A laser additive manufacturing process for aircraft materials

Abstract

A laser additive manufacturing process for aircraft materials. In order to improve the hardness and corrosion resistance of titanium alloy materials for aircraft, the present invention adds niobium pentoxide to the laser additive Al-BN composite coating, which can significantly improve the corrosion resistance of the material, and as the amount of niobium pentoxide increases, the corrosion resistance of the composite coating becomes stronger. However, excessive niobium pentoxide will cause the hardness of the composite coating to drop sharply, so in practice, the amount of niobium pentoxide powder needs to be strictly controlled.

Description

Technical Field

[0001] The invention relates to the field of additive manufacturing, and in particular to a laser additive manufacturing process for aircraft materials. Background Art

[0002] Titanium alloys have the advantages of high mechanical strength, high thermal strength, and good low-temperature performance, so they are widely used in aerospace, automobiles, ships, chemicals, marine engineering and other fields. Due to the high strength and low density of titanium alloys, they can effectively reduce the weight of aircraft, so titanium alloys can be seen in aircraft engine components, frames, landing gears, and fasteners. However, the lack of hardness and corrosion resistance will seriously affect the service life of titanium alloy aircraft materials. Summary of the invention

[0003] In view of the problems existing in the prior art, the purpose of the present invention is to provide a laser additive manufacturing process for aircraft materials, which can improve the corrosion resistance and hardness of titanium alloy materials for aircraft.

[0004] A laser additive manufacturing process for aircraft materials includes the following steps:

[0005] Pretreatment: TC4 titanium alloy was selected as the substrate, and the substrate was subjected to mechanical polishing, pickling and cleaning in sequence; the pickling treatment used a 15-18% hydrochloric acid solution to clean the substrate to remove the surface oxide layer; then the substrate was cleaned with anhydrous ethanol and deionized water in sequence and dried under nitrogen for later use;

[0006] Preparation of anodized layer: at an anodizing voltage of 25-28 V, using 1.5-1.8 mol / L H3PO4 solution and 1.1-1.5 wt% NaF solution as electrolyte solution, anodizing on the surface of the titanium alloy substrate for 90-100 minutes to prepare anodized layer;

[0007] Laser additive processing: 100-120 parts by weight of aluminum powder, 40-45 parts by weight of hexagonal boron nitride (BN) powder and 8-29 parts by weight of niobium pentoxide powder are mixed evenly, and the Al-BN-Nb2O5 composite coating is prepared by a laser additive process using a synchronous powder feeding method. In the laser additive process, the laser power is 900-920W, the scanning speed is 300-350mm / min, the spot diameter is 3.0-3.1mm, the overlap rate is 25-28%, and the energy density is 240-245W / mm 2 ;

[0008] Vacuum annealing post-treatment: The titanium alloy substrate containing the Al-BN-Nb2O5 composite coating is placed in a vacuum annealing furnace and annealed at 450-480°C for 3.5-3.8h.

[0009] Preferably, the laser power is 900W.

[0010] Preferably, the scanning speed is 300 mm / min.

[0011] Preferably, the annealing temperature is 450°C.

[0012] Preferably, the annealing time is 3.5 h.

[0013] Preferably, the anodization voltage is 28V.

[0014] In order to improve the hardness and corrosion resistance of titanium alloy materials for aircraft, the present invention adds niobium pentoxide to the laser additive Al-BN composite coating, which can significantly improve the corrosion resistance of the material, and as the amount of niobium pentoxide increases, the corrosion resistance of the composite coating becomes stronger. However, excessive niobium pentoxide will cause the hardness of the composite coating to drop sharply, so in practice, the amount of niobium pentoxide powder needs to be strictly controlled. DETAILED DESCRIPTION

[0015] The technical effects of the present invention are verified below through specific examples, but the embodiments of the present invention are not limited thereto.

