Zirconium oxide and tannic acid-based nanoceramic coatings for corrosion protection of cold-rolled steel

ABSTRACT

Current research has focused on investigating substances that are less toxic and harmful to human health and the environment. In the context of natural compounds for corrosion protection, this study examined the incorporation of tannic acid into a nanoceramic conversion treatment for cold-rolled steel. The research was structured around three different treatment methodologies, in which nanoceramic conversion and tannic acid application were performed by immersion in aqueous solutions. The addition of tannic acid was evaluated before, during, and after the nanoceramic conversion process. These treatments were then compared with a standard nanoceramic treatment and a control sample prepared using only the surface cleaning method. The results indicated a notable increase in corrosion protection, especially when tannic acid was introduced before the nanoceramic conversion stage, resulting in a protection efficiency of 79.3% compared to the control sample and 37.5% compared to the standard nanoceramic treatment. Contact angle measurements and Raman spectroscopy suggested surface modifications, with the simultaneous formation of iron and zirconium oxides, as well as the complexation of ferric tannate. Consequently, the proposed treatments offer a promising alternative to traditional methods used in industry; however, more detailed studies are needed to validate these findings in real-world applications.

Keywords: Cold-rolled steel; corrosion; hexafluorozirconic acid; nanoceramic conversion; tannic acid

1. INTRODUCTION

Carbon steel alloys are the most widely used group of metallic materials in the industrial and construction sectors. However, these alloys are also particularly vulnerable to corrosion, defined as spontaneous deterioration arising from electrochemical or chemical interactions between the metal and its environment. This issue not only compromises aesthetic appeal but also significantly impacts performance and safety under service conditions, leading to considerable costs in production and maintenance processes. To address this challenge, various mitigation strategies have been explored, including the use of corrosion inhibitors and a range of surface treatments/coatings [¹,²,³,⁴,⁵,⁶,⁷,⁸,⁹,¹⁰,¹¹,¹²,¹³,¹⁴,¹⁵,¹⁶,¹⁷,¹⁸].

Due to the toxicity of many compounds commonly used in industry, particularly those containing phosphates and chromates, these substances are gradually being restricted or banned by environmental regulations. Consequently, attention has shifted towards the development of eco-friendly treatments, such as nanoceramic coatings. These treatments, which are a type of chemical conversion coating typically involving zirconium or titanium oxides, can be produced via sol-gel routes or by immersion in acidic solutions, such as hexafluorozirconic acid (H₂ZrF₆) and hexafluorotitanic acid (H₂TiF₆). The primary advantage of this type of treatment is the reduction in the quantity and toxicity of process effluents and additional benefits include fewer processing steps and lower energy consumption as they do not require heating [¹⁷, ¹⁹, ²⁰].

Various nanoceramic treatments have been applied to both ferrous [²¹,²²,²³,²⁴,²⁵,²⁶,²⁷,²⁸,²⁹,³⁰,³¹] and non-ferrous alloys [³²,³³,³⁴,³⁵,³⁶,³⁷,³⁸,³⁹,⁴⁰,⁴¹,⁴²]. Additionally, some studies have investigated the incorporation of organic and inorganic compounds for a variety of purposes, including increasing layer thickness, modifying its structure, adding colour, imparting self-repair properties, and enhancing corrosion resistance and paint adhesion [¹⁷, ²⁰, ⁴³]. An example of this is provided by YI et al. [⁴³], who investigated the addition of tannic acid (TA).

TA is a commercial form of tannins, which are polyphenolic compounds extracted from tree bark. On ferrous alloys, this compound functions by physically or chemically adsorbing its macromolecules (C₇₆H₅₂O₄₆) onto surfaces, forming a Fe-tannate complex that acts as a corrosion inhibitor [¹²–¹⁸]. In this study, the influence of TA on the zirconium oxide-based conversion treatment was investigated. For this purpose, cold-rolled steel sheets (CRS) were treated in an aqueous conversion solution containing H₂ZrF₆. Analytical techniques such as scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), static contact angle measurement, and Raman spectroscopy were employed to perform the analysis.

2. MATERIALS AND METHODS

2.1. Materials

Cold-rolled steel sheets of SAE 1008 were supplied by ArcelorMittal Brasil S.A., with their chemical composition detailed in Table 1. Tannic acid (ACS grade, purity ≥ 95%) was sourced in powder form from Greentec Soluções & Reagentes (molar mass 1701.23 g/mol), while hexafluorozirconic acid was provided by Klintex Insumos Industriais Ltda as a diluted aqueous solution (45% v/v).

Table 1
CRS composition according to the ArcelorMittal Brasil S.A. technical data sheet.

