The industrial demand for wettability control has been increasing because wettability is a key factor for achieving novel anti-contaminant surfaces and related products. In this paper, the potential of angled fine particle peening (angled-FPP) was explored as a method of surface modification to control wettability. Angled-FPP, which is an abrasive jet machining process conducted using a peening nozzle set at an angle inclined to the material surface, is a potential texturing technique. With it, it is possible to create periodically aligned peaks and valleys (“ridges”) on the peened surface. Because control of wettability could possibly be achieved by varying the geometric characteristics of the texture, an attempt was made to vary ridge texture by conducting angled-FPP using three kinds of shot particles: steel, glass, and alumina grit. Thereafter, changes in the wettability owing to creation of a ridge texture on the surfaces were evaluated, with focus on the geometric and morphological features of the ridge texture. The results indicate that the size of the ridges depends on the size and shape of the shot particles, and the angled-FPP conducted using finer angular particles created densely concentrated ridges. The superficial appearance of the ridge texture differed depending on the shot particles used for angled-FPP. The topographies created by angled-FPP using steel particles and alumina grit were “hierarchical” (i.e., the ridge structure was overlapped by finer-scale roughness). In contrast, angled-FPP conducted using glass particles created ridge structure with a quite plain surface. Measurement of the water drop contact angle revealed that the surface became less hydrophilic after creation of the hierarchical topography. It was concluded that the predominant influence on the wettability of the angled-FPP surfaces came from the superficial morphology of the ridge texture.

1. [1] Y. Aono, W. Shinohara, and H. Tokura, “Laser Modification of Silicon and Borosilicate Glass Wettability for Micro-Fluidic Systems,” Int. J. Automation Technol., Vol.9, No.6, pp. 668-673, 2015.
2. [2] W. C. Chen, Y. S. Chen, C. L. Ko, Y. Lin, T. H. Kuo, and H. N. Kuo, “Interaction of progenitor bone cells with different surface modifications of titanium implant,” Mater. Sci. Eng. C, Vol.37, pp. 305-313, 2014.
3. [3] M. Kok and T. M. Young, “The evaluation of hierarchical structured superhydrophobic coatings for the alleviation of insect residue to aircraft laminar flow surfaces,” Appl. Surf. Sci., Vol.314, pp. 1053-1062, 2014.
4. [4] K. Tadanaga, N. Katata, and T. Minami, “Formation process of super-water-repellent Al₂O₃ coating films with high transparency by the sol-gel method,” J. Am. Ceram. Soc., Vol.80, No.12, pp. 3213-3216, 1997.
5. [5] J. Yu, X. Zhao, Q. Zhao, and G. Wang, “Preparation and characterization of super-hydrophilic porous TiO₂ coating films,” Mater. Chem. Phys., Vol.68, Nos.1-3, pp. 253-259, 2001.
6. [6] G. X. Shen, Y. C. Chen, L. Lin, C. J. Lin, and D. Scantlebury, “Study on a hydrophobic nano-TiO2 coating and its properties for corrosion protection of metals,” Electrochim. Acta., Vol.50, Nos.25-26, pp. 5083-5089, 2005.
7. [7] A. A. G. Bruzzone, H. L. Costa, P. M. Lonardo, and D. A. Lucca, “Advances in engineered surfaces for functional performance,” CIRP Annals, Vol.57, No.2, pp. 750-769, 2008.
8. [8] N. Moronuki, “Functional Texture Design and Texturing Processes,” Int. J. Automation Technol., Vol.10, No.1, pp. 4-15, 2016.
9. [9] M. Urabe, T. Takakura, S. Metoki, M. Yanagisawa, and H. Murata, “Mechanism of and Fuel Efficiency Improvement by Dimple Texturing on Liner Surface for Reduction of Friction between Piston Rings and Cylinder Bore,” SAE Tech. Pap., 2014-01-1661, 2014.
10. [10] T. Sugihara and T. Enomoto, “Development of a Cutting Tool with a Nano/micro-textured Surface – Improvement of Anti-adhesive Effect by Considering the Texture Patterns,” Prec. Eng., Vol.33, No.4, pp. 425-429, 2009.
11. [11] T. Enomoto and T. Sugihara, “Improving anti-adhesive properties of cutting tool surfaces by nano-/micro-textures,” CIRP Annals, Vol.59, No.1, pp. 597-600, 2010.
12. [12] T. Enomoto, T. Sugihara, S. Yukinaga, K. Hirose, and U. Satake, “Highly wear-resistant cutting tools with textured surfaces in steel cutting,” CIRP Annals, Vol.61, No.1, pp. 571-574, 2012.
