15 research outputs found
Predicting the Properties of the Refractory High-Entropy Alloys for Additive Manufacturing-Based Fabrication and Mechatronic Applications
No full textInfluence of high-temperature annealing on physical and mechanical properties of Nb-Si-N coating
No full textGuinier-Preston zone hardening during vacuum annealing of (Ti1-xAlx)0.92W0.08N (0.07 ≤ x ≤ 0.79) thin films
No full textWe present a systematic study on the formation of Guinier-Preston (GP) zones and corresponding age hardening in metastable cubic (Ti1-xAlx)0.92W0.08N thin films at annealing temperatures relevant to cutting tool applications. The Al content, which determines the compound's phase stability, varies widely from x = 0.07 to 0.79. The density of GP zones forming after 2 h long annealing in vacuum at 950 °C is assessed by cross-sectional transmission electron microscopy. Concurrent to the spinodal decomposition of c-(Ti,Al,W)N into c-Ti(W)N and c-Al(W)N, tungsten forms atomic-plane-thick W disks on (111) planes of the cubic matrix. The density of GP zones is ∼ 6.3·1011 – 1.2·1012 cm−2 in the 0.07 ≤ x ≤ 0.58 range and decreases to 1.8·1011 cm−2 with х = 0.65 concomitant with precipitation of w-AlN grains and bcc-W nanocrystallites. GP zone formation and age hardening is observed for all films with 0.07 ≤ x ≤ 0.58 with 2 to 14 % increase in hardness, starting from high levels between 23.5 and 32.9 GPa. Elevated hardness is, thus, retained over the entire temperature range: 520 to 950 °C. Finally, precipitation of bcc-W at х ≥ 0.65 during annealing above 950 °C is observed as a means to relax misfit strain between the c-Ti(W)N and w-Al(W)N components
High-mass metal ion irradiation enables growth of high-entropy sublattice nitride thin films from elemental targets
No full textSynthesis of high-entropy sublattice nitride (HESN) coatings by magnetron sputtering is typically done using custom-made alloyed targets with specific elemental compositions. This approach is expensive, requires long delivery times, and offers very limited flexibility to adjust the film composition. Here, we demonstrate a new method to grow HESN films, which relies on elemental targets arranged in the multicathode configuration with substrates rotating during deposition. TiVNbMoWN films are grown at a temperature of similar to 520(degrees)C using Ti, V, Nb, and Mo targets operating in the direct current magnetron sputtering mode, while the W target, operated by high power impulse magnetron sputtering (HiPIMS), provides a source of heavy ions. The energy of the metal ions EW+ is controlled in the range from 80 to 620 eV by varying the amplitude of the substrate bias pulses V-s, synchronized with the metal-ion-rich phase of HiPIMS pulses. We demonstrate that W(+ )irradiation provides dynamic recoil mixing of the film-forming components in the near-surface atomic layers. For EW+ >= 320 eV the multilayer formation phenomena, inherent for this deposition geometry, are suppressed and, hence, compositionally uniform HESN films are obtained, as confirmed by the microstructural and elemental analysis.(c) 2023 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license(http://creativecommons.org/licenses/by/4.0/
Multilayer and high-entropy alloy-based protective coatings for solving the issue of critical raw materials in the aerospace industry
No full textAerospace is an actively developing industry that continuously requires the implementation of modern technologies. The rapid growth in new vehicle production demands much support. Hence, the problem of resources with complicated supply and distribution is always of current interest. These critical raw materials (CRMs) are involved in almost all areas of aerospace manufacturing and service. An efficient and profitable solution to the problem of critical materials can be found in protective coatings, especially in such advanced concepts as multilayer and high-entropy alloy (HEA)-based coatings. In this paper, we study both ways of manufacturing effective coatings. We have shown that multilayer CrN/MoN coatings with exceptional toughness and hardness could find promising applications in the aerospace industry. The developed strategy for the novel materials screening based on the prediction of their properties has been demonstrated on the example of the refractory HEA-based coatings. A brief state of the art of the EU critical raw materials and their place in the aerospace/defence industry has been given.The study has been partially supported and funded by the Ukrainian state budget via the project
“Improved Physical and Mechanical Properties of Multilayer Protective Coatings Based on High Entropy Alloy Nitrides” (project № 0120U100475
Cross-ionization of the sputtered flux during hybrid high power impulse/direct-current magnetron co-sputtering
No full textTime-resolved ion mass spectrometry is used to analyze the type and the energy of metal-ion fluxes during hybrid high-power impulse/direct-current magnetron co-sputtering (HiPIMS/DCMS) in Ar. The study focuses on the effect of HiPIMS plasma plumes on the cross-ionization of the material flux sputtered from the DCMS source. Al, Si, Ti, and Hf elemental targets are used to investigate the effect of the metal's first ionization potential IPMe1 and mass on the extent of cross-ionization. It is demonstrated that the interaction with HiPIMS plasma results in the significant ionization of the material flux sputtered from the DCMS source. Experiments conducted with elements of similar mass but having different IPMe1 values, Si and Al (Si-HiPIMS/Al-DCMS and Al-HiPIMS/Si-DCMS) reveal that the ionization of the DCMS flux is favored if the sputtered element has lower ionization potential than the one operating in the HiPIMS mode. If elements having similar IPMe1 are used on both sources, the metal mass becomes a decisive parameter as evidenced by experiments involving Ti and Hf (Ti-HiPIMS/Hf-DCMS and Hf-HiPIMS/Ti-DCMS). In such a case, Ti+ fluxes during Hf-HiPIMS/Ti-DCMS may even exceed Hf+ fluxes from the HiPIMS cathode and are much stronger than Hf+ fluxes during Ti-HiPIMS/Hf-DCMS. The latter effect can be explained by the fact that heavier Hf+ ions require longer transit time from the ionization zone to the substrate, which effectively increases the probability of interaction between the Hf-HiPIMS plasma plume and the Ti-DCMS flux, thereby leading to higher Ti ionization. Thus, the common notion of low ionization levels associated with DCMS has to be revised if DCMS is used together with highly ionized plasmas such as HiPIMS operating at higher peak target currents. These results are particularly important for the film growth in the hybrid configuration with substrate bias pulses synchronized to specific ion types.</p
