Effect of dcMS and HPPMS in a hybrid dcMS/HPPMS process on plasma and coating properties (2023)

High Power Impulse Magnetron Sputtering (HiPIMS) as a high ionization sputtering technique is widely used to tailor the structure and properties of thin films. However, investigations of process-related effects are mainly obtained from HiPIMS of single-component metal targets, while examinations of complex targets are rarely found. Therefore, HiPIMS of MoS₂targets were conducted under a variation of pulse duration and frequency. During the process, the current and voltage values ​​were measured in order to investigate the characteristics of the discharge mode. Time-dependent current waveforms reveal a functional gas autopsy for HiPIMS of MoS₂. By reducing the pulse frequency or pulse duration, the peak current increases and the contribution of self-wetting and relative gas dilution is enhanced, leading to a reduced deposition rate.

This study reports the deposition and properties of Ta-B-C coatings from the co-inspection of tantalum, boron carbide and graphite targets using high-power pulsed magnetron spectroscopy (HiPIMS). It was possible to influence the microstructure of the deposited coatings by changing the deposition temperature or by applying RF-induced self-bias to the substrates without changing their chemical composition. The only identified crystalline phase from the present Ta-B-C system was TaC. The boron content of the coatings shows that the TaC crystallite size can be changed by a factor of 10 by changing the power on the boron carbide target. The mechanical properties of the coatings measured immediately after synthesis yield a hardness greater than 40 GPa. After relaxation of the internal stress in the coatings (after one year) and structural changes, the hardness of all coatings was close to 36 GPa. According to a priori calculations, B incorporation into the fcc lattice of TaC combined with C vacancies leads to a lower (higher) shear-to-volume ratio (Poisson's ratio), providing a good basis for improved ductility. Overall, the Ta–B–C system shows good potential as a new hard protective coating.

TiAlCrN ceramic coatings were prepared using a hybrid deposition technique consisting of High Power Pulse Magnetron Scattering (HiPIMS) and DC Magnetron Scattering (DCMS). The chemical composition, phase structure, morphologies, mechanical and tribological properties of such coatings were systematically investigated. The results showed that the Ti element content increased monotonically from 0 at.% to 22 at.% with increasing Ti target strength. TiAlCrN ceramic coatings showed a competitive growth tendency between (111) and (200) crystal plane through energetic ion bombardment. The higher Ti target strength resulted in stronger compressive intrinsic stress, which significantly suppressed the precipitation of the hcp-AlN phase. By enhancing the ion bombardment, the diffusion energy and nucleation rate of atoms on the growing surface increased, which caused a denser structure and ultra-smooth surface. Hardness and hardness also varied as a function of Ti target power, with a maximum hardness of 28.3 GPa under a Ti target power of 5 kW. Positive correlation between bond strength (i.e., scratch test critical load) and H³/ MI²The ratio was found to indicate a strong dependence of adhesion properties on hardness for TiAlCrN ceramic coatings in this study, which was in good agreement with the literature. In terms of tribological behavior, the lowest wear rate of 8.9×10^-17M³N^-1M^-1was obtained for the TiAlCrN ceramic coating deposited at a Ti target power of 5 kW.

A hybrid direct current magnetron scattering/high power pulsed magnetron (DCMS/HiPIMS) technique was used to improve the structural and electrical properties of titanium carbide (TiC) single crystal thin films. TiC hetero-epitaxial films, ∼60 nm thick, were grown on MgO (001) substrates at temperatures ranging from 200°C to 800°C, by simultaneous sputtering of Ti and C targets fed by DCMS and HiPIMS, respectively. The films' composition and structural, morphological and electrical properties were investigated in comparison with those of a set of samples deposited at the same temperatures by reactive-DCMS (R-DCMS) in Ar/CH₄atmosphere. The composition and FWHM of the rocking curves of films deposited by R-DCMS differed from TiC_0,84in TiC_0,94and from 1.38° to 0.64°, respectively, as the growth temperature increased. Contraction_0,94- TiC_0,96The layers were deposited by a hybrid DCMS/HiPIMS method at temperatures higher than 400°C, fully stretched over their entire thickness, with a FWHM of rocking curves of about 0.13°. The electrical resistivity values ​​measured for these films were about 155 μΩ cm, significantly close to those corresponding to bulk TiC_0,95single crystals. The resistivity of the R-DCMS films is 6% to 23% higher compared to that of the DCMS/HiPIMS-grown samples, depending on the growth temperature.

