Baja merupakan salah satu logam yang banyak digunakan pada industri karena sifat-sifat mekanis dan sifat-sifat fisiknya. Logam baja St.37 yang digunakan sebagai peralatan industri di lingkungan air sering mengalami korosi sehingga perlu dilakukan pengendalian terhadap lingkungan air tersebut. Salah satu pengendalian korosi di lingkungan air yang digunakan dengan metode inhibitor. Untuk itu dilakukan penelitian pengendalian korosi pada baja St.37 dengan menggunakan inhibitor campuran kromat dan magnesium oksida. Variabel proses yang diteliti adalah konsentrasi inhibitor. Dari hasil penelitian, konsentrasi yang dapat menghambat korosi adalah pada konsentrasi inhibitor magnesium oksida 0,5% dicampur dengan inhibitor kromat 0,2%;0,4%;0,6%;0,8%;0,9% menghasilkan effisiensi sebesar 100% pada 2-15 hari. Hasil fotomikro tampak lapisan oksida MgFeCrO4 yang melindungi logam baja St.37. Kata kunci: corrosion; inhibitor; chromate and magnesium oxide.

Steel is one of metals which are used in industry because of its mechanics characteristics and physics characteristics. Steel St.37 which used as industry equipment in water environment was often gotten corrosion and scale so it’s needed to do corrosion controlling on that water environment. One of corrosion controlling in water environment is using inhibitor. Therefore, the research of corrosion controlling on steel is conducted by using inhibitor of chromate and magnesium oxide. Process variable studied was the concentration of inhibitor. The research result, for the mixed inhibitors the concentration that decreased corrosion rates were magnesium oxide 0,5%, with chromate inhibitor were 0,2%, 0,4%, 0,6%, 0,8% ,0,9% chromate on 2 until 15 days occurs the corrosion controlling with efficiency of 100%. Based on the result of photomicro, there was oxide layer MgFeCrO4 that protected steel St.37. Key Words: corrosion; inhibitor; chromate and magnesium oxide.

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