Plasma Enhanced Magnetron Sputtering Research Articles

Microstructure, mechanical properties, and wettability of CrN and CrSiCN coatings with graded architectures

Protective CrN-based coatings are of interest for applications requiring a combination of corrosion resistance and toughness. Here, the processing-microstructure-properties relationships for metallic Cr, binary CrN, and quaternary CrSiCN coatings are reported. Hexamethyldisilazane (HMDS) was used as a single-source organosilicon precursor for Si and C during plasma-enhanced magnetron sputtering (PEMS). By varying the availability of reactive species during coating growth, graded coating architectures were produced. Scanning and transmission electron microscopy revealed that as Si and C content increased, the coating microstructure evolved from a coarse, columnar growth structure (0 at.% Si), to a nanocolumnar structure (3 at.% Si), and, finally, to a dense, nanoscale structure (6 at.% Si). Coating surface topography was characterized using optical microscopy and atomic force microscopy. While the CrSiCN coating deposited at the highest HMDS flow rate exhibited the lowest nanoscale surface roughness (Rq = 6.74 nm), it also had the greatest area fraction of microscopic surface defects. Evidence of the formation of secondary Cr2N phases within the graded interlayers of the coatings was acquired from selected area electron diffraction analysis. However, the practical adhesion of the coatings, as evaluated by the Rockwell C indentation test, was not adversely affected. Nanoindentation testing revealed that greater incorporation of Si and C into the CrN-based coatings increased coating hardness from 25.4 ± 1.6 GPa to 30.7 ± 1.8 GPa and decreased apparent elastic modulus from 295 ± 14 GPa to 284 ± 12 GPa. Contact angle goniometry was conducted to determine the wettability of the coatings. It was found that sessile water contact angles decreased from 86.5° ± 1.6° to 77.3° ± 2.1° as coating Si and C content increased.

Failure mechanisms of multilayer TiN films based on mechanical properties of film and substrate

The poor adhesion, which is related to the mechanical properties of the substrate and film, leads to the film peeling off from the substrate and failure. In this study, TiN films with various structure were prepared on Ti6Al4V titanium alloy (TC4), 316L stainless steel (316L), 4Cr5MoSiV1 hot work die steel (H13), and W6Mo5Cr4V2 high-speed steel (W6) by adjusting the discharge currents using a hot-wire plasma-enhanced magnetron sputtering rig. The morphologies of the single-layer TiN films varied from loose to dense and ductile to brittle, and the nanohardness and elastic modulus increased as the hot-wire discharge current increased. The morphologies, nanohardnesses, and elastic moduli of the multilayer TiN films gradually approached those of the dense TiN single-layer films as the thicknesses of the top dense layers increased. The results, both by numerical simulation and experimental tests, revealed that the interfacial tensile stress and surface strain of a TiN/substrate system increased as the elastic modulus differences between TiN and its substrate increased, resulting in a serious TiN film elastic and plastic deformation asynchrony and poor film–substrate adhesion. The loose layer between the top dense TiN layer and its substrate acts as a buffer because the elastic modulus of the loose layer is in the middle, higher than that of the substrate but lower than that of the top dense layer. For TiN/TC4 or 316L with large differences in elastic moduli, loose/dense thickness ratios of 1:2 or 1:4 for the multilayer TiN films were sufficient to improve their adhesion. For TiN/H13 or W6, with small elastic modulus differences, a ratio of 1:4 was sufficiently large and may not be necessary.

Microstructure and mechanical properties of Cr films with different orientations before and after plasma nitriding

In this paper, the Cr films with preferred orientation evolution from (110) to (200) were deposited on the surface of austenitic stainless steel. These films were driven by a pulsed bias with different duty cycles from 20% to 80%, followed by a postnitriding process for 1 h using a hot wire plasma-enhanced magnetron sputtering system. XRD result showed Cr film had a body-centered cubic lattice structure, and the orientation transformed from (110) to (200) with the increase in the duty cycle. SEM and EDS measurements revealed that Cr film structured with columnar crystals could contribute to the continuous diffusion of nitrogen into austenite lattice. N atoms tended to diffuse along the (200) orientation of Cr films than the close-packed (110) orientation. As a result, the best wear resistance and adhesion strength were obtained when Cr film deposited at 80% duty cycle was nitrided, and the wear volume decreased by 95.7% compared with that before nitriding.

