Fabrication of thin inorganic temperature-sensitive paint using ball milling and its temporal response delay

Abstract

Temperature-sensitive paint (TSP) is widely used to measure the temperature distribution. A TSP is advantageous in terms of cost and spatiotemporal resolution. However, regardless of its thickness, a finite thickness introduces errors. An important issue regarding the thickness of the TSP is the temporal response delay. In this study, a thin TSP was fabricated using ball milling, and TSPs with a thickness < 2 µm could be produced. However, the phosphorescence intensity decreased drastically after ball milling. A special system was designed to measure the temporal response delay caused by the TSP layer. A high-resolution measurement technique (210 kHz and 1.05 µm/pixel) was employed. Time delays were defined and calculated using both experimental and numerical approaches. Numerical simulations were conducted using the experimental data and the thermal properties of ZnO:Zn and epoxy, given that the thermal properties of TSP are unknown. From the time delay, it was found that the thermal diffusivity of the TSP was between those of ZnO:Zn and epoxy, and this result was considered reasonable. Although this study provides only a rough estimation of the thermal diffusivity of TSPs, it reveals a relationship between the time delay and thermal diffusivity, opening up the possibility of calculating the thermal diffusivity from the time delay. Our results can help advance the application of TSPs for temperature measurements in highly dynamic environments.