Method for improving corrosion resistance of pure aluminum surface in NaCl solution

Abstract

The invention discloses a method for improving corrosion resistance of a pure aluminum surface in a NaCl solution, and relates to the technical field of high-current pulsed ion beams, an experiment is carried out on a TEMP-6 type HIPIB device, and a polymer anode unipolar pulse mode external magnetic insulation ion diode is adopted to generate 70% C and 30% H ion beams for an irradiation experiment; the ion beam parameters are as follows: the acceleration voltage is 300kV, the pulse width is 70-80ns, the beam density is 100A / cm < 2 >, the irradiation frequency is five times, and the background vacuum degree of a vacuum chamber during irradiation is 10 <-3 > Pa.

Description

Technical Field

[0001] This invention relates to the field of high-current pulsed ion beam technology, and in particular to a method for improving the corrosion resistance of pure aluminum surfaces in NaCl solution. Background Technology

[0002] High-intensity pulsed ion beam (HIPIB) typically refers to an ion energy E = 10. 5 ~10 7 eV, pulse width τ≤1μs, ion beam current density J i >>1A / cm 2 Power density P = 10 7 ~10 14 W / cm 2 Energy density q > 1 J / cm³ 2 The ion beam; also known as the Intense Pulsed Ion Beam (IPIB) or High Power Ion Beam (HPIB). The application of HIPIB technology in the field of material surface engineering has become a research focus in recent years. Under HIPIB irradiation, the material undergoes three changes: (1) energy transfer process - rapid heating, melting and evaporation of the target material, and subsequent rapid cooling of the target surface; (2) mass transfer process - formation and expansion of surface ablation plasma, diffusion and segregation of surface components; (3) momentum transfer process - formation of shock waves and reaction momentum inside the target material. The significant energy, mass and momentum effects effectively cause changes in the surface morphology, crystallization state and its crystal structure, chemical composition, etc. of the material, thereby leading to corresponding changes in various surface properties of the material. Based on the characteristics of HIPIB's interaction with materials, its application research in the field of materials surface engineering can be divided into two main categories: one is the use of ablation plasma generated by the irradiated material for the preparation of new materials such as thin film deposition and nanopowders – ablation plasma process; the other is the direct irradiation of the material surface to be treated – material surface irradiation treatment process.

[0003] Rej et al. used HIPIB (300 keV, 30 kA, 1 μs, 2 and 5 J / cm) with C / H / O ion composition in an Anaconda-type device. 2 AISI 4620 stainless steel was treated with irradiation at 5 J / cm² for 1, 3, and 10 cycles respectively. 2A 0.2–1 μm inhomogeneous melting region and a 1–5 μm inhomogeneous heat-affected layer were observed on the surface of samples irradiated 10 times. Furthermore, it was found that with increasing pulse number, HIPIB-irradiated samples exhibited a micro-area smoothing phenomenon, where surface polishing scratches (Ra≈0.1 μm) disappeared, accompanied by a roughening phase over a larger scale (≥10 μm). At 2 J / cm² 2 Similar trends were observed under the same conditions, and ablation pits with a diameter of 1 μm appeared on the surface of all HIPIB-treated samples. The nanohardness distribution within a 1 μm depth on the surface indicates that at a hardness of 5 J / cm... 2 Under these conditions, the surface softened after one treatment, and the surface hardness increased to 1.8 times that of the original sample after three and ten treatments, while the elastic modulus of the sample surface remained essentially unchanged. Bystritskii et al. used HIPIB (200-250 keV, 10-150 A / cm²) 2 Ion beam mixing of a 500 nm thick Ti film deposited on an Al substrate (100 ns) yielded improved corrosion resistance. Furthermore, HIPIB, containing a large number of neutral atoms, can be used for direct ion beam mixing. Brenscheit et al. utilized Ti / Ni / N ions (6.5 J / cm³) to achieve this. 2 The surface of Si3N4 ceramic is irradiated with HIPIB, which contains neutral atoms. By mixing a large number of neutral particles in the ion beam with the molten matrix surface, a surface with better wear resistance is formed.