Due to various difficult-to-machine materials and increasingly severe machining conditions, more and more attention has been paid to physical vapor deposition (PVD) technology in recent decades for the deposition of hard coatings on cutting tools. In conjunction with the state of industrial application of PVD technology, this paper reviews the main PVD techniques for coated cutting tools from the perspective of total PVD coating equipment, including cathodic arc evaporation and magnetron sputtering, as well as hybrid of their techniques and plasma etching which is critical to the adhesion strength of the coating is also involved. Regarding hard coating deposition on cutting tools, the basic principle, cathode configuration, magnetron and power supply are described. Issues related to target ionization ratio, coating deposition rate, coating properties, and industrial application of numerous PVD techniques are also highlighted. Regarding plasma etching, inert gas ion etching and metal ion etching are discussed. Finally, this paper summarizes and perspectives PVD technology used for coated cutting tools.

The increasing demand to reduce corrosion and wear in modern tribological systems places high demands on hard coatings deposited by physical vapor deposition (PVD) technology in numerous technical applications, e.g. A possible approach to excessive wear resistance is tool coating with hard PVD coatings of the Cr-Al-O-N system. Each of the components can provide the coating with particular characteristics in terms of its performance under different loading conditions. Therefore, continuous improvement in modern surface engineering requires comprehensive knowledge of the elastoplastic deformation and cracking behavior of such coatings. To this end, several modifications and extensions of established experiments are required to overcome the limitations involved in the characterization of thin hard coatings, e.g., as a result of μm ranges. In the present work, three CrN, (Cr,Al)N and (Cr,Al)ON coatings deposited on a quenched and tempered AISI 420 steel substrate were investigated. All coating systems were deposited via a hybrid technology, consisting of direct current and high power pulsed magnetron sputtering (dcMS/HPPMS). The deformation and cracking behavior of the coatings and coating/substrate joints was studied by applying static loadings with nanoindentation and Rockwell tests as well as dynamic loading conditions using nanoscratch tests. Complementary quantitative investigations were performed through depth profiling using confocal laser scanning microscopy (CLSM). Qualitative analyzes of the Rockwell indentations and nanoscratch marks were performed by scanning electron microscopy (SEM). Based on the results, accurate analyzes of the force-displacement curves of nanodentations can improve the understanding about the possible crack formation in the coatings. Compared to (the binary) CrN, the ternary (Cr,Al)N coating system shows more promising characteristics in terms of elastic-plastic deformation behavior and crack resistance. The crack resistance is reduced through the incorporation of oxygen into the ternary nitride and the deposition of quaternary oxynitrides (Cr,Al)ON. This character of oxynitrides can be observed by considering only static loadings and thus, application of both static and dynamic loading conditions is required to obtain accurate knowledge of the deformation and cracking behavior of thin hard coatings.

Applied Surface Science, Volume 363, 2016, pp. 477-482

Si-rich silicon carbide (Si_1−Xdo_X) prepared radio frequency (2MHz, 13.56MHz and 27.12MHz) magnetron thin films. Their structural properties were investigated by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM). The effect of ion energy on film deposition was also analyzed with a retardation field energy analyzer. The results show that the compositions of the films are related to the energy of the ions impacting the SiC target. At the lowest firing power, Si rich in Si_1−Xdo_X(1−X=0.57–0.90) thin films can be deposited well.

Surface and Coatings Technology, Volume 286, 2016, pp. 239-245

Diamond-like carbon (DLC) films were fabricated by sputtering a graphite target using a high-power pulsed magnetron sputtering (HiPIMS) technology operating with short pulses. The pulse duration was 7μs with a maximum source voltage of −2400V, which effectively facilitated the ionization of the sputtered carbon species. In order to show the effectiveness of short-pulse operation, the fabricated DLC films were investigated by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and spectroscopic ellipsometry. The XPS spectra were curve fitted using three Gaussian functions of the sp³-C, sp²-C and C–O bonding. Information from Raman and XPS spectra showed that the sp³fraction in DLC films fabricated using a 7μs pulse duration was greater than that obtained with a 50μs pulse duration. It was found that sp³/sp²ratio was greater than 40%, which was about 1.5 times compared to that obtained with a pulse duration of 50μs. A high sp³Fractionation was performed due to the application of high voltage without arcing carried by magnetron sputtering (MS) flash discharge. To get the high sp³fraction in the fabricated DLC films, a parametric investigation was performed, in which the background gas pressure, the bias voltage applied to the substrate, the power source voltage, and the target-to-substrate distance were varied. There were optimal deposition parameters to reduce the intensity ratio of D band and G band (I_Hey/I_G) in the Raman spectra. The optimal source voltage was in the range of −1200 to −1600V. For voltages higher than -1600 V, the energetic carbon and argon ions may deteriorate the film properties. The hardness of the fabricated DLC films at 7 μs pulse width and -1200 V source voltage was obtained as 37 GPa measured by nano-indentation. The hardness decreased in a range from 20 to 27 GPa with increasing pulse width in the range from 40 to 60 μs.

