ICMCTF 2023 Session BP-ThP: Hard Coatings and Vapor Deposition Technologies (Symposium B) Poster Session

Modern industry requires highly wear-resistant materials in many applications. Some demands can only be met by superhard materials. While diamond and cubic boron nitride are very popular in many areas of industry they possess also major drawbacks – high pressure during synthesis or affinity to iron. Superhard tungsten borides may be alternative to traditional superhard materials in many applications. They are superhard, have good thermal and chemical stability. They are also thermally and electrically conductive. Additionally they do not require high pressures during synthesis and their properties can be enhanced by alloying with transition metals, like titanium[1], zirconium[2], and others.

High power impulse magnetron sputtering was successfully recognised by industry. Because of high ionization during the process this technique can produce high quality, dense materials with comparatively low substrate temperatures. Studies on tungsten borides prepared by HiPIMS have not been sufficiently researched yet.

In this work we present deposition and characterization of tungsten-tantalum diboride (W,Ta)B₂ coatings prepared by HiPIMS. We evaluated the influence of pulse duration, substrate temperature and substrate bias on properties of (W,Ta)B₂ films. Crystalline structure was obtained at 250°C. High hardness above 40 GPa measured by nanoindentation was obtained simultaneously with good adhesion to steel substrates evaluated by scratch-test. Changing the pulse duration highly affected the B/(W+Ta) ratio which had influence on properties of coatings. Deposited films was thermally stable up to 1000°C in vacuum, and was able to withstand oxidation in 500°C

[1]Mościcki T., Psiuk R., Słomińska H., Levintant-Zayonts N., Garbiec D., Pisarek M., Bazarnik P., Nosewicz S., Chrzanowska-Giżyńska J., Influence of overstoichiometric boron and titanium addition on the properties of RF magnetron sputtered tungsten borides, SURFACE AND COATINGS TECHNOLOGY, 2020

[2]Garbiec D., Wiśniewska M., Psiuk R., Denis P., Levintant-Zayonts N., Leshchynsky V., Rubach R., Mościcki T., Zirconium alloyed tungsten borides synthesized by spark plasma sintering, ARCHIVES OF CIVIL AND MECHANICAL ENGINEERING, 2021

“Density Functional Theory” (DFT) is a well established and powerful method for modeling and calculating materials properties from the atomic scale point of view. The also called “First Principles Calculations” uses the Quantum Mechanics to give us unprecedented access to the origin of macroscopic behavior of materials. It is the ultimate tool to explore, understand and design materials performance in a wide range of operational demands.

Despite of its power, DFT has a significant disadvantage, namely its high computational cost when modeling complex materials or structures that request a large number of atoms (hundreds) to describe the corespondent unit cell. At the same time, nowadays, High Performance Computing (HPC) Centers and, obviously, ingenuity have been used to expand our possibilities.

In this work, we present the initial step of a long term study devoted to model aeronautic materials to be submitted to extreme operational conditions, mainly temperature. We chose inconel 718 as the base material that will be protected by a Thermal Barrier Coating (TBC) as, for example, yttria-stabilized zirconia. Due to the high computational cost described above, the very first step was to calculate the thermal conductivity of pure Ni, that corresponds to more than 50% of the alloy composition and whose results are presented here.

In the next steps, we plan to improve the inconel 718 description and devote special care to the modeling of the inconel and TBC interface, always taking into account the compromise between computational cost and results quality.

We employed the ABINIT code [1] for the ground state and forces over atoms calculations. The pseudopotential was taken from the PSEUDO DOJO site [2] and thermal conductivity was obtained using the PHONO3PY code [3]. The main calculations were performed at CENAPAD-SP (National Center for High Performance Computing in São Paulo – Brazil).

[1] https://doi.org/10.1016/j.cpc.2019.107042 ; https://www.abinit.org/sites/default/files/ABINIT20.pdf ; https://www.abinit.org/

[2] https://doi.org/10.1016/j.cpc.2018.01.012 ; http://www.pseudo-dojo.org/

[3]Atsushi Togo, Laurent Chaput, and Isao Tanaka, Phys. Rev. B, 91, 094306 (2015) ; https://phonopy.github.io/phono3py/