ELEMENT	Fe	C	Si	Mn	S	P	Al	Cr	Mo
wt.%	balance	0.0662	0.0070	0.3420	0.0081	0.0160	0.0370	0.0260	0.0010

2.2. Nanoceramic treatments

A surface cleaning procedure (see Table 2) was carried out prior to subjecting the samples to nanoceramic treatments. The conversion process employed during these treatments (nanoceramic stage) involved immersing the samples in a 0.01 mol/L of H₂ZrF₆ solution (pH 4.0) at room temperature for 2 minutes without stirring. Following this, the samples were rinsed in deionised water and dried in an oven at 120 °C for 15 minutes. The standard nanoceramic treatment (Nano) refer only to the nanoceramic stage described above.

Table 2
Surface cleaning procedure.

STAGE	PROCEDURE
1	Griding (SiC sandpaper: 120, 320, 600, 1200, 2000#)
2	Washing in tap water
3	Degreasing (ethanol, 1 min.)
4	Alkaline degreasing (35 g.L-1 NaOH + 1 g.L-1 surfactant, 80 ºC, 5 min.)
5	Washing in deionised water (DI)
6	Acid pickling (5% v/v H2SO4, 10 min.)
7	Washing in DI water
8	Cold air drying

Three distinct methods for incorporating TA into the nanoceramic treatments were evaluated: before (TA_Nano), during (Nano+TA), and after the nanoceramic conversion (Nano_TA). Both the first and third treatments were carried out in two stages, with TA applied through immersion in a separate aqueous solution (800 mg/L, pH 3.5) for 30 minutes at room temperature without stirring. After the TA immersion stage (TA_Nano or Nano_TA), the samples were rinsed in deionised water and dried using a cold air jet. In the case of treatment during nanoceramic conversion (Nano+TA), it was carried out in a single stage, in which TA was added directly to the aqueous H₂ZrF₆ solution. Thus, the conversion solution contained 0.01 mol/L for H₂ZrF₆ and 800 mg/L for TA. The immersion time of this treatment was 2 minutes, with rinsing and drying procedures as described in nanoceramic stage. The designations used for all nanoceramic treatments are detailed in Table 3.

Table 3
Nomenclatures of the treatments.

NOMENCLATURE	TREATMENT
Blank	Control sample - Only surface cleaning procedure
Nano	Standard nanoceramic conversion
TA_Nano	TA immersion before the nanoceramic conversion stage
Nano+TA	TA on the nanoceramic conversion solution
Nano_TA	TA immersion after the nanoceramic conversion stage

2.3. Electrochemical impedance spectroscopy

EIS measurements were performed across a frequency range of 10 kHz to 10 mHz, with an amplitude voltage of 10 mV relative to the open circuit potential (OCP). The experiments utilised a Metrohm Drop Sens 400 is potentiostat/galvanostat connected to Drop View 8400 software. The electrochemical cell, with a volume of 130 mL, employed a three-electrode configuration, comprising a platinum counter electrode, an Ag/AgCl reference electrode, and the metal sample serving as the working electrode, with the test area defined as 1.0 cm². To ensure a stable state, the working electrode was immersed in the electrolyte (0.1 mol/L NaCl, pH 3.5) for 30 minutes prior to each measurement. All experiments were conducted at room temperature and under naturally aired conditions.

2.4. Surface characterization

The surface morphology was examined using a Zeiss Evo MA10 scanning electron microscope (SEM) with an accelerating voltage of 15 kV, at magnifications of 500_× and 10,000_×. To evaluate the effect of tannic acid, contact angle measurements and Raman spectroscopy were employed. Static contact angles were determined using the sessile drop method, with droplets of approximately 2 µL of deionised water applied at room temperature; images were captured using a digital microscope (VD3035). Raman spectroscopy was conducted with Renishaw Invia equipment, employing a 532 nm laser (0.5 mW power) and covering a spectral range from 150 cm^-1 to 2000 cm^-1, with three accumulations every 10 seconds of exposure to the laser beam. The laser beam was focused using an optical microscope at a magnification of 50_× to ensure proper alignment.

3. RESULTS AND DISCUSSION

3.1. Scanning electron microscope

Figure 1 shows SEM micrographs of the control sample and the Nano treatment. Only minor differences were observed, suggesting that the Nano treatment replicated the surface without significantly altering its topography. This result was expected due to the nanometric scale of the layer formation. However, the abscence of cracks in the surface (Figs. 1b and 1d) may indicate a potential improvement in corrosion resistance, as cracks and cavities can act as conductive pathways for electrolyte permeation into the substrate [²⁴], leading to localised corrosion. Furthermore, the treated sample exhibited a slight golden hue, possibly resulting from the formation of lepidocrocite (γ-FeO(OH)) during the conversion process [³⁰], thus acting as a qualitative indicator of the treatment.

Figure 1
SEM micrographs of CRS samples: (a) Blank at 500×, (b) Nano treatment at 500×, (c) Blank at 10,000×, (d) Nano treatment at 10,000×.

