Improvement of the Tribological Properties and Corrosion Resistance of Epoxy–PTFE Composite Coating by Nanoparticle Modification

Lixia Ying,Chongyang Nie,Yunlong Wu,Chunxi Wu,Guixiang Wang

doi:10.3390/coatings11010010

Abstract

In order to meet the requirements of high corrosion resistance, wear resistance, and self-lubrication of composite coatings for marine applications, epoxy matrix composite coatings containing PTFE and TiO2 nanoparticles were prepared on the steel substrate. With silane coupling agent KH570 (CH2=C(CH3)COOC3H6Si(OCH3)3), titanium dioxide nanoparticles were modified, and organic functional groups were grafted on their surface to improve their dispersion and interface compatibility in the epoxy matrix. Then, the section morphology, tribological, and anticorrosion properties of prepared coatings, including pure epoxy, epoxy–PTFE, and the composite coating with unmodified and modified TiO2, respectively, were fully characterized by scanning electron microscopy, friction–abrasion testing machine, and an electrochemical workstation. The analytical results show that the modified TiO2 nanoparticles are able to improve the epoxy–PTFE composite coating’s mechanical properties of epoxy–PTFE composite coating including section toughness, hardness, and binding force. With the synergistic action of the friction reduction of PTFE and dispersion enhancement of TiO2 nanoparticles, the dry friction coefficient decreases by more than 73%. Simultaneously, modified titanium dioxide will not have much influence on the water contact angles of the coating. A larger water contact angle and uniform and compact microstructure make the composite coating incorporated modified TiO2 nanoparticles show excellent anti-corrosion ability, which has the minimum corrosion current density of 1.688 × 10−7 A·cm−2.

Highlights

For the advantages of excellent friction, stable chemical property, and low cost [1,2,3], epoxy resin is one of the excellent polymer coating materials, which is widely applied in the metal protection, electronics, and medical equipment [4,5]
For unmodified TiO2 nanoparticles, the absorption band between 3400 and 3500 cm−1 corresponds to the hydroxyl group (–OH) due to the partial electron–hole pairs migration on the surface of TiO2 nanoparticles
The new absorption bands appear in the FT-IR spectrum of modified TiO2 nanoparticles in curve b, and there are Coatings 2021, 11, x FOR PEER REVIE(sWCom=Oe )c,h1a6r2a0ctcemris−t1ic(Cab=sCo)r,p5ti0o0n–7p5e0akcms o−f1K(HTi5–7O0–aSti)2,9s1o7itcmco−u1ld(–bCeHin3 faenrrde–d5CotfHh14a2t),th17e1o7rgcman−ic1 functional group has been grafted onto the surface of TiO2 nanoparticles successfully

Summary

Introduction

For the advantages of excellent friction, stable chemical property, and low cost [1,2,3], epoxy resin is one of the excellent polymer coating materials, which is widely applied in the metal protection, electronics, and medical equipment [4,5]. Epoxy–PTFE composite coatings have low friction coefficient and anticorrosion ability as well as high temperature resistance [6]. Such coatings could increase the anticorrosion capacity of metals and the self-lubricity of bearings as well as modify the hydrophobic and ice-phobic properties for wind turbine blades [7,8,9]. The low hardness of PTFE will lead to the poor wear resistance of the epoxy–PTFE composite coating [10,11]. A viable solution is to add hard or inorganic particles, such as TiO2, CuO, CuF2, CuS, and Al2O3, which will improve the tribological properties of the coating [12,13,14,15]

Methods

Results

Conclusion