The effect of sputtering power on the structural and tribological behaviors at elevated temperature of Ta/Si co-doped DLC films

Ta and Si with various concentrations was co-doped into DLC films by plasma enhanced magnetron sputtering technique to improve its thermal stability and frictional performance at elevated temperature from 25 °C to 300 °C. Results showed that the doped Si and Ta mainly formed carbide in the film but play different role in the structure of the film. The sp3C content, surface roughness, hardness and adhesion strength increased firstly and then decreased with increasing content of doped elements in the film. The thermal stability and frictional performances at higher temperature was improved by higher content of doped element. It is notable that the film (with Si content of 4.47 at.% and Ta content of 2.44 at.%) exhibited low wear rates from 10−7 to 1 × 10−6 mm3/Nm at different temperatures owing to its higher sp3C content (18.2 %), proper nano-carbide, and thus higher hardness (11.09 GPa) and lower internal stress (0.24 GPa). The excellent frictional performances of this film tested at 300 °C was due to the reduced graphitization of the film, accompanied with the SiC nanoparticles and Ta5Si3 phase formed during the friction.

Development and evaluation of CrAlAgN self-lubricating coatings for high temperature metal forming dies

Conventional lubricants are widely used for die release as well as for cooling assistance on the die surface. However, lubrication is difficult at high temperatures. Oxidation and scaling occur on the work pieces that lead to poor surface finish and a possible warping of the material during cooling. The aim of this research is to develop self-lubricating CrAlAgN nanocomposite coatings for metal forming dies and evaluate their thermal fatigue resistance and wear behavior at elevated temperatures. The CrAlAgN coatings with different Ag contents have been deposited by plasma-enhanced magnetron sputtering. The structure and properties of the coatings were systematically studied to determine the optimal Ag content for achieving a combination of good adhesion, thermal fatigue resistance, and surface lubricity at elevated temperatures. The thermal fatigue resistance of the coatings was evaluated using thermal cyclic testing by cycling the coatings from room temperature to 800 °C up to 1200 cycles. The high temperature wear behavior of the coatings was evaluated using a tribometer up to 900 °C. Good thermal fatigue resistance and low coefficient of friction (COF) were observed in the CrAlAgN coatings with an Ag content in the range of 5–10 at. % at 800 °C. The CrAlAgN coating with 10 at. % Ag exhibited the lowest average COF of 0.05 at 800 °C. The COF of thick CrAlAgN coatings (8 at. % Ag) decreased from 0.5 to 0.2 from 500 to 900 °C, accompanied by an increase in the wear rate under more aggressive wear test conditions. The lubricity of the CrAlAgN coatings at high temperatures was attributed to the lubrication effects from the mixed oxides and encapsulated Ag diffused toward the surface. To further evaluate the coating performance, a hydraulic hot forging punch was coated with a thick CrAlAgN (8 at. % Ag) coating and evaluated in the industrial forging process. The preliminary in-plant trials demonstrated that the coating significantly reduced the dimensional distortion and wear for the forging punch.