3.2. Electrochemical impedance spectroscopy

EIS results are presented in Figure 2. The Nyquist plot (Fig. 2a) illustrates the impedance data plotted against the real (Z’) and imaginary (-Z’’) axes, while the Bode plots (Fig. 2b) display the impedance modulus (|Z|) and phase angles (-θ) as functions of frequency (f).

Figure 2
EIS results after 30 minutes immersion in 0.1 mol/L NaCl at pH 3.5. (a) Nyquist plot and (b) Bode plots.

The nanoceramic treatments exhibited larger semicircle diameters in comparison to the control sample (Fig. 2a), indicating a significant enhancement in corrosion resistance within this electrochemical system. Furthermore, it is evident that the shape of these semicircles is not ideal, as the impedances along the real axis exceed those along the imaginary axis. This behaviour, combined with the observations regarding the phase angles (showing a single peak at approximately 40°) suggests the presence of a non-ideal capacitive element, likely attributable to defects and surface roughness [²³].

An overview of the results presented reveals remarkably similar curves, suggesting that the same fundamental phenomena may be occurring across these treatments. The electrochemical behaviour was analysed using an equivalent electrical circuit model (see Fig. 3), which corroborates with the literature [²³, ²⁷, ³⁰, ³¹]. The fitted values are shown in Table 4 and were obtained through the fitting and simulation procedures of the Drop View 8400 software.

Figure 3
Equivalent electrical circuit model.

Table 4
EIS fitting data after 30 minutes immersion in 0.1 mol/L NaCl, pH 3.5.

PARAMETERS	BLANK	NANO	TA_NANO	NANO+TA	NANO_TA
Rs (Ωcm2)	61.76	68.12	72.51	63.67	84.52
Rp (kΩcm2)	0.34	1.02	1.63	0.96	1.26
n	0.79	0.67	0.55	0.62	0.63
Y0 (Ω-1cm-2sn)	1.96 × 10-4	6.57 × 10-4	5.92 × 10-4	7.07 × 10-4	7.73 × 10-4
C (μFcm-2)	95.49	539.60	363.50	556.90	762.20

The model [R_s(R_pCPE)] illustrated in Fig. 3 consists of a solution resistor (R_s) in series with a circuit that includes a constant phase element (CPE) and a polarisation resistor (R_p) in parallel at the metal-electrolyte interface. R_s represents the resistance attributed to the electrolyte, while R_p denotes the resistance of the surface. The CPE was employed instead of a perfect capacitor to account for the non-ideal behaviour of the electrical double layer, with its impedance (ZCPE) and capacitance (C) described by Equations 1 and 2.

(1) $${\mathrm{Z}}_{\mathrm{C}\mathrm{P}\mathrm{E}}=\frac{1}{{\mathrm{Y}}_0{(\mathrm{j}\mathrm{\omega })}^{\mathrm{n}}}$$

(2) $$\mathrm{C}={({\mathrm{Y}}_0{\mathrm{R}}_{\mathrm{p}}{}^{1-\mathrm{n}})}^{1/\mathrm{n}}$$

where ω = 2πf is the angular frequency, j is the imaginary number, Y₀ is the magnitude of admittance (the reciprocal of the impedance), n is a constant, being n = 1 a perfect capacitor.

An analysis of the polarisation resistances, particularly those incorporating the addition of TA, revealed that the first treatment (TA_Nano) exhibited the highest resistance at 1.63 kΩcm², followed by the third treatment (Nano_TA) at 1.26 kΩcm² and the second treatment (Nano + TA) at 0.96 kΩcm². Furthermore, it is important to note that, compared to the Nano treatment, both the TA_Nano and Nano_TA treatments resulted in increased R_p values, whereas the Nano + TA treatment led to a decrease in R_p. Consequently, by using these values, the corrosion protection efficiency of these treatments (as mentioned in equations 3 and 4) was detemined in comparison to Blank (η) and Nano (η*) treatments and shown in Table 5.

Table 5
Protection efficiencies (η, η*) of the treated CRS.

EFFICIENCIES	NANO	TA_NANO	NANO+TA	NANO_TA
η (%)	66.82	79.28	64.64	73.19
η* (%)	–	37.55	-6.57	19.19

(3) $$\mathrm{\eta }=1-\left(\frac{{\mathrm{R}}_{\mathrm{p}}^0}{{\mathrm{R}}_{\mathrm{p}}^{*}}\right)$$

(4) $${\mathrm{\eta }}^{*}=1-\left(\frac{{\mathrm{R}}_{\mathrm{p}}^{*}}{{\mathrm{R}}_{\mathrm{p}}^{}}\right)$$

Where R_p⁰ is the polarisation resistance of Blank, R_p^* is the polarisation resistance of Nano and R_p is the polarisation resistance of nanoceramic treatments with TA addition.

