| Ti alloy has been widely used in various fields, according to high strength, good corrosion resistance and high heat resistance, but it has the high surface energy, shows a hydrophilic, and does not have self-cleaning performance. Ti alloy corrosion can occur in moist air for a long time, and some Ti alloy parts in equipment are easy to produce the icing phenomenon, which limits its application in some fields. Creature skin represented by the lotus leaf in nature shows super-hydrophobic and self-cleaning properties, which offers us an important idea. It is found that a waxy material with low surface energy and the mastoid with micro-and nano-composite structure result in the hydrophobicity and self-cleaning function of the lotus leaf. If the manufacturing technology of hydrophobic surface can be developed according to the hydrophobic theory, and can be applied in the titanium alloy and other metal materials, it will make them have self-cleaning, inhibition of corrosion and oxidation, moistureproof and anti-icing functions. Besides the daily items, at present, other fields also need the surface technology with long life, for example aviation, it can be applied for anti-icing of the engine intake, to prevent loss of engine performance and the failure, it also can be used for other parts such as air data sensors and wing leading edge for anti-icing, to solve the increased resistance. The need in the field of electronic components and medical equipment is also very obvious.Currently, super-hydrophobic coating usually is prepared by chemical method. Although the method is simple and easy to operate, the coating has some bad properties such as low adhesion strength, poor environmental adaptability and impact resistance, often produce some failure behaviors including powdering, blistering, cracking, etc. Diamond like-carbon (DLC) films possesses excellent mechanical propertis, but has higher surface energy and poor hydrophobic performance. If the surface energy of it could be reduced by the element doping, it will improve the hydrophobicity. At the same time, if the environmental adaptability and service life of the film could be enhanced, it will greatly improve the applicability. In this thesis, Ti metal and nonmetal F doped DLC films will mainly be studied, to reveal the element doping effect on hydrophobic performance and mechanical properties. It is noticed the super-hydrophobic surface and good comprehensive performance are usually the result of a low surface energy material combinded with the rough surface morphology. So, in this thesis, WC coating prepared by supersonic flame spraying (HVOF) and micro blind holes prepared by nanosecond laser manufacturing are used to generate the microstructure of super-hydrophobic surface. Finally the doped DLC film with low surface energy is deposited on the coarse surface.The concrete research contents and results are as follows:(1) Ti-DLC film was prepared by the microwave electron cyclotron resonance (MW-ECR) plasma reactive magnetron sputtering. The film’s chemical structure and composition changing were studied, the effect of the different preparation conditions on the mechanical properties and hydrophobicity were focused on. The results showed the film was a nano-composite DLC film with TiC crystal, its nanohardness up to33GPa, abrasion losss down to12μm3, critical loading up to50, and water contact angle at a maximum of106.5°. It was found that the surface energy of Ti-DLC film increased firstly and then decreased with the increase of Ti element percentage, and the improving of the hydrophobicity was mainly owing to the changing of the chemical structure and composition.(2) The F-DLC film was prepared by the MW-ECR plasma chemical vapor deposition technique. The effect of different energy and percentage of F element on the surface morphology and chemical structure of F-DLC film was mainly studied. The change rules of the hydrophobic property and mechanical properties were focused on. The results showed that the film was composited of C-Fx (x=1,2,3) and C=C (F, H) crosslinking structure, which resulted in worse mechanical properties. For instance, the nano-hardness was generally between3GPa and2GPa, the maximal critical load was about31N, but the hydrophobic performance was greatly improved, under the optimized processing parameters, the water contact angle increased to159.2°. It was noticed that F atomic percentage content of the film had an important influence on the surface energy. With the increasing of F content, the surface energy gradually became low, when the content was32.6%, the surface energy achieved a minimum of14.74mJ/m2.(3) The influence of different morphology on the hydrophobic property was studied by three methods including ion bombardment, supersonic flame spraying and nanosecond laser processing. The super-hydrophobic surface with micro-nano secondary structure was fabricated by the micro-nano manufacturing combining with the film with low surface energy deposition. The results showed that the contact angle of the substrate showed a trend of rising with bombardment energy increasing. WC coating prepared by supersonic spraying was used as the bottom of the hydrophobic surface, and with complexity increasing of the surface morphology, the wacter contact angle of the sample gradually rose. After the microstructure was modified by the F-DLC film, the water contact angle of the sample reached the highest value of166°. The changing trend of the sample with periodic micro blind holes used as the underlying microstructure was similar to WC coating, after the modification of F-DLC film, the water contact angle reached165.6°.(4) Based on the fractal geometry theory, by projective covering method and Matlab software, the actual surface area and fractal dimension of WC coating was calculated, and the simulation value and the measured value of the water contact angle were compared and analyzed. Based on the theory of Wenzel and Cassie, the mathematical physics models of periodic micro blind hole were established, and were used for the actual surface area and water contact angle calculation. It was principally analyzed that the effect of micro blind hole structure on the hydrophobic properties of Ti alloy surface. Simulation results showed that the above microstructures could increase the actual surface area and fractal dimension of the samples, so the hydrophobic performance was further improved. |
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