Change in the properties of composite coatings during climatic tests in a salt spray chamber

В статье представлен анализ изменения в ходе климатических испытаний в камере соляного тумана защитных свойств композиционных покрытий, полученных на магниевом сплаве МА8 методом плазменного электролитического оксидирования с последующей обработкой в водной суспензии ультрадисперсного политетрафторэтилена. Изучена динамика изменения электрохимических свойств композиционных полимерсодержащих покрытий. Оценено влияние кратности нанесения композиционного слоя на стойкость покрытий к коррозии. Установлено, что полимерсодержащее покрытие, полученное плазменным электролитическим оксидированием и трехкратной обработкой в суспензии ультрадисперсного политетрафторэтилена, обладает наибольшей стойкостью к коррозионному разрушению в связи с высокой однородностью получаемого композиционного слоя. После 40 сут нахождения в агрессивной коррозионной среде значения поляризационного сопротивления и модуля импеданса для данного вида покрытия выше на один порядок в сравнении с базовым ПЭО-покрытием до начала испытаний. The paper presents analysis of changes in the protective properties of composite coatings obtained on the MA8 magnesium alloy by plasma electrolytic oxidation followed by treatment in an aqueous suspension of superdispersed polytetrafluoroethylene, during salt spray test. The dynamics of changes in the electrochemical properties of composite polymer-containing coatings was studied. The effect of the multiplicity of the application of the composite layer on the corrosion resistance of the coatings was estimated. It was established that the polymer-containing coating obtained by the plasma electrolytic oxidation and threefold treatment in the superdispersed polytetrafluoroethylene suspension has the highest resistance to corrosion due to the greater homogeneity of the obtained composite layer. After 40 days of exposure to an aggressive corrosive environment, the values of polarization resistance and impedance modulus for this type of coating are one order of magnitude higher than those for the base PEO-coating before test.

Download Full-text

Composite Coatings Formed on PEO Pretreated MA8 Magnesium Alloy in Aqueous Suspension of PTFE

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.885.95 ◽

2021 ◽

Vol 885 ◽

pp. 95-102

Author(s):

Evgeny A. Belov ◽

Konstantine V. Nadaraia ◽

Dmitry V. Mashtalyar ◽

Igor M. Imshinetsky ◽

Andrey P. German ◽

...

Keyword(s):

Composite Coatings ◽

Aqueous Suspension ◽

Corrosion Current ◽

Composite Polymer ◽

Corrosion Properties ◽

Composite Layers ◽

Electrolytic Oxidation ◽

Subsequent Application ◽

Plasma Electrolytic ◽

Scratch Tests

The paper presents results of the composite polymer-containing layers formation by plasma electrolytic oxidation (PEO) with subsequent application of the superdispersed polytetrafluoroethylene (SPTFE) aqueous suspension. The corrosion properties and adhesion of coatings have been investigated using potentiodynamic polarization and scratch tests. Incorporation of SPTFE decreased the corrosion current density for composite layers by more than 3 orders of magnitude in comparison with the base PEO-coating and increased the coatings adhesion by 30 %.

Download Full-text

Inhibitor-Containing Composite Coatings on Mg Alloys: Corrosion Mechanism and Self-Healing Protection

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.245.89 ◽

2015 ◽

Vol 245 ◽

pp. 89-96 ◽

Cited By ~ 9

Author(s):

Andrey S. Gnedenkov ◽

Sergey L. Sinebryukhov ◽

Dmitry V. Mashtalyar ◽

Sergey V. Gnedenkov

Keyword(s):

