Abstract
A series of high solid content (30 wt%) epoxy resin (EP) composite coatings reinforced with differently sized cubic boron nitride (CBN) particles were fabricated successfully on 304L stainless steel. Polydopamine (PDA) was used to improve the dispersibility of CBN particles in EP. The structural and morphological features of the CBN particles and the composite coatings were characterized by Raman spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Moreover, a UMT-3 tribometer and surface profiler were used to investigate the tribological behaviors of the as-prepared composite coatings. Electrochemical impedance spectroscopy (EIS) and Tafel analysis were used to investigate the coatings’ anti-corrosion performance. The results demonstrated that the CBN fillers could effectively enhance the tribological and anti-corrosion properties of the EP composite coatings. In addition, when the additive proportion of the microsized (5 μm) and nanosized (550 nm) CBN particles was 1:1, the tribological property of the EP composite coatings was optimal for dry sliding, which was attributed to the load carrying capability of the microsized CBN particles and the toughening effect of the nanosized CBN particles. However, when the additive proportion of the microsized and nanosized CBN particles was 2:1, the tribology and corrosion resistance performance were optimal in seawater conditions. We ascribed this to the load-carrying capacity of the microparticles, which played a more important role under the seawater lubrication condition, and the more compact structure, which improved the electrolyte barrier ability for the composite coatings.
Highlights
Epoxy resin (EP) has been widely used as an adhesive, a coating, and an automotive and aeronautics material in many fields due to its excellent chemical resistance, mechanical behavior, and electrical insulating properties [1,2,3]
To dispel the aggregation caused by high activity, micro/nano-cubic boron nitride (CBN) particles were treated with dopamine hydrochloride, so that after chemical modification the CBN fillers would be well-dispersed in the EP matrix. 5 g of CBN particles was dispersed in a mixed solution of 800 mL of tris buffer solution (10 mM, pH 8.5). 100 mg and 250 mg of dopamine hydrochloride was added to the microsized and nanosized CBN particle solutions, respectively, and the mixtures were stirred for 12 h at 25 °C
After allowing the EP dispersion of xylene to stand for 2 d, we could clearly see that the EP dispersions of unmodified CBN particles showed obvious delamination and many CBN particles at the bottom of sample bottle
Summary
Epoxy resin (EP) has been widely used as an adhesive, a coating, and an automotive and aeronautics material in many fields due to its excellent chemical resistance, mechanical behavior, and electrical insulating properties [1,2,3]. Polymer reinforced with differently sized particles shows different mechanical properties, including Young’s modulus, strength, hardness, and toughness, which have a significant impact on its tribological performance [12]. Barmouz et al [15] fabricated copper-base composites reinforced with 30 nm and 5 μm SiC particles on the surface of pure copper, and showed that decreasing the reinforcing particle size would enhance the tensile strength and wear resistance, and decease the percent elongation. Yu et al [3] compared the tribological properties of EP composite coatings reinforced with functionalized CBN or hexagonal boron nitride (HBN) fillers. The tribological mechanism of the composite coating was elaborated based on the above results We believe this binary-scale particle enhancement strategy for composites may extend their potential application areas, especially under harsh environments
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