Unbalanced Magnetron Sputter Ion Plating Research Articles

Comparative Performance Evaluation of Magnetron Sputtered TiN, AlCrN, and TiAlCrN Coatings

This study presents a comparative performance evaluation of magnetron-sputtered TiN, AlCrN, and TiAlCrN coatings on tool steel substrates. Coatings play a pivotal role in enhancing the durability of engineering components exposed to harsh conditions. TiN is known for outstanding hardness and durability, AlCrN for superior wear resistance, and TiAlCrN for exceptional thermal stability and oxidation resistance. The substrate (EN 1.2363) underwent PVD coating using a closed-field unbalanced magnetron sputter ion plating (CFUBMSIP) process in a water-cooled stainless-steel vacuum chamber with four magnetron ports, operating for 3 hours per batch followed by 12 hours of natural convection cooling, utilizing TiN, AlCrN, and TiAlCrN films deposited for 180 minutes in an Ar and nitrogen atmosphere. X-ray diffraction (XRD) revealed distinctive crystal structures, with all coatings exhibiting a common preferred orientation of the (111) plane and TiAlCrN showing a ternary nitride phase. Scanning electron microscopy (SEM) images displayed the compact nature of TiAlCrN with finer grains, while TiN exhibited a densely compacted with no evidence of delamination and AlCrN showed denseness with smaller grains. Nano-indentation test was conducted to assess the coatings' hardness and elastic modulus. TiAlCrN exhibited the highest hardness (3091±243 HV), highest elastic modulus (369.86±54.19 GPa), and the best wear rate (0.1887 x 10-4 mm3/Nm-1) suggesting potential suitability for applications demanding superior rigidity and wear resistance. The study provides valuable insights for materials scientists and engineers in optimizing coating selection for specific applications.

A comprehensive performance study of NiCrCN coated 316L stainless steel as bipolar plates for proton exchange membrane fuel cell

NiCrCN coatings are deposited on the surfaces of 316 L stainless steel (SS316L) substrates via closed field unbalanced magnetron sputtering ion plating (CFUMSIP) to improve the corrosion resistance and electrical conductivity of proton exchange membrane fuel cell (PEMFC) bipolar plates. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results show that CrN, Cr2N, Ni, and Cr7C3 phases exist in NiCrCN coatings. As the Cr target current grows from 2 A to 6 A, the Cr7C3 content in the carbon compounds increases from 3.39% to 11.46%, and the interfacial contact resistance (ICR) value is reduced from 18.0 mΩ cm2 to 11.2 mΩ cm2. When the Cr target current reaches 4 A, the NiCrCN coating shows the most intensive cross-sectional growth pattern by cold-field scanning electron microscopy (CFSEM) results, and the current density after prolonged polarization (0.11 μA cm−2) is much lower than that of SS316L (1.86 μA cm−2).

Investigation of corrosion protection with conductive chromium-aluminum carbonitride coating on metallic bipolar plates

To further enhance the performance of metal bipolar plates, the CrAlCN coating with high corrosion resistance and conductivity was deposited on the SS316L substrate by using Closed Field Unbalanced Magnetron Sputter Ion Plating (CFUMSIP) technique. Meanwhile, the inexpensive acetylene gas (C2H2) was utilized as a carbon source. XRD and XPS results indicate that the proportion of carbides in the coating increase with increasing carbon contents. Electrochemical measurements show that the C-doped coating significantly improves the corrosion resistance of the SS316L bipolar plates. The C doping enhances the conductivity of the CrAlN coating, and the C-doped sample obtains the lowest ICR value (2.94 mΩ cm2, before corrosion), which is well below the DOE target (≤10 mΩ cm2). The excellent conductivity and hydrophobicity of C-doped coating increase the power density of a single cell. This study demonstrates that the CrAlCN coatings have great application prospects in the bipolar plates field.

