Microstructural changes in multilayer TiAlN cathodic arc evaporation coatings during milling of titanium α+β alloys

Microstructure and mechanical properties evaluation of cathodic arc deposited CrCN/ZrCN multilayer coatings

Modifying the architecture of multilayer hard coatings allows to adjust the mechanical properties of these materials for a given application. Within this work, the effect of the bilayer thickness (Λ) and the individual sublayer thickness ratio on the microstructure and mechanical properties of ZrN/TiN multilayer coatings was investigated. Multilayer coatings with Λ of 570, 320 and 35 nm were deposited by cathodic arc evaporation and compared to TiN and ZrN single-layer coatings. The microstructure was investigated by X-ray diffraction (XRD) and scanning electron microscopy. All coatings exhibit a single phase face-centred cubic structure and a predominant (111) texture. A columnar structure was observed for all coatings and grain growth extending beyond the ZrN/TiN interfaces was evident in all multilayers. For all coatings, compressive residual stresses were determined by XRD using the sin 2 ψ method, where the multilayer sample with the largest Λ exhibited the highest compressive residual stress of −1.7 ± 0.2 GPa. Lower compressive residual stresses could be correlated with decreasing Λ and decreasing ZrN:TiN thickness ratio. Nanoindentation experiments as well as micro-mechanical bending tests were conducted to assess the mechanical properties of the coatings. The ZrN/TiN multilayer sample with Λ of 35 nm showed the highest hardness of 28.0 ± 1.1 GPa. This value is similar to the TiN single-layer and higher compared to the ZrN single-layer, which exhibited a hardness of 27.9 ± 1.4 GPa and 25.8 ± 1.3 GPa, respectively. While the ZrN single-layer showed the highest fracture toughness, the ZrN/TiN multilayer samples were identified as the mechanically stiffest and strongest of the investigated coatings, since they exhibited a higher fracture stress compared to the single-layer coatings. The obtained results allow to optimise the architecture of ZrN/TiN multilayer coatings yielding the desired coating properties for application in the cutting industry. • Arc evaporated ZrN/TiN multilayer coatings with varying bilayer thickness Λ • Smaller Λ leads to grain refinement and more pronounced (111) texture. • Multilayer coating with lowest Λ exhibits the highest hardness. • Highest fracture toughness for ZrN single-layer coating • Improved fracture stress for multilayers compared to single-layers

ABSTRACTAlTiN, AlTiBN, and AlTiTaN coatings were deposited on cemented carbide substrate by cathodic arc evaporation. Scanning electron microscopy, X-ray diffraction, nanohardness testing, and scratch testing were used to examine the coating thickness, microstructure, hardness, adhesion strength, and oxidation resistance. The incorporation of B and Ta into the AlTiN coatings increased their hardness and oxidation resistance. In titanium-milling experiments using these three coatings, AlTiBN-coated carbide tools had the longest lifetime at cutting speed of 60 m/min. This is attributed to less delamination and chipping at the cutting edge, due to the coating’s high hardness, good oxidation resistance, and sufficient adhesion strength. The major wear mechanisms of these coated tools are adhesive wear, oxidation, and chipping.

The main goal of this study is to compare the electrochemical behavior of CrN/TiN multilayer coating and TiN single-layer coating applied by cathodic arc evaporation (CAE) -physical vapor deposition (PVD) on the substrate of Ti-6Al-4 V in Hank’s solution. So, a TiN single-layer coating was formed using PVD method as well as CrN/TiN multilayer coating under totally the same conditions including deposition temperature, working pressure, bias voltage, cathode current and deposition time. To identify the phases in the coatings, X-ray diffraction (XRD) was utilized in order and field emission scanning electron microscopy (FE-SEM) was used in order to study the microstructure of coating. Potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) tests were also carried out for corrosion measurements. In the corrosion evaluation, the PDP and EIS tests were performed for the samples after immersion in Hank’s solution for 24 hours to reach the steady state. The obtained results from PDP curves showed that the specimen with CrN/TiN multilayer coating exhibited better corrosion behavior than the TiN single-layer coatings. This improvement in corrosion resistance is probably due to the high density of the layers in the CrN/TiN multilayer coating that prevents the penetration of the corrosive solution to the substrate.