Based on the protection efficiencies presented in Table 5, the TA_Nano treatment was selected for further evaluation using contact angle measurements and Raman spectroscopy.

3.3. Contact angle measurements

Figure 4 shows the images obtained for the contact angle measurements by the sessile drop method. A surface is said to be hydrophobic if the contact angle value is higher than 90° and hydrophilic if the angle value is less than 90º. Hydrophobic surfaces are considered anti-corrosives because they repel water, minimizing the corrosion electrochemical reaction [⁴⁴]. Figure 4c illustrates that the contact angle varied with TA_Nano treatment, reaching a value close to 90°, making it almost hydrophobic. This is significant as it implies that water is repelled from the surface, which helps to minimise the corrosive process. In contrast, the Nano treatment (Figure 4b) displayed behaviour deemed highly hydrophilic. The noticeable difference between these results is likely related to changes in surface composition and roughness [²⁶].

Figure 4
Images of measured static contact angles of CRS samples: (a) Blank, (b) Nano, (c) TA_Nano.

3.4. Raman spectroscopy

The Raman spectrum shown in Figure 5 reveals three main bands. According to the literature [⁴⁵,⁴⁶], the band at 560 cm^-1 is likely associated with the formation of ZrO₂, while the bands at 1305 cm^-1 and 1510 cm^-1 are attributed to lepidocrocite and ferric tannate, respectively. Therefore, the Raman spectrum results align with expectations for the compounds formed on the surface, suggesting the presence of both iron and zirconium oxides in addition to ferric tannate.

Figure 5
Raman spectrum of the CRS after treatment with TA and noceramic conversion.

3.5. Proposed mechanism

As evident from the Raman spectrum (Fig. 5), a complex involving TA can coexist simultaneously with oxides related to nanoceramic conversion. Therefore, to propose a mechanism, it is essential first to comprehend the processes associated with the conversion of the nanoceramic and the adsorption of TA on the CRS.

According to CEREZO et al. [³⁵], during the initial seconds of immersion in the H₂ZrF₆ solution, the free fluorides present dissolve the oxide layer, initiating the anodic dissolution process. This is followed by reductions in oxygen and the evolution of hydrogen, which result in an increase in pH at the metal/solution interface. At this stage, the fluorine ligands of the zirconium fluoride complexes are exchanged for hydroxide ligands, leading to the precipitation of zirconium hydroxide species with low solubility on the surface. Subsequently, the dehydration process begins, resulting in the formation of ZrO₂. The reactions outlined below (5–9) summarise this mechanism.

(5) $$\text{Fe}\to {\text{Fe}}^{+\text{2}}+{\text{2e}}^{-}$$

(6) $${\text{2}}^{\text{H}+}+{\text{2e}}^{-}\to {\text{H}}_{\text{2}}$$

(7) $${\text{O}}_{\text{2}}\mathrm{+}{\text{H}}_{\text{2}}\text{O}+{\text{4e}}^{-}\to {\text{4OH}}^{-}$$

(8) $${\text{Fe}}^{+\text{2}}+\frac{1}{4}{\text{O}}_{\text{2}}+{\text{H}}^{+}\to {\text{Fe}}^{+\text{3}}+\frac{1}{2}{\text{H}}_{\text{2}}\text{O}$$

(9) $${\text{ZrF}}_{\text{6}}{}^{\mathrm{-}\text{2}}+{\text{4OH}}^{-}\to {\text{ZrO}}_{\text{2}}.{\text{2H}}_{\text{2}}\text{O}+{\text{6F}}^{-}$$

Regarding TA adsorption, XU et al. [¹⁵] propose various pathways, as detailed in reactions 10–14. Specifically, hydroxyl groups in the ortho position of the aromatic rings can form chelates with iron. When ferrous or ferric ions react with these hydroxyl groups in an aerated aqueous solution, a highly insoluble complex is produced, which acts as a protective coating.

(10) $$\text{Tannin}\to \text{tannate}+{\text{ne}}^{-}+{\text{nH}}^{+}$$

(11) $$\text{Tannate}+{\text{nFe}}^{+\text{3}}\to {\left({\text{Fe}}^{+\text{3}}\right)}_{\text{n}}\text{Tannate}$$

(12) $$\text{Tannate}+{\text{nFe}}^{+\text{2}}\to {\left({\text{Fe}}^{+\text{2}}\right)}_{\text{n}}\text{Tannate}$$

(13) $${\text{nFe}}^{+\text{3}}+\text{Tannin}\to {\left({\text{Fe}}^{+\text{2}}\right)}_{\text{n}}\text{Tannate}+{\text{nH}}^{+}$$

(14) $${\left({\text{Fe}}^{+\text{2}}\right)}_{\text{n}}\text{Tannate}+{\text{nO}}_{\text{2}}+{\text{nH}}^{+}\to {\left({\text{Fe}}^{+\text{3}}\right)}_{\text{n}}\text{Tannate}+\frac{1}{2}{\text{nH}}_{\text{2}}\text{O}$$

It can be proposed that the protection mechanism might result from a combined effect of each treatment stage, as illustrated in Fig. 6. For the first and third treatments (TA_Nano and Nano_TA), the final stage (immersion in H₂ZrF₆ solution or TA) may serve to cover areas that were not fully addressed in the previous stage. In the case of the second treatment (Nano+TA), TA adsorption may have been hindered because the processing time was constrained by the nanoceramic conversion, leading to possible competition between reactions and thus reducing treatment efficiency.

