To provide the polyethylene terephtalate (PET) plastic material with photocatalytic property, anatase TiO 2 powders were plasma sprayed under various plasma spraying conditions. The effects of spraying parameters and surface morphology of substrates such as PET and PET pre-coated with Cu on the microstructure, phase composition and photocatalytic activity of TiO 2 coating were systematically studied. The photocatalytic activity of the TiO 2 coating was evaluated by the decomposition test of acetaldehyde gas. From the experimental result, it was found that fabrication of TiO 2 coating was possible on PET substrate at arc currents of 200, 300 and 400A. The TiO 2 coatings were thicker with increasing arc current. However, the coating was not attained when the plasma spraying was carried out on steel substrate even at a high arc current of 400 A. In case of plasma spraying on PET substrate pre-coated with Cu, the coating was locally formed at the arc current of 200 A. At the current of 300 A, the coating was attained. It was found that all fabricated TiO 2 coatings exhibited photocatalytic activity regardless of undercoat materials and spraying parameters from the acetaldehyde decomposition test. Even coatings with thin and locally formed layers also showed the same photocatalytic performance as other thick coatings. From the XRD analysis, the reason for the efficient photocatalytic activity in the coatings was due to the high anatase phase content.

The polyethylene terephtalate (PET) is widely utilized for high performance as a food and beverage container due to its excellent mechanical and chemical properties. The consumption of PET material is expected to increase more rapidly. Consequently, the recycling of waste PET is urgently needed to reduce environmental problems and economic costs. The purpose of this research is to endow waste PET materials with a new function by spraying of metal and ceramics such as Cu and TiO 2 . The recycled PET plate substrate for plasma spraying was prepared from waste PET bottles. It is found that Cu and TiO 2 powder could be sprayed on the surface of the recycled PET plate without heat damage and transformation of the substrate. In specific spray conditions, the implantation of melted Cu and TiO 2 particles, which retained their original shape, into the PET substrate was also observed and this is an unusual phenomenon in plasma spraying. In this research, the possibility of production of functional PET plates with electric conductivity and wear resistance was found by controlling the plasma spray conditions.