Investigation of corrosion properties with Ni–P/TiNO coating on aluminum alloy bipolar plates in proton exchange membrane fuel cell

Aluminum alloy bipolar plates have unique application potential in proton exchange membrane fuel cell (PEMFC) due to the characteristics of lightweight and low cost. However, extreme susceptibility to corrosion in PEMFC operation condition limits the application. To promote the corrosion resistance of aluminum alloy bipolar plates, a Ni–P/TiNO coating was prepared by electroless plating and closed field unbalanced magnetron sputter ion plating (CFUMSIP) technology on the 6061 Al substrate. The research results show that Ni–P interlayer improves the deposition effect of TiNO outer layer and increase the content of TiN and TiOxNy phases. Compared to Ni–P and TiNO single-layer coatings, the Ni–P/TiNO coating samples exhibited the lowest current density value of (1.10 ± 0.02) × 10−6 A·cm−2 in simulated PEMFC cathode environment. Additionally, potential cyclic polarization measurements were carried out aiming to evaluate the durability of the aluminum alloy bipolar plate during the PEMFC start-up/shut-up process. The results illustrate that the Ni–P/TiNO coating samples exhibit excellent stability and corrosion resistance.

Study on Corrosion Resistance and Conductivity of TiMoN Coatings with Different Mo Contents under Simulated PEMFC Cathode Environment.

TiMoN coatings with different Mo contents on a SS316L substrate are deposited by using closed field unbalanced magnetron sputtering ion plating (CFUMSIP) technology to enhance the corrosion resistance and durability of stainless steel (SS) bipolar plates (BPs) in proton exchange membrane fuel cell (PEMFC) during the start-up/shut-down process. The electrochemical test results illustrate that TiMoN-4A coating has extremely good corrosion resistance compared to other coatings. The potentiostat polarization (+0.6 VSCE) tests indicate that the corrosion current density (Icorr) of TiMoN-4A coating is 5.22 × 10−7A cm−2, which meets the department of energy 2020 targets (DOE, ≤1 × 10−6 A cm−2). Otherwise, TiMoN-4A coating also exhibits the best corrosion resistance and stability in potentiostatic polarization, electrochemical impedance spectroscopy (EIS), and high potential (+1.2VSCE) polarization tests. The interfacial contact resistance (ICR) measurement results show that TiMoN-4A coating has the minimum ICR of 9.19 mΩ·cm2, which meets the DOE 2020 targets (≤10 mΩ·cm2).

Influence of substrate bias on the scratch, wear and indentation response of TiSiN nanocomposite coatings

TiSiN coatings were synthesised onto AISI M42 tool steel substrates via closed field unbalanced magnetron sputtering ion plating , using bias voltages of −40 and −50 V. The aim of this study is to investigate the underlying deformation mechanisms of TiSiN coatings, prepared at two different substrate bias voltages, following scratching, wear and indentation tests . A graded columnar microstructure evolved in these coatings. A hardness value of ~30.2 GPa was determined in the coating prepared at the lower bias voltage (i.e., −40 V), which was correlated to the fine nanocomposite structure and the presence of a high compressive residual stress. Of note, for the coating deposited at −40 V enhanced scratch adhesion strength , i.e., higher critical loads (L c1 and L c2 ) against cohesive and adhesive failure were determined with the higher H/E r and H 3 /E r 2 values. The improved scratch resistance was ascribed to the hierarchical structure that hindered crack propagation in the TiSiN coatings during progressive loading. An approximately 21% decrease in wear rate was obtained at the lower bias voltage, which was attributed to the slightly lower Si concentration (~8.3 at.%) and, in turn, higher hardness. Deformation behaviour under indentation loading was dominated by shear sliding along the columnar grain boundaries. • ~20% increase in L c1 was found in the TiSiN coating with the lower Si content. • The scratch resistance was enhanced by the coating's hierarchical structure. • ~21% reduction in wear rate was achieved in the coating with the lower Si content. • Indentation deformation was governed by columnar shear sliding.