Figure 6
Corrosion protection mechanism proposed for nanoceramic treatments with TA.

4. CONCLUSIONS

The Nano treatment resulted in a crack-free, slightly golden surface, which may indicate the occurrence of nanoceramic conversion. Furthermore, it was observed that this treatment significantly enhanced corrosion protection (66.82%) in a saline environment. The addition of TA to the nanoceramic treatment provided a further improvement in corrosion protection when used separately from the nanoceramic conversion solution, as shown as TA_Nano and Nano_TA treatments (79.28% and 73.19%, respectively). The Raman spectrum confirmed the simultaneous presence of ferric tannate, zirconium oxide and lepidocrocite on the metal surface, suggesting that the combined effect of these elements may have contributed to the enhanced corrosion resistance. Finally, the study shows that it is indeed possible to use a nanoceramic treatment in conjunction with TA. However, further research focusing on long-term corrosion resistance, mechanical properties and the integration of organic coatings (e.g. paint) is still needed to ensure the use this type of coating in industrial applications.

5. ACKNOWLEDGMENTS

The authors are grateful to Fundação de Amparo à pesquisa do Estado do Rio Grande do Sul (19/2551-0001881-9), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior/Programa de Excelência Acadêmica (23038.00341/2019-71) and Universidade Federal do Rio Grande do Sul for their financial support.