[0004] Currently, surface treatment of aluminum alloys using energy-carrying beams mainly focuses on two processes: conventional ion implantation and laser beams. While conventional ion implantation can implant a wide variety of ions and is not limited by thermodynamic conditions, its most prominent problem is the shallow modified layer. A shallow modified layer cannot guarantee a long service life, thus limiting the modifying effect of ion implantation. Although laser surface modification technology plays an increasingly important role in improving the wear and corrosion resistance of titanium alloys, metal evaporation loss occurs during laser treatment, causing localized surface dissolution. At the edge of the beam spot, the metal hardly dissolves, increasing the tendency for localized corrosion, making it impossible to simultaneously improve wear and corrosion resistance. Furthermore, the small laser beam spot requires multiple repeated scans for larger workpieces requiring a certain melting depth, making the process extremely complex. Moreover, laser-treated materials typically experience severe surface roughening, which significantly deteriorates the fatigue resistance and wear and corrosion resistance of titanium alloy surfaces, necessitating further post-treatment, further increasing the complexity and cost of laser treatment. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a method for improving the corrosion resistance of pure aluminum surfaces in NaCl solution. The method involves directly irradiating pure metallic aluminum with HIPIB, thereby refining the microstructure and smoothing the surface, thus improving corrosion resistance in NaCl solution. The process is simple and convenient.

[0006] The objective of this invention is achieved through the following solution:

[0007] A method for improving the corrosion resistance of pure aluminum surfaces in NaCl solution includes the following steps:

[0008] S1: Select a pure aluminum plate sample of appropriate size and pretreat the sample surface.

[0009] S2: Irradiate the sample using HIPIB;

[0010] S3: Place the irradiated pure aluminum plate sample into a NaCl solution;

[0011] S4: Determine the corrosion resistance of pure aluminum sheet samples in NaCl solution.

[0012] Furthermore, the specific operation of step S1 includes the following steps:

[0013] S11: Select a size of 18×18×8mm 3 Pure aluminum sheet samples;

[0014] S12: Use 220# SiC wet sandpaper to polish all surfaces of the sample to remove surface burrs and oil stains;

[0015] S13: Grind the polished sample sequentially with 400#, 600#, and 800#.

[0016] S14: After grinding, clean with acetone, dry with cold air, seal in a sealed bag, and place in a drying oven for irradiation.

[0017] Furthermore, in step S2, a polymer anode unipolar pulsed mode external magnetically insulated ion diode is used to generate an ion beam of 70% C and 30% H; the ion beam parameters are: accelerating voltage 300 kV, pulse width 70-80 ns, and beam current density 100-300 A / cm². 2 The number of irradiation sessions is 1-10, and the background vacuum level of the vacuum chamber during irradiation is 10. -3 Pa.

[0018] Furthermore, in step S2, the beam current density is 100 A / cm. 2 The number of irradiation sessions was 5.

[0019] Furthermore, the concentration of the NaCl solution in step S3 is 0.01 mol / L.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] 1. This invention addresses the challenge of integrating corrosion performance improvement and surface smoothing of pure aluminum and aluminum alloys. It utilizes large-area high-current pulsed ion beam technology to provide conditions for developing new surface engineering technologies that integrate modification and surface smoothing of pure aluminum and aluminum alloys, thereby achieving simple, efficient, and reliable surface modification of aluminum alloys.