Anticorrosive yet conductive Hf/Si3N4 multilayer coatings on AZ91D magnesium alloy by magnetron sputtering

Ti-Al-Si target and Cr-Si target are sputtered alternately to develop a multi-layered nitride coating on a steel mold to improve die-casting lifetime. Prior to the multi-layer deposition, a CrN layer is developed as a buffer layer on the mold to suppress the diffusion of reactive elements and enhance the cohesive strength of the multi-layer deposition. Approximately 50 nm CrSiN and TiAlSiN layers are deposited layer by layer, and form about three μm-thickness of multi-layered coating. From the observation of the uncoated and coated steel molds after the acceleration experiment of liquid metal injection casting, the uncoated mold is severely eroded by the adhesion of molten metallic glass. On the other hand, the multi-layer coating on the mold prevents element diffusion from the metallic glass and mold erosion during the experiment. The multi-layer structure of the coating transforms the nano-composite structured coating during the acceleration test. Since the nano-composite structure disrupts element diffusion to molten metallic glass, despite microstructure changes, the coating is not eroded by the 1,050 oC molten metallic glass.

Microstructure, mechanical properties and cutting performance of Cr1-yTayN single layer and Ti1-xAlxN/Cr1-yTayN multilayer coatings

The single-layer nitride coatings (TiN; ZrN; (Ti,Zr)N; (Ti,Al)N; (Ti,Zr,Al)N) were deposited by DC magnetron sputtering (MS), cathodic arc evaporation (CAE), pulsed magnetron sputtering (PMS), and combined methods (CAE + MS and CAE + PMS). During the single-layer coating deposition period, only one of the technological parameters was changed: evaporator arc current (Iarc = 75–80 A), magnetron discharge power (N = 1.5–9.0 kW), bias voltage on the substrate (Ubias = 40–200 V), partial pressure of the gas mixture of nitrogen and argon (P = 0.24–1.4 Pa), the nitrogen content in the gas mixture (N2 = 12–100%) and the duration of the coating deposition (Tc = 5–45 min). The single-layer nanostructured coatings with preset structure, elemental and phase composition were obtained after optimization of deposition technological parameters. The failure pattern and surface morphology, grain size and coating thickness of single-layer and multi-layer coatings were examined using the field emission electron microscope Ultra 55 with EDAX microanalyzer. To determine metal concentration in the coatings, a local chemical analysis was carried out by EDAX microanalyzer. The corrosion behavior of the single-layer two-, three- and multicomponent nitride coatings on the hard alloy, tool steel, and low carbon steel in the 5% NaOH and 3% NaCl was evaluated employing electrochemical techniques such as electrochemical impedance spectroscopy (EIS) and polarization curves. Multilayer nitride coatings were developed on the basis of single-layer coatings with a maximum protective effect in the 5% NaOH and 3% NaCl. The data of phase and elemental composition, and corrosion properties of single layer nitride coatings was presented in detail.

Failure and deformation mechanisms during indentation in nanostructured Cr/CrN multilayer coatings

Erosion resistance of the nanostructured Cr/CrN multilayer coatings on Ti6Al4V alloy

Mechanical and tribological properties evaluation of cathodic arc deposited CrN/ZrN multilayer coatings

X-ray residual stress analysis on CrN/Cr/CrN multilayer PVD coatings deposited on different steel substrates

Corrosion, wear, and friction behavior of a number of multilayer two-, three- and multicomponent nitride coatings on different substrates, depending on the phase and elemental composition gradient

In this research, a ZrN/CrN multilayer nanostructured coating was applied on AISI 304 stainless steel substrate using physical vapor deposition (PVD) in type of cathodic arc evaporation (CAE). The microstructure evaluation of the specimens were analyzed by x-ray diffraction and scanning electron microscopy. Impedance spectroscopy tests were utilized to evaluate the corrosion behavior of ZrN/CrN multilayer nanostructured coating and the substrate in 3.5 wt% NaCl solution. Applying CAE technique, ZrN/CrN multilayer nanostructured coating having high density and adhesion was successfully made. The corrosion results revealed that ZrN/CrN multilayer nanostructured coatings had an exceptionally high polarization resistance compared to AISI 304 stainless steel substrate. Moreover, the corrosion results showed the desired corrosion behavior in the ZrN/CrN multilayer nanostructured coating towards the AISI 304 substrate within the 3.5 wt% NaCl solution due to the presence of distinct layer resulting in a barrier against penetration of the corrosive solution. Scanning electron microscopy micrographs revealed that the surface of the ZrN/CrN multilayer coating is free of pits or any serious damage.

Modulation periods and ratios induced changes of microstructure and mechanical properties of AlN/ZrB 2 multilayered coatings