6. BIBLIOGRAPHY

• ^[1] BUCHWEISHAIJA, J., “Phytochemicals as green corrosion inhibitors in various media: a review”, Tanzania Journal of Science, Dar es Salaam, v. 35, pp. 77–92, 2009.
• ^[2] LIPIAR, K.M.O.G., MOHAMMAD, A.J.M., “Green corrosion inhibitors”, In: SINGH, A. (ed), Corrosion inhibitors, London, IntechOpen, pp. 1–18, 2019.
• ^[3] NAGESWAR, Y.V.D., RAO, V.J., “Green organic inhibitors for corrosion protection”, In: INAMUDDIN, M.I.A., MOHAMMAD, L., TARIQ, A. (eds), Sustainable Corrosion Inhibitors,Millersville, PA, Materials Research Forum LLC, pp. 101–129, 2021. doi: http://doi.org/10.21741/9781644901496-5.
  » https://doi.org/10.21741/9781644901496-5
• ^[4] MARZORATI, S., VEROTTA, L., TRASATTI, S., “Green corrosion inhibitors from natural sources and biomass wastes”, Molecules (Basel, Switzerland), v. 24, n. 1, pp. 1–24, 2018. PubMed PMID: 30583586.
• ^[5] ASLAM, R., MOBIN, M., ASLAM, J., et al., “Inhibitory effect of sodium carboxymethylcellulose and synergistic biodegradable gemini surfactants as effective inhibitors for MS corrosion in 1 M HCl”, Journal of Materials Research and Technology, v. 8, n. 5, pp. 4521–4533, 2019. doi: http://doi.org/10.1016/j.jmrt.2019.07.065.
  » https://doi.org/10.1016/j.jmrt.2019.07.065
• ^[6] BAYOL, E., GURTEN, A., DURSUN, M., et al., “Adsorption behavior and inhibition corrosion effect of sodium carboxymethyl cellulose on mild steel in acidic medium”, Wuli Huaxue Xuebao, v. 24, pp. 2236–2243, 2008.
• ^[7] SOLOMON, M.M., UMOREN, S.A., UDOSORO, I.I., et al., “Inhibitive and adsorption behaviour of car-boxymethyl cellulose on mild steel”, Corrosion Science, v. 52, pp. 1317–1325, 2010. doi: http://doi.org/10.1016/j.corsci.2009.11.041.
  » https://doi.org/10.1016/j.corsci.2009.11.041
• ^[8] UMOREN, S.A., SOLOMON, M.M., UDOSORO, I.I., et al., “Synergistic and antagonistic effects between halide ions and carboxymethyl cellulose for the corrosion inhibition of mild steel in sulphuric acid solution”, Cellulose (London, England), v. 17, n. 3, pp. 635–648, 2010. doi: http://doi.org/10.1007/s10570-010-9409-7.
  » https://doi.org/10.1007/s10570-010-9409-7
• ^[9] UMOREN, S.A., BANERA, M.J., ALONSO-GARCIA, T., et al., “Inhibition of mild steel corrosion in HCl so-lution using chitosan”, Cellulose (London, England), v. 20, n. 5, pp. 2529–2545, 2013. doi: http://doi.org/10.1007/s10570-013-0021-5.
  » https://doi.org/10.1007/s10570-013-0021-5
• ^[10] MENAKA, R., SUBHASHINI, S., “Chitosan Schiff base as eco-friendly inhibitor for mild steel corrosion in 1 M HCl”, Journal of Adhesion Science and Technology, v. 30, n. 15, pp. 1–20, 2016. doi: http://doi.org/10.1080/01694243.2016.1156382.
  » https://doi.org/10.1080/01694243.2016.1156382
• ^[11] SHARMA, V., “Green inhibitors (plants extracts) for corrosion protection of mild steel in different acidic conditions: an overview”, International Journal of Research, v. 7, pp. 1142–1147, 2018.
• ^[12] KACO, H., TALIB, N.A.A., ZAKARIA, S., et al., “Enhanced corrosion inhibition using purified tannin in HCl medium”, The Malaysian Journal of Analytical Sciences, v. 22, pp. 931–942, 2018.
• ^[13] KUSMIEREK, E., CHRZESCIJANSKA, E., “Tannic acid as corrosion inhibitor for metals and alloys”, Materials and Corrosion, v. 66, n. 2, pp. 169–174, 2015. doi: http://doi.org/10.1002/maco.201307277.
  » https://doi.org/10.1002/maco.201307277
• ^[14] QIAN, B., HOU, B., ZHENG, M., “The inhibition effect of tannic acid on mild steel corrosion in seawater wet/dry cyclic conditions”, Corrosion Science, v. 72, pp. 1–9, 2013. doi: http://doi.org/10.1016/j.corsci.2013.01.040.
  » https://doi.org/10.1016/j.corsci.2013.01.040
• ^[15] XU, W., HAN, E.-H., WANG, Z., “Effect of tannic acid on corrosion behavior of carbon steel in NaCl solution”, Journal of Materials Science and Technology, v. 35, n. 1, pp. 64–75, 2019. doi: http://doi.org/10.1016/j.jmst.2018.09.001.
  » https://doi.org/10.1016/j.jmst.2018.09.001
• ^[16] PANTOJA-CASTRO, M.A., GONZÁLEZ-RODRÍGUEZ, H., “Study by infrared spectroscopy and thermogravimetric analysis of tannis and tannic acid”, Revista Latinoamericana de Química, v. 39, pp. 107–112, 2011.
• ^[17] COSTA, J.S., AGNOLI, R.D., FERREIRA, J.Z., “Corrosion behavior of a conversion coating based on zirconium and colorants on galvanized steel by electrodeposition”, Tecnologica em Metalurgia, Materiais e Mineração, v. 12, n. 2, pp. 167–175, 2015. doi: http://doi.org/10.4322/2176-1523.0852.
  » https://doi.org/10.4322/2176-1523.0852