[0022] 2. HIPIB possesses characteristics such as high temperature, high pressure, and strong magnetic field, enabling high-density energy deposition on material surfaces instantaneously (pulse width < 1 μs). With increasing injected energy, the material surface rapidly heats up (10⁻⁶ rpm) due to intense heating. 9-10 When a material undergoes melting, evaporation, or ablation (K / s), the resulting ablation plasma rapidly expands outward from the material surface with a specific directional energy, forming a high-intensity recoil impulse and impact thermal stress on the substrate. This generates a shock wave propagating from the surface inward, causing strong thermal and mechanical effects far from equilibrium. This leads to significant changes in the microstructure and physical, chemical, and mechanical properties of the material surface, thereby improving its performance. This invention utilizes high-current pulsed ion beam technology to study the surface smoothing and corrosion resistance of pure aluminum under direct irradiation with a high-current pulsed ion beam. Based on the analysis of the microstructure and structural changes of the irradiated modified layer, combined with the results of corrosion and wear performance studies, a composite modification of pure aluminum under the thermo-mechanical coupling effect of high-current pulsed ion beam irradiation was obtained, achieving both corrosion resistance and surface smoothing. Attached Figure Description

[0023] Figure 1 The original beam current density is 100 A / cm. 2 SEM images and surface contour curves of pure aluminum surface under 5 irradiation conditions;

[0024] Figure 2 The original beam current density is 100 A / cm. 2 XRD patterns of pure aluminum surface under 5 irradiation conditions;

[0025] Figure 3 The original beam current density is 100 A / cm. 2 The curve of open circuit potential of pure aluminum in 0.01 mol / L NaCl solution as a function of time under five irradiation conditions;

[0026] Figure 4 The original beam current density is 100 A / cm. 2 Potentiodynamic polarization curves of pure aluminum in 0.01 mol / L NaCl solution under 5 irradiation conditions;

[0027] Figure 5The original beam current density is 100 A / cm. 2 Nyquist plot of pure aluminum in 0.01 mol / L NaCl solution under 5 irradiation conditions. Detailed Implementation

[0028] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0029] A method for improving the corrosion resistance of pure aluminum surfaces in NaCl solution includes the following steps:

[0030] S1: Select a pure aluminum plate sample of appropriate size and pretreat the sample surface.

[0031] Specifically, S11: Select a size of 18×18×8mm. 3 Pure aluminum sheet samples;

[0032] S12: Use 220# SiC wet sandpaper to polish all surfaces of the sample to remove surface burrs and oil stains;

[0033] S13: Grind the polished sample sequentially with 400#, 600#, and 800#.

[0034] S14: After grinding, clean the sample with acetone, dry it with cold air, seal it in a sealed bag, and place it in a drying oven for irradiation.

[0035] S2: Irradiate the sample using HIPIB.

[0036] Specifically, a polymer anode unipolar pulsed mode external magnetically insulated ion diode was used to generate 70% C and 30% H ion beams to irradiate the sample. The ion beam parameters were: accelerating voltage 300 kV, pulse width 70-80 ns, and beam current density 100 A / cm². 2 The irradiation was performed 5 times, and the background vacuum level of the vacuum chamber during irradiation was 10. -3 Pa.

[0037] Table 1 Typical operating parameters of the TEMP-6 type monopolar pulsed ion beam

[0038]

[0039] S3: Place the irradiated pure aluminum plate sample into a 0.01 mol / L NaCl solution;

[0040] S4: Determine the corrosion resistance of pure aluminum sheet samples in 0.01 mol / L NaCl solution.

[0041] Furthermore, the irradiated pure aluminum sheet samples were analyzed and tested. The specific testing methods are as follows:

[0042] 1. Surface morphology and composition characterization

[0043] The surface morphology changes of the samples before and after irradiation were observed using a JSM-5600LV scanning electron microscope equipped with an EDS (Energy Dispersive X-ray Spectrometer), and surface composition energy dispersive spectroscopy analysis was performed. The surface profile curves and roughness of the samples before and after irradiation were measured using a Surfcorder ET 4000M surface profiler with a 2μm tip.