Direct CVD diamond coating deposition on ferrous alloy substrates, such as stainless steel and high-speed steel, has been hardly achieved, owing to the catalytic effect of iron and the rapid diffusion coefficient of carbon in iron. These problems originally come from the high substrate temperatures in CVD diamond coating processes, typically >750^°C. Also, this high process temperature leads to substrate deterioration like thermal softening of steel substrates. To overcome these problems, several counter measures have been developed in terms of the surface stabilization of the substrate. Having an interlayer between the ferrous substrate and the diamond film has been most frequently used to prevent carbon diffusion and catalytic reaction. In this present study, nano-crystalline diamond (NCD) films have been directly deposited on stainless steel (Grade 301) substrate without any interlayer via Hot-filament CVD process. Grit blasting (for better coating-substrate interface) followed by proper nano-diamond seeding surface pre-treatment procedure is adopted prior to diamond deposition for better quality NCD film. To prevent substrate deterioration from high temperature, the filament to substrate distance was carefully chosen so that the substrate temperature was ≈600^°C. Physical characterization of deposited film was analyzed through Raman spectroscopy, Scanning electron microscopy and X-ray diffraction method. The cross-section study of the substrate-coating interface confirms the formation of a carbide layer and non-diamond carbon phases before the NCD film formation. Hence, direct deposition of NCD film on SS 301 substrate has been accomplished successfully with visibly strong coating adherence. Further studies such as tribological analysis and adhesion study of coated samples and change in substrate material properties after diamond deposition are underway. All these results will be presented and discussed.

Solid films containing gas-filled nanopores (nanobubbles) have several unique characteristics: they allow a large amount of gas to be trapped in a condensed state with high stability, and provide a route to tailor the overall mechanical, optical and electromagnetic properties of the films [1-3]. In addition to ion implantation procedures, the bottom-up magnetron sputtering (MS) using He as process gas has been proven to be an innovative and versatile methodology to produce He-charged silicon films [1,2,4,5]. Of particular interest is the use of these “solid-gas” nano-composite materials containing ⁴He and ³He as solid targets for nuclear reaction studies [4,5]. The incorporation of heavier noble gases such as Ne and Ar is also of interest in this field. In this work, we demonstrate a synergistic effect when using He-Ne and He-Ar mixtures during the MS deposition of Si films. Together with the He incorporation, higher amounts of Ne and Ar can be trapped as compared to pure Ne and Ar plasmas. Microstructural and chemical characterizations are reported in this work by Ion Beam Analysis (IBA) and Scanning and Transmission Electron Microscopy (TEM and SEM, including EDS). In addition to gas incorporation, He promotes the formation of larger nanobubbles. Most interestingly, for the case of Ne, a combination ofhigh resolution X-ray photoelectron and absorption spectroscopies (XPS and XAS) reveal that the binding energy of the Ne 1s photoemission peak and the inflection point in the Ne K-edge absorption spectra show a strong dependence on the nanobubbles size. The proposed methodology provides a new way to optimize the fabrication of Ne and Ar solid targets by achieving the required amounts of trapped gas. New perspectives appear to characterize the spectroscopic properties of the noble gases in a condensed state without the need for cryogenics or high-pressure anvil cells.

[1] R. Schierholz et al. Nanotechnology 26 (2015) art.nr. 075703

[2]J. Caballero-Hernández et al. ACS Appl. Mater. Interfaces 7 (2015) 13889−13897

[3] J. G. Ovejero et al. Materials and Design 171 (2019) 107691

[4] V. Godinho et al. ACS Omega 1 (2016) 1229−1238

[5] A. Fernández et al. Materials & Design 186 (2020) art.nr. 108337.

When coating stamps, punches and coin minting dies, ensuring surface quality is essential. These surfaces require smooth, dustless coatings with excellent adhesion to accurately replicate highly detailed relief structures. The requirements increase when minting dies are used to produce proof coins, where temperature-sensitive materials are often used. They have narrow tolerances and can only be coated within a certain temperature range.

For coin minting dies, PLATIT has developed a Custom Coating Solution for high-quality coatings. With this contribution we present Ceramicoin, a dedicated PVD coating for coin minting dies and its dedicated PVD unit named S-MPuls. Specific holders were developed for various stamp sizes and geometries or customized upon request. Guaranteed smooth dust-free coatings were realized, since the surface to be coated faces downwards; the target is placed on the bottom of the coating chamber.

The SPUTTER technology from PLATIT is supported by LGD® (Lateral Glow Discharge) to ensure very good coating adhesion to the base material; thus, there are no droplets and no layer defects on the subtrates. Ceramicoin is a TiB2-based hard coating replicates every detail of the surface and is thus a significant advantage for coin appearance and design features.

Diamond is the material with the highest hardness in nature, the highest thermal conductivity, chemically stable, and excellent wear resistance, so it has been applied industrial. Microwave plasma CVD method is one of diamond synthesis methods.In this study, we investigated the effects of differences of the gas introduction point on the surface morphologies and quality of diamond films prepared on 2-inch Si substrates using of mode-conversion microwave plasma CVD.