13. [13] N. Kawasegi, H. Sugimori, N. Morita, and T. Sekiguchi, “Improvement of Machining Performance of Small-Diameter End Mill by Means of Micro- and Nanometer-Scale Textures,” Int. J. Automation Technol., Vol.10, No.6, pp. 882-890, 2016.
14. [14] H. Sawada, K. Kawahara, T. Ninomiya, K. Kurosawa, and A. Yokotani, “Precise Periodic Structuring with Femtosecond-laser,” J. Jpn. Soc. Prec. Eng., Vol.69, No.4, pp. 554-558, 2003 (in Japanese).
15. [15] H. Sawada, K. Kawahara, T. Ninomiya, A. Mori, and K. Kurosawa, “Effect of Precise Periodic Structures with Femtosecond-laser on Tribological Characteristics under Sliding Tests,” J. Jpn. Soc. Prec. Eng., Vol.70, No.1, pp. 133-137, 2004 (in Japanese).
16. [16] S. Kodama, S. Suzuki, A. Shibata, K. Shimada, M. Mizutani, and T. Kuriyagawa, “Effect of Crystal Structure on Fabrication of Fine Periodic Surface Structures with Short Pulsed Laser,” Int. J. Automation Technol., Vol.12, No.6, pp. 868-875, 2018.
17. [17] M. Yoshino, T. Ueno, and M. Terano, “Nano Texturing and Self-Organization Process for Development of Optical Functional Surface,” Int. J. Automation Technol., Vol.10, No.1, pp. 41-47, 2016.
18. [18] T. Matsumura, F. Iida, T. Hirose, and M. Yoshino, “Micro Machining for Control of Wettability with Surface Topography,” J. Mater. Process. Technol., Vol.212, pp. 2669-2677, 2012.
19. [19] T. Matsumura, M. Serizawa, T. Ogawa, and M. Sasaki, “Surface Dimple Machining in Whirling,” J. Manuf. Sys., Vol.37, No.2, pp. 487-493, 2015.
20. [20] T. Pratap and K. Patra, “Fabrication of Micro-textured Surfaces using Ball-end Micromilling for Wettability Enhancement of Ti-6Al-4V,” J. Mater. Process. Technol., Vol.262, pp. 168-181, 2018.
21. [21] R. Kurniawan, G. Kiswanto, and T. J. Ko, “Micro-dimple Pattern Process and Orthogonal Cutting Force Analysis of Elliptical Vibration Texturing,” Int. J. Machine Tools Manuf., Vol.106, pp. 127-140, 2016.
22. [22] T. Sato, T. Niimi, Y. Kanda, S. Nisio, S. Hayakawa, and H. Usami, “Effects of Dimple Geometry Applied by Means of Interrupted Micro Cutting on the Tribological Properties of Aluminum Casting Alloys,” J. Jpn. Soc. Tribologists, Vol.63, No.9, pp. 629-640, 2018 (in Japanese).
23. [23] V. Lertphokanont, M. Oi, T. Sato, M. Ota, K. Egashira, K. Yamaguchi, M. Yamada, and Y. Tomita, “Effect of Discharge Duration and Pulse Frequency on Surface Characteristics Using Whirling Electrical Discharge Texturing,” Int. J. Automation Technol., Vol.8, No.4, pp. 561-568, 2014.
24. [24] Y. Kameyama, H. Ohmori, H. Kasuga, and T. Kato, “Fabrication of micro-textured and plateau-processed functional surface by angled fine particle peening followed by precision grinding,” CIRP Annals, Vol.64, No.1, pp. 549-552, 2015.
25. [25] Y. Kameyama and J. Komotori, “Effect of Micro Ploughing during Fine Particle Peening Process on the Microstructure of Metallic Materials,” J. Mater. Process. Technology, Vol.209, No.20, pp. 6146-6155, 2009.
26. [26] Y. Kameyama, K. Nishimura, H. Sato, and R. Shimpo, “Effect of fine particle peening using carbon-black/steel hybridized particles on tribological properties of stainless steel,” Tribol. Int., Vol.78, pp. 115-124, 2014.
27. [27] A. B. D. Cassie and S. Baxter, “Wettability of porous surfaces,” Trans. Faraday Soc., Vol.40, pp. 546-551, 1944.
28. [28] H. S. Arora, Q. Xu, Z. Xia, Y. Ho, N. B. Dahotre, J. Schroers, and S. Mukherjee, “Wettability of nanotextured metallic glass surfaces,” Scr. Mater., Vol.69, pp. 732-735, 2013.