[0044] 2. Characterization of surface phase structure and microstructure

[0045] X-ray diffraction analysis was performed on a SHIMADZU XRD-6000 X-ray diffractometer, using a Cu target, a tube voltage of 40 kV, a tube current of 30 mA, and a wavelength of 0.154056 nm (Cu K). α The scanning mode adopts an θ-2θ linkage mode, with an angle (2θ) range of 20°-100°, a step size of 0.02°, a scanning speed of 4° / min, and an arc-shaped monochromator. <0002> Single-crystal graphite.

[0046] 3. Corrosion performance test

[0047] The potentiodynamic polarization curves of the samples were determined using a computer-controlled EG&G PAR 2273 electrochemical testing system. A 0.01 mol / L NaCl solution was prepared using analytical grade NaCl and double-distilled water as the experimental medium. The solution was allowed to stand for 2-4 hours after preparation to ensure homogeneity. A three-electrode system was used, with the sample as the working electrode, and a saturated calomel electrode (SCE) and a Pt electrode as the reference and auxiliary electrodes, respectively. During measurement, after the open-circuit potential stabilized, the potentiodynamic polarization of the sample was scanned at a rate of 0.5 mV / s from an initial potential 150 mV below the open-circuit potential.

[0048] Experimental results:

[0049] 1. Characteristics of surface smoothing of pure aluminum by high-current pulsed ion beam irradiation

[0050] Figure 1 The original beam current density is 100 A / cm. 2 SEM images and surface profile curves of pure aluminum surface under five irradiation conditions. Figure 1As shown in (a), mechanical grinding scratches approximately several μm wide, formed during sample preparation, are observed on the surface of the original sample. Micro-protrusions and metal debris of varying sizes, ranging from several μm to tens of μm, are also distributed, revealing the inhomogeneity of the micro-geometric structure of the original sample surface. Figure 1 As shown in (b), after five irradiations with a high-current pulsed ion beam, the scratches on the sample surface disappeared due to melting and ablation. During the scratch melting and ablation process, micron-sized ablation particles and localized ablation pits were formed, indicating that localized selective ablation occurred on the irradiated surface within a small scale. Figure 1 As shown in (c), the original sample exhibits fluctuations within a range of 10 μm, ±0.8 μm, at 100 A / cm. 2 After five irradiations, the surface roughness decreased from 0.23 to 0.15, indicating that irradiation smoothed the surface of pure aluminum. Meanwhile, as... Figure 1 As shown in (d), the surface roughness decreased to ±0.3 μm, but the range of roughness increased to 25 μm. This indicates that after irradiation with a high-current pulsed ion beam, the pure aluminum surface exhibits a large-scale overall smoothing characteristic, which is consistent with the SEM observation of the irradiated surface.

[0051] 2. Preferred orientation of pure aluminum surface irradiated by high-current pulsed ion beam, as well as diffraction peak broadening and shift to higher angles.

[0052] Figure 2 The original beam current density is 100 A / cm. 2 XRD patterns of pure aluminum surfaces under five irradiation conditions. Figure 2 As can be seen, the original sample exhibited Al(111),(200), and(222) diffraction peaks, and the pure aluminum phase structure did not change significantly after irradiation. However, irradiation caused all diffraction peaks to shift to higher angles and broaden, indicating that the modified layer of the irradiated sample generated compressive stress and a refinement of the microstructure. Simultaneously, it was observed that irradiation significantly enhanced the intensity of (111) and (200) relative to (222), resulting in a preferred orientation, indicating that the sample underwent intense plastic deformation during irradiation, forming a deformation texture.

[0053] 3. The corrosion resistance of pure aluminum surfaces is significantly improved.

