Effect of nano-silica on the mechanical properties of acrylic polyurethane coatings

[Display omitted] •Erosion resistance of polyurethane clearcoats is significantly enhanced by nano-silica reinforcement.•Redispersibility, adhesion strength, micro-hardness, SEM analysis tests are performed.•Adhesion strength is enhanced by the addition of nano-reinforcements.•Micro-structure of the eroded clearcoats are studied for the better understanding of the main erosion mechanisms.•Inexpensive precipitated type of reinforcement is presented as replacement for the fumed type. A special focus has recently been made on the enhancement of the mechano-tribological properties of the clearcoats commonly used in several industries such as the automotive manufacturing sectors. However, still further investigations are needed for the better understanding of the behavior of such clearcoats in different working conditions. The purpose of the current research was investigating the erosion resistance, adhesive strength, micro-hardness and weathering stability of the acrylic-based polyurethane nano-composites which were reinforced by precipitated and fumed nano-silica particles. To achieve this, Zeta Sizer, scanning electron microscope (SEM), X-ray diffraction (XRD) and fourier transform infrared spectroscopy (FTIR) analyses were used. Furthermore, a series of experimental tests including the adhesive strength, toughness, micro-hardness and erosion resistance were carried out to measure the mechanical response of the fabricated clearcoats. It was concluded that the nano-silica additives significantly improve the adhesive strength, and highly increase the micro-hardness as well as the erosion resistance. It is also found that the precipitated nano-silica is able to create an inexpensive, hard and tough coatings rendering it very durable against wear, weathering conditions, and, thus, can be potentially employed as a reinforcing filler and as a replacement to the fumed clearcoats that are usually much more expensive than the proposed reinforcement.