Seamless Integration of Laser-Induced Papertronics with Parafilm-Based Microfluidics as a Versatile Paper-Based Electroanalytical Platform
No full textThe widespread use of nonrenewable materials in point-of-care (PoC) electroanalysis, such as test strips with electronic meters, has inadvertently contributed to electronic waste. Paper, traditionally used as a passive substrate, offers a renewable alternative as a sustainable and versatile electroanalytical platform for on-site analysis. Here, we present the fabrication and integration of laser-induced electronic components and Parafilm-based microfluidics on a single sheet of paper as a versatile electroanalytical platform for both aqueous and organic systems. Using a flame retardant and laser treatment, we enable a direct conversion of passive cellulose paper into laser-induced graphite (PLIG), allowing for the fabrication of conductive pathways and various electronic components with customized geometries on a single sheet of paper, a process termed laser-induced papertronics. Microfluidic channels were then successfully patterned by hot-pressing hydrophobic Parafilm into hydrophilic cellulose paper (paper-para) at a low temperature (60 degrees C) for just 15 s, achieving a submillimeter resolution of similar to 0.45 mm. The resulting paper-para demonstrated compatibility with a wide range of aqueous solutions and organic solvents. This process facilitates the seamless integration of laser-induced papertronics with Parafilm-based microfluidics on a single monolithic paper sheet, denoted microfluidic PLIG (mu PLIG), preserving both the structural integrity and electrochemical performance of the papertronics as well as the fluidic character of the Parafilm-based paper microfluidics. Demonstrative applications include pH sensing with a sensitivity of -40.3 mV pH-1, lactate biosensing with a sensitivity of 0.92 mu A mM-1, and Vitamin D3 detection in ethanol mixtures exhibiting a linear range of 5-65 mu M, indicating the platform's compatibility and versatility for sensor applications in both aqueous and organic systems. This study establishes a foundation for a uniquely integrated, cost-effective, and environmentally friendly electroanalytical platform, mu PLIG, uniting paper-based LIG electronics and Parafilm-based microfluidics on a single disposable substrate.Funding Agencies|Swedish strategic research area Security Link; Swedish Strategic Research Area Security Link</p
Nanocomposite Nb-Al-N coatings: Experimental and theoretical principles of phase transformations
No full textThe crucial influence of Al on the high-temperature oxidation resistance of Ti<sub>1-x</sub>Al<sub>x</sub>B<sub>y</sub> diboride thin films (0.36 ≤ x ≤ 0.74, 1.83 ≤ y ≤ 2.03) [Elektronisk resurs]
No full textThe high-temperature oxidation resistance and mechanical properties of Ti1-xAlxBy (0.36 ≤ x ≤ 0.74, and 1.83 ≤ y ≤ 2.03) films grown by hybrid HiPIMS/DCMS co-sputtering from TiB2 and AlB2 targets at substrate temperatures lower than180 °C are studied. The air-annealing experiments conducted at temperatures ranging from 700 to 900 °C reveal a strong correlation between the starting Al concentration and the oxidation resistance. Low Al content films (x ≤ 0.49 ± 0.03 in the as-deposited state) show higher oxidation rates and develop B-depleted porous oxide scales as the original film is consumed. In contrast, oxides growing on top of high-Al content films (x ≥ 0.58 ± 0.03) are compact, composed of amorphous alumina (Al2O3) and borate (Al18B4O33), which effectively passivate the surface against oxidation . Oxide scales on films with x ≥ 0.58 ± 0.03 are, on average, 60 % harder and have 18 % higher elastic moduli. The hardest scale grew on the Ti0.42Al0.58B1.87 film, with the nanoindentation hardness of 27.3 ± 2.7 GPa, which is comparable to that of as-deposited TiAlN, used widely for high-temperature wear protection. Electron microscopy also shows that for x ≥ 0.58 ± 0.03, the oxide scales adhere well to the unoxidized portions of Ti1-xAlxBy films, which is explained by a better match of the respective thermal expansion coefficients.</p
Synthesis of Hard Boron Thin Films by Low Frequency Magnetron Sputtering
No full textThe synthesis of hard boron (B) films using low frequency (4000 Hz) magnetron sputtering of B target in Ar is demonstrated. Dense B films are deposited with the substrate bias Vs applied synchronously with the cathode pulses. The substrate temperature does not exceed 150 °C during growth. The contamination levels are below 5.9 at.%, which is markedly lower than previously reported. Ion mass spectrometry analysis reveals that ion flux incident at the growing film surface is dominated by Ar+. B+ ions exhibiting broad high-energy tails are also detected. B films are amorphous containing 1–2 nm crystallites, changing from rhombohedral- at floating substrate bias to a metastable tetragonal-α-B at Vs ≥ 160 V. Higher Vs of up to 240 V results in a lowered film density due to the (1) Ar gas bubble formation, and (2) the ion-induced α-phase transition, which leads to a sparser packing of B atoms. The nanoindentation hardness and elastic modulus reach 29.1 ± 1.1 and 438.7 ± 20.4 GPa, respectively, while the residual stresses are lower than −1.1 GPa. The presented approach outlines a low-temperature growth of dense B films with attractive mechanical properties for applications on temperature sensitive substrates
