A method and application of laser additive repair of ZCuPb10Sn10 lead bronze

Abstract

The present invention relates to the field of laser additive repair of copper alloys, and specifically discloses a method and application for laser additive repair of ZCuPb10Sn10 lead bronze. The method comprises cleaning the area to be repaired, laser cleaning the end face of the area to be repaired on a substrate to remove the oxide layer until the surface is clean and the metallic luster is exposed, and cleaning the area to be repaired with acetone. The area to be repaired is subjected to non-destructive testing, the location of the repair area is determined based on the non-destructive testing results, and the repair area is laser additively repaired using alloy powder A. The weight percentages of the components in the alloy powder A are: Sn 11%-13%; Ni 1.8%-2.2%; Al 4%-6%; O 0.01%-0.025%, with the remainder being Cu. A novel alloy powder A for laser additive repair has been developed and can be mass-produced. By preferentially increasing the content of Ni and Al elements and eliminating Pb, the safety of the alloy powder A during mass production and use is ensured, while also improving the wear resistance of the repaired surface and the bonding performance between the substrate and the additive repair layer.

Description

Technical Field

[0001] The present invention relates to a repair method, in particular to a method and application of laser additive repair of ZCuPb10Sn10 lead bronze, belonging to the field of laser additive repair of copper alloys. Background Art

[0002] ZCuPb10Sn10 is a cast bronze alloy with excellent lubricity, wear resistance, and corrosion resistance. It can withstand cutting processes well and is widely used in sliding bearings subjected to high surface pressure and lateral pressure. Lead-bronze aircraft parts made of ZCuPb10Sn10 alloy are subject to airflow erosion during use, resulting in cross-sectional wear. Because the hardness of the ZCuPb10Sn10 alloy is lower than the abrasive particles in the airflow, this wear causes degradation of the ZCuPb10Sn10 alloy parts during use, reducing their performance and increasing aircraft safety risks. At the same time, a large number of these parts are used on aircraft, and the damage to these parts is in batches. The cost of replacing them with new ones is high, and the procurement cycle is long, which seriously affects production efficiency. The repair layer obtained by brush coating and thermal spraying technology is a mechanical bond, not a metallurgical bond, and is only suitable for surface shape repair, but cannot repair damaged parts. The brazing joint formed by brazing repair has a small bonding strength. The heat-affected zone (>1.5mm) of fusion welding repairs such as argon arc welding is large. In comparison, laser additive repair has high energy density, small heat input, fast crystallization speed, fine grains in the repair layer, and good mechanical properties of the repair layer, and is gradually being used in the repair of damaged aviation parts.

[0003] At present, the research on ZCuPb10Sn10 laser additive technology mainly focuses on the preparation of laser additive repair coatings on ZCuPb10Sn10 alloy. The master's thesis of North University of China, "Research on the Microstructure and Properties of Cu15Ni8Sn Alloy Coatings Repaired by Laser Additive on CuPb10Sn10 Alloy Surface", introduces the preparation of laser additive repair coatings on CuPb10Sn10 alloy. First, the powder for laser additive repair is made of Cu elemental powder, Ni elemental powder and Sn elemental powder through mechanical mixing. This method of preparing alloy powder is difficult to carry out large-scale and stable production, and difficult to carry out engineering applications; second, the laser additive repair coating only detects the friction and wear performance of the coating and the substrate, and does not detect and compare the bonding performance of the coating and the substrate. The room temperature tensile properties of the laser additive repaired joint are determined by the bonding force between the additive repair zone, the heat-affected zone and the substrate. The important application indicator of laser additive repair in aviation maintenance is whether the room temperature tensile properties after repair meet the performance requirements.

[0004] The Pb element in the ZCuPb10Sn10 alloy is extremely easy to evaporate at high temperatures and is toxic. If it is prepared into powder and laser additive repair is carried out, it is easy to pose a threat to human health. At the same time, the alloy powder of the same material cannot ensure that the mechanical properties and wear resistance of the ZCuPb10Sn10 alloy after wear repair meet the use requirements. Based on the health of personnel and the performance requirements after repair, this patent provides a laser additive repair method suitable for ZCuPb10Sn10 alloy, so that the mechanical properties and airflow erosion resistance of aircraft ZCuPb10Sn10 alloy parts after laser additive repair are better than those of the substrate. Summary of the Invention

[0005] In response to the problems in the prior art, the present invention provides a method and application of laser additive repair of ZCuPb10Sn10 lead bronze.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A method for laser additive repair of ZCuPb10Sn10 lead bronze, the method comprising the following steps:

[0008] Step 1: Clean the area to be repaired. Use laser cleaning to remove the oxide layer on the end surface of the area to be repaired on the substrate until the surface is clean and the metallic luster is exposed. Use acetone to clean the area to be repaired.

