Search

Abstract The fracture resistance of nanoscale MEMS films under high frequency impact seriously influences its service life. Nano impact test is a reliable technique to evaluate the fatigue fracture resistance of films by simulating the dynamic cyclic loading conditions. In this paper, a kind of Cu film was prepared by magnetron sputtering. The effects of loading parameters and indenter size on the fatigue damage behavior were studied for the Cu films during by nano impact test technique. The dislocation propagation and crack initiation during the nano impact process were also analyzed by molecular dynamics simulation. The results show that: Nano impact failure of Cu film can be divided into three stages and the main failure forms are cracks and delamination. The increase of the indenter radius leads to the increase of fatigue indentation size. The deformation range and damage accumulation degree of thin film material also increased correspondingly. With the increase of nano impact loading rate, the film material suffered more momentum from the indenter. The fatigue damage energy accumulation accelerates the damage. Highlights • Fatigue property of Cu Film was tested by nano-impact technology. • The nanometer impact fatigue process is simulated by molecular dynamics. • The damage mechanism of nanometer impact fatigue is analyzed. • Relationships between indenter size and loading rate and fatigue property are explained. [ABSTRACT FROM AUTHOR]

Abstract: Ni/nano-Al2O3 composite coating was fabricated by automatic brush-plating technique and manually plated Ni/nano-Al2O3 composite coating was also prepared as a comparison. The surface morphology, microstructure, microhardness and wear resistance performance of the coatings were investigated. The results showed that the automatically plated Ni/nano-Al2O3 composite coating possessed smoother, finer, denser microstructure and more uniform performance as compared to the manually plated Ni/nano-Al2O3 composite coating. The former exhibited higher microhardness and better wear resistance under lubricant condition compared with that of the latter. The results presented herein lay the groundwork for future systematical studies in producing nanocomposite coating by brush-plating technique in order to optimize mechanical and tribological properties. [Copyright &y& Elsevier]

Abstract: The 3Cr13 coating was prepared on the surface of 1045 steel by high velocity arc spraying method, and then treated by low temperature ion sulfuration to obtain the solid lubrication composite 3Cr13/FeS layer. SEM was used to observe the surface, cross-section and worn scar morphologies. XRD was utilized to analyze the phase structure. X-ray stress determinator was utilized to measure its residual stress. The nano-hardness and elastic modulus of composite 3Cr13/FeS layer were surveyed by the nano-indentation tester. The tribological properties were investigated on a ball-on-disk wear tester under dry and oil lubrication conditions. The results showed that the friction coefficient and wear scar depth of the composite 3Cr13/FeS layer were always lower than those of FeS film and 1045 steel under dry and oil lubrication conditions. Therefore the composite 3Cr13/FeS layer had excellent Friction-reduction and anti-wear properties. [Copyright &y& Elsevier]