• ^[18] BENALI, O., BENMEHDI, H., HASNAOUI, O., et al., “Green corrosion inhibitor: inhibitive action of tannin extract of Chamaerops humilis plant for the corrosion of mild steel in 0.5 M H2SO4”, Journal of Materials and Environmental Science, v. 1, pp. 127–138, 2013.
• ^[19] SCHULZ, D., “Painting trends in the automotive industry”, Metal Finishing, v. 111, n. 5, pp. 38–40, 2013. doi: http://doi.org/10.1016/S0026-0576(13)70268-X.
  » https://doi.org/10.1016/S0026-0576(13)70268-X
• ^[20] MILOŠEV, I., FRANKEL, G.S., “Review - conversion coatings based on zirconium and/or titanium”, Journal of the Electrochemical Society, v. 165, n. 3, pp. 127–144, 2018. doi: http://doi.org/10.1149/ 2.0371803jes.
  » https://doi.org/10.1149/2.0371803jes
• ^[21] ADHIKARI, S., UNOCIC, K.A., ZHAI, Y., et al., “Hexafluorzirconic acid based surface pretreatments: characterization and performance assessment”, Electrochimica Acta, v. 56, n. 4, pp. 1912–1924, 2011. doi: http://doi.org/10.1016/j.electacta.2010.07.037.
  » https://doi.org/10.1016/j.electacta.2010.07.037
• ^[22] ANJOS-MORAES, J., GIACOBBO, A., SÁNCHEZ-TOVAR, R., et al., “Electrochemichal behavior during the zirconium convertion coating formation on AISI 1006 steel”, Materials Research, v. 22, n. 5, pp. 1–7, 2019. doi: http://doi.org/10.1590/1980-5373-mr-2018-0322.
  » https://doi.org/10.1590/1980-5373-mr-2018-0322
• ^[23] MOHAMMADLOO, H.E., SARABI, A.A., ALVANI, A.A.S., et al., “Nano-ceramic hexafluorzirconic acid based conversion thin film: surface characterization and electrochemical study”, Surface and Coatings Technology, v. 206, pp. 4132–4139, 2012.
• ^[24] MOHAMMADLOO, H.E., SARABI, A.A., ALVANI, A.A.S., et al., “The effect of solution temperature and pH on corrosion performance and morphology of nanoceramic-based conversion film”, Materials and Corrosion, v. 64, n. 6, pp. 535–543, 2013. doi: http://doi.org/10.1002/maco.201106384.
  » https://doi.org/10.1002/maco.201106384
• ^[25] MOHAMMADLOO, H.E., SARABI, A.A., HOSSEINI, R.M., et al., “A comprehensive study of the green hexaflourzirconic acid-based conversion coating”, Progress in Organic Coatings, v. 77, n. 2, pp. 322–330, 2014. doi: http://doi.org/10.1016/j.porgcoat.2013.10.006.
  » https://doi.org/10.1016/j.porgcoat.2013.10.006
• ^[26] KERSTNER, E.K., KUNST, S.R., BELTRAMI, L.V.R., et al., “Anticorrosive performance of commercial nanoceramic coatings on AISI 1010 steel”, Materials Research, v. 17, n. 6, pp. 1497–1506, 2014. doi: http://doi.org/10.1590/1516-1439.263514.
  » https://doi.org/10.1590/1516-1439.263514
• ^[27] HOSSEINI, R.M., SARABI, A.A., MOHAMMADLOO, H.E., et al., “The performance improvement of Zr conversion coating through Mn incorporation: with and without organic coating”, Surface and Coatings Technology, v. 258, pp. 437–446, 2014. doi: http://doi.org/10.1016/j.surfcoat.2014.08.056.
  » https://doi.org/10.1016/j.surfcoat.2014.08.056
• ^[28] KUHN, N.W., FRANKEL, G.S., “Composition and corrosion protection of hexafluorzirconic acid treatment on steel”, Materials and Corrosion, v. 66, pp. 1222–1255, 2015.
• ^[29] ASEMANI, H.R., AHMADI, P., SARABI, A.A., et al., “Effect of zirconium conversion coating: adhesion and anti-corrosion properties of epoxy organic coating containing zinc aluminum polyphosphate (ZAPP) pigment on carbon mild steel”, Progress in Organic Coatings, v. 94, pp. 18–27, 2016. doi: http://doi.org/10.1016/j.porgcoat.2016.01.015.
  » https://doi.org/10.1016/j.porgcoat.2016.01.015
• ^[30] WU, A.-H., WANG, Y.-Z., XU, T.-K., et al., “Corrosion resistance properties of colored zirconium con-version coating and powder coating on cold-rolled steel”, Rare Metals, v. 42, n. 3, pp. 1005–1010, 2018. doi: http://doi.org/10.1007/s12598-017-0969-7.
  » https://doi.org/10.1007/s12598-017-0969-7
• ^[31] GOLOBADI, M., ALIOFKHAZRAEI, M., TOORANI, M., “Corrosion behavior of zirconium-pretreated/epoxy-coated mild steel: new approach for determination of cathodic disbondment resistance by electrochemical impedance spectroscopy”, Journal of Alloys and Compounds, v. 873, pp. 1–19, 2021. doi: http://doi.org/10.1016/j.jallcom.2021.159800.
  » https://doi.org/10.1016/j.jallcom.2021.159800
• ^[32] VERDIER, S., VAN DER LAAK, N., DALARD, F., et al., “An electrochemical and SEM study of the mechanism of formation, morphology, and composition of titanium or zirconium fluoride-based coatings”, Surface and Coatings Technology, v. 200, pp. 2955–2964, 2006.
