RESUMEN
This study investigates the effect of deposition pressure on the microstructure and tribological properties of CrAgCeN coatings synthesized via unbalanced magnetron sputtering. The CrAgCeN coatings presented a face-centered cubic structure. As the deposition pressure increased, the surface grain topography of the CrAgCeN coatings transformed from a looser pyramidal structure to a denser structure, while their hardness H and elastic modulus E first increased and then decreased. The strengthening effect was mainly attributable to Ag and Ce elements. Conversely, the coefficient of friction (COF) and wear rates of the coatings reduced and then increased. Under 0.6-Pa deposition pressure, the COF and wear rate of the CrAgCeN coating were minimized (0.391 and 3.2 × 10-7 mm3/(N·m), respectively) while the H and E were maximized (14.2 and 206.2 GPa, respectively). The values of hardness, wear resistance, resistance of elastic strain to failure (H/E) and resistance to plastic deformation (H3/E2) were improved for the coatings by Ce. The wear mechanisms were adhesion and delamination. The wear mechanisms were adhesion and delamination. Selecting the appropriate deposition pressure can improve the tribological properties of the CrAgCeN coatings. The received results of research in this study allow us to establish a rational coating composition for deposition on tools providing an increase in machining efficiency of the materials used in engineering. CrAgCeN coating with excellent properties may be applied to steel substrate through the combined action of corrosion, high temperature and mechanics.
RESUMEN
Based on the wave absorption model of 3D woven fabric and the zero-reflection equations, a new structural design method of 3D electromagnetic (EM) wave-absorbing woven fabrics was obtained. The 3D woven fabrics fabricated by the proposed method had the structure of a bidirectional angle interlock. Continuous S-2 glass fibers were used as the matching layer of this 3D woven fabric, and continuous carbon fibers were used as the absorbing layer. The absorbing layer satisfied the equivalent EM parameters under the condition of zero reflection. The results of the simulation and experiment showed that the performance trends of the 3D wave-absorbing fabric obtained by this method were consistent with the theory, which verified the correctness of the structure design method. The 3D fabrics obtained by this method have the advantages of wide absorbing frequencies and good absorbing performance (-20 dB). This structural design method also has theoretical guiding significance for the development of 3D wave-absorbing fabrics.
RESUMEN
As the basic materials with specific properties, fabrics have been widely applied in electromagnetic (EM) wave protection and control due to their characteristics of low density, excellent mechanical properties as well as designability. According to the different mechanisms and application scenarios on EM waves, fabrics can be divided into three types: EM shielding fabric, wave-absorbing fabric and wave-transparent fabric, which have been summarized and prospected from the aspects of mechanisms and research status, and it is believed that the current research on EM wave fabrics are imperfect in theory. Therefore, in order to meet the needs of different EM properties and application conditions, the structure of fabrics will be diversified, and more and more attentions should be paid to the research on structure of fabrics that meets EM properties, which will be conductive to guiding the development and optimization of fabrics. Furthermore, the application of fabrics in EM waves will change from 2D to 3D, from single structure to multiple structures, from large to small, as well as from heavy to light.