## 2 Experimental Investigations
### Experimental Setup
#### 2.2.3 Curing Methods and Test Conditions  
A sample plate sprayed with a powder coating was placed on the internal platform underneath the radiant panel, and the coating temperature was increased to 180 \({}^{\circ}\)C, 190 \({}^{\circ}\)C, 200 \({}^{\circ}\)C, 210 \({}^{\circ}\)C, 220 \({}^{\circ}\)C, 230 \({}^{\circ}\)C, and 240 \({}^{\circ}\)C by controlling the gas flow into the radiation \begin{table}
\begin{tabular}{c c c} \hline \hline
**Index** & **Value** & **Unit** \\ \hline Dimensions & 745 \(\times\) 395 \(\times\) 5 & mm \\ Catalyst loading per area & 350 & g/m\({}^{2}\) \\ Average diameter & 5 & \(\upmu\)m \\ Average particle size & 18 & nm \\ Specific surface area & 150 & m\({}^{2}\)/g \\ Pore volume & 0.14 & cm\({}^{3}\)/g \\ Average pore size & 5.25 & nm \\ Elemental content & Pt \(\leq\) 1 wt.\%, Al\({}_{2}\)O\({}_{3}\)\(\geq\) 95 wt.\%, SiO\({}_{2}\)\(\leq\) 4 wt.\% & / \\ Ignition temperature & 120 (LPG), 180 (natural gas) & \({}^{\circ}\)C \\ Service life & 30,000 & h \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Physical properties of fiber-supported noble metal catalyst (Cat-1). \begin{table}
\begin{tabular}{c c} \hline \hline
**Index** & **Parameter** \\ \hline \hline \multirow{4}{*}{Composition} & Polyester-based powder coating + \\  & triplycidylisocyanurate crosslinker, acrylic acid, \\  & barium sulfate, titanium dioxide, pigments, \\  & and various additives \\ Average particle size & 34–38 \(\upmu\)m \\ Color & White \\ Thermal conductivity (average) & 0.1 W/m\({}^{\circ}\)C \\ Glass transition temperature & 53 \({}^{\circ}\)C \\ Curing conditions (hot-air oven) & 200 \({}^{\circ}\)C for 10 min and 180 \({}^{\circ}\)C for 20 min \\ Storage stability & Below 25 \({}^{\circ}\)C; the storage time was 12 months \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Characteristics of the powder coating used in this study. panel. The sample plate was held at these seven temperatures with 1 min intervals for 1 to 5 min, respectively. After heating, the sample plate was removed and cooled to ambient temperature. The curing process potentially affects the mechanical properties of cured samples, such as the hardness, flexibility, impact resistance, appearance of the film surface, and chemical resistance [4; 30]. Therefore, five mechanical properties of these cured samples were tested: adhesion, impact resistance, gloss, pencil hardness, and coating color. The test equipment and processes are shown in Figure 5.  
The test methods were as follows:  
**Adhesion**: This test was conducted according to ASTM Test Method D3359, Method B using a multi-toothed blade (QFH-A, Dongguan Huanguo Precision Instrument Co., Ltd., Dongguan, China) suitable for standard adhesion tests. Specific method: Firstly, the cured coating template was fixed, and the multi-toothed cutter blade was set perpendicular to the template and drew a scratch. Then, the template was evenly covered with transparent tape before it was removed to observe the scratching off, using the observer's judgment to determine the size of the adhesion area;  
**Gloss**: This test was performed with a gloss meter measuring instrument (HG-60, Shenzhen Threenh Technology Co., Ltd., Shenzhen, China). Specific method: A calibrated gloss meter was placed on the coating so that no light entered, and the beam of the internal light source of the instrument was at an angle of 60\({}^{\circ}\) from the normal line of the tested coating surface. Figure 5: Test equipment and processes: (**a**) adhesion test, (**b**) gloss test, (**c**) hardness test, (**d**) film impact resistance test, and (**e**) color test. Then, the instrument was initiated and it read the gloss value of the coating. This test was conducted according to ASTM Test Method D523;  
**Hardness**: The pencil thickness meter (Shanghai Gaozhi Precision Instrument Co., Ltd., Shanghai, China) was used to test the hardness of the cured films. This test was conducted according to ASTM Test Method D3363.