Investigation of anti-corrosion properties of composites based on epoxy resin and zinc nanoparticles

ABSTRACT

The article presents the results of a study of the anti-corrosion properties of composite materials based on epoxy resin modified with a mixture of AGM-9 and TGM-3 in a ratio of 1:3 and treated with zinc oxide nanoparticles.  It is established that the coating of metals with epoxy oligomers and zinc nanoparticles significantly increases their resistance to corrosion.   After holding in a 3.5% NaCl solution for 90 days, the hardness of metals without coating decreases by 22%, modified with AGM-9 and TGM-3 composites - by 11%, and modified with epoxy oligomers in combination with zinc nanoparticles-by only 3 %.

АННОТАЦИЯ

В статье представлены результаты исследования антикоррозийных свойств композиционных материалов на основе эпоксидной смолы  модифицированной смесью АГМ-9 и ТГМ-3 в соотношении 1:3 и обработанного наночастицами оксида цинка. Установлено, что покрытие металлов эпоксидными олигомерами и наночастицами цинка значительно повышает их устойчивость к коррозии. После выдержки в 3,5 % растворе NaCl в течение 90 дней твердость металлов  уменьшается без покрытия на 22 %, модифицированных композитами АГМ-9 и ТГМ-3 - на 11 %, а  модифицированных эпоксидными олигомерами в сочетании с наночастицами цинка всего на 3 %.  

Keywords: anti-corrosion coating, modifiers, epoxy resin, zinc oxide nanoparticles, composites, hardener.

Ключевые слова:  антикоррозийное покрытие, модификаторы, эпоксидная смола, наночастицы оксида цинка, композиты, отвердитель.

Introduction

Increasing requirements for the quality and pace of equipment repair work require the creation of a wide range of highly efficient systems capable of restoring metal surfaces and various structures damaged by wear, abrasives, shocks and corrosion. In this regard, the production of composite materials based on epoxy oligomers with high adhesion to many materials is relevant and in demand in practice in various fields [6, p.56].

A very important task is the development and implementation of highly effective composite materials based on polymer binders that work reliably in extreme conditions, the solution of which largely determines the acceleration of the pace of scientific and technological progress [1, p.53].

Currently, there is a huge demand for Functional Materials for various industries. The problem of creating materials for carrying out repairs, especially for large-sized equipment and when it is impossible to stop the technological process, is relevant. At the same time, spare parts of a unique equipment mechanism are often missing or their replacement is economically unprofitable [2, p.43].

The purpose of this work is to develop composite materials based on modified epoxy oligomers with improved operational properties.

Methods and objects of research

As a binder, epoxy oligomers of the ED-20 brand were used, since this resin has a low viscosity, is characterized by stability of dielectric and physico-chemical properties. Under normal conditions, it is a viscous, transparent liquid. Molecular weight-390 g / mol, density -20°C-1.14 g / cm³ [2, p.24].

Polyethylenpoliamine(PEI) acted as a hardener. The obvious advantage of this substance is the high strength and reliability of the binding with epoxy resin. Polyethylenepoliamine is a liquid substance with an ammonia smell and a light yellow or brownish-brown color, depending on the degree of oxidation and storage method. Molecular weight-230 g/mol, density 20°C-1,017 g/cm³ [1, p.21].

Used as modifications:

- 3-aminopropyltriethoxysilane AGM-9 (TU 6-02-724-77)

- Triethylene glycol dimethacryl ether-TGM-3 (TU 2257-004-43007840-200)

-Zinc oxide nanoparticles produced by Bochemie, czeck (nZ-BOCH 01)

Zinc oxide nanoparticle is one of the inorganic nanoparticles. It has high hardness and low refractive index, hydrophobicity and excellent dispersion without aggregates [7, p.147].

For the study of the Anticorrosive coating of metal, 13 samples from steel pipes of Grade 3-FHA were used.

Ultrasonic dispersant UZDN-M1200 was used to disperse zinc oxide nanoparticles. UZDN-M1200 is a universal multifunctional device: uniform emulsification, used as a separator, as a mixer [6, p.33].

The introduction of zinc oxide nanoparticles was carried out by intercalation[8, p.149].

The resistance of the coating to the effects of aggressive environments was determined in accordance with GOST 9.403-80. After tests on salt solutions (3.5% NaCl), the decorative and protective properties of coatings are determined [3,p.1].

