TiN Coatings Research Articles

The Effect of Match between High Power Impulse and Bias Voltage: TiN Coating Deposited by High Power Impulse Magnetron Sputtering

Practical experience in the use of high power impulse magnetron sputtering (HiPIMS) technology has revealed that output bias current depends on the total energy output of the cathodes, which means that bias voltage settings do not necessarily match the actual output. In this study, we investigated the effects of bias current and voltage on the characteristics of titanium nitride thin films produced using high impulse magnetron sputtering. The bias current and voltage values were adjusted by varying the supplied cathode power and substrate bias under DC and pulsed-DC output models. Our results revealed that pulse delay (PD) and feed forward (FF) settings can be used to control bias current and voltage. Increasing the bias current from 0.56 to 0.84 was shown to alter the preferred orientation from (111) to (220), increase the deposition rate, and lead to a corresponding increase in film thickness. The surface morphology of all titanium nitride samples exhibited tapered planes attributable to the low bias current and voltage (−30 V). The maximum hardness values were as follows: DC mode (23 GPa) and pulsed-DC mode (19 GPa). The lower hardness values of pulsed-DC samples can be attributed to residual stress, preferred orientation, and surface morphology. The surface of the samples was shown to be hydrophobic, with contact angles of >100°.

Obtaining TiN Coatings by Reactive Anodic Evaporation of Titanium in a Gas Discharge with a Self-Heated Hollow Cathode

Obtaining TiN Coatings by Reactive Anodic Evaporation of Titanium in a Gas Discharge with a Self-Heated Hollow Cathode

Deposition of TiN and TiAlN Thin Films on Stainless Steel Tubes by a Cylindrical Magnetron Sputtering Method

Abstract Titanium nitride (TiN) and titanium aluminum nitride (TiAlN) coatings are very hard materials that are mostly coated on cutting tools to increase the tool life. These coatings have also been successfully applied as a coating material for biomedical applications mainly due to their tribological properties, biocompatibility, and affordable price. In an attempt to develop transition metal nitride coatings on specimens of cylindrical geometry, TiN and TiAlN thin films were deposited successfully on stainless steel tubes using a direct-current cylindrical magnetron cosputtering method. Both types of coatings were uniform in nature and had good adherence to the substrate. TiN and TiAlN thin films were characterized systematically to determine their structure, surface morphology, chemical states, chemical structure, and electrochemical behavior using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and potentiodynamic methods, respectively. The XRD patterns of the TiN and TiAlN coatings indicated (111) preferential orientation. Cross-sectional SEM images revealed a columnar growth of the coatings with an arrow-headed geometry. XPS characterization showed the presence of TiN, Titanium dioxide, titanium oxynitride, aluminum oxide, and aluminum nitride phases. Potentiodynamic polarization tests in 3.5 % sodium chloride solution revealed that the TiAlN coating exhibited superior corrosion resistance compared with the TiN coating. Furthermore, TiAlN coating showed 94 % of average absorption in ultraviolet-visible region using photospectrometry. The cylindrical magnetron sputter deposition technique enables development of uniform protective coatings on tubular geometries, which are frequently employed in solar thermal and nuclear applications.

Development of technology for forming vacuum-arc TiN coatings using additional impulse action

Development of technology for forming vacuum-arc TiN coatings using additional impulse action

Electrochemical, Tribological and Biocompatible Performance of Electron Beam Modified and Coated Ti6Al4V Alloy

Vacuum cathodic arc TiN coatings with overlaying TiO2 film were deposited on polished and surface roughened by electron beam modification (EBM) Ti6Al4V alloy. The substrate microtopography consisted of long grooves formed by the liner scan of the electron beam with appropriate frequencies (500 (AR500) and 850 (AR850) Hz). EBM transformed the α + β Ti6Al4V mixed structure into a single α’-martensite phase. Тhe gradient TiN/TiO2 films deposited on mechanically polished (AR) and EBM (AR500 and AR850) alloys share the same surface chemistry and composition (almost stoichiometric TiN, anatase and rutile in different ratios) but exhibit different topographies (Sa equal to approximately 0.62, 1.73, and 1.08 μm, respectively) over areas of 50 × 50 μm. Although the nanohardness of the coatings on AR500 and AR850 alloy (approximately 10.45 and 9.02 GPa, respectively) was lower than that measured on the film deposited on AR alloy (about 13.05 GPa), the hybrid surface treatment offered improvement in critical adhesive loads, coefficient of friction, and wear-resistance of the surface. In phosphate buffer saline, all coated samples showed low corrosion potentials and passivation current densities, confirming their good corrosion protection. The coated EBM samples cultured with human osteoblast-like MG63 cells demonstrated increased cell attachment, viability, and bone mineralization activity especially for the AR500-coated alloy, compared to uncoated polished alloy. The results underline the synergetic effect between the sub-micron structure and composition of TiN/TiO2 coating and microarchitecture obtained by EBM.

