표면 온도 측정을 위한 스마트 페인트 개발

Abstract

Thermal energy is a fatal factor that causes errors in mechanical parts such as aircraft and satellites. Temperature is measured with a temperature sensor to monitor the source of thermal energy. However, the commercially available temperature sensor has a limited shape and a number of temperature sensors are required to measure the temperature distribution. If the shape of the temperature sensor is limited, it is difficult to attach to the curved surface, resulting in measurement error. In addition, the use of numerous temperature sensors to measure the temperature distribution increases the likelihood of error. To overcome these drawbacks, smart paint has been proposed. This adds conductivity and temperature measurement properties to liquid paints. Smart paints use conductive materials and are made by imparting certain properties to conductive paints, which are commonly used in the field of circuit printing. Smart paint has been mainly used to measure vibration and pressure using piezoelectric materials, but research on smart paint to measure temperature is still insufficient. This paper has developed smart paint for surface temperature measurement, and further confirmed the possibility of temperature distribution measurement. The PTC thermistor features a principle of increasing resistance when the temperature rises. , a ferroelectric ceramic, was used as the main material of the PTC thermistor. Polymer solutions were prepared for the proper viscosity of the paint and ferroelectric ceramics were added to enable temperature measurements. Ag paste was also added to have electrical conductivity. Previous studies confirmed the possibility of smart paint by experimenting with the property of increasing resistance when the temperature rises. Smart paint needed to be optimized for production. The optimization experiment was carried out by dividing into two kinds of characteristics according to the material and process. The order of addition of the materials used to make the paint was experimented. The unstructured order of adding materials will affect the resistance and temperature measurement capabilities of smart paint. Therefore, optimization was necessary. Next, the characteristics according to the ceramic ratio were experimented. The higher the ceramic ratio, the better the PTC characteristics. However, it was expected to affect the resistance characteristics and it was necessary to identify the most economic ratio of ceramics. In the manufacturing process, a stirrer and a convection oven were used. The experiment was carried out to enable a stable paint production through the stirring time of the stirrer. In addition, through the curing characteristic experiments using a convection oven was optimized for the storage of paint at room temperature and the appropriate curing method. The produced smart paint had a defect that the surface was not stable because of very low adhesion. In order to solve this problem, a coating was proposed. Commercially available epoxy coating solutions were not stable at elevated temperature, resulting tn new coating solutions. The coating method of the new coating solution was optimized and the rotational speed and rotation time of the spin coater were experimented to verify the coating properties. The coating ensured surface stability. Application experiment of smart paint confirmed the possibility of measuring distribution. As a result of the distribution measurement, the resistance with temperature was measured stably. The smart paint produced by this study can measure the temperature of curved surface and the temperature distribution of the desired position. Furthermore, if the monitoring technology for temperature distribution is secured, it is expected to be a highly available temperature sensor.