Development of Corrosion Rust Removing Unit for Small Ship Propeller

J. Ocean Eng. Technol. 2005;19(6):72-77.

Kim, Gui-Shik;Han, Se-Woong;Hyun, Chang-Hae;

Faculty of Mechanical and Energy System Eng., Cheju National University;Department of Mechanical Eng., Graduate School, Cheju National University;Mechatronics Majors, Cheju Tourism Collage;

소형선박용 프로펠러의 부식 녹 제거장치 개발

김귀식;한세웅;현창해;

제주대학교 기계에너지시스템공학부;제주대학교 대학원 기계공학과;제주관광대학 메카트로닉스 계열;

Keywords: Propeller, Blasting, Corrosion Rust, Grinding, Polarization Curve, Cavitation

핵심용어: 프로펠러, 블라스팅, 부식 녹, 연마, 분극곡선, 공동현상

Abstract

The materials used in a ship screw propeller are commonly made with brass. The seawater corrosion and seawater cavitation of the screw propeller reduces the propulsive performance of the ship. In screw manufacturing, the corrosion rust of the screw propeller is removed through a hand grinding method. The grinding process produces dust of the heavy metals from the brass. The dust creates a poor working environment that is harmful to the health of the workers. An automatic corrosionrust removing apparatus, using a blasting method, was developed for the improvement of screw polishing conditions and its working environment. The performance of this apparatus was investigated by surface roughness, weight loss rate, hardness, electrochemical corrosion resistance, and cavitation erosion, after removing of the corrosion rust under various blasting conditions. Two medias of alumina and emery were used in this experiment. The surface roughness and hardness of the screw were improved by this apparatus. The electrochemical corrosion potential (Ecorr) and current density (Icorr) were measured by the dynamic polarization method, using a potentiostat,under the conditions of surface polishing with grinding, blasting, wire brushing, and fine sand papering. The test results prove that the new corrosion rust-removing apparatus improves the surface performance of a screw propeller.