[0009] Step 2: Perform non-destructive testing on the area to be repaired, determine the location of the repair area based on the results of the non-destructive testing, and cover the area outside the repair area with aluminum foil;

[0010] Step 3: Use alloy powder A to perform laser additive repair on the repair area;

[0011] The weight percentages of the components in the alloy powder A are as follows: Sn 11%-13%; Ni 1.8%-2.2%; Al 4%-6%; O 0.01%-0.025%; and the rest is Cu.

[0012] Optionally, during the laser additive repair process, the laser cladding head is tilted 8-10 degrees based on a plumb line of the repair area.

[0013] Optionally, the process parameters during the laser additive repair process are:

[0014] 99.999% high-purity argon is used as the protective carrier gas of alloy powder A, the gas flow rate of the protective carrier gas is 18-20 L / min, the laser power is 1500-1600 W, the laser cladding scanning speed is 8-10 mm / s, the laser spot diameter is 1.2 mm, the powder feeder speed is 0.8-1 r / min, the powder feeding gas flow rate is 4-6 L / min, and the overlap rate is 40%-50%.

[0015] Optionally, during the laser additive repair process, the repair area is repaired by stacking multiple repair layers in sequence, and after each layer is repaired, the next layer is repaired by laser additive when the temperature between the layers drops below 40°C.

[0016] Optionally, during the laser additive repair process, after repairing one layer, laser cleaning is used to clean the surface of the repaired layer to remove the oxide layer until the surface of the repaired layer is clean and the metallic luster is exposed. Acetone is then used to clean the repaired layer before the next layer is repaired by laser additive.

[0017] Optionally, after the repair area is repaired, it is trimmed to reach a preset standard size.

[0018] Optionally, the repaired area after the size modification is qualified if no cracks are found using fluorescent testing.

[0019] Optionally, the alloy powder A is prepared by a gas atomization method or a plasma rotating electrode method, and the powder particle size of the alloy powder A is 50 μm-150 μm, wherein 48 μm≤D10≤55 μm, 90 μm≤D50≤110 μm, and 120 μm≤D90≤150 μm.

[0020] Optionally, after the alloy powder A is prepared, the sample substrate is repaired using the alloy powder A, and the bonding performance between the repair layer and the substrate and the friction and wear performance of the repair layer are tested. The sample can be repaired only after both properties meet preset standards.

[0021] Optionally, a method for laser additive repair of ZCuPb10Sn10 lead bronze is also provided for application in the field of ZCuPb10Sn10 lead bronze repair.

[0022] Beneficial effects of the present invention:

[0023] 1. Develop and mass-produce a new type of alloy powder A for laser additive repair. By preferentially increasing the content of Ni and Al elements and eliminating the Pb element, the safety of alloy powder A during large-scale preparation and use is guaranteed. At the same time, it can improve the wear resistance of the repaired surface and the bonding performance between the substrate and the additive repair layer.

[0024] 2. During the repair process, small-diameter spot and high-energy-density laser additive repair is used to effectively reduce the heat-affected zone, reduce deformation, and improve repair quality.

[0025] 3. During the repair process, laser cleaning is used to clean the interlayer slag, effectively reducing metallurgical defects and reducing damage to the part matrix compared to mechanical cleaning.

[0026] 4. The repair cycle is greatly reduced, the cycle is greatly shortened, and the repair efficiency is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] To facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0028] Figure 1 This is a top view of the sampling of the tensile specimen for laser additive repair according to the present invention.

[0029] Figure 2 This is a stereoscopic diagram of the sampling of the tensile specimen for laser additive repair according to the present invention.

[0030] Figure 3 This is the laser additive repair of the friction and wear specimen of the present invention.

[0031] Figure 4 This is a flow chart of the preparation process of alloy powder A of the present invention. DETAILED DESCRIPTION

[0032] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0033] The substrates described in the following embodiments are all ZCuPb10Sn10 alloys.

