Mechanical Properties Of Multilayer Coatings Research Articles

Modeling Mechanical Properties of Multilayer Coatings TiAlN

The paper outlines two approaches (the ANSYS finite element modeling and the differential scheme of the self-consistency method) to model the mechanical properties of TiAlN multilayer coatings. To validate the experimental results, these findings were compared with the nanoindentation test results for single and multilayer coatings. This work has revealed the effect of Ti/Al ratio on the mechanical properties of multilayer coatings. The given approaches could be applied to calculate, with an acceptable margin of error, the mechanical properties of TiAlN multilayer coatings.

Mechanical properties of multilayer coatings TiAlN

This study aims to examine multilayer TiAlN coatings. The mechanical properties of the coatings were obtained based on micromechanics methods and finite element modeling of a representative volume of a layered medium in ANSYS. Our findings are in line with the data on coating nanoindentation. Besides, we have succeeded in finding the dependence of the mechanical properties of multilayer coatings on various Al/Ti ratios.

Effect of different topologies on microstructure and mechanical properties of multilayer coatings deposited by laser cladding with Inconel 625 wire

Different topologies of clad coatings mean different cladding strategies and cyclic thermal histories. In this study, two types of Inconel 625 multilayer coatings with parallel topology (The cladding direction between adjacent layers was parallel.) and perpendicular topology (The cladding direction between adjacent layers was perpendicular.) were fabricated respectively on 316 L substrate using an off-axis wire cladding system. The effects of different topologies on microstructure and mechanical properties of the coatings were investigated. The finite element (FE) model was adopted to predict the cyclic thermal histories in different topologies. The results showed that morphologies of the two topologies both presented good surface finish and free of crack and pore defects. Compared with perpendicular topology, for coatings with parallel topology, columnar dendrites in the upper and lower layers exhibited relatively consistent orientation since they complied with the movement direction of heat source. The parallel topology also exhibited better mechanical properties along the cladding direction due to the uniform cyclic thermal history. Although Laves phase pinned the migration of grain boundaries, it was also the main cause of producing microvoids that led to the fracture.

Fabrication of Ultralow Stress TiO2/SiO2 Optical Coatings by Plasma Ion-Assisted Deposition

Optical and mechanical properties of multilayer coatings depend on the selected layer materials and the deposition technology; therefore, knowledge of the performances of thin films is essential. In the present work, titanium dioxide (TiO2) and silicon dioxide (SiO2) thin films have been prepared by plasma ion-assisted deposition (PIAD). The optical, structural, and mechanical properties of thin films have been investigated using spectrometer/ellipsometer, X-ray diffraction (XRD), atomic force microscopy (AFM), and laser interferometer. The results show that TiO2 film fabricated by PIAD induces a high refractive index, wide optical band gap, amorphous structure, smooth surface, and tensile stress. In the case of SiO2 film, high bias voltage leads to dense structure and compressive stress. As an application, a three-wavelength high reflectance at 632.8, 808, and 1550 nm was optimized and deposited. The dependence of total stress in the multilayer on the substrate temperature was studied as well. In conclusion, it was demonstrated that PIAD is an effective method for the preparation of ultralow stress TiO2/SiO2 multilayer films. The achieved stress was as low as 1.4 MPa. The result could provide guidance to the stress optimization of most optical components without prefiguring, backside coating, and postdeposition treatments.

STRUCTURE AND MECHANICAL PROPERTIES OF MULTILAYER COATINGS (TiAlCrY)N/ZrN

Multiperiodic nitride coatings (TiAlCrY)N/ZrN with different layer thicknesses are formed by vacuum-arc evaporation in a nitrogen atmosphere (0.2…0.6 Pa) of two targets, TiAlCrY and Zr. The targets were located along one straight line at equal distances from the perpendicular axis on which the substrates were placed. The rotation of the axis with the substrates was carried out either continuously or with a fixed delay at the evaporators. The duration of the process was chosen so that the total thickness of the coating (total thickness of the bilayers) was 10…11 μm. The effect of nitrogen pressure and modulation period on the structural-phase state, elemental composition, and mechanical properties of multilayer coatings has been studied. An increase in the partial pressure of nitrogen and, consequently, its content in the coating leads to an increase in hardness. Reducing the thickness of the layers in the coatings increases the adhesive strength of the coatings and does not have a significant effect on the microstresses in the coating.

Influence of Modifying Nanoadditives on the Properties of a Multilayer Composite Coating Obtained by Laser Surfacing

This paper presents the results of an experimental investigation of the influence of modifying nanoadditives on the structure and mechanical properties of multilayer coatings obtained by the laser surfacing of a composite powder with a strengthening phase. The powder of a nickel-based Ni–Cr–B–Si–Fe self-fluxing alloy with a strengthening phase of tungsten carbide was used as the surfacing material; and a mixture of nanosized refractory powders of titanium nitride and yttrium oxide clad with iron and chromium was used as the modifying additive. It has been established that the surfaced coating represents a complex system of phases formed in the process of melting and interaction of chemical elements of the substrate and of the surfaced powder mixture. The main component of the coating is the compound of nickel with iron of an Ni3(Fe, Cr) type. A partial dissolution of the strengthening phase occurs in the melting process depending on the concentration of the nanomodifier. In the case under consideration, the optimal amount of the modifying additive, which provides a maximum increase in the hardness and wear resistance of the composite coatings of the Ni–Cr–B–Si–Fe/WC system, is 0.1 wt % refractory TiN + Y2O3 nanopowders in the composite material.