Selective strategy of reactive hysteresis loop for coatings on alloy substrates with different moduli

The structure and properties of nitride films, such as titanium nitride (TiN), depend on the reactive gas (N2) flow rates, which are normally selected according to the reactive hysteresis loops. Film-substrate adhesion depends on the properties of the films and substrates. A selective strategy for the reactive gas flow rate within the hysteresis loop was investigated by characterizing the structure, properties, and failure mechanisms of TiN films on Ti6Al4 V titanium alloy (TC4) and 4Cr5MoSiV1 hot-work die steel (H13). The hysteresis loop of the titanium (Ti) target potential as a function of the N2 flow rate was measured, and flow rates in different sputtering modes were used to prepare TiN films using plasma-enhanced magnetron sputtering. As the N2 flow rate increased from 5 cm3/min, 10 cm3/min, 15 cm3/min to 20 cm3/min, from the metallic mode to the compound mode, the morphologies of the films changed from loose to dense, the phase structures changed from TiN0.3 (002) to TiN (111), (200), and (220), and the nano-hardness and elastic moduli increased. Applying a Rockwell normal load, asymmetric circular cracks appeared and became significant for TiN/TC4 as the N2 flow rate increased to 15–20 cm3/min; cracks were only observed in TiN/H13 at an N2 flow rate of 20 cm3/min. Applying normal and shear scratch stresses, the TiN films peeled off from the TC4, except for TiN, with an N2 flow rate of 10 cm3/min, indicating that the adhesion between TiN and TC4 was weak. No peel-off chips were observed in the scratch morphologies of TiN/H13, indicating excellent adhesion between the films and H13 substrate. Circular cracks appeared in the scratch morphology of TiN0.3, indicating that cohesion had broken within the film. The possible failure mechanism was the large difference in the elastic moduli and hardness of TiN and TC4, which led to TC4 elastic and plastic deformation much earlier than in TiN films. According to numerical simulation, the interfacial tensile stress of TiN/TC4 under a normal load was higher, and the interfacial strain near the indentation edges was larger than that of TiN/H13. Considering the comprehensive properties, a reactive flow rate near the critical point such as 15 cm3/min for TiN/TC4 should be used for the nitride film on a low-hardness and low-modulus substrate; in the compound mode stage, 20 cm3/min for TiN/H13 should be used for the nitride film on a high-hardness and high-modulus substrate.

Oil-lubricated sliding wear performance of TiSiCN-coated ductile iron

Improvements to internal combustion engine performance can be achieved by the application of advanced coatings to piston rings and cylinder bores. Here, the sliding wear performance of TiSiCN coatings on ductile iron was evaluated in heavy-duty diesel engine oil using a block-on-ring tribometer. The coatings were deposited by plasma-enhanced magnetron sputtering of titanium in a reactive environment containing nitrogen, acetylene, and hexamethyldisilazane. Coating characterization was conducted using X-ray spectroscopy and diffraction, electron microscopy, and nanoindentation. TiSiCN adhesion to ductile iron was qualified by Rockwell indentation testing. Wearing surface and counter surface material pairs were systematically varied. Intermittent friction oscillation was observed for self-mated TiSiCN, while tribosystems with only one TiSiCN surface exhibited improved friction stability relative to uncoated ductile iron. A 24% reduction in block wear rate was achieved by coating the block surface with TiSiCN. Solely coating ring surfaces with TiSiCN, however, increased the uncoated block wear rate by over 300%.

Tribological behaviour of a hyperlox coating deposited over nitrided martensitic stainless steel

Martensitic stainless steels are often used in machine components, where are exposed to different solicitations that require good surface properties. Different treatments such as plasma nitriding or coating deposition could be used to improve their wear and corrosion resistance, even combining both methods. In this work, the tribological behaviour of a TiAlN coating with a top layer of TiN, called ‘Hyperlox Gold’, deposited over both nitrided and non-nitrided martensitic stainless steels by PVD PEMS (Physical Vapour Deposition Plasma Enhanced Magnetron Sputtering) was studied. Quenched and tempered AISI 420 martensitic stainless steel was used as base material. A group of samples were plasma nitrided and were subsequently coated. Microstructure of the nitrided layer and the coating were analysed by SEM and XRD. Nanohardness was measured with a Berkovich tip. Wear behaviour was evaluated using pin-on-disk tests (ASTM G99 standard) under three different loads (5 N, 7 N and 10 N) with an alumina ball as a counterpart. Adhesion was evaluated using dynamic conditions such as variable load scratch test and under static condition with Rockwell indentation tests (using 60 kg, 100 kg, and 150 kg). Overall thickness of the coatings was 3.7 μm and their hardness about of 32 ± 2 GPa. The nitrided layer was about 10 μm thick, with a hardness of 17 ± 1 GPa. The coating had good mechanical resistance in sliding adhesive wear conditions under low loads and good adhesion was revealed in a static condition. The presence of a nitrided layer improved the wear behaviour under high loads and the adhesion in dynamic conditions. Critical load was higher for the duplex sample than the coated samples. This work is important for the development of the Argentinian industry where the use of coatings is not largely extended, especially with martensitic stainless steels as substrates.

