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| EFFECT OF A SMALL CONTENT OF NITRIC ACID ON CORROSION MECHANISM OF 316L & HASTELLOY C ALLOY IN CIRCULAR DISPOSAL ACID |
| GUO Jinbiao, CHEN Zhen, WANG Lu, ZHANG Ting |
| The Academy of Lanzhou Petrochemical Company Gansu, Lanzhou 730060 |
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Abstract Due to its excellent corrosion resistance to various media, Hastelloy C alloy has been widely used in chemical and other industries. Circular disposal acid is a kind of strongly corrosion solution which containing 72 mass% H2SO4 & 0.5 mass% HNO3, so Hastelloy C alloy was selected as the material of the circular disposal acid pump in aniline unit. However, the pump made of Hastelloy C alloy was corroded seriously in circular disposal acid. The correlative experiments showed that a small content of nitric acid in the circular has great effect on the corrosion rate of Hastelloy C alloy & 316L. So the effect of a small content of nitric acid on corrosion mechanism of 316L & Hastelloy C alloy in circular disposal acid was studied by using electrochemical method, SEM & EDS techniques. The results showed that a small content of nitric acid can cause the circular disposal acid to have strong oxidizing property, and decreased the corrosion rate of 316L stainless steel in circular disposal acid remarkably by forming compact passive film on the surface of 316L stainless steel, and increased the corrosion rate of Hastelloy C alloy by dissolving the passive film on the surface of Hastelloy C partially.
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Received: 02 March 2010
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