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In this work, the reaction films were generated on the Ti-6Al-4V alloy by means of high-speed wire electrical discharge machining (WEDM-HS) technology in order to improve its microhardness and corrosion resistance. The microhardness was evaluated by using a nanoindentation tester. The corrosion behaviour was studied using measurements of potentiodynamic polarisation and electrochemical impedance spectroscopy. The experimental results showed that the processed alloys presented a higher microhardness than the matrix, and the thicker film on the surface had a greater microhardness. Additionally, the corrosion resistances of the processed alloys were superior, which could have been due to the lower corrosion current densities and the higher impedance values. Furthermore, the corrosion current densities of the processed alloys would decrease with thicker reaction films. This research provides important insights into the surface modification of titanium alloys. [ABSTRACT FROM AUTHOR]

Superamphiphobic (both superhydrophobic and superoleophobic) surfaces on Al substrates are fabricated by the high speed wire electrical discharge machining (HS-WEDM) and chemical etching technology. The surface morphology, chemical composition and wettability of the sample surfaces are investigated using scanning electron microscopy, energy dispersive X-ray diffraction system and optical contact angle (CA) measurements. The results show that, after the HS-WEDM and chemical etching, the micrometer-scale craters and nanometerscale acicular structures are present on the sample surfaces. The obtained sample surfaces show superamphiphobicity after fluorination. The CAs of water, ethylene glycol and peanut oil are 155.9°, 153.1° and 151.7°, respectively. The sliding angles of water, ethylene glycol and peanut oil are 2°, 3.5° and 5°, respectively. The micro/nanometer-scale rough structures and the low surface energy are essential to fabricate superamphiphobic surfaces. Compared with the other methods, the main advantages of the HS-WEDM and chemical etching technology are simple, safe, highly effective and low cost. In addition, superamphiphobic Al surfaces have potential applications in fields such as self-cleaning, oil capture, oil transportation and anti-smudge. [ABSTRACT FROM AUTHOR]

The effect of power tubes on AZ91D magnesium (Mg) alloy was investigated by high-speed wire electrical discharge machine (WEDM-HS). This Letter presented the different surface characteristics and corrosion resistance of the fabricated surface. Chemical composition of the fabricated surface was analysed by energy-dispersive X-ray spectroscopy, and the surface salt water contact angle was also measured in this study. The machined surface evidenced a carbon layer and high hydrophobic property (contact angle between 146° and 150°). The corrosion resistance of the samples machined by the WEDM-HS process was studied in 3.5% NaCl solution through electrochemical impedance spectroscopy. The results have shown that when electrical parameters of the five power tubes were used, the good surface properties of the fabricated surface were obtained with few micropits, and using the higher power tube was helpful to improve the AZ91D corrosion resistance. A handy WEDM-HS technology for treating AZ91D is a useful way to improve the corrosion resistance of the AZ91D Mg alloy. [ABSTRACT FROM AUTHOR]

Inspired by the anisotropy of the rice leaf surface, high-speed wire electrical discharge machining (HS-WEDM) technology was used to build submillimetre-scale structures on the 304 stainless steel surfaces, and fluorination treatment was applied on the resulting surfaces. The wettability and microstructure of the resulting surfaces were investigated by a large depth 3D scanner, scanning electron microscopy and by the contact angle measuring instrument. The durability of the fabricated surface was evaluated by wear tests. Results show that the V-shaped groove arrays with a hierarchical structure on the processed surfaces are built by HS-WEDM. After the fluorination treatment, the as-machined surfaces show good one-direction superhydrophobicity and the obvious two-direction (the parallel and perpendicular groove directions) anisotropic wettability. The effect of the size of the V-shaped groove on the two-direction anisotropy is discussed. The wear tests show that the one-direction superhydrophobicity and the two-direction anisotropic sliding properties of the stainless steel surfaces are still exhibited after the tests. Fabricating rough surfaces by HS-WEDM is efficient and does not require complex process operation and large area three-dimensional features. This method can realise industrial production. [ABSTRACT FROM AUTHOR]