International Journal of Materials Engineering 2012; 2(2): 11-14 DOI: 10.5923/ij.me.20120303.01
Computational Simulation and Testing of Nano Particle Coating in Material Anti-Corrosion Jeremy (Zheng) Li University of Bridgeport, USA
Abstract The corrosion speed of metal materials varies based on weathering conditions, such as air quality, temperature, moisture, and some other factors of environment. To reduce the corrosion rates, different surface coating technologies have been applied to improve material anti-corrosion performance. In regular coatings, the adhesive bond is relatively weak that leads the delamination in coating layer and decrease in coating effective life. This paper studies the mechanism of anti-corrosion in nanocoating process through computational simulation and sample experiment. Both computational modeling and testing results indicate that the materials with nanocoating are being well protected with longer coated surface life and more durable anti-corrosion performance if compared to the regular coatings. Keywords Anti-corrosion, nanotechnology, computational simulation, effective material life, nanocoating
Copyright © 2012 Scientific & Academic Publishing. All Rights Reserved
1. Introduction Products of metal materials are normally subjected to the corrosion attack in bad weather conditions and corrosion speed will be increased if metals are exposed to more wet atmospheric conditions [1]. Under non-wet environmental condition, the oxide film is developed which can protect underneath substrate. In wet conditions, such as raining weather, the corrosion rate of metal products is accelerated up to the rate of under water products [2]. The wet atmosphere can produce the electrolytic droplets with anode in the centre and ferrous hydroxide is formed to enclose the droplet which can keep metal products from quick corrosion [3]. Some anti- corrosion surface coatings can decrease the metal corrosion by sacrificing the coating material elements. In this case, the coating elements with high electrochemical (corrosive) potential act as the anode to metal materials to further protect metal products from corrosion [4, 5]. Normally, the molecular bond in conventional surface coatings are relatively weak and coating life cycle is not very long in severe weathering condition [6]. The nanocoating technology has been developed to improve anti-corrosion of surface coating because of its superior function in anti-corrosion, reliable performance in corrosion resistance, and non-risk of pollution to environment.
2. Sample Testing * Corresponding author:
[email protected] (Jeremy (Zheng) Li) Published online at http://journal.sapub.org/ijme
The selected samples have been tested per following conditions: . Temperature: 120℃ . Relative humidity: 92% . The salt spray The electrochemical potential is measured by potentiostat on tested material samples. Table 1 Experimental results of current density vs. corrosion potential Potential (V) -1.06 -1.04 -1.02 -1.00 -0.98 -0.96 -0.94 -0.92 -0.90 -0.88
Nanocoating Current Density (µAcm-2) 8.08 16.88 28.55 48.35 66.42 92.55 142.38 175.68 185.56 201.36
Conventional Coating Current Density (µAcm-2) 25.38 45.85 78.82 138.88 215.35 342.88 408.35 512.45 595.38 654.96
Table 2 Experimental corrosion speed vs. percentage of coating film Percent of Materials in Coating Film (%) 1 2 3 4 5 6 7
Nanocoating Sample Material Removal (mg) 20.25 21.35 23.56 26.78 28.38 26.58 25.35
Conventional Coating Sample Material Removal (mg) 212.38 209.88 205.45 212.55 215.38 217.66 211.55
Table 1 displays the current density vs. electrochemical potential in nano and conventional coatings. Since the current density in conventional coatings is larger than in nanocoating, the conventional coatings have lower performance than nanocoating in anti-corrosion performance. Table 2 indicates the coating material removal vs. percentage of materials in coating film. It also confirms that the material removal in conventional coating is larger than in nanocoating due to superior corrosion-resistant function in nanocoating. These sample tests show that the nano surface coating has much better performance than conventional coating in anti-corrosion. The major reason is that the nanocoating can permeate through the material surface and evolve into substrate material through chemical bonding process. The experiment shows superior and durable anti-corrosion function in nanocoated materials.
3. Computational Simulation To compare with prototyped sample testing, the computational simulation has been performed based on the testing conditions defined in the section of sample tests. Fig. 1 shows the weight change of metal sample under conditions of 120℃ and 92% RH.
Fig. 2 Material removal vs. percent of coating material in coating film
The computer-aided modeling shows the higher anti-corrosion performance in nanocoating due to lower current density displayed in Fig. 1 and less coated material removal depicted in Fig. 2. Comparing with conventional coating, the nanocoating has stronger molecular bond with much less coating delamination. Both computational simulation and sample testing show the close results that verifies the credibility and feasibility of this nano coating research and analytic methodology.
4. Conclusions This paper studies and analyses the nanocoating on metal material products through computational simulation and sample testing. Both results show that the nano coating has much better surface corrosion-resistant function, superior anti-rust performance, longer service life cycle, and no risk of pollution to the environment. Further analysis and testing will be performed to get more understanding of anti-corrosion mechanism in nanocoating performance.
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Fig. 1 Electrochemical current density vs. electrochemical potential
Fig. 2 displays the material removal with different percent of materials in coating film.
