A facile, low temperature spray pyrolysed tungsten oxide (WO 3 ): an approach to antifouling coating by amalgamating scr
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Ó Indian Academy of Sciences Sadhana(0123456789().,-volV)FT3 ](0123456789().,-volV)
A facile, low temperature spray pyrolysed tungsten oxide (WO3): an approach to antifouling coating by amalgamating scratch resistant and water repellent properties ROBBI VIVEK VARDHAN, SUBODH KUMAR and SAUMEN MANDAL* Department of Metallurgical and Materials Engineering, National Institute of Technology Karnataka (NITK), Surathkal 575025, India *Author for correspondence ([email protected]) MS received 8 April 2020; accepted 7 September 2020 Abstract. In this study, a facile spray pyrolysed hydrophobic robust tungsten oxide (WO3) films were deposited at an annealing temperature of 400°C on inexpensive glass substrates, using clear and homogeneous precursor solution containing tungsten hexachloride and 2-methoxyethanol. The 10 and 15 times sprayed films were polycrystalline with the monoclinic crystal structure, uniform with the submicron-sized grain morphology (size *320–420 nm), with an average surface roughness ranging from 12 to 17 nm and transparent above 60% in the visible region with a thickness of 380 and 550 nm, respectively. Elemental existence of tungsten and oxygen was recognized on the surface of the films possessing the highest lattice oxygen percentage of 91.1. Increment in the scratch hardness of the films with the number of sprays compared to uncoated glass was identified. The films were hydrophilic in nature (water contact angle \8°), converted to hydrophobic ([120°) by treating chemically with octadecyltrichlorosilane to form a self-assembled monolayer on the top and the hydrophobicity remained same (*120°) even after a year. These films with unique and combined properties of scratch hardness and hydrophobicity can serve in the potential application as antifouling coatings. Keywords.
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Spray pyrolysis; tungsten oxide; scratch hardness; hydrophobic.
Introduction
In marine fields worldwide, biofouling is a significant concern due to an unwanted accumulation of marine species, such as microorganisms, plants and animals on submerged surfaces [1,2]. Biofouling causes notable operational problems, such as increment in weight and decrement in the speed of the ships, frictional resistance and excess fuel consumption, causing excess emission of harmful greenhouse gases. It also has adverse effects on underwater pipelines, desalination plants and industrial equipment [3]. Tributyltin (TBT) self-polishing copolymer paints, an antifouling material, is applied widely to combat biofouling, but these paints incorporated with environmental toxic biocide materials have affected the nontarget species [2,4]. Other antifouling coatings with triphenyltin (TPT) and organotin compounds (OTC) are also recognized as biocides [3]. The usage of TBT, TPT and other tin contained materials in antifouling coatings is intensively opposed by the International Maritime Organization (IMO) and the Marine Environmental Protection Committee (MEPC) [2,3]. This opposition led to the antifouling paint
industries as well as researchers to find the
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