In-Situ Synthesis Strategy of Monodispersed Ag2S Nanoparticles to Modify Wear Resistance of Polyamide-imide Nanocomposite Lubricating Coatings

Abstract

A novel in-situ-synthesis strategy via one-pot thermal decomposition of a single-source precursor was developed to fabricate silver sulfide (Ag2S) nanoparticles with monodispersity and narrow size distribution in the polyamide-imide (PAI) nanocomposite coatings. The crystalline phases, size, morphologies, and growth mechanism of the in-situ-synthesized Ag2S nanoparticles were characterized by X-ray diffraction, ultrahigh-resolution field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The enhancement effect of such in-situ-synthesized Ag2S nanoparticles on the microhardness and tribological behaviors of the PAI nanocomposite coatings were also investigated and compared with mechanically mixed Ag2S particles. Results show that the growth of Ag2S particles is greatly limited during the in-situ preparation process. The Ag2S nanoparticles with small size ranging from 100 to 130 nm are purely formed and exhibit monodispersibility in the PAI nanocomposite coatings. Besides, the appropriate Ag2S nanoparticles greatly promote the microhardness and antiwear performance of the PAI nanocomposite coatings, especially when their incorporation content reaches 5.0 wt%. The enhancement effects of these in-situ-synthesized Ag2S nanoparticles on microhardness and wear resistance of PAI nanocomposite coatings are superior to that of the mechanically mixed Ag2S particles. This is attributed to the improvement of cohesion strength and the load-carrying capacity of the PAI nanocomposite coatings enhanced by in-situ-synthesized Ag2S nanoparticles.