were put into liquid sodium silicate binder to prepare the cladding coating, which was pre-coated on Ni 60 Alloying area, coating thickness is 700μm; laser cladding process is used on Ni60 The surface of the alloying zone is clad to obtain the cladding zone, and the cladding zone is 60 The alloying zone forms a nickel-based deep melting unit of dual materials. It is distributed on the surface of the 7075 aluminum alloy substrate at the same spacing as the alloying zone, and a mesh bionic skeleton is formed on the substrate surface by adjusting the processing path. The laser cladding processing parameter range is: laser processing current 120A, pulse width 5ms, frequency 5hz, scanning speed 30mm / min, defocus amount -5mm;

[0090] The surface after the laser "alloying-cladding" is mechanically polished to achieve a roughness suitable for actual industrial use.

[0091] In this comparative example, the nickel-based bionic strengthening layer prepared on the aluminum alloy surface, wherein the nickel-based deep melting unit body is distributed on the aluminum alloy surface in a mesh shape, each nickel-based deep melting unit body has a width of 330 μm, and the side length of each nickel-based deep melting unit body grid is equal to 3 mm. 60 The depth of the alloying zone is 260 μm, and the depth of the cladding zone is 115 μm.

[0092] Comparative Example 4

[0093] This comparative example provides a method for preparing a cladding layer for surface enhancement of 7075 aluminum alloy. The difference from Example 1 is that a high-strength cladding layer is prepared only on the surface of the aluminum alloy by laser cladding. The specific operation is as follows:

[0094] (1) The surface of 7075 aluminum alloy was polished with sandpaper to increase the surface roughness Ra = 4.5 and increase the laser absorption rate of the substrate;

[0095] (2) Ni with a mass fraction of 60wt% 60 The granular powders of 15%wt% SiC and 25wt% AlSi10Mg are fully mixed by a mechanical method, and the mixed metal ceramic powder is put into liquid sodium silicate adhesive to prepare a cladding coating, which is coated on the surface of the aluminum-based substrate of the nickel-based deep-melting unit body with a coating thickness of 700μm; under the protection of argon atmosphere, a high-strength cladding layer is prepared on its surface by laser cladding process, and the laser cladding processing parameter range is laser processing current 120A, pulse width 5ms, frequency 5hz, scanning speed 30mm / min, overlap rate 10%, and defocus amount -5mm.

[0096] The surface after laser cladding is mechanically polished to achieve a roughness suitable for actual industrial use.

[0097] The thickness of the cladding layer prepared on the aluminum alloy surface in this comparative example is 156 μm.

[0098] Performance Testing

[0099] The aluminum alloys after surface strengthening treatment in the above embodiments and comparative examples were tested for hardness and wear performance, and the test method was as follows:

[0100] Hardness test: The hardness was measured using a FK-700 Vickers microhardness tester with a load of 25 gf and a load time of 15 s.

[0101] Wear test: The wear performance of the sample was tested using the Rtec MFT-5000 multifunctional friction and wear tester, with a load of 15N and a wear time of 1h; wear rate = (m 试验前 -m 试验后 ) / m 试验前 ×100%, where m 试验前 is the mass of the specimen before wear test, m 试验后 is the mass of the specimen after wear test.

[0102] The samples prepared in Examples 1 to 3 have different distribution forms of nickel-based deep-melting units on the surface of the aluminum alloy, which are distributed on the surface of the aluminum alloy in strips, meshes and dots, respectively. The influence of the distribution form of nickel-based deep-melting units on the surface hardness and wear rate of the aluminum alloy is shown in Table 1:

[0103] Table 1

[0104] Sample Distribution morphology of nickel-based deep melting units Maximum hardness (HV) Wear rate (%) Example 1 Strip 1235.82 0.13 Example 2 Mesh 938.12 0.19 Example 3 Point 268.32 0.27

[0105] As can be seen from Table 1, the nickel-based bionic strengthening layer prepared on the aluminum alloy surface of the present invention can adjust the surface hardness and wear rate by adjusting the distribution morphology of the nickel-based deep-melting units in the strengthening layer on the aluminum alloy surface, and can realize the precise repair and regional design of aluminum alloy parts.

[0106] Comparative Examples 1 to 4 use different materials or methods to strengthen the surface of the aluminum alloy. The surface hardness and wear rate of the aluminum alloy after strengthening are shown in Table 2 below:

[0107] Table 2

[0108] Sample Distribution of deep melting units Maximum hardness (HV) Wear rate (%) Example 2 Mesh 938.12 0.19 Comparative Example 1 Mesh 240.16 0.42 Comparative Example 2 Mesh 862.34 0.32 Comparative Example 3 Mesh 235.18 0.37 Comparative Example 4 / 220.46 0.48

[0109] From the comparison of the hardness and wear data of the embodiments and the comparative examples in the above table, it can be seen that the present invention first uses the laser alloying process to prepare the Ni alloying zone on the surface of the aluminum alloy, which can effectively improve the hardness of the strengthening layer and significantly reduce the wear rate of the strengthening layer; and by improving the cladding material, the hardness and wear resistance of the strengthening layer can be further improved.