A Si substrate (φ2 inch, t: 3 mm) scratched with diamond powder and ultrasonically cleaned with acetone was used as the substrate. CH₄-H₂ mixture gas was used as the reaction gas, CH₄ flow rate: 2, 20 sccm, H₂ flow rate: 200, 300 sccm, microwave power: 1250, 1750 W, pressure: 10, 13.4 kPa, synthesis time was fixed to 3 h, respectively. Reaction gas was supplied to the substrate from the upper and the side. For the evaluation of the deposit, surface observation by a scanning electron microscope (SEM), surface profile measurement using a microscope, and qualitative evaluation by a Raman spectrometer were performed.

As a result of SEM observation, a deposit with a clear shape was observed.The results of surface profile measurement using a microscope showed a concave profile when CH₄ gas was introduced from the upper direction and a convex profile when CH₄ gas was introduced from the lateral direction.From the Raman spectra of the products measured coaxially from the center of the substrate. A peak at 1333 cm^-1 attributed to diamond and a peak at 520 cm^-1 attributed to Si are observed at all measurement points. In addition, there is a tendency that the peak height attributed to diamond decreases from the center to the edge of the substrate. Evaluation of the IDia/IDLC ratio in the Raman spectra from the various distances on the same axis, film quality was decreased comparison with from the center and the edge of the substrate.

In this study, the influence of heat treatment temperatures on microstructure and mechanical properties of the magnetron co-sputtering (MoHf)N coatings were investigated. The relationships between phase, hardness, modulus, and tribological behavior were analyzed. The (MoHf)N films were fabricatedat a fixed Ar/N₂ inlet ratio of 12/8 sccm/sccm and 350°C with tunning of the Hf target input power. Three (MoHf)N thin films of Hf variation co-deposition at 2.3, 7.4 and 10.2at% were produced and compared. The vacuum annealing was conducted at 500, 650, and 750°C for 1 hr. The as-deposited (MoHf)N binary nitride coatings exhibited polycrystalline microstructure with B1-MoN, γ-Mo₂N, and β-Mo₂N multiple phases. After 750°C vacuum annealing, increase in hardness from 20.1 to 28.4GPa was obtained. Similarly, the H³/E² increased from 0.163 to 0.298, and the H/E ratio also increased from 0.1 to 0.102. The wear rate was reduced from 201.0 to 112.6 µm³/Nm. The microstructure of (MoHf)N binary nitride coatings did not evolve significantly, however the mechanical behavior become stronger after vacuum annealing, meaning (MoHf)N coatings exhibited a great resistance to elevated temperature environment.

Keywords: Heat treatment; Microstructure; (MoHf)N; Multiple phase; wear resistance

Machine-learning(ML)-based interatomic potentials can enable simulations of extended systems with an accuracy that is largely comparable to DFT but with a computational cost that is orders of magnitude lower.Molecular dynamics simulations further exhibit favorable linear (orderN) scaling behavior.

Remote plasma sputtering (RPS) is an industrial deposition technology with an increased processing space that overcomes challenges associated with improving coating characteristics through expanded control of deposition conditions. A high-density low-energy plasma is generated in a side chamber that is directed onto the sputter target using two electromagnets. Sputtering only occurs when a target bias is applied. This setup enables separate control over the target current and voltage. The high-density plasma at the target makes the technology an inherently energetic ionised PVD technique. Full target erosion and independent control of the plasma conditions allows high deposition rates of reactive processes to be achieved at large target-to-substrate distances. The addition of radio frequency (r.f.) substrate biasing further enables a range of energetic growth conditions achievable and allows deposition onto glass, silicon, and plastics. The large processing space and many processing parameters of RPS has previously been used to control the stress [1], grain size [2], and texture [3] of thin films deposited for a wide range of technologically important materials.

Titania thin films have been deposited by reactive RPS from a metallic target using simple constant mass flow control of oxygen with no feedback control. The deposition conditions and r.f. substrate bias have been varied. Different conditions allow selectivity of rutile or amorphous phases and the rutile texture. The correlations between processing parameters, thin film microstructure, and optical properties are discussed.

[1] – L. García-Gancedo, J. Pedrós, Z. Zhu, A.J. Flewitt, W.I. Milne, J.K. Luo, C.J.B. Ford, Room-temperature remote-plasma sputtering of c-axis oriented zinc oxide thin films, J. Appl. Phys. 112 (2012). https://doi.org/10.1063/1.4736541.

