Straight seam steel pipe joints get rid of corrosion passivation of iron and aluminum in dilute HNO3 or dilute H2SO4 solution can be quickly dissolved, but in concentrated HNO3 or dissolved in concentrated H2SO4 appearance almost completely halted, ordinary carbon steel pipe rust very briefly, if the steel participate in excess Ni, Cr, stainless steel has become a. Metal or alloy by a number of factors influence significantly enhanced chemical stability, appearance, known as passivation. By some of the passivation agent (chemicals) are caused by the appearance of metal passivation called chemical passivation. Such as concentrated HNO3, concentrated H2SO4, HClO3, K2Cr2O7, KMnO4 and other oxidants can make metal passivation. A reactive metal or alloy, during chemical activity greatly decreased, and the appearance of a precious metal condition, called passivation. Because the effects of the media generated metal corrosion products if a fine layout constitute a film, tight appearance of the metal cover, changing the apparent condition of the metal, the metal to the positive electrode potential Fangxiang Yue greatly changed, and a corrosion resistant passive.
Straight seam steel pipe get rid of corrosion of metal passivation, its electrode potential move in the positive direction, so that it lost its original features, such as passivation of iron in copper can not displace copper. In addition, the electrochemical approach also allows metal passivation, as will be placed in H2SO4 solution Fe as the anode, the anode with impressed current polarization, the choice of instruments will certainly increase the potential extent of iron, Fe on the passivation.
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