Structural and photocatalytic characteristics of TiO2 coatings produced by various thermal spray techniques

Pavel Ctibor,Zdenek Pala,Vaclav Stengl

doi:10.1007/s40145-013-0063-z

Pavel Ctibor, Zdenek Pala + Show 1 more

Open Access

https://doi.org/10.1007/s40145-013-0063-z

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Abstract

Titanium dioxide (TiO2) was elaborated by four different thermal spray techniques—(i) plasma spraying using a water-stabilized torch, (ii) plasma spraying using a gas-stabilized torch, (iii) high velocity oxy-fuel gun, and (iv) oxy-acetylene flame. The porosity of the coatings was studied by optical microscopy, nano-structural features by scanning electron microscopy (SEM), phase composition by X-ray diffraction (XRD); the microhardness, surface roughness and wear resistance were evaluated. The diffuse reflectance was measured by ultra-violet/visible/near-infrared (UV/Vis/NIR) scanning spectrophotometer. The kinetics of photocatalytic degradation of gaseous acetone was measured under a UV lamp with 365 nm wavelength. After all the applied spray processes, the transformation of anatase phase from the initial powders to rutile phase in the coatings occurred. In spite of this transformation, all the coatings exhibited certain photocatalytic activity, which correlated well with their band gap energy calculated from reflectivity. All the coatings offer relatively good mechanical properties and can serve as robust photocatalysts.

Highlights

Titanium dioxide (TiO2) photocatalyst has emerged as a promising clean advanced oxidation technology, which could address the ever-increasing global concerns for environmental pollution
The thermal spray techniques used for the current work differ markedly in temperature, gases participating in the employed chemical processes, particle velocity and feed rate, etc
The high velocity oxy–fuel (HVOF) process utilizes a combination of oxygen with various fuel gases, including hydrogen, propane, propylene, and kerosene

Summary

Introduction

TiO2 is an important material for ultra-violet (UV) assisted photocatalysis in the state of fine powders [1,2,3], thin coatings [3,4] as well as thermally sprayed coatings [5,6,7,8,9], and useful for water and air purification in advanced electrochemical applications. The thermal spray techniques used for the current work differ markedly in temperature, gases participating in the employed chemical processes, particle velocity and feed rate, etc. All these factors have influence on the resulting coatings [10,11,12,13].

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