Effect of N content on the microstructure and tribological properties of TiSiCN composite coatings

TiSiCN composite coatings with different N contents based on Cr buffer layer were prepared by plasma-enhanced magnetron sputtering. The surface and cross-sectional morphology, composition, and structure of the coatings were evaluated by scanning electron microscope with energy dispersive spectroscopy, atomic force microscope, x-ray photoelectron spectroscopy, x-ray diffraction, and Raman spectroscopy. The hardness, elastic modulus, and tribological performance were investigated. The results showed that with the addition of N content, the proportion of sp3-hybrized C bonds and amorphous Si3N4 in TiSiCN coatings gradually decreased, while the proportion of graphite phase and CNx gradually increased. The decrease in the sp3—C bonding ratio leads to the decrease of coating hardness, and the composite coating with N content of 7.3% has the highest hardness at 13.2 GPa. The friction experiments exhibited the self-lubrication feature of the internal graphite phase, and the strengthening of moderate amounts of the hard phase can significantly reduce the wear rate. The TiSiCN composite coating with N content of 13.2% had the lowest wear rate.

Tribological behaviour of a multilayer CrN/DLC coating obtained using PVD-MS

Diamond-like Carbon (DLC) coatings are used as protective layers for steel components due to their hardness, chemical inertia and interesting tribological properties. Reducing wear and friction coefficient is of great importance for industries today in order to increase energy efficiency and reduce harmful emissions to the environment. In this paper, a multilayer CrN/DLC coating is analysed. It was deposited using a commercial Plasma Enhanced Magnetron Sputtering over nitrided and not nitrided mild-alloy steel AISI 4140, produced for the first time in Argentina, at the firm Coating.Tech by Flubetech-Tantal. The base of the coating is an anchor layer made of CrN and the top layer is a chromium-dopped hydrogenated amorphous carbon (a-C:H:Cr), which provides excellent tribological properties. Wear tests were carried out in a Pin-on-Disk apparatus, using an Al2O3 ball as counterpart, with Hertzian contact stress from 1370 up to 1460 MPa. The friction coefficient was μ ∼ 0.1, which is 80% less than the untreated steel and the wear volume loss was reduced several times. The adhesion was evaluated by means of Scratch Test, where major improvement was noticed in the samples which were nitrided as pre-treatment, increasing critical load from 25 N up to 65 N.

Improvement of microstructure and tribological properties of titanium nitride films by optimization of substrate bias current

Severe wear is a key factor affecting the work character and service life of the cutting tools used for dry cutting. The deposition of wear-resistant films on the cutting tools via magnetron sputtering is one of the most effective strategies, and the further improvement of the properties of the deposited films has attracted much attention. Plasma-enhanced magnetron sputtering possesses a much higher ionization rate than conventional magnetron sputtering and has been used to deposit dense hard wear-resistant film, but the influence of substrate bias current (Is) on the structure and properties of the films should be further studied. In this paper, plasma-enhanced magnetron sputtering technique was utilized to obtain an individually adjustable Is and TiN film was taken as an example to study the effects of Is on the properties of the films. It is found that the microstructure of the films is transformed from a loose columnar microstructure into a dense and featureless microstructure with increasing Is from 0.1 to 3.0 A, and the preferred growth orientation along TiN(111) is found at a high level of Is. As Is increases from 0.1 to 1.5 A, the grain size of the films is abruptly decreased, and the mechanical properties are significantly improved; but when Is further increases, the mechanical properties stay nearly unchanged. When Is is increased, the wear rate of TiN-coated samples is distinctly decreased at first, and then gradually increased. When Is is 3.0 A, the highest hardness of 38.7 GPa and lowest wear rate of 9.4 × 10–16 m3/(N•m) are obtained for the TiN-coated sample.