Investigation of high potential corrosion protection with titanium carbonitride coating on 316L stainless steel bipolar plates

In order to improve the durability of stainless steel bipolar plates at high potential during the start-up/shut-down process of proton exchange membrane fuel cell (PEMFC), TiN and TiCN coatings with different C element contents are deposited on the 316L stainless steel substrates by using Closed Field Unbalanced Magnetron Sputter Ion Plating. The electrochemical test results show that the TiCN-2sccm sample possesses excellent corrosion resistance compared to other samples. The results of interfacial contact resistance (ICR) measurements show that the minimum ICR value of the TiCN-2sccm sample is 10 mΩ cm2, which meets the Department of Energy targets.

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.

Microstructure and High-Temperature Friction and Wear Properties of CrAlMoN Film

Closed-field unbalanced magnetron sputtering ion plating was used to form CrAlMoN films on the surface of single-crystal silicon and tool steel. The composition and morphology of the films were determined through energy-dispersive X-ray spectroscopy, scanning electron microscopy, and transmission electron microscopy. High-temperature friction and wear properties of CrAlMoN films were assed using a friction and wear tester and by studying the film cross-sections. The hardness of CrAlMoN films was determined using a nanoindenter. Results showed that CrAlMoN films have a nanomultilayer structure, with the same fcc structure as CrN. At room temperature, the hardness and wear resistance of CrAlMoN films are greater than that of CrAlN films. The friction properties of CrAlMoN films varied widely with an increase in the temperature. At 600 °C, the friction performance of CrAlMoN films degrades rapidly, and the degree of film wear is significantly increased. In contrast, CrAlN films retain high wear resistance at 600 °C.

Сравнительная оценка триботехнических характеристик твердосмазочных покрытий, нанесенных методом замкнутого поля несбалансированного магнетронно-ионного распыления, для различных условий функционирования

This paper presents a comparative assessment of the tribotechnical characteristics of friction pairs with solid lubricant coatings (SLC) based on the MoS2 suspension application of VNII NP 212 and SLCCFUBMSIP deposited by the closed field unbalanced magnetron sputter ion plating (CFUBMSIP) of combined compositions MoS2+Ti, MoS2+Zr, MoS2+Cr , MoS2+W. It was established that under normal atmospheric conditions in the friction modes corresponding to the contact friction temperature of 157 °С, the life of SLCCFUBMSIP was 42.1% higher, and the coefficient of friction (ffr) was on average 2 times lower than that of SLC VNII NP 212. The average value of the life reduction coefficient for SLCCFUBMSIP during the transition from normal atmospheric conditions to water was 2.98. Under normal atmospheric conditions and in water, the SLCCFUBMSIP coefficient of friction was in the range of 0.02–0.04, and in an oil environment it ranged from 0.03 to 0.08. SLCCFUBMSIP based on pure MoS2 in normal atmospheric conditions, in water and oil was practically unusable.

Enhancing the adhesion strength and wear resistance of nanostructured NiCrN coatings

NiCrN coatings, with varying Ni contents, were deposited on AISI M2 tool steel substrates using closed field unbalanced magnetron sputtering ion plating (CFUMSIP) where the NiCr target current (INiCr) was varied. An evolution of the graded columnar structures was found in these coatings, where increased incorporation of nickel induced grain refinement, as well as a reduction in values of both hardness (H), elastic modulus (Er) and elastic recovery (We). The influence of variations in the microstructure and mechanical properties on the adhesion behaviour and tribological performance of these NiCrN coatings was investigated. Scratch test results demonstrated that higher critical loads (Lc1 and Lc2) suppressed both cohesive and adhesive failure in coatings which exhibited higher values of H/Er, H3/Er2 and We. The failure mode under progressive scratch loading was controlled by the hierarchical design of the NiCrN coatings that enhanced adhesion and prevented crack propagation through the coating. For the coatings with lower Ni contents improved wear resistance was ascribed to not only higher H/Er, H3/Er2 and We values of these coatings, but also the graded interlayers that delocalised the stress distribution during dry sliding.