[0016] Example 1

[0017] Pretreatment: TC4 titanium alloy was selected as the substrate, and the substrate was subjected to mechanical polishing, pickling and cleaning in sequence; the pickling treatment used a 15% hydrochloric acid solution to clean the substrate to remove the surface oxide layer; then the substrate was cleaned with anhydrous ethanol and deionized water in sequence and dried under nitrogen for later use;

[0018] Preparation of an anodic oxide layer: at an anodic oxidation voltage of 28 V, using 1.5 mol / L H3PO4 solution and 1.1 wt% NaF solution as electrolyte solution, anodizing on the surface of the titanium alloy substrate for 90 minutes to prepare an anodic oxide layer;

[0019] Laser additive processing: 100 parts by weight of aluminum powder, 40 parts by weight of hexagonal boron nitride (BN) powder and 8 parts by weight of niobium pentoxide powder were mixed evenly, and the Al-BN-Nb2O5 composite coating was prepared by a laser additive process using a synchronous powder feeding method. In the laser additive process, the laser power was 920 W, the scanning speed was 300 mm / min, the spot diameter was 3.0 mm, the overlap rate was 25%, and the energy density was 240 W / mm 2 ;

[0020] Vacuum annealing post-treatment: The titanium alloy substrate containing the Al-BN-Nb2O5 composite coating is placed in a vacuum annealing furnace and annealed at 450°C for 3.5h.

[0021] Example 2

[0022] Pretreatment: TC4 titanium alloy was selected as the substrate, and the substrate was subjected to mechanical polishing, pickling and cleaning in sequence; the pickling treatment used a 15% hydrochloric acid solution to clean the substrate to remove the surface oxide layer; then the substrate was cleaned with anhydrous ethanol and deionized water in sequence and dried under nitrogen for later use;

[0023] Preparation of an anodic oxide layer: at an anodic oxidation voltage of 28 V, using 1.5 mol / L H3PO4 solution and 1.1 wt% NaF solution as electrolyte solution, anodizing on the surface of the titanium alloy substrate for 90 minutes to prepare an anodic oxide layer;

[0024] Laser additive processing: 100 parts by weight of aluminum powder, 40 parts by weight of hexagonal boron nitride (BN) powder and 12 parts by weight of niobium pentoxide powder were mixed evenly, and the Al-BN-Nb2O5 composite coating was prepared by a laser additive process using a synchronous powder feeding method. In the laser additive process, the laser power was 920 W, the scanning speed was 300 mm / min, the spot diameter was 3.0 mm, the overlap rate was 25%, and the energy density was 240 W / mm 2 ;

[0025] Vacuum annealing post-treatment: The titanium alloy substrate containing the Al-BN-Nb2O5 composite coating is placed in a vacuum annealing furnace and annealed at 450°C for 3.5h.

[0026] Example 3

[0027] Pretreatment: TC4 titanium alloy was selected as the substrate, and the substrate was subjected to mechanical polishing, pickling and cleaning in sequence; the pickling treatment used a 15% hydrochloric acid solution to clean the substrate to remove the surface oxide layer; then the substrate was cleaned with anhydrous ethanol and deionized water in sequence and dried under nitrogen for later use;

[0028] Preparation of an anodic oxide layer: at an anodic oxidation voltage of 28 V, using 1.5 mol / L H3PO4 solution and 1.1 wt% NaF solution as electrolyte solution, anodizing on the surface of the titanium alloy substrate for 90 minutes to prepare an anodic oxide layer;

[0029] Laser additive processing: 100 parts by weight of aluminum powder, 40 parts by weight of hexagonal boron nitride (BN) powder and 17 parts by weight of niobium pentoxide powder were mixed evenly, and the Al-BN-Nb2O5 composite coating was prepared by a laser additive process using a synchronous powder feeding method. In the laser additive process, the laser power was 920 W, the scanning speed was 300 mm / min, the spot diameter was 3.0 mm, the overlap rate was 25%, and the energy density was 240 W / mm 2 ;

[0030] Vacuum annealing post-treatment: The titanium alloy substrate containing the Al-BN-Nb2O5 composite coating is placed in a vacuum annealing furnace and annealed at 450°C for 3.5h.