[0054] Figure 3-5 The original and beam current densities are 100 A / cm², respectively. 2 The open-circuit potential, potentiodynamic polarization curve, and Nyquist plot of electrochemical impedance spectroscopy of pure aluminum in 0.01 mol / L NaCl solution under five irradiation conditions are shown. Figure 3As shown, in a 0.01 mol / L NaCl solution, the open-circuit potential of the original sample was approximately -580 mV. After irradiation, the open-circuit potential of the sample was significantly increased, rising to approximately -520 mV. Figure 4 As shown, the corrosion potential of the original sample was -570mV. The irradiated sample exhibited significantly better potentiodynamic polarization properties than the original sample, manifested as an increase in corrosion potential and a decrease in corrosion current density. From Figure 5 As can be seen, both the original and irradiated samples exhibit capacitive arcs in the mid-frequency and low-frequency regions. The diameter of the capacitive arc in the irradiated sample is significantly larger than that of the original sample, indicating an increase in electrode reaction resistance, a decrease in electrode corrosion rate, and enhanced corrosion resistance. The improvement in corrosion resistance of pure aluminum surfaces irradiated by high-current pulsed ion beams is mainly attributed to the refinement of the surface microstructure and surface smoothing caused by irradiation energy deposition.

[0055] In summary, after irradiation with a high-current pulsed ion beam, the surface of pure aluminum exhibits a large-scale overall smoothing characteristic. Although the phase structure of pure aluminum does not change significantly, irradiation causes all diffraction peaks to shift to higher angles and broaden, indicating that the modified layer of the irradiated sample generates compressive stress and refines the microstructure, resulting in preferred orientation. The sample undergoes strong plastic deformation during irradiation, forming a deformation texture. The open-circuit potential of the irradiated sample is significantly improved, and it also exhibits significantly better potentiodynamic polarization performance than the original sample, manifested as an increase in corrosion potential and a decrease in corrosion current density. Both the original and irradiated samples exhibit capacitive arcs in the mid-frequency and low-frequency regions. The diameter of the capacitive arc in the irradiated sample is significantly larger than that of the original sample, indicating an increase in electrode reaction resistance, a decrease in electrode corrosion rate, and enhanced corrosion resistance. The improvement in the corrosion resistance of pure aluminum surface irradiated with a high-current pulsed ion beam is mainly attributed to the refinement of the surface microstructure, the generation of deformation texture, and surface smoothing caused by irradiation energy deposition.

[0056] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for improving the corrosion resistance of pure aluminum surfaces in NaCl solution, characterized in that, Includes the following steps: S1: Select a pure aluminum plate sample of appropriate size and pretreat the sample surface. S2: Irradiate the sample using HIPIB; S3: Place the irradiated pure aluminum plate sample into a NaCl solution; S4: Determine the corrosion resistance of pure aluminum sheet samples in NaCl solution.

2. The method for improving the corrosion resistance of pure aluminum surfaces in NaCl solution according to claim 1, characterized in that, Step S1 includes the following steps: S11: Select a size of 18×18×8mm 3 Pure aluminum sheet samples; S12: Use 220# SiC wet sandpaper to polish all surfaces of the sample to remove surface burrs and oil stains; S13: Grind the polished sample sequentially with 400#, 600#, and 800#. S14: After grinding, clean with acetone, dry with cold air, seal in a sealed bag, and place in a drying oven for irradiation.

3. The method for improving the corrosion resistance of pure aluminum surfaces in NaCl solution according to claim 2, characterized in that, In step S2, a polymer anode unipolar pulsed mode external magnetically insulated ion diode is used to generate an ion beam of 70% C and 30% H. The ion beam parameters are: accelerating voltage 300 kV, pulse width 70-80 ns, and beam current density 100-300 A / cm². 2 The number of irradiation sessions is 1-10, and the background vacuum level of the vacuum chamber during irradiation is 10. -3 Pa.

4. The method for improving the corrosion resistance of pure aluminum surfaces in NaCl solution according to claim 3, characterized in that, In step S2, the beam current density is 100 A / cm. 2 The number of irradiation sessions was 5.

5. The method for improving the corrosion resistance of pure aluminum surfaces in NaCl solution according to claim 4, characterized in that, The concentration of the NaCl solution in step S3 is 0.01 mol / L.

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