Synthesis of Multilayered DLC Films with Wear Resistance and Antiseizure Properties.

Diamond-like carbon (DLC) films have attracted considerable interest for application as protective films in diverse industrial parts. This is attributed to their desirable characteristics, such as high hardness, low coefficient of friction, gas-barrier properties, and corrosion resistance. Antiseizure properties, in addition to wear resistance, are required during the die molding of polymer and polymer-matrix composite parts. Graphite films can be easily peeled because the vertically stacked graphene sheets are bonded via weak van der Waals forces. The present study demonstrates the fabrication of multilayered DLC/Cu films, where the Cu film functions as a catalyst for the formation of a graphite-like layer between the DLC and Cu films. The DLC/Cu film was synthesized on a Si (100) substrate via plasma-enhanced chemical vapor deposition and magnetron sputtering. The peelability, wear resistance, microstructure, texture, and cross-section of the film were experimentally analyzed. The results indicated a variation in the peelability with the deposition conditions of the Cu film that comprised particles with diameters of several nanometers. The DLC film at the interface in contact with the Cu film was transformed into a graphite-like state i.e., graphitized. The surface of the multilayered film exhibited antiseizure properties with the peeling of the upper DLC film. The multilayered film also exhibited wear resistance owing to the repeated appearances of a new DLC film. It is expected that the wear-resistant films with antiseizure properties demonstrated in the present study will be utilized in various industrial sectors.

Aluminum coating of twinning-induced plasticity plates via plasma-enhanced magnetron sputtering as a potential industrial technique

Challenges are encountered in the use of the conventional hot-dip galvanization process to deposit a protective layer on the surface of twinning-induced plasticity (TWIP) steel due to the low wettability, which is caused by manganese oxidation on the surface of the steel. In a vacuum environment and after conducting etching on the surface to remove surface oxides, corrosion-resistant aluminum (Al) coatings were prepared on the surface of TWIP steel via the hot-wire plasma-enhanced magnetron sputtering (PEMS) technique under various target and wire discharge currents (Ihot-wires/Itarget). The substrate ion current density at −50 V was as high as 0.88 mA/cm2 under a high hot wire discharge current of 20 A and a low target current of 3 A (20 A/3 A), which was 4 times the ion current under Ihot-wires/Itarget of 5 A/3 A, respectively. According to an analysis of the coatings via pulsed radio frequency glow discharge optical emission spectroscopy, Al, Fe and Mn elements diffused at the interface between the coating and steel substrate. The diffusion layers on both sides of the interface resulted in the Al coating remaining well adhered to the surface of the TWIP steel after Rockwell indentation, scratch testing and Erichsen cupping tests. As the sacrificial and passivated anode, the self-corrosion potential of the dense Al coating increased from −0.770 V of the TWIP steel to −0.471 V, and the corrosion current decreased from 3.91 × 10−4 A/cm2 to 6.14 × 10−5 A/cm2. The dense coating remained undamaged after electrochemical corrosion. Additionally, the structure of the TWIP steel was not affected by the PEMS coating processes.

