## 1 Introduction  
Powder coatings on metal surfaces and other materials can be used for protection, decoration, and other special functions. These coatings are widely used in the automobile, aerospace, machinery, and furniture industries, as well as others [1; 2; 3; 4]. However, for metal substrates, adequate protection is only possible if the coating remains bonded to the substrate for the design life of the metal structure and has excellent mechanical properties. The mechanical properties of the coating are usually tested in terms of adhesion, hardness, and impact resistance. In addition to ensuring the mechanical properties of the coating are appropriate, the aesthetic effect of the coating is significant. A natural and attractive appearance increases consumer satisfaction [5]. Gloss and color tests are usually performed to evaluate the gloss and color difference in cured coatings. [PERSON] et al. [6] used a hot-air curing oven at 180 \({}^{\circ}\)C for 10 min to cure a two-layer powder coating. Furthermore, they investigated the effects of two curing strategies--co-curing and layer-by-layer curing--on the mechanical properties of the coating. The results showed that the coatings' adhesion, gloss, and hardness were higher with the layer-by-layer curing than those obtained with the co-curing mode. [PERSON] et al. [7] cured polyester-based powder coatings with different organo-modified silica particle (OSP) concentrations (1, 2.5, 3.5, and 4.5 wt.%) using a hot air method at 180 \({}^{\circ}\)C for 15 min. Then, they tested the samples with different OSP concentrations for adhesion and impact resistance. The results showed that the samples with a 2.5% OSP concentration had improved adhesion and impact resistance. [PERSON] et al. [8] used a hot-air curing oven to cure epoxy powder (EP) coatings with a graphene nanosheet (G) added at 210 \({}^{\circ}\)C for 10 min, and the adhesion and impact resistance of the cured composite (G/EP) coating and EP samples were tested. The results confirmed that the G/EP coating could significantly improve adhesion and impact resistance compared to the EP coating. [PERSON] et al. [9] used a hot-air curing oven to cure powder coatings and studied the effect of curing temperature and curing time on the gloss of the powder coatings. The results showed that the coating gloss decreased to a great extent as the curing temperature and time increased. [PERSON] et al. [10] used ultraviolet light to cure coatings at different temperatures and found that the gloss of the coatings decreased more at higher temperatures. [PERSON] et al. [11] studied the color change in cured coatings with different near-infrared absorber (NIR-A) addition levels. They found that the coatings' a* and b* values decreased with increasing levels of NIR-A addition. According to the literature review, the mechanical properties and appearance of coatings are influenced by the their components. The curing temperature and time are also very important for the coating curing quality. In addition, most recent studies use hot-air ovens to cure powder coatings with curing times of 10-15 min, which undoubtedly increases the time required for the process and the energy consumption. As the output requires a conveyor device to ensure the continuity of production, longer curing times increase the length of the production line. Selecting the appropriate curing procedure helps to ensure high coating quality while conserving energy. It is currently difficult to achieve high-efficiency and low-energy mass production with conventional convection curing processes. Nevertheless, in recent decades, infrared heating technology and heat radiation systems have been significantly improved. [PERSON] et al. [12] applied an infrared oven system to a continuous coil coating line. Their results indicated that the quality of the products obtained with the infrared oven was better than with a traditional hot-air oven, and the energy consumption was reduced by approximately 30%. [PERSON] et al.