[0031] Example 4

[0032] Pretreatment: TC4 titanium alloy was selected as the substrate, and the substrate was subjected to mechanical polishing, pickling and cleaning in sequence; the pickling treatment used a 15% hydrochloric acid solution to clean the substrate to remove the surface oxide layer; then the substrate was cleaned with anhydrous ethanol and deionized water in sequence and dried under nitrogen for later use;

[0033] Preparation of an anodic oxide layer: at an anodic oxidation voltage of 28 V, using 1.5 mol / L H3PO4 solution and 1.1 wt% NaF solution as electrolyte solution, anodizing on the surface of the titanium alloy substrate for 90 minutes to prepare an anodic oxide layer;

[0034] Laser additive processing: 100 parts by weight of aluminum powder, 40 parts by weight of hexagonal boron nitride (BN) powder and 23.2 parts by weight of niobium pentoxide powder were mixed evenly, and the Al-BN-Nb2O5 composite coating was prepared by a laser additive process using a synchronous powder feeding method. In the laser additive process, the laser power was 920 W, the scanning speed was 300 mm / min, the spot diameter was 3.0 mm, the overlap rate was 25%, and the energy density was 240 W / mm 2 ;

[0035] Vacuum annealing post-treatment: The titanium alloy substrate containing the Al-BN-Nb2O5 composite coating is placed in a vacuum annealing furnace and annealed at 450°C for 3.5h.

[0036] Example 5

[0037] Pretreatment: TC4 titanium alloy was selected as the substrate, and the substrate was subjected to mechanical polishing, pickling and cleaning in sequence; the pickling treatment used a 15% hydrochloric acid solution to clean the substrate to remove the surface oxide layer; then the substrate was cleaned with anhydrous ethanol and deionized water in sequence and dried under nitrogen for later use;

[0038] Preparation of an anodic oxide layer: at an anodic oxidation voltage of 28 V, using 1.5 mol / L H3PO4 solution and 1.1 wt% NaF solution as electrolyte solution, anodizing on the surface of the titanium alloy substrate for 90 minutes to prepare an anodic oxide layer;

[0039] Laser additive processing: 100 parts by weight of aluminum powder, 40 parts by weight of hexagonal boron nitride (BN) powder and 29 parts by weight of niobium pentoxide powder were mixed evenly, and the Al-BN-Nb2O5 composite coating was prepared by a laser additive process using a synchronous powder feeding method. In the laser additive process, the laser power was 920 W, the scanning speed was 300 mm / min, the spot diameter was 3.0 mm, the overlap rate was 25%, and the energy density was 240 W / mm 2 ;

[0040] Vacuum annealing post-treatment: The titanium alloy substrate containing the Al-BN-Nb2O5 composite coating was placed in a vacuum annealing furnace and annealed at 450°C for 3.5h.

[0041] Comparative Example 1

[0042] Pretreatment: TC4 titanium alloy was selected as the substrate, and the substrate was subjected to mechanical polishing, pickling and cleaning in sequence; the pickling treatment used a 15% hydrochloric acid solution to clean the substrate to remove the surface oxide layer; then the substrate was cleaned with anhydrous ethanol and deionized water in sequence and dried under nitrogen for later use;

[0043] Preparation of an anodic oxide layer: at an anodic oxidation voltage of 28 V, using 1.5 mol / L H3PO4 solution and 1.1 wt% NaF solution as electrolyte solution, anodizing on the surface of the titanium alloy substrate for 90 minutes to prepare an anodic oxide layer;

[0044] Laser additive processing: 100 parts by weight of aluminum powder and 40 parts by weight of hexagonal boron nitride (BN) powder were mixed evenly, and the Al-BN composite coating was prepared by a laser additive process using a synchronous powder feeding method. In the laser additive process, the laser power was 920 W, the scanning speed was 300 mm / min, the spot diameter was 3.0 mm, the overlap rate was 25%, and the energy density was 240 W / mm 2 ;

[0045] Vacuum annealing post-treatment: The titanium alloy substrate containing the Al-BN composite coating is placed in a vacuum annealing furnace and annealed at 450°C for 3.5h.

[0046] Comparative Example 2

[0047] Pretreatment: TC4 titanium alloy was selected as the substrate, and the substrate was subjected to mechanical polishing, pickling and cleaning in sequence; the pickling treatment used a 15% hydrochloric acid solution to clean the substrate to remove the surface oxide layer; then the substrate was cleaned with anhydrous ethanol and deionized water in sequence and dried under nitrogen for later use;

[0048] Preparation of an anodic oxide layer: at an anodic oxidation voltage of 28 V, using 1.5 mol / L H3PO4 solution and 1.1 wt% NaF solution as electrolyte solution, anodizing on the surface of the titanium alloy substrate for 90 minutes to prepare an anodic oxide layer;

[0049] Laser additive processing: 100 parts by weight of aluminum powder, 40 parts by weight of hexagonal boron nitride (BN) powder and 50 parts by weight of niobium pentoxide powder were mixed evenly, and the Al-BN-Nb2O5 composite coating was prepared by a laser additive process using a synchronous powder feeding method. In the laser additive process, the laser power was 920 W, the scanning speed was 300 mm / min, the spot diameter was 3.0 mm, the overlap rate was 25%, and the energy density was 240 W / mm 2 ;

[0050] Vacuum annealing post-treatment: The titanium alloy substrate containing the Al-BN-Nb2O5 composite coating was placed in a vacuum annealing furnace and annealed at 450°C for 3.5h.