[2] – K. O’Grady, L.E. Fernandez-Outon, G. Vallejo-Fernandez, A new paradigm for exchange bias in polycrystalline thin films, J. Magn. Magn. Mater. 322 (2010) 883–899. https://doi.org/10.1016/j.jmmm.2009.12.011.

[3] – S. Han, A.J. Flewitt, Control of grain orientation and its impact on carrier mobility in reactively sputtered Cu2O thin films, Thin Solid Films. 704 (2020) 138000. https://doi.org/10.1016/j.tsf.2020.138000.

The hard machining of high strength materials such as powder metallurgical high-speed steel requires cutting tools with higher wear and crack resistance. TiAlCrSiN hard coatings deposited by physical vapor deposition (PVD) can potentially improve the tool life in such cases. However, the process gas used during PVD can influence the application behavior of the coated tools. Therefore, the present study aims to investigate the effect of argon and krypton atmospheres on coating morphology, residual stress state, elastic-plastic properties and cutting performance of coated tools. For this purpose, TiAlCrSiN coatings with comparable process parameters were deposited on cemented carbide substrates under Kr, Ar+Kr and Ar atmospheres. The resulting difference in the residual stress state of the coatings was analyzed using focused ion beam-digital image correlation (FIB–DIC) ring-core method. Moreover, the indentation hardness H_IT and indentation modulus E_IT were determined by nanoindentation. The cutting performance of the coated tools was investigated during milling of high-speed steel HS6-5-3C. The Rockwell indentation tests showed a good adhesion between the substrate and investigated coating variants. However, the morphology of the coatings changed from columnar under Kr to fine crystalline under Ar. The increased involvement of Ar in the deposition process led to higher residual stresses and indentation modulus E_IT of TiAlCrSiN coatings. Moreover, the Kr atmosphere resulted in a reduced indentation hardness H_IT of the deposited coating as compared to Ar+Kr and Ar atmospheres. Finally, the coated tools showed a comparable flank wear width VB after the cutting tests. The findings from the present study contribute to a viable process gas selection for improved cutting performance of PVD coated tools.

Demand for lightweight polymer mechanical parts is on the rise, but thermal softening of the polymer and reduced wear resistance in sliding contact with other surfaces significantly limit its application. Many research papers have reported the formation of DLC films with different sp³/sp² ratios on metallic and polymeric substrates. However, the bonding state of the DLC thin film coatings with the bulk substrate surface lacks detailed analysis and understanding. We put forward a proposal that takes care of the thermal softening and high wear volume by coating the polymer with hydrogenated diamond-like carbon (DLC), a high-strength thin film layer with a very low coefficient of friction. This inherent property of DLC film controls the frictional heat and wear volume under sliding conditions with other materials. Therefore, we can potentially realize applications of polymeric sliding mechanical parts of the same material or against a different material.

This research deals with the relationship between the structures, threshold bonding energy, and thermal expansion of a hydrogenated DLC film and polymer substrate to give insight into the adhesion of the two surfaces. We used radiofrequency plasma-enhanced chemical vapor deposition (RF-PECVD) with methane and argon gas as the precursors. Varied ion energy is irradiated to change the bonding state of the polymer and the hydrogenated DLC thin film. Our presentation details the evaluation of adhesion strength using X-ray photoelectron spectroscopy and Time-of-Flight secondary ion mass spectrometry compared to the adhesion strength measurements by scratch tests.

A facile and state-of-the-art approach to synthesize porous Ni/MoS₂ decorated with the Pt-nanoclusters for a synergistic effect on hydrogen evolution reaction (HER). The breakthrough of the research is to conduct a promising chemical vapor deposition approach to generate the 3D porous structure MoS₂ by completeness reactions between the sublimation and the deposition. Additionally, the Pt-nanoclusters and Ni are straightforwardly introduced by a hierarchical chemical reduction process to enhance the catalytic activity. Therefore, the porous MoS₂ and Pt-decorated porous Ni/MoS₂ were employed as the electrochemical catalyst for HER. The results showed that the CVD process and the decorated Pt-nanoclusters play important roles in determining the HER catalytic activity. The porous MoS₂ largely increased the surface area and active reaction site for the HER performance. In addition, the decoration of Pt-nanoclusters on porous Ni/MoS₂ can demonstrate the synergistic effect of the Pt-decorated porous Ni/MoS₂. So, the overpotential (η10) and the Tafel slope of the Pt-decorated porous Ni/MoS₂ are determined in 43 mV and 56 mV/dec, respectively. The promising approach to synthesizing Pt-decorated porous Ni/MoS₂ for adjustment of different compositions is discussed in this study.