Effect of N2/TMS Gas Ratio on Mechanical and Erosion Performances of Ti-Si-C-N Nanocomposite Coatings

To optimize the tribo-mechanical performance of thick Ti-Si-CN nanocomposite coatings for a wide range of harsh industrial applications, reactive gases of nitrogen and trimethylsilane were employed with specific flow rates of PEMS process. Plasma-enhanced magnetron sputtering (PEMS) was employed for depositing thick Ti-Si-C-N nanocomposite (22-27 µm) on Ti-6Al-4V substrates at relatively high deposition rate up to 4.5 µm/h. Controlling the nitrogen partial pressure ratio PN2/(PN2 + PTMS) from 0.29 to 0.69 resulted in controlling the chemical and physical properties of the coatings. The XRD results demonstrated that the crystallinity of the nanocomposite structure increased with the increase in nitrogen pressure ratio. The coating hardness, erosion resistance, sliding wear resistance and corrosion resistance were augmented with increasing the nitrogen content in the plasma atmosphere. The results displayed that the sliding wear resistance of Ti-Si-C-N coatings increased by approximately three orders of magnitude comparing with the uncoated Ti-6Al-4V substrate. At low nitrogen content, low coefficient of friction (0.13-0.15) was achieved. Furthermore, the coating prepared at high nitrogen content reflected greater values of ratios H/E* and H3/E*2 that correlated well with the coating erosion resistance.

Surface evolution analysis of CrxWyNz coatings on WC mold in glass molding process

The CrxWyNz coatings were synthesized on the cemented carbide (WC-8Co) by plasma-enhanced magnetron sputtering (PEMS). The detailed glass cylinder compression was tested for the molding performance of the coated molds in the precision glass molding machine (PGMM). This work examined the surface morphology evolution, elemental compositions and mechanical properties of the CrxWyNz coatings by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectrometer (EDS), nano-indentation tester and atomic force microscope (AFM). The results showed that with the increased W content in the CrxWyNz coatings, the nano-hardness and Young's modulus of the coatings increased, and the surface roughness of the coatings reduced. The contact zone had lower surface roughness than the non-contact zone because of inhibiting the oxidation reaction. The molded glass pressing on the surfaces of Cr27W24N49 and Cr18W28N54 coatings had relatively better light transmittance. Besides, the CrxWyNz coatings (18 ≤ x ≤ 27, and 24 ≤ y ≤ 28) exhibited better oxidation resistance, chemical inertness, and surface quality during thermal-mechanical cycles, more suitable for glass molding protective coatings. The work sheds light on the preparation and application of glass molding protective coatings.

Thermal Stability of CrWN Glass Molding Coatings after Vacuum Annealing

CrWN glass molding coatings were deposited by plasma enhanced magnetron sputtering (PEMS). The microstructure and thermal stability of these coatings were investigated by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscope, transmission electron microscope, atomic force microscope and nanoindentation tests. The as-deposited coating exhibited an aggravated lattice expansion resulting in a constant hardness enhancement. The vacuum annealing induced surface coarsening and the spinodal decomposition of the coating accompanied by the formation of nm-sized c-CrN, c-W2N, and h-WN domains. The annealed coating with low W content had mainly a face-centered cubic (f.c.c) matrix, strain fields caused by lattice mismatch caused hardness enhancement. Following an increase in W content, the annealed coating showed a mixed face-centered cubic (f.c.c) and hexagonal close-packed (h.c.p) matrix. The large volume fraction of h-WN phases seriously weakened the coating strengthening effect and caused an obvious drop in hardness.

Microstructure, wear and oxidation resistance of CrWN glass molding coatings synthesized by plasma enhanced magnetron sputtering

CrWN glass molding coatings with different W contents were synthesized by plasma enhanced magnetron sputtering (PEMS). The microstructure, mechanical, wear resistance, and anti-oxidation properties of as-deposited coatings were investigated using various techniques and tests. The results showed that the as-deposited coatings exhibited typical columnar growth structure, consisting of layered CrN and W2N, and showed increased lattice expansion and hardness enhancement with increasing W content. Whereas the coating with high H/E value showed better toughness to resist fatigue deformation and fracture, which eventually resulted in excellent wear performance and low wear rate of 0.89 × 10−6 mm3/Nm. Annealing revealed that the as-deposited coating with low W content showed a slight increase in thickness and Ra value because of high volume fraction of Cr2O3 phase, which effectively delayed the oxidation reaction and suppressed the expansion of WO3 phases. With the increase in W content, the rising volume fraction of WO3 phases weakened the stabilized effects of Cr2O3 phases and eventually led to a constant increase in thickness and Ra value of the annealed coating. The mold tests confirmed that the CrWN coating showed a stable structure and excellent chemical inertness and anti-sticking performance, making it a potential coating for glass molding processes.