TiN versus TiSiN coatings in indentation, scratch and wear setting

The indentation response, scratch behaviour and wear performance of binary TiN and ternary TiSiN coatings under a variety of loading conditions were comparatively studied. The coatings were fabricated onto M42 steel substrates via closed field unbalanced magnetron sputtering ion plating. A maximum hardness value of ~40 GPa was obtained for one of the TiSiN coatings as compared to ~28 GPa for TiN. This was attributed to the nanocomposite structure, grain refinement, solid solution hardening and the higher compressive residual stress in the ternary coatings. The damage resistance of both the TiN and TiSiN coatings under indentation loading was governed by the dampening effects of sliding or shearing of the columnar grains along the grain boundaries coupled with the coatings’ respective mechanical characteristics. Improved scratch adhesion properties (i.e., higher LC1, LC2 and CPR values) were also observed for the TiSiN coatings that were underlain by their superior mechanical properties along with the graded structure, promoting the capacity to resist crack formation and delamination. Lower wear rates for the TiSiN coatings during dry sliding were found to be consistent with their higher H/Er, H3/Er2 and We values.

Friction behavior of TiN–MoS2/PTFE composite coatings in dry sliding against SiC

To improve the dry friction behavior of traditional hard coatings, MoS2/PTFE lubricating coatings were prepared on the PVD TiN-coated cemented carbide using spray method. The influences of MoS2/PTFE lubricating coatings on the primary characteristics of TiN coatings were investigated. Reciprocating sliding tests were carried out with the TiN–MoS2/PTFE coated specimen (T-M-P) under dry sliding conditions, and the tribological behaviors were compared to those of the TiN-coated one (T-N). The test results indicated that the adhesion force of coatings with substrate for T-M-P specimen increased, the surface micro-hardness, roughness and friction coefficient significantly decreased. Meanwhile, the surface adhesions and abrasion grooves of T-M-P specimen were reduced, and the main wear forms of T-M-P were abrasion wear and coating delamination. The MoS2/PTFE lubricating coatings can be considered effective to improve the friction properties of traditional hard coatings.

Fabrication of Thermal Plasma Sprayed NiTi Coatings Possessing Functional Properties

Thick NiTi shape memory alloy coatings (300–500 µm) were produced on graphite and AISI 304 substrates by radio frequency inductively-coupled plasma spray technology (RF-ICP) from feedstock NiTi powders. Their microstructure as well as chemical and phase composition were characterized and a methodology for the characterization of functional shape memory properties of the thick coatings was developed. The coatings exhibited cubic to monoclinic martensitic transformation and shape memory effect. The presented results prove that NiTi coatings with functional thermomechanical properties can be easily produced on structural materials by RF-ICP. Further optimization will be needed to prepare NiTi coatings with better microstructural and chemical homogeneity.

Metallic Material Selection and Prospective Surface Treatments for Proton Exchange Membrane Fuel Cell Bipolar Plates-A Review.

The aim of this review is to summarize the possibilities of replacing graphite bipolar plates in fuel-cells. The review is mostly focused on metallic bipolar plates, which benefit from many properties required for fuel cells, viz. good mechanical properties, thermal and electrical conductivity, availability, and others. The main disadvantage of metals is that their corrosion resistance in the fuel-cell environment originates from the formation of a passive layer, which significantly increases interfacial contact resistance. Suitable coating systems prepared by a proper deposition method are eventually able to compensate for this disadvantage and make the replacement of graphite bipolar plates possible. This review compares coatings, materials, and deposition methods based on electrochemical measurements and contact resistance properties with respect to achieving appropriate parameters established by the DOE as objectives for 2020. An extraordinary number of studies have been performed, but only a minority of them provided promising results. One of these is the nanocrystalline β-Nb2N coating on AISI 430, prepared by the disproportionation reaction of Nb(IV) in molten salt, which satisfied the DOE 2020 objectives in terms of corrosion resistance and interfacial contact resistance. From other studies, TiN, CrN, NbC, TiC, or amorphous carbon-based coatings seem to be promising. This paper is novel in extracting important aspects for future studies and methods for testing the properties of metallic materials and factors affecting monitoring characteristics and parameters.