[0110] In addition, the present invention further studies the effect of the thickness of the cladding layer in Example 1 on the performance of the strengthening layer. The test results show that when the thickness H of the cladding layer is 0.27~0.29H1 (the depth of the nickel-based deep melting unit), the strengthening layer is not easy to fall off under stress and has better wear resistance.

[0111] The above-described embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or changes made by those skilled in the art based on the present invention are within the protection scope of the present invention. The protection scope of the present invention shall be subject to the claims.

Claims

1. A method for enhancing the surface of an aluminum alloy, It is characterized in that The following steps are involved: S1: Ni 60 Alloy powder is mixed with a binder to obtain Ni 60 The alloy coating is applied on the surface of the aluminum alloy, and a Ni with a preset morphological distribution is formed on the surface of the aluminum alloy by laser surface alloying process. 60 Alloying zone; the preset shape is one or more of point, strip, and mesh; S2: The cladding material SiC-AlSi10Mg-Ni 60 The cladding coating is mixed with a binder and coated on the Ni 60 In the alloying area, laser cladding process is used to 60 The surface of the alloying zone is clad in the Ni 60 A cladding zone is formed above the alloying zone; the cladding material is SiC-AlSi10Mg-Ni 60 It is composed of the following components in mass percentage: 15 wt%~35 wt% SiC, 25 wt% AlSi10Mg and 40 wt%~60 wt% Ni 60 ; S3: coating the cladding coating prepared in S2 on the surface of the aluminum alloy, performing cladding treatment on the surface of the aluminum alloy using a laser cladding process, and forming a cladding layer on the surface of the aluminum alloy; The Ni 60 The alloying zone, the cladding zone and the cladding layer constitute a strengthening layer, and the strengthening layer is used for strengthening the surface of the aluminum alloy.

2. The method according to claim 1, It is characterized in that The aluminum alloy is 7075 aluminum alloy.

3. The method according to claim 1, It is characterized in that In S1, the aluminum alloy surface is first polished to increase the surface roughness to Ra 3.9~6.5, and then Ni is coated on the aluminum alloy surface according to a preset pattern. 60 Alloy coating.

4. The method according to claim 1, It is characterized in that In S1, the Ni with preset morphology distribution is formed on the surface of the aluminum alloy by adjusting the laser processing path. 60 Alloying zone; When the preset shape is a dot, the dot Ni 60 Alloying zones are equally spaced on the surface of the aluminum alloy, and adjacent Ni 60 The interval of alloying zone is 720 μm~799 μm; When the preset shape is a strip, the strip Ni 60 Alloying zones are equally spaced and parallel on the surface of the aluminum alloy, and adjacent Ni 60 The interval of alloying zone is 1931 μm~1972 μm; When the preset shape is a mesh, the mesh Ni 60 The alloying zone consists of two groups of interlaced Ni strips. 60 Alloying zone composition, each group of strip Ni 60 Each Ni in the alloying zone 60 The alloying zones are equally spaced and parallel on the surface of the aluminum alloy, and the adjacent Ni 60 The interval of alloying zone is 1396 μm~1524 μm.

5. The method according to claim 1, It is characterized in that In S1, the Ni 60 The thickness of the alloy powder coated on the aluminum alloy surface is 300~500 μm; The process parameters of the laser surface alloying process are: laser processing current 85 A~120 A, pulse width 2 ms~5 ms, frequency 5 hz~15 hz, scanning speed 15 mm / min~30 mm / min, defocus amount -3 mm; The Ni 60 The alloying zone is embedded in the aluminum alloy, and the Ni 60 The depth h1 of the alloying zone is 339 μm~521 μm; After the laser surface alloying process is completed, the aluminum alloy is ultrasonically cleaned to remove the residual Ni on the surface. 60 Alloy coating.

6. The method according to claim 1, It is characterized in that In S2, the cladding coating is 60 The coating thickness on the alloying zone surface is 400 μm~700 μm; The process parameters of the laser cladding process are: laser processing current 85 A~120 A, pulse width 4 ms~6 ms, frequency 4 Hz~6 Hz, scanning speed 30 mm / min, defocus amount -5 mm; The cladding zone is embedded in the aluminum alloy, and the depth h2 of the cladding zone is 123 μm to 334 μm; After the laser cladding process is completed, the aluminum alloy is ultrasonically cleaned to remove the residual cladding coating on the surface.

7. The method according to claim 1, It is characterized in that In S3, the thickness of the cladding coating applied on the surface of the aluminum alloy is 400 μm to 700 μm; The process parameters of the laser cladding process are: laser processing current 85 A~120 A, pulse width 4 ms~6 ms, frequency 4 Hz~6 Hz, scanning speed 30 mm / min, overlap rate 10%~30%, defocus amount -5 mm; The thickness H of the cladding layer is 123 μm~334 μm.

8. The method according to claim 7, It is characterized in that The Ni 60 The sum of the depth of the alloying zone and the depth of the cladding zone is H1, and the thickness H of the cladding layer is 0.27H1~0.29H1.

9. An aluminum alloy product treated by the method according to any one of claims 1 to 8.

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