ENHANCEMENT OF MARINE CORROSION ANDTRIBOCORROSION RESISTANCE OF OFFSHORE MOORING CHAINSTEEL BY ALUMINIZING PROCESS

Brodogradnja

article

Alkan, Sabri¹ 

[1] Maritime Vocational School of Higher Education, Bandırma Onyedi Eylül University

关键词: Offshore;    mooring chain;    aluminization;    corrosive wear;    seawater;   

DOI  :  10.21278/brod73407

学科分类：工程和技术（综合）

来源: Brodarski Institut

【 摘 要 】

The safety of mooring systems and accessories is one of the most critical issues in thestructural integrity of floating oil/gas and renewable offshore structures. Mooring chains andaccessories operate under dynamic conditions in harsh marine environments. They are subjectto severe wear and corrosion between their links due to relative movement from waves, wind,and ocean currents that disrupt structural integrity. To cope with this problem, the packaluminizing process was applied on the R4 grade offshore mooring chain steel for 2 h at 850°C to improve corrosion and wear-corrosion (tribocorrosion) resistance in 3.5% NaCl. Thetribocorrosion behaviour of untreated and aluminized samples was investigated by a triboelectrochemical setup that simultaneously allows for collecting the wear and corrosion data.Potentiodynamic and potentiostatic corrosion and tribocorrosion tests were carried out tounderstand corrosion kinetics. Optical, SEM, XRD and EDS analyses were performed tocharacterize the aluminide layer and surface morphologies before and after tribocorrosioninvestigations. In polarization scans under corrosion and tribocorrosion conditions, the currentshowed a significant activation stretch of several orders of magnitude, with minor potentialchanges in the anodic region. Due to the galvanic effects of sliding under naturalelectrochemical conditions, the untreated R4 alloy exhibited cathodic properties in the weartrack, while the aluminium coating was out of the wear track due to its oxide-forming ability.At the cathodic potential, two hard Al2O3 materials under pure mechanical effects and thirdbodies emerging from cracks on the coating surface increase the friction coefficient (COF),while the oxide product film, which has a lubricating ability and pits which reduces thecontact area, caused a decrease in COF at the high anodic potential. The study revealed thatwhile the aluminide layer improved the corrosion and tribological character of R4 alloy,material loss from wear track increased due to micro fractures and cracks in the coating layerduring sliding tribocorrosion conditions.

【 授权许可】

CC BY