A Low Cost Tannic Acid Rust Converter Formulation
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A Low-Cost and High-Performance Rust Converter Suitable for Ocean Vessel Hull Treatment Xiqiu Fan, Xiaodong Zhao College of Electromechanical engineering, Zhejiang Ocean University. Zhoushn, Zhejiang Province, P.R. China ABSTRACT When ships are repaired, rust on hulls need to be removed. However, traditional rust removing methods such as grinding by hand, shoveling and sand blast and so on are very time-consuming. This paper presents a rust converter suitable for ocean vessel hull treatment, whose formulation is based on polyphosphoric acid and tannic acid. In order to improve the performance of the product, active agent, catalytic agent, corrosion inhibitor, penetrating agent and wetting agent, etc., are added. Some results of accelerating experiment such as the A. C. impedance experiment are also presented, which demonstrate the high performance of the product. All ingredients in the product are cheap, easily accessible, and environment-friendly. KEY WORDS: Rust converter; polyphosphoric acid; tannic acid; vessel hull. INTRODUCTION The 21st century is a century focusing on ocean. China is witnessing the fast growth of her ocean economy and ocean industries after the strategy of ocean development. In order to exploit ocean, shipping industry development should be given priority. However, Ocean vessels are very prone to corrosion due to the heavy-duty corrosive marine environment. When ships are repaired, the rusty hull surface should be repainted. Before repainting, rust on hulls need to be removed first. However, traditional rust removing methods such as grinding by hand, shoveling and sand blast and so on are very time-consuming. In addition, some hull area such as corner and notch, rust removing is very inconvenient. Rust converter is a liquid metal treatment agent that is sprayed on rusty surfaces and converts rust into adherent chemical compounds, thus it not only removes the rust, but also can prevent further corrosion and protect the surface eventually. Moreover, it reduces labor strength and pollution to a great extent. This paper presents a rust converter suitable for ocean vessel hull treatment, whose formulation is based on polyphosphoric acid and tannic acid. INGREDIENTS The product is made up of two portions, i.e. pretreatment agent and post-treatment agent. The ingredients of the pretreatment agent are as follow: Ferrous powder 10-20% Urotropine 20-10% Glycerol 10-20% Water 60-50% The ingredients of the post-treatment agent are as follow: Polyphosphoric acid 40-50% Water 40% Manganese monoxide (MnO) 2-1% Ethylic acid 10-6% Tannic acid 8-3% All ingredients in the product are cheap, easily accessible, and environment-friendly. When the rust on hulls need to be removed, first, brush or spray the pretreatment agent on the rusty vessel hull area. After 30-60 minutes or so, the post-treatment agent is brushed or sprayed. Corrosion conversion time needs 5-12 hours, depending on environment temperature and relative humidity, etc. In the case of mass production, the pretreatment agent and the post-treatment agent can be integrated into a formula to facilitate mass production. MECHANISMS The Role of Polyphosphoric Acid Phosphoric acid is the most important ingredient of rust converter products because it can react with main ingredients of rust such as Fe 2 O 3 ¡H 2 O, FeOOH, FeO¡ H 2 O (Fe (OH) 2 ) and Fe 3 O 4 ¡ xH 2 O. Fe 2 O 3 ¡H 2 O + 6H 3 PO 4 = 2Fe (H 2 PO 4 ) 3 + 4H 2 O (1) FeOOH+ 3H 3 PO 4 = Fe (H 2 PO 4 ) 3 + 2H 2 O (2) 2FeO ¡H 2 O/Fe (OH) 2 + 4H 3 PO 4 = 2Fe (H 2 PO 4 ) 2 + 3H 2 O (3) Fe 3 O 4 ¡ xH 2 O+8H 3 PO 4 = Fe 3 (H 2 PO 4 ) 8 + (4+x)H 2 O (4) At the very beginning, phosphoric acid is excessive, so dihydric phosphate, the reactive product dissolves in phosphoric acid, and can not form an intact cover film on metal surfaces. With the depletion of phosphoric acid, the dihydric phosphate begins to turn into indissoluble phosphate. Fe (H 2 PO 4 ) 3 → Fe 2 (HPO 4 ) 3 → FePO 4 (5) Fe (H 2 PO 4 ) 2 → FeHPO 4 → Fe 3 (PO 4 ) 2 (6) Proceedings of the Twentieth (2010) International Offshore and Polar Engineering Conference Beijing, China, June 2025, 2010 Copyright © 2010 by The International Society of Offshore and Polar Engineers (ISOPE) ISBN 978-1-880653-77-7 (Set); ISSN 1098-6189 (Set); www.isope.org 38
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A low cost tannic acid rust converter formulation
Transcript of A Low Cost Tannic Acid Rust Converter Formulation
A Low-Cost and High-Performance Rust Converter Suitable for Ocean Vessel Hull Treatment
Xiqiu Fan, Xiaodong Zhao College of Electromechanical engineering, Zhejiang Ocean University.
