Corrosion resistance of surface-conditioned 301 and 304 stainless steels by salt spray test

The corrosion rate of surface-conditioned 301 and 304 stainless steels (SS) was determined by salt spray test in a controlled accelerated corrosive medium (9.5 L of pure distilled water + 500 g NaCl). By surface conditioning via mechanical attrition treatment, a gradient-structured layer was firstly generated on the surface of the samples before the salt spray test. The corrosion rate was determined by the weight loss before and after the salt spray test. Compared to the untreated 301 SS sample with a weight loss of 0.15 g, the surface-conditioned samples treated for 300 s and 1200 s experienced a lower weight loss of 0.04 and 0.02 g, respectively. A similar reduction in weight loss was achieved for 304 SS sample when treated for 5, 10, and 20 mins.

Effect of Magnesium on Corrosion Resistance of Galvalume Coating

In order to improve the performance of Galvalume coating, the expected microstructure and the better property could be obtained by adding 1∼3% Magnesium into Galvalume coating (55%Al-Zn). In this paper, effect of magnesium on the corrosion resistance of 55%Al-Zn coating was studied. The morphology and microstructure of coatings, polarization curve and surface corrosion of two different kinds of samples were analysed by SEM, EDS, electrochemistry workstation and salt spray test. The results show that the numbers of surface spangles by adding 2% magnesium are not changed obviously; the corrosion resistance of 55% Al-Zn-2%Mg coating becomes much better.

Comparative Study on the Corrosion Resistance of Inorganic Zinc-Rich Coating and Thermal-Spray Zinc Coating

The corrosion resistance of two steel coatings (inorganic zinc-rich coating and thermal-spray zinc coating) was studied in detail by using the electrochemical and salt spray test, and the salt spray corrosion thickness was calculated by the time-varying equation established from the mathematical fitting method. The result show that the corrosion mechanism of the two types of coatings was the same that based on the sacrificed of zinc through anodizing phenomenon. The main reason for the difference of corrosion resistance between the two anticorrosive coatings was that the coating density and shielding effect of corrosion products were different. The 7500-hours salt spray test showed that the corrosion rates and microstructure characteristics of both types of zinc coatings were homogeneous on the premise of ensuring coating reliability. The time-varying equation can be used to evaluate the service life of the zinc coatings and judge their corrosion resistance quickly, that providing theoretical support for the maintenance of steel structures as well as the accelerated selection and design of coating formulations.

CORROSION BEHAVIOR STUDY OF STEEL POLE IN DIFFERENT COATING TECHNOLOGY

—Corrosion of steel pole is a serious issue as they used steel pole to support overhead power line in distribution. A lot of money and time are spent for maintenance and repair of existing steel pole. This paper presents investigation on various coating technologies of steel pole for initial corrosion activity. Five types of coating were used on steel samples; epoxy, VEF polyglass, galvanized, epoxy galvanized and polyglass galvanized. The accelerated ageing test, salt spray test and water absorption test were used to determine coating degradation and severity of corrosion process. It was found that, the corrosion rate for epoxy galvanized and VEF polyglass galvanized were higher as the samples were undergoing accelerated ageing test. While VEF polyglass steel showed higher percentage of weight loss during salt spray test. In addition, the results of water absorption behavior showed that epoxy steel gave higher average of absorption rate. The results obtained lead to low degradation of coating as the corrosion rate seem to be uniform