[0034] See also Figure 1-4 As shown, a method for laser additive repair of ZCuPb10Sn10 lead bronze, the method comprising the following steps:

[0035] Preparation of alloy powder A:

[0036] The amounts of the components in the alloy powder A are, by weight, 11%-13% Sn; 1.8%-2.2% Ni; 4%-6% Al; 0.01%-0.025% O, and the remainder is Cu. The alloy powder A is prepared by a gas atomization method or a plasma rotating electrode method, and the prepared alloy powder A has a powder particle size of 50 μm-150 μm, wherein 48 μm ≤ D10 ≤ 55 μm, 90 μm ≤ D50 ≤ 110 μm, and 120 μm ≤ D90 ≤ 150 μm.

[0037] Currently, the primary failure mechanism for lead-bronze aircraft parts manufactured from the ZCuPb10Sn10 alloy in the aviation maintenance field is friction and wear. Therefore, after Alloy Powder A is prepared, it is used to repair the sample substrate. The repair layer's bonding with the substrate and its friction and wear properties are tested. Only when both properties meet the pre-set standards can the repair be used. If one or both of the test results fail to meet the pre-set standards, Alloy Powder A must be re-prepared.

[0038] Preferably, the weight percentage of each component is Sn12%, Ni2.0%, Al4%, O0.02%, and the rest is Cu. The alloy powder A is prepared by gas atomization method. The prepared alloy powder A is used to perform laser additive repair on the sample matrix to obtain the following figure: Figure 1 The room temperature tensile specimens shown and Figure 3 The friction and wear specimens shown were then subjected to tensile testing and friction and wear testing on the room temperature tensile specimens and friction and wear specimens respectively.

[0039] Sample Type Tensile strength (MPa) Friction coefficient Sample matrix 260 0.18 Test specimens 239.2 0.10

[0040] After performance comparison, alloy powder A was used for laser additive repair, and the tensile strength of the repaired sample reached 92% of the sample matrix. At the same time, the friction coefficient of the repaired layer was less than the friction and wear coefficient of the sample matrix, so the wear resistance of the repaired layer was better than that of the matrix.

[0041] The pre-set performance criteria are that the repaired bonding performance (i.e., the tensile strength of the repaired specimen) should be no less than 90% of that of the substrate, and that the wear resistance should be superior to that of the substrate. The alloy powder A prepared by the above method meets the requirements for laser additive repair and can be mass-produced for subsequent substrate repair.

[0042] The preparation process of alloy powder A is as follows Figure 4 As shown, formulate the technical indicators of the repair powder → prepare the powder → laser additive repair test → laser additive repair material-level performance test. If the mechanical properties meet the use requirements, continue with the following product repair. If not, re-formulate the powder and repeat the steps in this process until the material-level performance of alloy powder A meets the use requirements before product repair.

[0043] The area to be repaired is cleaned by using laser cleaning to remove the oxide layer on the end face of the area to be repaired on the substrate until the surface is clean and the metallic luster is exposed, and the area to be repaired is cleaned with acetone; the area to be repaired can be determined by manual identification or non-destructive testing, and finally an area to be repaired that meets the actual repair needs is determined.

[0044] Perform nondestructive testing on the area to be repaired, determine its location based on the results, and cover the rest of the area with aluminum foil. Accurately determining the location of the repair area facilitates checking whether impurities have been removed before repair, and also allows areas not intended for repair to be separated and covered with aluminum foil for protection, preventing laser irradiation and damage to other parts during the repair process.

[0045] Laser additive repair was performed on the repaired area using alloy powder A. The process parameters for the laser additive repair process were: 99.999% high-purity argon gas was used as the shielding carrier gas for alloy powder A, with a shielding carrier gas flow rate of 18-20 L / min, a laser power of 1500-1600 W, a laser cladding scanning speed of 8-10 mm / s, a laser spot diameter of 1.2 mm. Using a small-diameter spot and high-energy density laser additive repair effectively reduces the heat-affected zone, minimizes deformation, and improves repair quality. The powder feeder speed was 0.8-1 r / min, the powder feed gas flow rate was 4-6 L / min, and the overlap rate was 40%-50%.

[0046] During the laser additive repair process, the laser cladding head is tilted 8-10 degrees based on the plumb line of the repair area.

[0047] Since copper alloy has a high reflectivity to 1080 wavelength laser, the laser cladding head is tilted 8-10 degrees during the laser additive repair process to prevent the laser from reflecting vertically and damaging the focusing lens.

