Papers by Keyword: Dezincification

Abstract: Dezincification is one of the specific types of corrosion attack on brass, very often on brass fittings in particular and is caused by the selective removal of zinc from brass, resulting in the formation of areas of spongy and brittle copper, and eventually leading to the total destruction of the component. The dezincification process is greatly facilitated by the presence of chlorine in the water and is also aided by poor aeration, low fluid circulation rates, higher temperatures and permeable deposits or coatings on the surface. This paper describes the analyses of two cases of dezincification of brass fittings, one appearing in hot water distribution pipeline and another in the nozzle of a lion's head shaped urban fountain. Although each of these components operated under different operating conditions, both were confirmed to have been damaged from this specific form of corrosion attack, often permeating the entire wall thickness.

Abstract: Against the problem of roller surface nodular of Baotou sheet steel factory galvanized vertical reduction annealing furnace, products defects of dezincification, leak plating, scratches before galvanized and so on, and from these aspects of analysis including the vertical annealing furnace’s working principle and structural characteristics, it was found that these main reasons causing this fault was that entry seal roller did not turn for high temperature deformation and condensed water of roller surface pollute strip steel, by improving the design and transformation of entry seal structure, the defects which caused by these reasons is solved, greatly improved the quality of the products, and there for provide the safeguard for the continuous and stable operation galvanized units.

Abstract: This paper summarizes the fundamental regularities and characteristics of vacuum distillation of aluminum alloy. It includes the vapor pressure values of aluminum alloy, the possibility and extent of distilling separation of the alloy, the proper temperature and time of distillation. With the temperature higher than 750°C，the distillation time longer than 30min，the content of zinc in the residue can be less than 0.3%．In this paper, the use of vacuum distillation resolved the difficulties of removing zinc from aluminum alloy, which is friendly to the environment and will not cause secondary pollution.. The theoretical analyses are in correspondence with the experimental data closely.

Abstract: Base on reduction experimental data, considering the reduction process factors like carbon content, reductive removal of ZnO, changing size of pellet, and partial pressure of reducing gas, also coupled heat transfer, mass transfer and chemical reactions, a direct reduction mathematical model on carbon-bearing pellet containing zinc has been established. The reliability of the model was testified by programming and experiments. Experiments showed that, under the reduction conditions that carbon and oxygen mole ratio at 1.0 and reduction temperature 1603K, metallization rate 87% and dezincification rate 99% were observed after 15 minutes of heating.