Harmonizing mechanical responses of nanostructured CrN coatings via Ni additions

CrN coatings are often brittle and prone to abrupt failure. Incorporation of Ni is known to have significant effects on the chemical composition, microstructure and mechanical behaviour of chromium nitride coatings synthesised by PVD, and thus imparting toughness. In this study, a series of NiCrN coatings, with varying Ni concentrations, were deposited onto AISI M2 tool steel substrates through closed-field unbalanced magnetron sputtering ion plating (CFUMSIP). The phase compositions, microstructure, mechanical properties and deformation behaviour of the coatings were characterised by XRD, AFM, FIB, TEM/EDS and indentation testing. Residual stresses of these as-prepared coatings were measured by the XRD-sin2ψ method. A columnar structure was observed in all coatings, although grain refinement at higher NiCr target currents was noted. High hardness values of ~20 GPa were found in the coatings with the lower Ni (~5–14 at%) contents, associated with the effects of solid solution hardening, high compressive residual stress and grain refinement. Moreover, significant damage-tolerance, coupled with good hardness values (greater than ~12 GPa), was found in the NiCrN coatings deposited at INiCr ≥ 2 A. The presence of a metallic nickel-rich phase, together with nanoscale porosity, may contribute to stress dissipation and help maintain structural integrity.

Effect of Ni doping on the microstructure and toughness of CrAlN coatings deposited by magnetron sputtering

This study determines the effects of nickel (Ni) doping on the composition, phase structure, chemical valence state, hardness, and toughness of CrAlNiN coatings. CrAlNiN coatings with various Ni contents (0.00 at%–27.71 at%) were deposited on the surfaces of M2 tool steel and monocrystalline silicon (Si) using unbalanced magnetron sputter ion plating. The results showed that the CrAlNiN coatings possess a nanomultilayer structure, maintaining the face centered cubic crystal structure of the chromium aluminum nitride (CrAlN) coatings. The Ni in the coatings acts as a toughening phase to ease stress, to increase resistance to crack growth, and to delay the generation of cracks, thereby having an obvious toughening effect. At an Ni content of approximately 20.33%, the Ni toughening phase in the modulation layer tends to saturate and the effect of continuing the increase in Ni content is limited from the viewpoint of improving the toughness.

Physico-chemical properties of CrMoN coatings - combined experimental and computational studies

In this study, Cr−Mo−N thin films with different Mo contents were synthesised via closed field unbalanced magnetron sputtering ion plating. The effects of Mo content on the microstructure, chemical bonding state, and optical properties of the prepared films were investigated by X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy, and ultraviolet-visible spectrophotometry. XRD results determined the face centered cubic (fcc) structure of pure CrN film. The incorporation of molybdenum (Mo) in the CrN matrix was confirmed by both XRD and XPS analyses. The CrMoN coatings demonstrate various polycrystalline phases including CrN, γ-Mo2N, Cr with oxides layers of MoO3, CrO3, and Cr2O3. Microstructural results of the Cr-Mo-N coatings show that the grain size increased with an increase in Mo content due to the formation of MoN phase, in which the Mo atoms interact with N atoms around the grain boundaries of the CrN phase. XPS investigations confirmed the presence of Cr, Mo, N, C and O elements in the studied coatings. The optical results revealed that the synthesised coatings exhibit low reflection magnitudes in the visible region of the solar spectrum indicating good antireflection surfaces. Mo doped thin coatings improve the solar absorptance by ~76% in the wavelength range of 200–800 nm with a low thermal emittance of ~ 20% in the infrared range (up to 4000 nm). Furthermore, by applying density functional theory, the computational simulation provides similar trends as the experimental finding of absorption coefficient in the wavelength range.

