Fabrication of Titanium Dioxide Photocatalyst Coatings by Cold Spray

Abstract

Titanium dioxide (TiO 2 ) is a promising material for photocatalyst coating. However, it was difficult to fabricate TiO 2 coatings which have excellent photocatalytic property by thermal spray processes. Because anatase phase of TiO 2 transforms into rutile phase under high temperature i.e. the photocatalytic property of TiO 2 declines by heating. In this study, TiO 2 photocatalyst coatings were fabricated by cold spray process. Agglomerated TiO 2 powder with 100% anatase phase was injected into helium gas stream and deposit onto steel substrate. It was possible to fabricate TiO 2 coatings with anatase phase. The deposition efficiency was increased with working gas temperature. The photocatalytic property of the coatings was evaluated by NOx elimination test. From the results, it became clear that cold sprayed TiO 2 coatings have outstanding photocatalytic property.

Development of Sustainable Cold Spray Coatings and 3D Additive Manufacturing Components for Repair/Manufacturing Applications: A Critical Review

“…In AM, the component is developed by repeated deposition of coatings with respect to component cross-section. This technology enables the manufacturing of functional components in a single step, and the time and cost of the manufacturing does not depend on the complexity of the component [58,59]. The need for AM occurs due to its ability to (a) reduce manufacturing cost by eliminating production steps, hence small production is feasible, runs integrated functionality, (b) improved productivity, as tooling requirement is minimized, and (c) scrap waste by developing finished product directly from feedstock, and helping green manufacturing.…”

“…The rotating shaft is detached later on and end machining applied. The following are the various advantages of using the cold spray process [59][60][61]:…”

Effect of Powder Calcination on the Cold Spray Titanium Dioxide Coating

“…TiO 2 also known as road warrior as to clean the nitrogen oxide (NO x ) in the air that was produced by vehicles emissions 4) . Various techniques have been used to fabricate TiO 2 coating for photocatalyst applications including chemical vapor deposition (CVD), physical vapor deposition (PVD), dip-coating and sol gel method [5][6][7][8] . However, these methods have some restrictions such as high production cost and complex large-scale equipment 5) .…”

“…However, a signi cant challenge in the conventional thermal spray techniques including atmospheric plasma-spray (APS) process and high-velocity oxy fuel (HVOF) is high processing temperature uses during the process to melt the feedstock powders for coating deposition 7,8) . The high process temperature may lead to the phase transformation of TiO 2 from anatase to rutile and also increase the initial crystallite size of the TiO 2 powders.…”

“…Therefore, cold spray process is one of the suitable processes to fabricate thick and large scale of anatase TiO 2 coating 7) . Generally, in cold spray process, the feedstock materials are usually plastically deformed on the substrate upon impact, forming layer of coating.…”