Fabrication and characterization of high-performance Mo-doped TiN coatings

To realize the fabrication of Ti–Mo–N coatings with novel properties predicted towards industrial applications, Mo-doped TiN coatings have been fabricated by multi-arc ion plating with varied substrate bias, and systematically characterized. The as-deposited coatings show a 1.5 at% Mo content deficit due to melting point difference between Mo and Ti elements. X-ray diffraction (XRD) and X-ray photoelectron spectrum (XPS) results show the as-deposited coatings demonstrate a fcc-TiN + bct-Ti2N dual phase structure, with Mo solution into TiN lattice. The hardness of TiMo0.08N coatings is above 31.97 GPa, which first increases then decreases slightly, peaking at 34.26 GPa. The phenomenon is correlated to the decreased (111) while enhanced (220) preferred orientation. All coatings show adhesion properties above 65 N (>100 N when bias voltage is above −50 V) and friction coefficients (COFs) below 0.24, which is attributed to the formation of lubricant MoO3 phase in a surface tribochemical process, as confirmed by XPS and Raman spectra evidences. Electrochemical polarization curves reveal that all samples have higher corrosion potential and corrosion currents two order of magnitudes lower than the WC-Co substrates. Additionally, substrate bias voltage has little impacts on structures and properties of the coatings, which means a wide process window.

Effect of Si content on microstructure and tribological properties of Ti5Si3/TiC reinforced NiTi laser cladding coatings

NiTi98-xSixC2 (x = 0, 4, 8 wt%) coatings were prepared on Ti-6Al-4V substrate by laser cladding to improve the surface mechanical properties of NiTi coatings. The effects of Si content addition on the microstructure, phase composition, microhardness, and tribological properties of the coatings were systematically analyzed. The results show that NiTi98-xSixC2 (x = 0, 4, 8) coatings are mainly composed of NiTi, NiTi2, TiC, and Ti5Si3 phases. The rod-like phase of Ti5Si3 was found in NiTi90Si8C2 coating, while the rod-like phases were found broken. The fragmentation of the rod-like phase is related to the growth of the NiTi phase around it. At the same time, TEM results show that the NiTi (B2) phase and Ti2Si second phase are exited in the NiTi90Si8C2 coating. Ti2Si, which has not been decomposed into Ti5Si3, remains during the laser cladding process. In addition, the eutectic structure in NiTi90Si8C2 coating was observed in some regions. The average microhardness of the NiTi98-xSixC2 (x = 0, 4, 8) coating were at 534.08 HV0.5, 598.06 HV0.5, and 974.08 HV0.5, respectively. The wear resistance of NiTi98-xSixC2 (x = 0, 4, 8) coatings increased with the increased Si content. The NiTi90Si8C2 coating exhibits the highest microhardness (974.08 HV0.5) and wear resistance (friction coefficients, wear trace, widths loss weight, and wear rate are 0.320, ~1.25 mm, 12.2 mg, and 5.78 × 10−6 g/Nm, respectively). In NiTi90Si8C2 coating, Ti5Si3 phase plays a significant role in the second phase strengthening to improve its tribological properties. The above analysis confirms that NiTi90Si8C2 coating has optimal tribological properties.

Controlled Oxygen Incorporation in TiN Coatings via Heat Treatment for Applications in PEMFC Metallic Bipolar Plates

Improving the corrosion resistance while maintaining good electrical conductivity is of vital importance for the application of stainless steel in bipolar plates of polymer electrolyte membrane fuel cells (PEMFCs). Transition nitride coatings on steel surfaces, such as TiN, is considered as a possible solution. However, most coatings still fail to exhibit good corrosion resistance and high electrical conductivity simultaneously, especially after corrosion testing. This study prepares TiN on 316L stainless steel (SS) and conducts heat treatment on the TiN deposited samples at different temperatures. The corrosion behaviours of the prepared samples are investigated under the simulated working environments of fuel cell. Our results demonstrate that heat treatment at appropriate temperatures is an effective approach to improve the corrosion resistance of TiN coatings while maintaining a considerable electrical conductivity. The interfacial contact resistance (ICR) test results indicate that high temperature (450 °C) heat treatment has detrimental effect on the electrical conductivity of samples due to the formation of a thick oxide dominated layer, while samples heat treated at 300 °C only form graded layers with suitable oxide amount which endows the coated specimens with a very low ICR value both before and after corrosion tests. This suggests that the heat treatment of TiN coatings under suitable conditions is a feasible strategy to simultaneously achieve an enhanced corrosion resistance and a good electrical conductivity of the TiN coated samples for bipolar plates in PEMFCs.