[0048] During the laser additive repair process, the repaired area is repaired in multiple layers, stacked sequentially. After each layer is repaired, the next layer is repaired only when the interlayer temperature drops below 40°C. During the repair process, an infrared thermometer is used to monitor and strictly control the interlayer temperature to prevent heat accumulation between layers, which can lead to coarsening of the grains and deterioration of the repair layer's performance.

[0049] During the laser additive repair process, after each layer is repaired, laser cleaning is used to clean the surface of the repaired layer, removing the oxide layer until the surface is clean and reveals a metallic luster. The repaired layer is then cleaned with acetone before the next layer is repaired. This removes slag between layers, effectively minimizing metallurgical defects and reducing damage to the part substrate compared to mechanical cleaning.

[0050] After the repair area is repaired, it is trimmed to a preset standard size by mechanical processing to meet the use requirements of the part base.

[0051] If the repaired area after the size modification is free of cracks using fluorescent testing, it is considered to be repaired properly, thus avoiding the situation where the use is affected due to incomplete repair.

[0052] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the content of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for laser additive repair of ZCuPb10Sn10 lead bronze, characterized in that: The method comprises the following steps: Step 1: Clean the area to be repaired. Use laser cleaning to remove the oxide layer on the end surface of the area to be repaired on the substrate until the surface is clean and the metallic luster is exposed. Use acetone to clean the area to be repaired. Step 2: Perform non-destructive testing on the area to be repaired, determine the location of the repair area based on the results of the non-destructive testing, and cover the area outside the repair area with aluminum foil; Step 3: Use alloy powder A to perform laser additive repair on the repair area; The weight percentages of the components in the alloy powder A are: Sn 11%-13%; Ni 1.8%-2.2%; Al 4%-6%; O 0.01%-0.025%; and the rest is Cu. During the laser additive repair process, the laser cladding head is tilted 8-10 degrees based on the plumb line of the repair area; The process parameters during the laser additive repair process are: Argon is used as the protective carrier gas of alloy powder A, the protective carrier gas flow rate is 18-20 L / min, the laser power is 1500-1600 W, the laser cladding scanning speed is 8-10 mm / s, the laser spot diameter is 1.2 mm, the powder feeder speed is 0.8-1 r / min, the powder feeding gas flow rate is 4-6 L / min, and the overlap rate is 40%-50%.

2. The method for laser additive repair of ZCuPb10Sn10 lead bronze according to claim 1, characterized in that: During the laser additive repair process, the repair area is repaired by stacking multiple repair layers in sequence. After each layer is repaired, the next layer is repaired by laser additive when the temperature between the layers drops below 40°C.

3. The method for laser additive repair of ZCuPb10Sn10 lead bronze according to claim 2, characterized in that: In the laser additive repair process, after repairing one layer, the surface of the repaired layer is cleaned by laser cleaning to remove the oxide layer until the surface of the repaired layer is clean and the metallic luster is exposed. The repaired layer is then cleaned with acetone, and then the next layer is repaired by laser additive.

4. The method for laser additive repair of ZCuPb10Sn10 lead bronze according to claim 3, characterized in that: After the repair area is repaired, it is trimmed to reach a preset standard size.

5. The method for laser additive repair of ZCuPb10Sn10 lead bronze according to claim 4, characterized in that: If the repair area has been modified to the preset standard size and no cracks are found using fluorescent testing, the repair is considered qualified.

6. The method for laser additive repair of ZCuPb10Sn10 lead bronze according to claim 1, characterized in that: The alloy powder A is prepared by a gas atomization method or a plasma rotating electrode method, and the powder particle size of the alloy powder A is 50 μm-150 μm, wherein 48 μm≤D10≤55 μm, 90 μm≤D50≤110 μm, and 120 μm≤D90≤150 μm.

7. The method for laser additive repair of ZCuPb10Sn10 lead bronze according to claim 6, characterized in that: After the alloy powder A is prepared, the sample substrate is repaired using the alloy powder A, and the bonding performance between the repair layer and the substrate and the friction and wear performance of the repair layer are tested. The sample can be repaired only after both properties meet the preset standards.

8. A method for laser additive repair of ZCuPb10Sn10 lead bronze according to any one of claims 1 to 7, used in the field of ZCuPb10Sn10 lead bronze repair.

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