Measuring Elastic Properties of the Constituent Multilayer Coatings for Different Modulation Periods

This paper is developed to characterize mechanical properties of multilayer coatings for different modulation periods. To that end, Dimensional Analysis Method (DAM) and Finite Element Method (FEM) are applied. Based on these methodologies, two dimensionless forms for the new model are expressed. Numerical nanoindentation tests are carried out for different set properties of multilayer coatings in order to validate the proposed model. Therefore, the mechanical properties of multilayer thin films are identified according to the reverse analysis algorithm. Hence, the input and the identified properties are consistent which ensure the effectiveness and the reliability of the proposed model. Moreover, a case study of Ti-TiN multilayer coating deposited on Zr-based metallic glasses was considered. As a result, the new model is useful for multilayer coatings for different modulation periods and can be used for technological applications.

Improvement in mechanical properties of nano-structured HA/TiO2 multilayer coatings deposited by high velocity suspension flame spraying (HVSFS)

In order to improve mechanical properties of HA coatings, nano-structured HA/TiO2 multilayer coatings composed of TiO2 bond layer, HA/TiO2 intermediate layer with different TiO2 contents and HA top layer were prepared by a high velocity suspension flame spraying (HVSFS) method using nano-sized HA and TiO2 powders. Phase constitution, compositions and microstructures were characterized by XRD, XPS, FTIR and SEM. Mechanical properties of multilayer coatings were investigated in comparison with the pure HA coating. Results show that multilayer coatings were mainly composed of HA and TiO2 phases, and presented well-bonded coating/substrate interfaces and porous surfaces as well as graded chemical compositions in coating thickness. Microhardness and Young's modulus of HA/TiO2 intermediate layers were increased with the TiO2 contents due to its reinforcement, and HA/TiO2 multilayer coatings revealed gradual mechanical properties from the TiO2 bond layer to HA top layer. Tensile strengths of HA/TiO2 double-layer coatings were improved due to TiO2 reinforcement in comparison with the pure HA coating. Wear properties of HA/TiO2 multilayer coatings were tested by a pin-on-disc method and were improved due to the presence of intermediate layers resulting in lower wear rates than that of the pure HA coating.

Mechanical behavior of TiN/TiC multilayer coatings fabricated by plasma assisted chemical vapor deposition on AISI H13 hot work tool steel

In the present paper, mechanical properties of multilayer coatings were investigated. Titanium nitride/titanium carbide (TiN/TiC) multilayer coatings were prepared on the surface of AISI H13 hot work tool steel by the pulsed-DC plasma assisted chemical vapor deposition (PACVD). The microhardness, the toughness, the wear loss and the friction coefficient were measured by the Knoop and the Vickers hardness test and the pin on disk wear test. The optical microscopy was also used to examine worn surfaces and to characterize wear mechanisms. The field emission scanning electron microscopy (FE-SEM) and the grazing incidence X-ray diffraction (GIXRD) were applied to study the crystalline structure of multilayer coatings. Multilayer coatings with 10 layers exhibited lower friction coefficient (as 0.2), lower wear loss and higher toughness (17.7MPa·m1/2) than those values in other multilayer coatings. Increasing the number of layers increased the microhardness, the fracture toughness and the wear resistance with respect to single-layer coatings.

A Numerical Study on the Mechanical Behaviour of Hard Coatings with Ductile Interlayers under Depth-Sensing Indentation

In the present study, numerical simulations of nanohardness tests of titanium aluminium nitride (TiAlN) hard coatings with titanium and aluminium ductile interlayers were performed in order to determine the influence of interlayers of ductile metals on the overall mechanical properties of multilayer coatings. The investigation was designed to determine the role of ductile interlayers in altering the hardness value and the Young´s modulus of the multilayer coating as a whole, in comparison with a monolayer TiAlN hard coating, for the cases of composites with different numbers and thicknesses of interlayers.

Measurement of mechanical properties of multilayer coatings by nanoindentation

Multilayer protective coatings of alternate aluminium and titanium diboride TiB2 layers have been tested by nanoindentation to measure both hardness and Young's modulus values. The initial results show that the values obtained depend upon the depth of indentation. An alternative view is presented to show that by considering the percentage of each coating in contact with the indenter a single relationship between either hardness or Young's modulus and the amount of aluminium layer penetrated can be produced. This technique allows the influence of the percentage ceramic on the results obtained to be identified. Comparison of the nanoindentation results with three point bending tests show how the coating structure influences the results obtained.