High throughput optimization of hard and tough TiN/Ni nanocomposite coatings by reactive magnetron sputter deposition

A combinatorial thin-film synthesis approach together with a high throughput analysis methodology was successfully applied to synthetize TiN/Ni coatings with optimum mechanical properties. The synthesis approach consists of the deposition of TiN/Ni coatings with the Ni content ranging from around 0 to 20 at.% by reactive magnetron sputtering with a well-defined composition gradient, so that almost all possible compositions are produced in one single coating under identical conditions, removing uncertainties from processing conditions. The analysis methodology continuously screened the microstructure, residual stresses, hardness and fracture toughness of TiN/Ni coatings. The results show that a nanocomposite microstructure of equiaxed nanograins of crystalline δ-TiN embedded in a Ni rich amorphous phase is formed in the composition window between 8 and 12 Ni at.%. This microstructure offers a superior combination of hardness and toughness and a simultaneous reduction of residual stresses with respect to TiN coatings grown in the same conditions. Higher Ni contents are however detrimental because they compromise the integrity of the coatings.

Performance evaluation of titanium-based metal nitride coatings and die lifetime prediction in a cold extrusion process

Abstract Surface coating can greatly enhance the lifetime of cold extrusion die. It is a significant issue to evaluate the performance of coatings and even predict the lifetime of cold extrusion die. In this work, the titanium-based nitride coatings including TiN, TiAlN, and TiAlCrN were, respectively, deposited on the surface of high-speed steel substrate W6Mo5Cr4V2 (M2) by the physical vapor deposition technology. The hardness test, scratch test, Rockwell adhesion test, and pin-on-disc (POD) wear test were carried out aiming to investigate the performances of the three coatings including hardness, adhesion strength, and wear resistance. The results show that the TiAlCrN coating exhibits the highest hardness of 3,033 HV in comparison with TiN coating (1,222 HV) and TiAlN coating (1,916 HV), while it possesses poor adhesion strength and inferior wear resistance. Furthermore, the TiAlN coating presents the highest resistance to wear and spalling from the substrate. In addition, the Archard wear model of the coatings was solved and applied in the finite element model of cold extrusion to calculate the wear depth and lifetime of the cold extrusion dies. The results suggest that TiAlN coating is the optimal option for cold extrusion die as compared with TiAlCrN and TiN coatings. TiAlN coating can prolong the lifetime of the substrate die up to 260%.

INFLUENCE OF CORROSION PROCESSES ON FRICTION AND WEAR OF TIN COATINGS OF WIRE CONNECTORS

The paper describes the results of metallographic, tribological, and microscopic tests of wire connectors. It was shown that the structure and thickness of the tin layer on the copper element varies greatly. The paper describes the results of tribological investigations for electrical connectors in the initial state and covered with a layer of oxides formed as a result of corrosion. The results of tribological tests have shown a great influence of the oxide layer on friction and wear of tin coatings. The results of friction factor measurements were confirmed by microscopic observations. The tests confirmed that the oxide layer reduces plastic deformation of the tin coating and limits its tribological wear. Due to the brittleness and low adhesion of the oxide layer, friction-induced chipping was observed.

Cavitation erosion of monolayer PVD coatings – An influence of deposition technique on the degradation process

TiN, Cr–N, W, WC and WC/a-C: H coatings produced using Physical Vapour Deposition (PVD) method were investigated. TiN and Cr–N coatings were deposited using the cathodic arc evaporation (CAE-PVD) and reactive magnetron sputtering (RMS-PVD) techniques. W, WC and WC/a-C: H coatings were produced by the reactive magnetron sputtering (RMS-PVD) technique. Coatings were exposed to cavitation using a tunnel with a system of barricades. The influence of the deposition technique on the structure of the coating as well as on the degradation process has been discussed. It has been shown which degradation processes are independent of deposition techniques and which are dependent on them. The deposition technique had a higher impact on the droplet density (over 20-fold) than the deposited compound (nearly 2-fold). The highest density of droplets had TiN coatings deposited by the CAE-PVD technique, while the lowest had W-based coatings deposited by the RMS-PVD technique. The first symptoms of cavitation erosion of PVD coatings included the removal of some droplets from the coating surface and the coating undulation. The size of droplets did not affect their removal. Droplets can be divided into 1) droplets easy removable from the coating, 2) droplets requiring specific impact energy for their removal, and 3) droplets not removable from the coating, regardless of the degree of cavitation erosion development. Regardless of the deposition technique (CAE and RMS) and coating type (TiN or Cr–N), cavitation caused the phase transformation Fe-γ→Fe-α′ in the austenitic steel substrate. The intensity of this transformation depends on the deposition technique. High intensity of the phase transformation was obtained in the RMS coatings which are characterised by a low density of droplets. On the surface of the RMS coatings a larger size of puncture was formed than on the CAE coatings. It is shown that the droplets play an important role in the degradation as they are stress concentrators and also absorb some of the impact energy and affect the amount of energy used for fracture and transferred to the substrate.

