Effects of 3D Roughness Parameters of Sandblasted Surface on Bond Strength of HVOF Sprayed WC-12Co Coatings

Abstract

This work aims to reveal the effects of 3D roughness parameters of sandblasted surfaces on bond strength between thermal spray coatings and substrates. The investigation was carried out on the surface of AISI 4140, which were pretreated with automatic-sandblasting system. 3D topography and roughness parameters were analyzed by a 3D optical profiler. The bond strength of WC-12Co coatings was measured using a pull-off test method. Scanning electron microscope revealed that the morphology of the surface after sandblasting was rough. Furthermore, the surface topography was characterized by several irregular peaks and pits with different directions and no fixed orientation randomly distributed on sandblasted surface. The average values for surface roughness Sa = 4.84 ± 0.34 μm and bond strength = 32.8 ± 2.8 MPa were obtained. In terms of 3D roughness parameters, Sa, Sdr, Sdq and Sq were found to have more significant impact on affecting the bond strength, showing a nonlinear regression relationship. Furthermore, bond strength was positively correlated with Sa, Sdr and Sdq, while inversely proportional to Sq. This confirmed that a greater surface roughness of a sandblasted surface was not more conducive to the improvement of bond strength. The influence mechanism of each parameter was discussed, which was consistent with the regression mathematical model.

Interface Bonding Properties and Mechanism of Steel Fiber and Hot Melt Adhesive via Interface Design Engineering

“…As can be seen from the data in Figure a, the bond strength of the sandblasting/HMA composite increased by 54% compared to the untreated/HMA composite. During sandblasting, driven by compressed air, sand particles hit the surface of the fiber at high speeds, randomly colliding and repeatedly scouring a large number of uneven sand particles. , As a result, the sandblasting samples exhibited a variety of anisotropic surfaces without any specific orientation, which favors the combination of HMAs and fiber surfaces. During this process, surface oils and other impurities are also removed, further enhancing the bond strength of the composite.…”