Effect of Y content on the microstructure, tribological and corrosion properties of CrAlYN coatings deposited by magnetron sputtering

CrAlYN coatings with various Y contents (0.00 at%–2.67 at%) were deposited by closed-field unbalanced magnetron sputtering ion plating, and the effects of Y content on the microstructural, mechanical, and tribological properties of the CrAlYN coatings were investigated. The results showed that the synthesised CrAlYN coatings exhibited a face-centred cubic (fcc) structure. When the Y content increased to 2.67 at%, the preferential orientation of the CrAlYN coating changed from the (111) to the (200) plane. The hardness and Young’s modulus of the CrAlYN coatings first increased and then decreased with an increase in Y content; the highest values were 29.4 GPa and 390.6 GPa, respectively, at 1.13 at% Y. The wear properties of the CrAlYN coatings showed that the lowest wear rate and best wear resistance occurred at 1.13 at% Y. When the Y content was increased to 1.98 at%, the corrosion potential of the CrAlYN coating reached the maximum value of −0.4461 V, and the corrosion current decreased to 3.564 × 10−6 A cm−2. This CrAlYN coating exhibited the strongest corrosion resistance.

Durability and degradation of CrMoN coated SS316L in simulated PEMFCs environment: High potential polarization and electrochemical impedance spectroscopy (EIS)

The high potential on the cathode side originated from the start-up/shut-down processes is the one that cannot be ignored, which will accelerate degradation of the bipolar plates and increase the interfacial contact resistance (ICR) eventually degrade the performance of PEMFCs. Therefore, the coating with corrosion resistance and conductivity is in urgent need of development. CrMoN coating is deposited on SS316L by closed field unbalanced magnetron sputter ion plating (CFUMSIP) with an aim to improve corrosion resistance and conductivity of SS316L under PEMFCs at shut-up/shut-down stages. In terms of high potential polarization test, the corrosion current density and ICR values are found to increase as the applied potential increases. The electrochemical degradation of CrMoN coated SS316L is investigated by electrochemical impedance spectroscopy (EIS). After 40 days of immersion, the charge transfer resistance (Rct) of the CrMoN-4A coated SS316L is approximately 14 times greater than that of the uncoated SS316L and the ICR values are 11.2 mΩ cm2, indicating that the CrMoN-4A coating still has high corrosion resistance and well conductivity after long time immersion.

Niobium doped amorphous carbon film on metallic bipolar plates for PEMFCs: First principle calculation, microstructure and performance

Metallic bipolar plates (BPPs) are a promising candidate to replace conventional graphite BPPs due to higher power density and lower cost in proton exchange membrane fuel cells (PEMFCs). Surface coating is essential to enhance interfacial conductivity and corrosion resistance. Amorphous carbon (a-C) films have attracted broad attention from both academia and industry. This study incorporated Niobium (Nb) into a-C to further enhance its performance. First principle calculation was introduced to investigate the evolution mechanism of bond and phase by Nb doping and instruct the coating design. Then, a series of Nb-doped a-C samples were deposited by closed field unbalanced magnetron sputtering ion plating (CFUBMSIP) method. The microstructure was systematically characterized by SEM, XRD, Raman spectrum, and XPS. Interfacial contact resistance (ICR) and electrochemical corrosion were also tested to evaluate the effect of Nb doping. A higher C-sp2/C-sp3 ratio was observed in a-C film with moderate Nb doping. As a result, the ICR decreased to 1.22 mΩ•cm2 from initial value of 4.41 mΩ•cm2. Besides, the doped Nb also refined grain size and increased the film compactness, which was beneficial for corrosion resistance. Rct, which reflects the relative anti-corrosive property, was increased from 1.8 × 106 Ω•cm2 to 3.29 × 106 Ω•cm2. Moreover, the current density in 0.84 V (vs. SHE) potentiodynamic polarization is 3.59 × 10−7 A/cm2, lower than 4.59 × 10−7 A/cm2 of a-C films. Besides, the current density in 0.84 V (vs. SHE) potentiostatic polarization shows the same tendency. The enhanced performance of Nb-doped a-C coatings would advance the commercialization of metallic BPPs for PEMFCs.