To determine the depth of corrosion, the hardness is determined by the Vickers method GOST 2999-75. the hardness test by the Vickers method was performed on the FV-810 device [4,p.1].

Methods for obtaining the coating for testing were obtained according to ISO 1514-84 [5,p.2].

Experimental part

To study the modification and effectiveness of nano coating, 3 samples were studied: sample №1 without coating, sample № 2 with TGM-3 and AGM-9 modifiers, and sample №3 with zinc oxide nanoparticles.

 Sample №1 was used as the original sample and was not covered with a coating.

For Sample №2, the following сomposite was developed: first, a complex modifier was added to the ED-20 resin at a temperature of 25°C in the ratio of

TGM-3:AGM-9= 3: 1. Then the modifiers were mixed until they were completely mixed, a hardener-polyethylenpolamine was added in the presence of 1:10 PEI/ED-20[5]. Thoroughly mixed for 15 minutes, until the hardener is completely dissolved, the composite is taken with a spatula and applied with a brush to the prepared surface, that is, to the surface of the sample №2. Then this material is left to completely freeze for 24 hours.

The introduction of ZnO nanoparticles into sample №3 was carried out by intercalation: ZnO powder nanoparticles solution (30 mas.% ethyl alcohol + 70 mas.% xylene) dissolved in a mixture in a mass ratio of 8:2. This is due to the fact that in ethyl alcohol and xylene solute, nanoscale particles of zinc oxide swell [8, p.147]. Then this solution was mixed for 30 minutes in a magnetic stirrer with a rotation speed of 800 rpm, and then treated with an ultrasonic device UZDN-M1200 for 15 minutes. The dissolved nanoparticles were added to the ED-20 by mass ratio and mixed for 20 minutes at a volume of 1000 rpm, and then treated this composite with ultrasound for 15 minutes before adding a hardener (table.1). Later, a hardener was added to the composite in the mass ratio. The finished composite is inserted into the sample №3 with a spatula and left for 24 hours for complete solidification.

To study the effect of nanoparticles on the anticorrosive properties of epoxy coatings, these coatings were stored in a 3.5% NaCl solution for 90 days [3,p.2].

An epoxy oligomer modified with zinc oxide (sample № 3) was not found after the end of testing of corrosion products visible on the surface of the coated steel pipe.

Table 1.

Mass ratio of components in the composition

An epoxy oligomer modified with zinc oxide (sample №3) was not found after the end of testing of corrosion products visible on the surface of the coated steel pipe. The "1" coating, which does not contain nanoparticles and other impurities of myrzh oxide, showed poor corrosion resistance compared to other coatings selected for research (2,3). In general, the corrosion resistance of coatings varies in the following order: 3> 2> 1

To determine the hardness by the Vickers method, use the hardness of the original 3 samples on the FV-810 , on the device F-294.2 H /30 KGF was calculated in 10 seconds. The results obtained are shown in table 2.

 Hardness after holding the coatings for 3.5 days in NaCl 90% solution on the device FV-810 by  F-294.2 N/30 KGF was calculated in 10 seconds.The results obtained are shown in Table 2.

Table 2.

Results of testing the hardness of Metal Coatings by the Vickers method

Figure 1. Results of Vickers ' study of the hardness of Metal Coatings

According to the results of testing the hardness of metal coatings from figure 1, it can be seen that the hardness of sample №1, which is not coated with the coating, decreased by 22 %, sample №2 with the addition of AGM-9: TGM-3 modifiers by 11 %, sample №3, modified with zinc oxide nanoparticles by 3%.

It is proved that the increase in the anti-corrosion properties of the metal surface treated with zinc oxide nanoparticles is associated with an increase in the adhesion strength and an increase in the hydrophobicity of the epoxy resin, which corresponds to literary data [8,p.151].

Сonclusion

As a result of the study, the hardness of epoxy oligomers coated with zinc oxide nanoparticles decreased by 3%, modified with AGM-9 and TMM-3 composites decreased by 11 %, and the hardness of non-coated metals decreased by 22 %.

As a result of the conducted studies, metal coating modified with zinc oxide nanoparticles showed increased resistance to aggressive environments, anti-corrosion properties compared to joint AGM-9:TGM-3 modifiers. The epoxy oligomer, obtained on the basis of zinc oxide nanoparticles, allows you to use it as a coating to protect metal products operating in aggressive environments.

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