tailieunhanh - Determination of atmospheric corrosion rate of metals in 12 Vietnamese areas

The results show that for all types of studied metals, their corrosion rates which are determined from climatic data are higher than the corrosion rates in reality, especially for carbon steel and aluminum. This difference is more visible in the rural areas. | Vietnam Journal of Science and Technology 55 (5B) (2017) 272-278 DETERMINATION OF ATMOSPHERIC CORROSION RATE OF METALS IN 12 VIETNAMESE AREAS Pham Duy Nam, Nguyen Hong Du, Ha Huu Son*, Nguyen Hong Phong, Nguyen Van Vinh Institute of Tropical Durability/ Vietnam-Russia Tropical Centre, 63 Nguyen Van Huyen, Cau Giay, Ha Noi, Viet Nam * Email: hahuuson@ Received: 30 August 2017; Accepted for publication: 9 October 2017 ABSTRACT The corrosion of materials is a result of complex impact from many climatic factors such as temperature, humidity, air pollutant content in the air, rainfall etc. In addition, the corrosion rate of metals can be measured. Each climatic zone is characterized by its corrosion rate. This article presents the testing results to determine the corrosion rate of carbon steel, copper, aluminum and zinc in 12 districts characterizing different climate zones of Vietnam. Testing, evaluation, and classification of atmospheric corrosion were conducted in accordance with the standard ISO 9223. The results show that for all types of studied metals, their corrosion rates which are determined from climatic data are higher than the corrosion rates in reality, especially for carbon steel and aluminum. This difference is more visible in the rural areas. Keywords: atmospheric corrosion; corrosivity categories; carbon steel; metals and alloys. 1. INTRODUCTION Atmospheric corrosion is a complex process. This process is a part of the natural cycle in which metals tend to be moved to the most stable state (oxide or mineral) through chemical and electrochemical processes. In addition, atmospheric corrosions of different metals under different climatic conditions are not the same. In other words, the corrosion rates of different metals in certain climatic zones vary in different ways. The atmospheric corrosion rate depends on many factors such as temperature, relative humidity, rainfall, rainwater pH, concentration of major pollutants and contact time etc. .