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In order to obtain films with better mechanical properties and fracture toughness, the (TiAlCrZrNb)- Six-N (x=0, 4%, 8%, 12% and 16%) high entropy ceramic nanocomposite films with different Si contents were deposited on Si substrate by magnetron sputtering technology. The effects of Si doping on the microstructure, mechanical properties! and fracture toughness of the films were investigated by X-ray diffractometry, scanning electron microscopy, high-resolution transmission electron microscopy and Nano indentation apparatus. The results show that the mechanical properties and fracture toughness of the films increase first and then decrease with the addition of Si element, which can be attributed to the formation of nanocomposite structures. When Si content is 4%, (TiAlCrZrNb)-Six-N film has the best comprehensive mechanical properties, and Us maximum hardness and elastic modulus are 22.7 GPa and 192.0 GPa, respectively. In this case, the fracture toughness reaches the best, and the radial crack length C as 6.760 µm, The K1C was 1.77 MPa • m1/2. [ABSTRACT FROM AUTHOR]

In order to explore the influence of the thickness of Ni-P transition layer on the preparation of Ni-P-PTFE coating on stainless steel surface. Ni /N-P /Ni-P-PTFE three-layers structure gradient coating was prepared on stainless steel by electroplating combined with electroless plating. Scanning electron microscopy (SEM), X-ray diffraction (XRD), nano indentation, friction and wear tester, scratch tester and contact angle tester were used to characterize and test the microstructure, mechanical properties, adhesion and anti-adhesion property of the gradient coating. The results showed that, with the increased of N-P transition layer deposition time, the transition layer gradually thickened, the PTFE content in N-P-PTFE first decreased and then increased, the hardness and adhesion of N-PTFE coating first increased and then decreased. The maximum values of hardness and adhesion reach to 4.18 GPa and 13.49 N respectively when the N-P deposition time was 20 min. When the N-P deposition time was 25 min,the friction coefficient reached the minimum value of 0.17, and the contact angle between the surface of Ni-P-PTFE coating with water-based and oil-based liquid reached the maximum value of 101.1° and 60.06° respectively. At this time, the Ni-P-PTFE coating showed excellent adhesion resistance. [ABSTRACT FROM AUTHOR]