Effect of annealing environment on the microstructure and mechanical property of CrWN glass molding coating

The CrWN glass molding coating was synthesized by plasma enhanced magnetron sputtering (PEMS). The effect of annealing environment (e.g., vacuum, N2 and Air) on the microstructure and mechanical property of as-deposited coating was investigated by the X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), atomic force microscope (AFM) and nanoindentation tests. Results showed that the as-deposited coating exhibited dense columnar structure consisting of multilayer CrN and W2N phases. The vacuum annealed coating showed similar thickness to that of as-deposited coating, but underwent visible surface coarsening because of slight oxygen erosion. The N2 and air annealed coatings suffered from varying degree of oxidation damage accompanied by the formation of mixed WO3-CrWO4 phases, which consequently resulted in severe thickness expansion and surface coarsening. The vacuum annealing induced a spinodal decomposition of supersaturated solid solution to form nm-sized CrN and W2N domains. Strain fields originating from the lattice mismatch eventually caused a pronounced age-hardening in the vacuum annealed coating. Whereas the N2 and air annealed coatings showed significant mechanical degradation because these loose WO3-CrWO4 oxides degraded the stable matrix structure. Our results clearly demonstrated that vacuum environment effectively suppressed the oxidation damage and mechanical degradation of glass molding coating.

Influence of Al Content on Micro-Properties of TiAlSiN Coatings Deposited by Plasma Enhanced Magnetron Sputtering

TiN coating has attracted substantial attention due to its high hardness and good wear resistance. To meet the current more demanding service environment, Al and Si were added to TiN coating to further improve its comprehensive performance in this work. TiAlSiN coatings with different Al content governed by Al target power were prepared on GH169 superalloy by plasma enhanced magnetron sputtering, and the Al content effects on microstructure and mechanical properties of the coatings were explored in detail. The crystal structure, chemical composition, micromorphology and surface roughness of the coatings were analyzed by XRD, SEM, EDS and AFM, respectively. The mechanical properties of the coatings at room temperature including micro-hardness, elastic modulus and bonding strength were evaluated by nano-indentation and nano-scratch, respectively. With the increase of Al target power, Al content in coatings increased, and the preferred orientation of TiN(111) plane was also more and more obvious. At the same time, the surface morphology of the coatings changed from the round cell shape to the hexagonal star shape. The hardness, elastic modulus and adhesion of the coatings increased first and then decreased with the Al content. The TiAlSiN coating with Al content of 19.25% possesses the best comprehensive properties.

Al Content Effects on Mechanical and Tribological Properties of Cr/CrN/CrAlN Multilayer Nanocomposite Coatings

In this study, four Cr/CrN/CrAlN multilayer nanocomposite coatings with various Al content controlled by Al target power were successfully prepared on 316L stainless steels by plasma enhanced magnetron sputtering (PEMS). The surface morphology, chemical composition, phase structure and surface roughness of the coatings were characterized by SEM, EDS, XRD and AFM, respectively. The micro-hardness, Young’s modulus and adhesion of the coatings were measured by nano-indentation and nano-scratch, respectively. The friction and wear behavior of the coatings was investigated by a friction and wear tester. The effects of Al content on the microstructure, mechanical properties and wear resistance of the coatings were studied in detail. Results show that Al content in coatings increased with the increase of Al target power. The coatings exhibited the NaCl crystal structure. As the Al content increased, the hardness, Young’s modulus, bonding force and wear resistance of the coatings increased first and then decreased. The Cr/CrN/CrAlN coating with Al content of 37.8% has the optimal comprehensive properties.