Effects of Mo content on the interfacial contact resistance and corrosion properties of CrN coatings on SS316L as bipolar plates in simulated PEMFCs environment

CrMoN films with different Mo contents are deposited on SS316L by closed filed unbalanced magnetron sputtering ion plating (CFUBMSIP) to investigate corrosion resistance and electrical conductivity. The sputtering current of Mo target was altered to obtain various Mo contents. The result of SEM confirms that CrMoN coatings have a dense and uniform microstructure. X-ray diffraction (XRD) result shows that CrMoN coated samples have a preferred orientation of (111) direction. Interfacial contact resistance (ICR) between bipolar plate and gas diffusion layer (GDL) decreases with Mo incorporation, and CrMoN-4A coated sample has the lowest ICR value of 5.8 mΩ cm2 at 1.4 MPa. The result of potentiodynamic polarization test in the simulated PEMFCs environment shows that incorporation of Mo doped CrN coating can obviously improve the corrosion resistance of samples and CrMoN-4A has the highest corrosion potential which is 0.1341 V in simulated PEMFCs cathode environment. Electrochemical impedance spectroscopy (EIS) result indicates that the incorporation of Mo can improve better corrosion resistance, and CrMoN-4A has the highest corrosion resistance. The corrosion mechanism of coating also has been investigated.

Microstructure, mechanical and tribological characterization of CrN/DLC/Cr-DLC multilayer coating with improved adhesive wear resistance

Adhesive wear is one of the major reasons for the failure of components during various tribological application, especially for rubbing with viscous materials. This study presents CrN/DLC/Cr-DLC multilayer composite coatings prepared on a plasma enhanced chemical vapor deposition (PECVD) device with the close field unbalanced magnetron sputtering ion plating (CFUBMSIP) technique. SEM, XRD and Raman spectroscopy were used to determine the structure of multilayer coatings. It was found that the multilayer coatings are composed by the alternating CrN and DLC layers. Compared with the single CrN coatings, the friction coefficient of the CrN/DLC/Cr-DLC multilayer coating decreases about more than seven times after sliding a distance of 500 m. This helps to reduce the adhesive wear of multilayer coatings. Compared with the single CrN and DLC coating, the wear rate of the CrN/DLC/Cr-DLC multilayer coating is reduced by an order of magnitude to 7.10 × 10−17 (sliding with AISI 440C) and 2.64 × 10−17 (sliding with TC4) m3/(N m). The improved tribological performance of multilayer coatings mainly attributes to the introduction of lubricant DLC and hard support CrN layers, the enhancement of crack propagation inhibition, and the increment of elastic recovery value We (71.49%) by multilayer design method.

The corrosion behavior and mechanical properties of CrN/Ni[sbnd]P multilayer coated mild steel as bipolar plates for proton exchange membrane fuel cells

This research mainly studies on the interfacial conductivity and corrosion resistance of mild steel (MS)/electroless plating nickel (EN)/CrN composite coating. The MS/EN/CrN composite coating is deposited on a mild steel substrate using a combination of electroless nickel plating process and closed field unbalanced magnetron sputter ion plating system. The simulative working environment of proton exchange membrane fuel cell (PEMFC) is implemented to test the electrical and corrosion properties of uncoated mild steel and coated samples. Results show that the performance of the MS/EN/CrN coated samples was greatly improved. The SEM results indicate that the surface of MS/EN/CrN is dense and smooth. CrN (111) and Ni (111) are observed in the MS/EN/CrN coating by XRD. The potentiodynamic polarization and EIS tests show that the incorporation of electroless nickel deposits into the CrN coating can provide better corrosion resistance. Potentiostatic polarization tests reveal that MS/EN/CrN coating has the lowest current density both in anodic and cathodic environment. The Interfacial contact resistance (ICR) results show that the ICR of MS/EN/CrN coated sample reduces to 3.3 mΩ cm2 at a compaction force of 140 N/cm2. Moreover, after potentiostatic polarization, the ICR values of the MS/EN/CrN coating are still less than DOE's 2020 target. In addition, compared with other samples, the hardness and adhesion property of the MS/EN/CrN multilayer coating were greatly improved, which is beneficial for resisting the shock and wear during the assembly process of fuel cell stacks.