In this research, ozone (O₃) plasma with high oxidation ability has been applied for high quality interfacial layer (IL) formation. However, an undesirable equivalent oxide thickness (EOT) growth seems to be unavoidable, which may degrade the electrical performance for germanium (Ge) n-type metal oxide semiconductor field effect transistor (nMOSFET). Notably, the EOT can be thinned and quality of IL of Ge nMOSFET can be kept with an additional post hydrogen plasma treatment. As a result, Ge nMOSFET with O₃+H₂ plasma treatment exhibits lower subthreshold swing and higher on-off current ratio.

Recently, magnetron sputter deposition has been demonstrated to be a suitable deposition technique for the preparation of metallic glasses as thin films (TFMGs). TFMGs can be prepared in a wide composition range by exploiting the sputter deposition advantages. Moreover, TFMGs have shown properties and characteristics that are superior to BMGs, and metallic and ceramic coatings, e.g., a better balance of ductility and strength. The amorphous structure of TFMGs, along with their unique properties, also provides a possibility to combine TFMGs with nanocrystalline materials in a heterogenous dual-phase structure. This might allow us to overcome the shortcomings of both types of materials and further improve the properties or even discover novel properties based on the synergetic effect of the two phases.

The study focuses on the preparation of dual-phase thin-film materials in the ternary Zr‒Cu‒N system by reactive magnetron co-sputtering and systematic investigation of their structure and properties. The coatings were deposited in argon-nitrogen gas mixtures using three unbalanced magnetrons equipped with two Zr targets and one Cu target, operated in HiPIMS and DC regime, respectively. All the coatings were deposited onto rotating substrates with rf biasing without external heating. The elemental composition of the coatings was controlled in a very wide composition range.

We have demonstrated that reactive magnetron co-sputtering allows the preparation of a new type of the Zr‒Cu‒N coatings with a nanocomposite structure consisting of two phases, crystalline ZrN and glassy ZrCu. So far, only the nanocomposite Zr‒Cu‒N coatings based on ZrN and Cu phases have been reported in the literature [1,2]. We show that by varying the process parameters, such as the target power densities, repetition frequency and nitrogen fraction in the gas mixture, we are able to control the elemental composition of the coatings so that the stoichiometry of the two phases remains as much the same as possible and only the volume fraction of the phases is varied. The structure of the as-deposited coatings exhibits a gradual transition from amorphous-like to very fine-grained to nanocrystalline. This transition is reflected in changes in the microstructure and surface morphology and affects the mechanical properties, deformation behavior and corrosion resistance.

[1] J. Musil, J. Vlcek, P. Zeman et al.: Jpn. J. Appl. Phys. 41 (2002) 6529.
[2] J. Musil, M. Zítek, K. Fajfrlík, R. Čerstvý: J. Vac. Sci. Technol. A 34 (2016) 021508.

Silica has numerous applications across various sectors of technology, including concrete production, glass production, and semiconductor technology. The surface chemistry of amorphous silica is critical for enabling these technologies, yet many aspects of the detailed surface chemistry of amorphous silica are still not fully understood when surface functional groups are present. In this study, we use computational simulations to understand the bonding mechanisms and atomistic structure of the amorphous silica surfaces passivated with different functional groups. Amorphous silica surfaces are first generated by melt-quench dynamics using classical molecular dynamics (MD). Then, subdomains of these surfaces containing an undercoordinated surface atom are selected for ab initio density functional theory (DFT) calculations. Relaxed surface geometries including hydroxyl, methyl, and fluoromethyl passivating groups are determined from DFT-based structural relaxation calculations, along with Born-Oppenheimer MD at 300 K to determine the bond dissociation energy, bond length, and angle. This study provides a deeper understanding of the structure of functionalized silica surfaces, leading to pathways to produce new advanced silica-based materials.

In this study, a PVD thick film was developed with Filtered Arc Ion Plating (FAIP). The features of the hard coating film made through FAIP was investigated, including mechanical properties, surface characteristics and corrosion resistance on different thickness films. The result shows the DLC film developed has advanced mechanical properties and compactness from the high ionized rate of FAIP process.

For the mechanical properties, the adhesiveness of the multi-layer DLC film by FAIP reached 14~15N and the hardness reached 15~16 GPa. The film also passed 30 hours of Salt Spray Test. The Ultra-thick DLC Film has been successfully adopted by various industries like car/truck components.