Adhesive Pull and Shear Strength of Epoxy Nanocomposite Coatings Filled with Ultradispersed Diamond

摘要

In this work, epoxy diane oligomer éD-20 is used to form nanocomposite materials, polyethylene polyamine is used as a hardener, ultradispersed diamond with a particle size of 4–6 nm is used as a filler. The epoxy diane resin éD-20 was heated to 353 K. Then the éD-20 oligomer and the nanofiller were subjected to hydrodynamic mixing and subsequent ultrasonic treatment of the obtained composition. The effect of the concentration of diamond nanoparticles on the adhesion properties of composites was studied. The adhesion pull strength of materials was studied by measuring breaking stresses of cylindrical specimens glued by the nanocomposite adhesive. The adhesive shear strength was evaluated by the breaking stress of the lap joints of flat metal specimens glued by the nanocomposite adhesive. In both types of specimens, the glued sections had the same area. It has been found that the incorporation of nanoparticles in the concentration from 0.010 to 0.025 parts by weight per 100 parts by weight of éD-20 epoxy oligomer yields the adhesive pull strength of 25.0–26.3 MPa. The optimal concentration increases the latter value by a factor of 1.5 (to 34.3 MPa) and the adhesive shear strength – by a factor of 1.3 (to 10.8 MPa). The further increase in the concentration (0.075–1.0 parts by weight) is shown to deteriorate the adhesion strength. The nanocomposite coating–metal substrate bond breaking surface has been investigated. It is experimentally proved that the coatings with the cohesive nature of failure have the maximum adhesive pull strength, while those with the mixed (adhesive-cohesive) mode of failure exhibit an improved adhesive shear strength.