Plasma Electrolytic Oxidation ◽

Composite Coatings ◽

Healing Process ◽

Corrosion Mechanism ◽

Self Healing ◽

Protective Properties ◽

Oxidation Method ◽

Electrolytic Oxidation ◽

Plasma Electrolytic ◽

Electrode Technique

The way of self-healing coating formation at the surface of magnesium alloys by means of plasma electrolytic oxidation method (PEO) with subsequent filling of the obtained layer with inhibitor has been suggested. The electrochemical properties of such coatings have been described in details. The obtained experimental results indicate that the protective properties of the samples with inhibitor-containing coating were increased (IC = 8.6×10–8 A/cm2) in comparison with the samples without coating (5.3×10–5 A/cm2) and the base coating obtained by plasma electrolytic oxidation method (PEO) (3.4×10–7 A/cm2). The local scanning electrochemical methods of surface investigation, notably Scanning Vibrating Electrode Technique (SVET) and Scanning Ion-Selective Electrode Technique (SIET) were used for determining the kinetics and mechanism of the self-healing process. The treatment by the solution containing 8-hydroxyquinoline, which inhibits the corrosion process, enables one to increase the protective properties of the composite coating in 30 times in the corrosion-active environment in comparison with the base PEO-coating and avert the intensive destruction of the material.

Download Full-text

Formation of Protective Coatings on AMg3 Aluminum Alloy Using Fluoropolymer Nanopowder

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.312.330 ◽

2020 ◽

Vol 312 ◽

pp. 330-334

Author(s):

Valeriia S. Filonina ◽

Konstantine V. Nadaraia ◽

Dmitry V. Mashtalyar ◽

Andrey S. Gnedenkov ◽

Igor M. Imshinetsky ◽

...

Keyword(s):

Aluminum Alloy ◽

Isopropyl Alcohol ◽

Protective Coatings ◽

Composite Coatings ◽

Protective Properties ◽

Composite Layers ◽

Electrolytic Oxidation ◽

Order Of Magnitude ◽

Plasma Electrolytic ◽

Subsequent Modification

The paper presents the results of a study of the protective properties of composite coatings obtained on AMg3 aluminum alloy by plasma electrolytic oxidation (PEO) and subsequent modification of formed oxide layer with superdispersed polytetrafluoroethylene (SPTFE) from a suspension based on isopropyl alcohol. The incorporation of fluoropolymer decreased the porosity of base PEO-coating more than one order of magnitude. Formed composite layers increased wearproof of the samples by more than two orders of magnitude in comparison with PEO-coating. Additionally, polymer-containing coatings has higher adhesion compared to substrate. Formed composite layers possess superhydrophobic properties: contact angle attains 155°.

Download Full-text

Characterization of Composite Coatings Produced by Plasma Electrolytic Oxidation Plus Cathodic Electrophoretic Deposition on Magnesium Alloy

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.146-147.1126 ◽

2010 ◽

Vol 146-147 ◽

pp. 1126-1131

Author(s):

Yong Feng Jiang ◽

Hua Shan Yang ◽

Ye Feng Bao ◽

Ying Yue Zhang

Keyword(s):

Magnesium Alloy ◽

Electrophoretic Deposition ◽

Plasma Electrolytic Oxidation ◽

Composite Coatings ◽

Salt Spray ◽

Immersion Test ◽

Organic Layer ◽

Electrolytic Oxidation ◽

Plasma Electrolytic

The composite coatings were prepared on AZ91D magnesium alloy by plasma electrolytic oxidation (PEO) plus cathodic electrophoretic deposition (E-coat) to improve corrosion protection. SEM observation revealed that the organic layer was integrated with PEO film by physically interlocking; Potentiodynamic polarization(E-i) measurements in 3.5% NaCl solution, copper accelerated acetate salt spray(CASS) test and immersion test were employed to evaluate corrosion principle and corrosion rate of composite coatings. It is indicated that the corrosion resistance of composite coatings was improved obviously compared to the PEO film. There is no noticeable pitting corrosion on the composite coatings after 320h CASS test. The adhesion of composite coatings was evaluated by cross-cut and pull-off test. The results show that adhesion of composite coatings can reach to level 0 and 11.3 N/mm2 as a result of the blocking effect between organic layer and PEO film.

Download Full-text