To prioritize superior surface modifications for severely corroded weathering steel (WS) in highly corrosive marine atmospheres, this study assessed the effects of five efficient preparation processes: power tool (PT), abrasive blasting with steel grit (AB(S)) and garnet (AB(G)), continuous-wave laser (CWL), and abrasive water-jet treatment with garnet (AWT(G)). Beyond careful analysis of environmental corrosivity, evaluation methods such as cleanliness level, re-corrosion resistance, and texturing were employed to optimize surface characteristics. These factors were quantified to ascertain their correlation with adhesion properties. The findings revealed that cleanliness-related factors became a priority when the coating target shifted from new to severely corroded steel substrates. A strong correlation was observed among re-corrosion resistance, visualized via the rust-back area, macro fractured area, and pull-off strength. The adhesion performance was compromised by both aggressive external conditions (“foreign attack”) and internal factors (“domestic unrest”) such as residual rust clusters or spots, embedded abrasive materials, soluble chloride salts, and undesirable oxide layers. Both factors challenged the adhesive properties, such as zinc-rich paint, being attacked from both the front and back. Nevertheless, the AWT(G) method demonstrated significant potential for optimizing surface characteristics, followed by the CWL method; however, the byproduct of the laser oxide scale posed challenges to adhesion.

DOI： 10.1016/j.apsusc.2025.163613

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Surfaces and Interfaces  

This study investigated the corrosion resistance and durability of Al-5Mg coatings deposited by transferred arc plasma spraying (TAPS) and flame spraying (FS) methods. The corrosion performance was evaluated through a 6000-hour accelerated corrosion test, complemented by electrochemical impedance spectroscopy and polarization measurements. The TAPS coating exhibited significantly lower initial porosity of 3.78%, reducing further to 1.09% after 1000 corrosion cycles, compared to the FS coating with an initial porosity of 9.93%, decreasing to 5.46%. Electrochemical tests revealed a lower corrosion current density in the TAPS coating (1.90 μA/cm²) than in the FS coating (2.54 μA/cm²) after 1000 cycles, indicating a superior corrosion resistance of the TAPS coating. Additionally, adhesion strength measurements indicated that the TAPS coating exhibited approximately 20% higher adhesion strength compared to the FS coating, further enhancing its durability and mechanical reliability. The enhanced performance of TAPS is attributed primarily to its dense and uniform pore structure and the resultant formation of a compact, protective oxide passive layer, effectively inhibiting electrolyte penetration. Overlay tests further confirmed that TAPS coatings exhibited significantly reduced blistering under linear defect conditions. These findings suggest that the TAPS process is a highly effective method for enhancing the corrosion protection of Al-5Mg coatings on complex steel structures.

DOI： 10.1016/j.surfin.2025.106377

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Scopus

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Progress in Organic Coatings  

The effects of abrasive water-jet treatment (AWT) on the deformation of carbon steel surfaces and the adhesion of epoxy adhesives were analyzed. Different abrasive sizes and standoff distances were considered to evaluate the changes in surface properties of carbon steel produced during the AWT process in terms of surface roughness, surface topography, and residual abrasive distribution. Compared to conventional abrasive blasting, the AWT processing provided higher surface roughness and surface deformation ratio (DR), and significantly lower residual abrasives amount. Notably, the study found a tendency for adhesion to decrease with increasing surface roughness. This is in contrast to the conventional literature, which suggests that adhesion to paints and adhesives improves with increasing surface roughness up to a certain threshold level. On the other hand, DR showed a strong positive correlation with adhesion, but above a certain value, adhesion tended to be lower than that of the blast treatment. The findings indicate that it is preferable to consider both conventional surface roughness and DR concurrently when assessing adhesion. This study will contribute to a deeper understanding of the influence of surface properties during AWT on the adhesion performance of epoxy adhesives and suggest optimal surface treatment conditions for practical engineering applications.

DOI： 10.1016/j.porgcoat.2025.109137

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Scopus

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Progress in Organic Coatings  

Thermal spray coatings, such as Zn, Zn-15Al, Al, and Al-5Mg, combined with heavy-duty paint, are increasingly used to enhance the corrosion resistance of steel structures. However, the overlaid areas of these coatings, particularly in damaged regions, can become weak points for corrosion initiation. To investigate the deterioration mechanisms at the overlaid zones of heavy-duty paint and thermal spray coatings on carbon steel plates, this study designed atmospheric exposure experiments and employed 3D scanning, electrochemical testing, and scanning electron microscope (SEM) - energy-dispersive X-ray spectrometer (EDX) analysis to systematically assess the degradation of the overlaid coatings in marine atmospheric environments. The results indicate that electrochemical reactions at coating defects drive the blistering and delamination of the overlaid coatings. Zn-based coatings, which provide sacrificial protection, exhibit slower failure progression compared to Al-based coatings, which show blistering due to passivation film formation. These findings provide valuable insights for optimizing thermal spray selection and overlaid coating strategies in marine atmospheric environments.

DOI： 10.1016/j.porgcoat.2025.109057

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Scopus

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Corrosion Science  

The surface texture of 144 weathering steel samples were analyzed under marine atmospheres to assess the effects of the exposure conditions and structural factors. Comprehensive methods were used to characterize the corrosion evolution and pitting performance. Geospatial variability was introduced as a new method for quantifying non-uniform and irregular surface substrates. The results showed significant variations in corrosion severity under identical environmental conditions. Closely spaced pits formed clustered patterns with an increased range, whereas isolated sparse pits demonstrated the converse. Sill effectively captured serrated surface variations. Explainable machine learning models were developed to regenerate and predict the steel surface texture.

DOI： 10.1016/j.corsci.2024.112602

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Scopus

開催年月日： 2025年6月

開催年月日： 2025年3月

開催年月日： 2025年3月

開催年月日： 2024年9月

開催年月日： 2024年9月

発表場所：九州大学中央分析センター報告（４２）  

種別：大会・シンポジウム等 

令和７年度土木学会全国大会の座長

日本・韓国・中国の研究者が一堂に会し，鋼構造物の維持管理に関する意見交換・技術交流を通じて，国際共同研究の推進および若手人材の国際育成を目的とした研究セミナーを開催

日本・韓国・中国の研究者が一堂に会し，鋼構造物の維持管理に関する意見交換・技術交流を通じて，国際共同研究の推進および若手人材の国際育成を目的とした研究セミナーを開催