Zhoushn, Zhejiang Province, P.R. China
ABSTRACT When ships are repaired, rust on hulls need to be removed. However, traditional rust removing methods such as grinding by hand, shoveling and sand blast and so on are very time-consuming. This paper presents a rust converter suitable for ocean vessel hull treatment, whose formulation is based on polyphosphoric acid and tannic acid. In order to improve the performance of the product, active agent, catalytic agent, corrosion inhibitor, penetrating agent and wetting agent, etc., are added. Some results of accelerating experiment such as the A. C. impedance experiment are also presented, which demonstrate the high performance of the product. All ingredients in the product are cheap, easily accessible, and environment-friendly. KEY WORDS: Rust converter; polyphosphoric acid; tannic acid; vessel hull. INTRODUCTION The 21st century is a century focusing on ocean. China is witnessing the fast growth of her ocean economy and ocean industries after the strategy of ocean development. In order to exploit ocean, shipping industry development should be given priority. However, Ocean vessels are very prone to corrosion due to the heavy-duty corrosive marine environment. When ships are repaired, the rusty hull surface should be repainted. Before repainting, rust on hulls need to be removed first. However, traditional rust removing methods such as grinding by hand, shoveling and sand blast and so on are very time-consuming. In addition, some hull area such as corner and notch, rust removing is very inconvenient. Rust converter is a liquid metal treatment agent that is sprayed on rusty surfaces and converts rust into adherent chemical compounds, thus it not only removes the rust, but also can prevent further corrosion and protect the surface eventually. Moreover, it reduces labor strength and pollution to a great extent. This paper presents a rust converter suitable for ocean vessel hull treatment, whose formulation is based on polyphosphoric acid and tannic acid. INGREDIENTS The product is made up of two portions, i.e. pretreatment agent and post-treatment agent. The ingredients of the pretreatment agent are as follow:
Ferrous powder 10-20%
Urotropine 20-10% Glycerol 10-20% Water 60-50% The ingredients of the post-treatment agent are as follow: Polyphosphoric acid 40-50% Water 40% Manganese monoxide (MnO) 2-1% Ethylic acid 10-6% Tannic acid 8-3% All ingredients in the product are cheap, easily accessible, and environment-friendly. When the rust on hulls need to be removed, first, brush or spray the pretreatment agent on the rusty vessel hull area. After 30-60 minutes or so, the post-treatment agent is brushed or sprayed. Corrosion conversion time needs 5-12 hours, depending on environment temperature and relative humidity, etc. In the case of mass production, the pretreatment agent and the post-treatment agent can be integrated into a formula to facilitate mass production. MECHANISMS The Role of Polyphosphoric Acid Phosphoric acid is the most important ingredient of rust converter products because it can react with main ingredients of rust such as Fe2O3¡H2O, FeOOH, FeO¡ H2O (Fe (OH) 2) and Fe3O4¡xH2O.
Fe2O3¡H2O + 6H3PO4 = 2Fe (H2PO4)3 + 4H2O (1) FeOOH+ 3H3PO4 = Fe (H2PO4)3 + 2H2O (2) 2FeO ¡H2O/Fe (OH) 2+ 4H3PO4 = 2Fe (H2PO4)2 + 3H2O (3)
Fe3O4¡xH2O+8H3PO4 = Fe3 (H2PO4)8 + (4+x)H2O (4) At the very beginning, phosphoric acid is excessive, so dihydric phosphate, the reactive product dissolves in phosphoric acid, and can not form an intact cover film on metal surfaces. With the depletion of phosphoric acid, the dihydric phosphate begins to turn into indissoluble phosphate.
Fe (H2PO4)3 → Fe2 (HPO4)3 → FePO4 (5) Fe (H2PO4)2 → FeHPO4 → Fe3 (PO4)2 (6)
Proceedings of the Twentieth (2010) International Offshore and Polar Engineering Conference Beijing, China, June 2025, 2010 Copyright © 2010 by The International Society of Offshore and Polar Engineers (ISOPE) ISBN 978-1-880653-77-7 (Set); ISSN 1098-6189 (Set); www.isope.org
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