Fabrication of hierarchical structures on titanium alloy surfaces by nanosecond laser for wettability modification

2022 ◽  
Vol 148 ◽  
pp. 107728
Author(s):  
Chunfang Guo ◽  
Meiju Zhang ◽  
Jun Hu
2021 ◽  
Vol 11 (12) ◽  
pp. 5406
Author(s):  
Fei Yin ◽  
Xia Ye ◽  
Hongbing Yao ◽  
Pengyu Wei ◽  
Xumei Wang ◽  
...  

In order to study the spallation phenomenon of titanium alloy under the shock of nanosecond laser, the Neodymium-Yttrium-Aluminum Garnet laser was used to carry out laser shock experiments on the surface of titanium alloy. By observing and measuring the surface morphology of the target material, the forming factors and the changes of the surface morphology under different parameter settings, the forming criteria of the titanium alloy were obtained. The results show that under the single variable method, the change of laser energy can affect the target shape variable, and there is a positive correlation between them. When the thickness was greater than or equal to 0.08 mm, no obvious cracks were found in the targets. Moreover, the number of impact times was the key factor for the target deformation; with the growth of impact times, the target deformation gradually became larger until the crack appeared. The larger the diameter of the spot, the more likely the target was to undergo plastic deformation. The surface of titanium alloy with a thickness of 0.08 mm appeared to rebound under specific laser shock condition. The changes in the back of the target material were observed in real time through a high-speed camera, and the plasma induced by the laser was observed in the process. This study is based on the results of previous studies to obtain the titanium alloy forming criteria, which provides a basis for the setting of laser parameters and the thickness of the target when the nanosecond laser impacts the Ti-6AL-4V target.


Author(s):  
Ю.Р. Колобов ◽  
С.С. Манохин ◽  
Г.В. Одинцова ◽  
В.И. Бетехтин ◽  
А.Г. Кадомцев ◽  
...  

The microstructure of a thin subsurface layer of VT1-0 titanium alloy samples in the initial submicrocrystalline state after exposure to nanosecond laser pulses has been studied using scanning and transmission electron microscopy (with the possibility of X-ray microanalysis).


Materials ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 278 ◽  
Author(s):  
Zhen Yang ◽  
Yanling Tian ◽  
Yuechao Zhao ◽  
Chengjuan Yang

Nanosecond laser ablated metallic surfaces showed initial super-hydrophilicity, and then experienced gradual wettability conversion to super-hydrophobicity with the increase of exposing time to ambient air. Due to the presence of hierarchical structures and change of surface chemistry, the laser-induced Inconel alloy surfaces showed a stable apparent contact angle beyond 150° over 30-day air exposure. The wetting states were proposed to elucidate the initial super-hydrophilicity and the final super-hydrophobicity. The basic fundaments behind the wettability conversion was explored by analyzing surface chemistry using X-ray photoelectron spectroscopy (XPS). The results indicated that the origins of super-hydrophobicity were identified as the increase of carbon content and the dominance of C–C(H) functional group. The C–C(H) bond with excellent nonpolarity derived from the chemisorbed airborne hydrocarbons, which resulted in dramatic reduction of surface-free-energy. This study confirmed that the surface chemistry is not the only factor to determine surface super-hydrophobicity. The laser-induced super-hydrophobicity was attributed to the synergistic effect of surface topography and surface chemical compositions. In this work, the corresponding chemical reaction was particularly described to discuss how the airborne hydrocarbons were attached onto the laser ablated surfaces, which reveals the generation mechanism of air-exposed super-hydrophobic surfaces.


2017 ◽  
Vol 744 ◽  
pp. 223-227 ◽  
Author(s):  
Chun Ling Li ◽  
Chang Hou Lu

Laser color marking experiments on titanium alloy substrates were carried out to investigate the impact of selected laser processing parameters on the resulting colors. The CIE L*a*b* color space was used to quantify these colors. The surface roughness of the marked color areas was measured by using a TR200 hand-held surface roughness instrument. The relationships between laser parameters and CIE L*a*b* values and surface roughness of the colors were obtained. Results clearly showed that different colors ranging from blue and gray to yellow were produced. Some colors can be obtained by different sets of parameters, while some colors can only be produced by a specific combination of process parameters due to the existence of different forms of heat input and thermal process. The b* value increased to the maximum which represented yellow then decreased. The surface roughness of color areas decreased with the increase of focal plane offset, scanning velocity, or hatch space.


2019 ◽  
Vol 298 ◽  
pp. 00051 ◽  
Author(s):  
Ivan Ushakov ◽  
Yuri Simonov

The alterations in the microhardness of a titanium alloy Ti85.85Al6.5Zr4Sn2Nb1Mo0.5Si0.15 subjected to laser treatment were investigated. Laser processing consists of a series of pulses with durations 20 ns. We used various methods of laser processing, which differed in power density, wavelength, geometrical pattern of irradiation and so on. The dependences of the microhardness on the load on the indenter were found. The laser processing modes providing the increased microhardness are determined. The investigations were carried out at loads from 0.49 N to 4.9 N, with maximum indentation depth of the Vickers pyramid up to 12 μm. Vickers microhardness can be increased by 20 – 40 %. At the same time, the plastic properties of the hardened layer are improved. The probability of crack formation during indentation of the initial alloy increased with a load on the indenter and reached 0.52 for a load of 4.9 N. In two of the treated areas of the three presented, crack formation was not recorded at any load. The mechanisms of hardening of the material surface layer under the influence of a laser pulse are discussed. Using the methods of computational mathematics, the character of sample heating under the influence of a single laser pulse is determined. The perspectives for the development of the proposed processing method are permitting to obtain the optimal mechanical properties of the hardened layer are discussed.


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