Qibao Yang,Shaobai Sang,Fuyun Yang,Yawei Li,Tianbin Zhu,Heng Wang
RO-R 2 O-Al 2 O 3 -SiO 2 enamel coatings with varying Al 2 O 3 and MgO contents were prepared for the oxidation protection of 06Ni9DR alloy steels at 1100–1200 °C. The oxidation protection ratios of these coatings were investigated under different oxidation temperatures and time, and the degradation mechanism as well as the improvements in oxidation protection were explored. The results revealed that the oxidation protection ratio of traditional enamel coating with low crystalline phase content significantly decreased with oxidation test temperatures and time. The viscosity of the liquid phase in coating reduced with temperatures, facilitating oxygen diffusion. Additionally, the interaction between the coating and the oxidation products of alloy steel further reduced the liquid phase viscosity, decreasing coating thickness and shortening oxygen diffusion paths. However, the oxidation protection of coating with higher Al 2 O 3 and MgO content were enhanced. These coatings exhibited higher crystalline phases content, which effectively increased the apparent viscosity of enamel coating and prolonged oxygen diffusion paths. The thermal stability of coating with high crystalline phases content also were improved. Among these coatings, the coating with 27.47 wt% Al 2 O 3 and 9.93 wt% MgO achieved superior oxidation protection, up to 92.1 %, 76.6 %, and 73.4 % at 1100 °C, 1150 °C, and 1200 °C for 180 min, respectively.
Qibao Yang,Shaobai Sang,Yawei Li,Tianbin Zhu,Heng Wang
The development of highly oxidation-protective and stable coatings is crucial for significantly reducing the oxidation of 06Ni9DR alloy steels during heating before hot rolling, thereby enabling the products with superior surface quality. In this study, three types of coatings—Al 2 O 3 -glass coating, a 10 wt% NiO-90 wt% Al 2 O 3 ceramic coating, and a double-layer coating Al 2 O 3 -glass top layer and NiO-Al 2 O 3 ceramic bottom layer)—were prepared, and their oxidation protection and underlying mechanisms were systematically investigated. The results revealed that the oxidation protection ratio of the glass coating sharply decreased from 96.6 % for 10 min to 44.9 % for 180 min at 1200 °C. In contrast, the oxidation protection of the ceramic coating increased slightly with the oxidation time. Notably, the excellent oxidation protection ratio of the double-layer coating was obtained as 86.2 % for 180 min. The rapid densification of the Al 2 O 3 -glass layer in the double-layer design provided good oxidation protection and significantly reduced the formation of iron oxides in the initial oxidation stage; NiO-Al 2 O 3 ceramic layer reacted with Fe 2+ to form a relatively dense composite spinel barrier layer, which further improved the thermal stability of the Al 2 O 3 -glass layer, and greatly enhanced the oxidation protection and stability of the double-layer coating.
危险品化学品经营许可证（带存储）