Structure, mechanical properties and thermal stability of CrAlNbN/TiN multilayers

In this study, TiN coatings with favorable phase stability were introduced to CrAlNbN coatings for stabilizing the structure of CrAlNbN coatings during annealing. The structure, mechanical properties and thermal stability of CrAlNbN/TiN multilayers and the monolithic counterparts were comparatively studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), Thermogravimetric analysis (TGA) and nanoindentation. All coatings exhibit face-centered cubic structure, and CrAlNbN/TiN multilayer with smaller bilayer period reveals superlattice structure. The coherent growth of CrAlNbN sublayers along with TiN template layers, and the relatively higher binding energy of Ti–N bonds than Cr–N retards the thermal decomposition procedure of CrAlNbN/TiN multilayers, where the initiation temperatures of w-AlN precipitation and N-loss are elevated by 100 and 200 °C, respectively. The architecture of CrAlNbN/TiN multilayers effectively improves the capability of corresponding monolithic layers to maintain hardness upon thermal load, which is beneficial for their high-temperature applications.

Relationship between structure, surface topography and tribo-mechanical behavior of Ti-N thin films elaborated at different N2 flow rates

Titanium nitride films were deposited by reactive magnetron sputtering on Si (100) wafers, glass and Ti6Al4V substrates. The film deposition was carried out in a gas mixture of Ar and N2. The nitrogen content was varied between 0 and 30 % of the total gas mixture. This variation led to the formation of different films with different microstructures. The microstructure of the Ti-N coatings presented nanocomposites with a low tendency to surface oxidation. From a pure Ti to tetragonal Ti2N and cubic Ti-N microstructures, the films showed a (111) TiN plane growth that led to an increase in the lattice strain and a decrease in the grain size when increasing the nitrogen flow rate. The water-film contact angle measurements showed that the surface hydrophobicity increased with the increase of nitrogen content in the film. Mechanical properties were measured and a strong dependence between microstructure and hardness was found. The Ti-N deposited under 20 % of N2 exhibited the highest hardness, the best adhesion and wear resistance, and the lowest friction coefficient with the presence of (111) fiber texture.

Formation of highly uniform tin oxide nanochannels by electrochemical anodization on cold sprayed tin coatings

Abstract In this study, the self-organized nanoporous tin oxide films were prepared on cold sprayed tin and tin foil through a voltage-controlled anodization method. The optimized cold spray parameters were used to obtain a dense structure. The morphology and crystallinity of the samples were investigated by FE-SEM and XRD, respectively. Firstly, an amorphous oxide film (SnO) with a compact and less regular outer layer and an almost regular and uniform inner layer was grown during anodization. This structure cause formation of close pores at the surface, which reduces the appropriate properties of the porous structure. Herein, a simple way to attain a totally open nanoporous structure is reported. Pulsed ultrasonic anodization ensured to be an effective way to create a mostly uniform open pores structure with few lateral inner cracks. It was found that the porous structure prepared on cold sprayed tin and tin foil are different because of the difference in surface topography and imperfections. The current vs. time curves and the pores formation mechanism of cold sprayed tin and tin foil are discussed. The highest applicable annealing temperature for anodization of cold sprayed tin was 350 °C. Nanoporous structure and adhesion to the substrate were maintained perfectly during the annealing at this temperature. Subsequent annealing at higher temperatures leads to the collapse of the pores structure.

Effect of TiN Coating on the Fouling Behavior of Crud on Pressurized Water Reactor Fuel Cladding

A titanium nitride film was applied to mitigate the deposition of fouling deposits (crud) on pressurized water reactor fuel cladding. Titanium nitride was chosen as it reduces the van der Waals force, believed to be the dominant surface force at pressurized water reactor conditions, between crud and the substrate. Crud deposition experiments were conducted in a heated, flowing pressurized water reactor-simulant loop with uncoated and titanium nitride-coated Zr-Nb-Sn alloy tubes for 1–2 weeks. Crud morphology and thickness were investigated using focused ion beam–scanning electron microscopy, and crud chemical composition was measured via energy-dispersive X-ray spectroscopy. Results demonstrate that the titanium nitride coating effectively reduced crud deposition thickness compared to uncoated Zr-Nb-Sn alloy in the 2-week experiment. In addition, the titanium nitride coating increased the Ni/Fe ratio of the crud, which may help mitigate crud-induced power shifts.