| XUE Jinghui,GAO Dong,ZHANG Gui,ZHOU Wangfan.Mechanism of Improving Bonding Performance of PA66 by Laser Texturing Combined with Plasma Surface Treatment[J],54(9):204-213, 259 |
| Mechanism of Improving Bonding Performance of PA66 by Laser Texturing Combined with Plasma Surface Treatment |
| Received:August 14, 2024 Revised:November 26, 2024 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2025.09.017 |
| KeyWord:PA66 laser texturing plasma surface treatment bonding strength contact angle elemental analysis |
| Author | Institution |
| XUE Jinghui |
School of Mechanical Engineering, Jiangsu University, Jiangsu Zhenjiang , China |
| GAO Dong |
School of Mechanical Engineering, Jiangsu University, Jiangsu Zhenjiang , China |
| ZHANG Gui |
School of Mechanical Engineering, Jiangsu University, Jiangsu Zhenjiang , China |
| ZHOU Wangfan |
School of Mechanical Engineering, Jiangsu University, Jiangsu Zhenjiang , China |
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| Abstract: |
| Polyamide 66 (PA66) has been widely used due to its excellent mechanical properties. Due to its advantages of reduced structural weight, good sealing, and uniform stress distribution, adhesive bonding is suitable for connecting PA materials. The low surface energy and poor wettability result in poor bonding performance of PA66. The work aims to improve the bonding strength of PA66 by laser texturing combined with plasma surface treatment. The laser texturing experiments were carried out by a pulsed laser with a wavelength of 1 064 nm, a laser pulse width of 104 ns, a frequency of 20 kHz, a spot diameter of 50 µm, and an "S"-shaped scanning path. The low-temperature atmospheric pressure air plasma treatment equipment was used for plasma surface treatment, with a working pressure of 0.2-0.3 MPa. The mechanism of bonding performance improvement of PA66 was investigated through tensile shear experiments, contact angle testing, surface morphology observation, and XPS testing. The geometry of the specimen for the single lap shear test was shown in Fig.1. To ensure a constant thickness of the adhesive layer, glass microspheres with a diameter of 0.25 mm were added during bonding. The Taguchi method was used to optimize parameters for laser texturing. The hatch spacing and scanning velocity were the main factors affecting the bonding strength, while the laser power had a relatively low impact. The optimal laser texturing parameters were a laser power of 7 W, a hatch spacing of 50 µm, and a scanning velocity of 1 500 mm/s. The power (P), the height of plasma treatment nozzle (H), and the spray velocity (v) during plasma treatment were studied. The maximum bonding strength of plasma treatment was achieved at P=750 W, H=11 mm, and v=2 mm/s. The maximum bonding strength after laser texturing and plasma surface treatment was 6.58 MPa and 7.45 MPa, respectively. The bonding strength of untreated PA66 was 0.44 MPa. Laser texturing and plasma surface treatment both significantly improved the bonding strength of PA66. By utilizing the optimal parameters of laser texturing and plasma treatment for composite processing, the bonding strength increased to 8.67 MPa. Compared with that subject to laser texturing and plasma surface treatment, the bonding strength increased by 31.76% and 16.38%, respectively. 10 repeated experiments were conducted on different treatments to study their process stability. The standard deviation of the bonding strength under composite treatment was 0.371, so the composite treatment had higher process stability than plasma treatment. Laser texturing significantly changed the surface morphology of PA66 by forming groove structures on the surface. The groove structure on the surface greatly enhances the mechanical interlocking force between the material and the adhesive. Plasma treatment significantly alters the chemical composition of the PA66 surface, increasing the surface oxygen content from 2.92% to 28.47%. The oxygen groups on the surface form a strong chemical bonding force with the adhesive. After composite treatment, the surface contact angle decreases from 89.7° to 13.9°, enhancing the adsorption capacity. Under the comprehensive effect of mechanical interlocking, adsorption capacity, and chemical bonding, the bonding strength is significantly improved after laser texturing followed by plasma surface treatment. |
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