Vacuum, Volume 122, Part A, 2015, pp. 201-207

Target properties and pulse shaping are important factors in high-power magnetron pulsed scattering. The present work deals with analyzes of the effects of pulse length, i.e. duty cycle on the HPMS process and the properties of Al-rich (Cr_1−xAl_X)N coatings deposited with plugged targets in an industrial-scale unit. The results showed that the maximum power density increased from 0.32 kW/cm²up to 0.86 kW/cm²as the pulse length decreased from t_on=200µsto40µs. (Cr_1−xAl_X)N coatings with high aluminum content between x=68at% and x=76at% were produced. The deposition rate reveals a constant behavior using different Al-rich targets at the same pulse length. A mixture of cubic and hexagonal (Cr_1−xAl_X)N phases were found for each coating. Additionally, a thinner and denser morphology as well as a smoother surface were observed at reduced pulse length compared to long pulse modulation due to the high peak current and power density. The maximum hardness of H_U=30.0GPa and moderate modulus of elasticity E_THE=421GPa were achieved for (Cr_0,30Al_0,70)N coating deposited at pulse length t_on=40 μs, i.e. 2% duty cycle.

Vacuum, Volume 136, 2017, pp. 129-136

In this study, AlTiCrN coatings with different Cr contents were deposited from AlTi and Cr targets using a hybrid coating process that combines high-power pulsed magnetron sputtering with DC magnetron sputtering. The microstructure and mechanical properties of the AlTiCrN coatings were investigated using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy and nano-indentation. The tribological behaviors of the AlTiCrN coatings were evaluated by pin-on-disk friction tests at 400°C, 600°C and 800°C, respectively. The results showed that all AlTiCrN coatings exhibited (Al,Ti,Cr)N solid solution phases with an FCC NaCl type structure. With increasing Cr target strength, the Cr content increased from 0 to 25 at. %, adjusting for changes in coating microstructure and properties. First, the preferred orientation shifted from (111) to (200). Second, the hardness and elastic modulus of AlTiCrN coatings increased from 31.4±1.4GPa and 448.8±9.3GPaat 0at.% Cr to 33.7±1.4GPa and 469.5±8.2GPaat 8, 9at.% Cr and then decreased with further increase in Cr content. Third, the coefficient of friction and wear rates of the coatings against Al₂THE₃The balls also showed some relationship with coating compositions and test temperatures. The intrinsic mechanism was analyzed and discussed.

Surface and Coating Technology, Volume 358, 2019, pp. 43-49

Diamond-like carbon (DLC) coatings were deposited by a novel HiPIMS method that incorporates positive voltage pulses at the end of the conventional HiPIMS discharge. Different positive voltage amplitudes (100, 200, 300, 400 and 500 V) were used to evaluate the effect of this mode on the discharge process and mechanical properties of the deposited DLC coatings. The application of positive pulses was observed to enhance the ionization of both sputtered carbon and argon. Mass spectroscopy measurements showed that a larger amount of high-energy C⁺ions are produced, with ion energies proportional to the amplitude of the overvoltage. The ion bombardment induced by the positive pulses led to higher compressive residual stresses and densification of the deposited DLC coatings. In addition, the Raman spectra showed lower D and G band intensity ratios (I_Hey/I_G) as the pulse voltage increased, which is indicative of a higher sp³content. The mechanical properties were evaluated by nanocharacterization test and the hardness of the deposited DLC films was observed to increase from 9.6 GPa (for no applied voltage pulse) to 22.5 GPa (for applied positive pulse voltage of 500 V).

Surface and Coatings Technology, Volume 292, 2016, pp. 54-62

To modify the physical surface of a composite workpiece, incoming particles are difficult to reach the inclined surface of the composite workpiece due to the self-shadowing effect. This will result in non-uniform distribution of the structure and properties of the films on different surfaces of the composite workpiece. In order to mitigate the self-shadowing effect and improve the uniformity of the film structure and properties, high-power pulsed magnetron sputtering (HPPMS) was used to fabricate TiN films on a 316L stainless steel substrate with different tilt angles. During deposition, the electrical characteristics of the HPMS were recorded with an oscilloscope and the plasma component was diagnosed with optical emission spectroscopy. The structure, mechanical and corrosion properties of TiN films deposited on substrate with different tilt angles by DC magnetron sputtering (DCMS) and HPMS respectively were also studied. Compared with DCMS, the results showed that the high ion/atom ratio and large ion flux in HPMS led to stronger ion bombardment and atom mobility, which caused densification of TiN films. The uniformity of hardness and corrosion resistance of TiN films deposited on the substrate with different tilt angles were improved by HPMS. And for HPMS, longer pulses in the same duty cycle could effectively mitigate the self-shadowing effect and improve the hardness and corrosion resistance of TiN-coated stainless steel.