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This application relates to a clean steel and its preparation method. The clean steel composition includes: C: ≤0.0030%; N ≤0.0020%. Such a pure composition meets the requirements of steel used in high-end fields. The method obtains clean steel through electric furnace smelting of all scrap steel or high scrap ratio steel, ladle refining process, continuous casting, heating, and rolling. It effectively controls the nitrogen and oxygen content in the molten steel, ensuring the high purity of the steel. In particular, at the end of the decarburization treatment of the RH vacuum circulation degassing refining process, a certain amount of methane is mixed into the bottom blowing gas. The methane reacts with the oxygen in the molten steel to generate a large number of CO bubbles, which enhances the stirring of the molten steel, promotes the flotation of inclusions, and improves the cleanliness of the molten steel. At the same time, the CO bubble effect improves the denitrification efficiency of the molten steel. Furthermore, since the methane gas consumes some of the oxygen in the molten steel, the oxygen content of the molten steel is reduced at the end of the decarburization treatment, thereby reducing the amount of aluminum alloy used for deoxidation and further improving the cleanliness of the molten steel.

This invention discloses a liquid-phase functional urethane antifouling coating, its preparation method, and its application. The preparation method includes the following steps: S1. Mixing monohydroxy-terminated polydimethylsiloxane and polypropylene glycol and removing water to obtain solution A; S2. Dissolving hexamethylene diisocyanate trimer in xylene to obtain solution B; slowly adding solution B dropwise to solution A while continuously stirring; S3. After the addition is complete, heating the reaction to 80-85°C and continuously stirring to ensure a complete reaction, finally obtaining prepolymer C; S4. Adding curing agent polyaspartic acid ester, leveling agent, and defoamer to solution C, and stirring to obtain solution D; S5. Applying solution D to the surface of a substrate and curing at room temperature for 2 hours to obtain a liquid-phase functional urethane antifouling coating. The antifouling coating of this invention can cure at room temperature, is environmentally friendly, inhibits the adhesion of fouling organisms, and has good anti-icing properties.