• ^[33] GEORGE, F.O., SKELDON, P., THOMPSON, G.E., “Formation of zirconium-based conversion coatings on aluminium and Al-Cu alloys”, Corrosion Science, v. 65, pp. 231–237, 2012. doi: http://doi.org/10.1016/ j.corsci.2012.08.031.
  » https://doi.org/10.1016/j.corsci.2012.08.031
• ^[34] GOLRU, S.S., ATTAR, M.M., RAMEZANZADEH, B., “Morphological analysis and corrosion perfor-mance of zirconium based conversion coating on the aluminum alloy 1050”, Journal of Industrial and Engineering Chemistry, v. 24, pp. 233–244, 2015. doi: http://doi.org/10.1016/j.jiec.2014.09.036.
  » https://doi.org/10.1016/j.jiec.2014.09.036
• ^[35] CEREZO, J., POSNER, R., VANDENDAEL, I., et al., “The effect of conversion bath convection on the formation of Zr-based thin-film coatings on multi metal surfaces”, Materials and Corrosion, v. 67, n. 4, pp. 361–367, 2016. doi: http://doi.org/10.1002/maco.201508597.
  » https://doi.org/10.1002/maco.201508597
• ^[36] ŠEKULARAC, G., MILOŠEV, I., “Electrochemical behavior and self-sealing ability of zirconium con-version coating applied on aluminum alloy 3005 in 0.5 M NaCl solution”, Journal of the Electrochemical Society, v. 167, n. 2, pp. 021509, 2020. doi: http://doi.org/10.1149/1945-7111/ab6b0d.
  » https://doi.org/10.1149/1945-7111/ab6b0d
• ^[37] ZHU, W., CHEN, F., YI, A., et al., “Titanium, zirconium and vanadium conversion coatings (TZVCCs) on AZ91D magnesium alloy sheets”, Materials Research Express, v. 7, n. 8, pp. 086402, 2020. doi: http://doi.org/10.1088/2053-1591/ababbe.
  » https://doi.org/10.1088/2053-1591/ababbe
• ^[38] HAN, J., THIERRY, D., OGLE, K., “Zr-based conversion coating on Zn and Zn-Al-Mg alloy coating: understanding the accelerating effect of Cu (II) and NO3-”, Surface and Coatings Technology, v. 402, pp. 12636, 2020. doi: http://doi.org/10.1016/j.surfcoat.2020.126236.
  » https://doi.org/10.1016/j.surfcoat.2020.126236
• ^[39] MOREIRA, V.B., MENEGUZZI, A., JIMÉNEZ-PIQUÉ, E., et al., “Aluminum protection by using green zirconium oxide layer and organic coating: an efficient and adherent dual system”, Sustainability (Basel), v. 13, n. 17, pp. 1–17, 2021. doi: http://doi.org/10.3390/su13179688.
  » https://doi.org/10.3390/su13179688
• ^[40] YONG, J., LI, H., LI, Z., et al., “Effect of (NH4)2ZrF6, voltage and treating time on corrosion resistance of micro-arc oxidation coatings applied on ZK61M magnesium alloys”, Materials (Basel), v. 14, n. 23, pp. 7410, 2021. doi: http://doi.org/10.3390/ma14237410.PubMed PMID: 34885565.
  » https://doi.org/10.3390/ma14237410
• ^[41] SHARIKABAD, S.M.J.Y., HESSAN, R., AGHILI, H., et al., “Improvement of pitting corrosion re-sistance and anti-corrosion performance of aluminum 1200 by eco-friendly Zr-based conversion coatings: efect of deposition parameters”, Journal of Bio- and Tribo-Corrosion, v. 9, pp. 1–16, 2023.
• ^[42] SHEN, G.-T., CHEN, S.-Y., HUANG, C.-Y., et al., “Microstructural evolution and corrosion behavior of constituent particles of AA2024-T3 Al alloy during zirconium conversion coating”, Applied Surface Science, v. 635, pp. 157657, 2023. doi: http://doi.org/10.1016/j.apsusc.2023.157657.
  » https://doi.org/10.1016/j.apsusc.2023.157657
• ^[43] YI, A., LI, W., DU, J., et al., “Preparation and properties of chrome-free colored Ti/Zr based conversion coating on aluminum alloy”, Applied Surface Science, v. 258, n. 16, pp. 5960–5964, 2012. doi: http://doi.org/10.1016/j.apsusc.2011.12.045.
  » https://doi.org/10.1016/j.apsusc.2011.12.045
• ^[44] XAVIER, J.R., “Improvement in corrosion resistance and mechanical properties of epoxy coatings on steel with the addition of thiadiazole treated ZrC”, Journal of Materials Engineering and Performance, v. 32, n. 9, pp. 3980–3994, 2023. doi: http://doi.org/10.1007/s11665-022-07387-y.
  » https://doi.org/10.1007/s11665-022-07387-y
• ^[45] LOSTAK, T., TIMMA, C., KREBS, S., et al., “Organosilane modified Zr-based conversion layer on Zn-Al alloy coated steel sheets”, Surface and Coatings Technology, v. 305, pp. 223–230, 2016. doi: http://doi.org/10.1016/j.surfcoat.2016.08.030.
  » https://doi.org/10.1016/j.surfcoat.2016.08.030
• ^[46] HENRIK-KLEMENS, A., BENGTSSON, F., BJORDAL, C.G., “Raman spectroscopic investigation of iron-tannin precipitates in waterlogged archaeological oak”, Studies in Conservation, v. 67, pp. 1–11, 2021.

Publication Dates

• Publication in this collection
  13 Dec 2024
• Date of issue
  2024

History

• Received
  27 Aug 2024
• Accepted
  16 Oct 2024