Development of nanocomposite coatings with improved mechanical, thermal, and corrosion protection properties

2017 ◽  
Vol 52 (8) ◽  
pp. 1045-1060 ◽  
Author(s):  
Majid TabkhPaz ◽  
Dong-Yeob Park ◽  
Patrick C Lee ◽  
Ron Hugo ◽  
Simon S Park

In this study, new composite coatings are fabricated and investigated for their applications as the metal coating. The studied coatings consist of two-layered composites with various nanoparticulates as fillers in a polymeric matrix (styrene acrylic). The first layer bonded to the steel plate uses a combination of zinc particles, multi-walled carbon nanotubes, and graphene nanoplatelets. For the second layer, hexagonal boron nitride with high electrical insulation properties is added to the matrix. The morphology of the nanoparticulates is conducted using a scanning electron microscope. The coefficient of thermal expansion, cathodic disbondment resistance, gas penetration, and scratch resistance of the coatings are evaluated. The corroded area on the cathodic disbondment test specimens reduced down up to 90% for the composite with zinc (20 wt%), multi-walled carbon nanotubes (2 wt%), and graphene nanoplatelets (2 wt%), compared to a specimen coated with a pure polymer. It is seen that the presence of nanoparticulates decreased gas permeation and thermal expansion of the matrix by 75% and 65%, respectively. The addition of nanoparticulates also enhanced scratch resistance of the coating composites.

2017 ◽  
Vol 52 (4) ◽  
pp. 449-464 ◽  
Author(s):  
Roger H Bello ◽  
Luiz AF Coelho ◽  
Daniela Becker

The effects of the silanization of multi-walled carbon nanotubes and graphene nanoplatelets with 3-APTES on thermal, mechanical and electrical properties of epoxy nanocomposites were investigated. Nanocomposites containing pristine, oxidized and silanized nanoparticles of multi-walled carbon nanotubes or graphene nanoplatelets at two different concentrations (0.15 and 0.50 vol.%) were prepared by in situ polymerization without using solvents. The functionalized nanoparticles were characterized by Fourier-transform infrared, X-ray photoelectron spectroscopy, Raman spectroscopy and transmission electron microscope techniques. The oxidation and the silanization on the surface of both nanoparticles were confirmed by Fourier-transform infrared, X-ray photoelectron spectroscopy, Raman and transmission electron microscope analysis. The thermal properties of all studied materials were analyzed by differential scanning calorimetry and the mechanical properties by nanoindentation. The addition of both nanoparticles (pristine and functionalized) into the matrix did not show significant variations on thermal properties, but decreased values for glass transition temperature (Tg) compared to the neat resin. Higher values for modulus of elasticity and hardness of epoxy/nanocomposites were obtained when silanized multi-walled carbon nanotubes or oxidized graphene nanoplatelets were added into the matrix. Adding 0.15 vol.% of silanized multi-walled carbon nanotubes the modulus of elasticity increased in approximately 60%, whereas 0.50 vol.% this increase was greater than 90% compared to the neat resin. While adding 0.15 vol.% of oxidized graphene nanoplatelets, the modulus of elasticity increased approximately 83%, whereas 0.50 vol.% this increase was greater than 88% compared to the neat resin. The formation of percolating networks has been achieved only by pristine multi-walled carbon nanotubes addition at a concentration of 0.50 vol.% and by silanized graphene nanoplatelets at a concentration of 0.15 vol.%. However, for both carbon-based nanoparticles conductivities on the order of 10−7 S/m for frequencies near 100 Hz were observed.


Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 84
Author(s):  
Yi-Ming Jen ◽  
Hao-Huai Chang ◽  
Chien-Min Lu ◽  
Shin-Yu Liang

Even though the characteristics of polymer materials are sensitive to temperature, the mechanical properties of polymer nanocomposites have rarely been studied before, especially for the fatigue behavior of hybrid polymer nanocomposites. Hence, the tensile quasi-static and fatigue tests for the epoxy nanocomposites reinforced with multi-walled carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) were performed at different temperatures in the study to investigate the temperature-dependent synergistic effect of hybrid nano-fillers on the studied properties. The temperature and the filler ratio were the main variables considered in the experimental program. A synergistic index was employed to quantify and evaluate the synergistic effect of hybrid fillers on the studied properties. Experimental results show that both the monotonic and fatigue strength decrease with increasing temperature significantly. The nanocomposites with a MWCNT (multi-walled CNT): GNP ratio of 9:1 display higher monotonic modulus/strength and fatigue strength than those with other filler ratios. The tensile strengths of the nanocomposite specimens with a MWCNT:GNP ratio of 9:1 are 10.0, 5.5, 12.9, 23.4, and 58.9% higher than those of neat epoxy at −28, 2, 22, 52, and 82 °C, respectively. The endurance limits of the nanocomposites with this specific filler ratio are increased by 7.7, 26.7, 5.6, 30.6, and 42.4% from those of pristine epoxy under the identical temperature conditions, respectively. Furthermore, the synergistic effect for this optimal nanocomposite increases with temperature. The CNTs bridge the adjacent GNPs to constitute the 3-D network of nano-filler and prevent the agglomeration of GNPs, further improve the studied strength. Observing the fracture surfaces reveals that crack deflect effect and the bridging effect of nano-fillers are the main reinforcement mechanisms to improve the studied properties. The pullout of nano-fillers from polymer matrix at high temperatures reduces the monotonic and fatigue strengths. However, high temperature is beneficial to the synergistic effect of hybrid fillers because the nano-fillers dispersed in the softened matrix are easy to align toward the directions favorable to load transfer.


Wear ◽  
2019 ◽  
Vol 418-419 ◽  
pp. 290-304 ◽  
Author(s):  
Nidhi Sharma ◽  
Syed Nasimul Alam ◽  
Bankim Chandra Ray ◽  
Surekha Yadav ◽  
Krishanu Biswas

2008 ◽  
Vol 8 (4) ◽  
pp. 1669-1678
Author(s):  
Zhihang Fan ◽  
Suresh G. Advani

Carbon nanotubes (CNTs) do have the potential to improve the interlaminar shear strength (ILSS) of composites if they can be successfully integrated into the matrix as it infuses into the fiber preform. The infusion under capillary action of Multi-Walled Carbon Nanotubes (MWNT)/Epoxy suspension with tubes of length 0.3∼1 μm in glass fiber bundles containing pores of the order of 5 nm∼100 μm was investigated. The influence of parameters such as suspension concentration, viscosity, porous media architecture, surface tension and contact angle were explored. It was found that filtering of the suspension is a major challenge for uniform infusion for concentrations beyond 0.5% MWNT by weight. This is even truer for fiber bundles that are compacted. Hence for successful manufacturing, new infusion techniques that rely on fabrics of high permeability will have to be developed to fabricate such nanocomposites.


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