[0051] Hereinafter, we evaluate the hardness and corrosion resistance of the samples in Examples 1-5 and Comparative Examples 1-2, and the specific method is as follows:

[0052] Hardness: Nano-indenter G200 produced by MTS was used to perform nano-indentation experiments on the samples to obtain the hardness data of the film. The experiment used Berkovich triangular pyramid diamond indenter, and the indentation depth did not exceed 10% of the film thickness.

[0053] Corrosion resistance: The electrochemical test was performed on each sample in a 3.5% NaCl aqueous solution using an electrochemical workstation. The non-working surface was sealed with nail polish and the test was performed at room temperature. The test results are shown in Table 1:

[0054] Table 1

[0055] serial number Hardness / HV <![CDATA[Self - corrosion current density / A·cm -2 > Example 1 801.2 <![CDATA[5.36×10 -6 ]]> Example 2 845.5 <![CDATA[1.03×10 -6 ]]> Example 3 823.0 <![CDATA[8.79×10 -7 ]]> Example 4 821.3 <![CDATA[4.69×10 -7 ]]> Example 5 794.4 <![CDATA[4.32×10 -7 ]]> Comparative Example 1 783.3 <![CDATA[7.02×10 -6 ]]> Comparative Example 2 700.9 <![CDATA[3.20×10 -7 ]]>

[0056] As can be seen from Table 1, adding niobium pentoxide to the laser-added Al-BN composite coating can significantly improve the corrosion resistance of the material, and as the amount of niobium pentoxide increases, the corrosion resistance of the composite coating becomes stronger. However, excessive niobium pentoxide will cause the hardness of the composite coating to drop sharply (Comparative Example 2), so the amount of niobium pentoxide needs to be strictly controlled in practice.

[0057] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A laser additive manufacturing process for aircraft materials, characterized in that: The manufacturing process comprises the following steps: Pretreatment: TC4 titanium alloy was selected as the substrate, and the substrate was subjected to mechanical polishing, pickling and cleaning in sequence; the pickling treatment used a 15-18% hydrochloric acid solution to clean the substrate to remove the surface oxide layer; then the substrate was cleaned with anhydrous ethanol and deionized water in sequence and dried under nitrogen for later use; Preparation of anodized layer: at an anodizing voltage of 25-28 V, using 1.5-1.8 mol / L H3PO4 solution and 1.1-1.5 wt% NaF solution as electrolyte solution, anodizing on the surface of the titanium alloy substrate for 90-100 minutes to prepare anodized layer; Laser additive processing: 100-120 parts by weight of aluminum powder, 40-45 parts by weight of hexagonal boron nitride powder and 8-29 parts by weight of niobium pentoxide powder are mixed evenly, and the Al-BN-Nb2O5 composite coating is prepared by a laser additive process using a synchronous powder feeding method. In the laser additive process, the laser power is 900-920W, the scanning speed is 300-350mm / min, the spot diameter is 3.0-3.1mm, the overlap rate is 25-28%, and the energy density is 240-245W / mm 2 ; Vacuum annealing post-treatment: The titanium alloy substrate containing the Al-BN-Nb2O5 composite coating is placed in a vacuum annealing furnace and annealed at 450-480°C for 3.5-3.8h.

2. A manufacturing process as claimed in claim 1, characterized in that: The laser power is 900W.

3. A manufacturing process according to claim 1 or 2, characterized in that: The scanning speed is 300 mm / min.

4. A manufacturing process as claimed in claim 1, characterized in that: The annealing temperature is 450°C.

5. A manufacturing process as claimed in claim 1, characterized in that: The annealing time is 3.5h.

6. A manufacturing process as claimed in claim 1, characterized in that: The anodization voltage is 28V.