| Summary: | 碩士 === 國立臺灣科技大學 === 機械工程系 === 99 === This study worked at creating a regression model for predicting the zinc corrosion rate by use the data from the study of corrosive factors of atmosphere in Taiwan which planed by Harbor & Marine Technology Center, I. O. T., M. O. T. C. The model will show the influences of chloride deposition、sulfure dioxide deposition and the time of wetness on zinc corrosion rate. Furthermore, in order to establish a meaningful model, we completed the significant tests and the basic assumptions of regression analysis based on the statistical principles. The result shows that chloride is the most significant factor to impact zinc corrosion rate among chloride deposition, sulfur dioxide deposition and the time of wetness in Taiwan. Moreover, the zinc corrosion rate should be stay in steady state or it will overestimate the influence of independent variables. By testing a number of models, a simple regression model, Rcorr = 4.108 + 0.541 × Cl, has been proposed in order to predict corrosion rate values of zinc exposed at very high corrosive atmospheres.
In addition, in order to find the relationship between the salt spray test and atmospheric corrosion, this study used three forms of zinc specimens for salt spray test to determine the experiment period which will achieve the C1 ~ C5 corrosion rating defined in the ISO standard. The experimental results are presented as rulers. The salt spray test shows that the specimen shape and placement are the important factors on corrosion rate. The one-sided exposure specimen has a protective wax coating and is placed with the vertical angle of 15 degree. Therefore, the one-sided exposure specimen should be more suitable in the experimental under ASTM B117 conditions.
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