腐食防止剤

腐食防止剤は、水系流体中の金属部品や設備の電気化学的腐食を抑える添加剤です。 In industrial manufacturing they split by the metal they protect: azole film-formers such as benzotriazole guard copper, brass, and other yellow metals, while anodic inhibitors such as sodium nitrite and sodium molybdate passivate ferrous surfaces. A mixed-metal system u2014 a cast-iron machine wetted with brass fittings u2014 usually needs both a yellow-metal azole and a ferrous inhibitor, because each protects metals the other does not.

Benzotriazole (BTA) is the standard yellow-metal inhibitor. It forms a thin, insoluble complex on copper and brass that blocks the corrosion reaction, and it stays effective at low dose, often a fraction of a percent of the fluid. Specify BTA wherever a metalworking fluid, coolant, or cleaner contacts copper alloys. It does little for bare steel, so it complements rather than replaces a ferrous inhibitor.

For ferrous protection the choice is between sodium nitrite and sodium molybdate, and that is the real trade-off on this page. Sodium nitrite is a strong, low-cost anodic inhibitor, but it is not used in fluids containing secondary amines, because the two can react to form N-nitrosamines; many modern water-soluble metalworking fluids use sodium molybdate or amine-carboxylate chemistry instead. Molybdate works at higher dose and cost but avoids that reaction. Confirm regulatory status for your application and jurisdiction.

• 金属加工油剤・クーラント中の銅系金属（銅・真鍮・青銅）の保護
• 水溶性切削油・研削油における鉄系金属の腐食防止
• 密閉循環系および循環水系の腐食抑制
• 機械加工した鉄系部品の一時防錆および工程間防錆
• 鉄と銅合金が同一の加工液を共有する混合金属系の防食

• Benzotriazole u2014 PubChem
• Sodium molybdate u2014 PubChem
• Sodium nitrite u2014 PubChem