Search

In this study, NbTaMoW medium-entropy alloy films were prepared using a cosputtering apparatus with four sputter guns. Pure-element targets were used for sputtering. The rotational speeds of the substrate holder (RS) were 1–30 rpm. Lower RS values resulted in the formed films exhibiting a multilayer stacked structure with a cyclical gradient concentration. The crystalline phases, mechanical properties, and oxidation behavior of the prepared NbTaMoW films were investigated. The uniformity of the prepared multilayered alloy films increased with the RS value. The monolithic NbTaMoW alloy films prepared at 30 rpm exhibited a single body-centered cubic (BCC) phase, hardness of 12.9 GPa, and Young's modulus of 278 GPa. The BCC phase evolved into a combination of multiple BCC phases when RS was

In this study, TiNbTa and TiNbTaZr films were utilized as protective coatings on a Ti-6Al-4V alloy to inhibit corrosive attacks from NaCl aqueous solution and simulated body fluid. The structural and mechanical properties of multicomponent TiNbTa(Zr) films were investigated. The corrosion resistance of the TiNbTa(Zr)-film-modified Ti-6Al-4V alloy was evaluated using potentiodynamic polarization tests in a NaCl aqueous solution. The results indicate that the TiNbTa(Zr) films with high Ti and Zr contents exhibited inferior corrosive resistance related to the films with high Ta and Nb contents. Moreover, the TiNbTa(Zr)-coated Ti-6Al-4V plates were immersed in Ringer’s solution for eight weeks; this solution was widely used as a simulated body fluid. The formation of surficial oxide layers above the TiNbTa(Zr) films was examined using transmission electron microscopy and X-ray photoelectron spectroscopy, which prevented the elution of Al and V from the Ti-6Al-4V alloy. Ti33Nb19Ta21Zr27, Ti15Nb68Ta8Zr9, and Ti8Nb8Ta79Zr5 films are suggested as preferential candidates for TiNbTa(Zr)/Ti-6Al-4V assemblies applied as biocompatible materials.

This study explored the structural characteristics, mechanical properties, and oxidation behavior of W-enriched TaWSiN films prepared through co-sputtering. The atomic ratios [W/(W + Ta)] of the as-deposited films maintained a range of 0.77–0.81. The TaWSiN films with a Si content of 0–13 at.% were crystalline, whereas the film with 20 at.% Si was amorphous. The hardness and Young’s modulus of crystalline TaWSiN films maintained high levels of 26.5–29.9 GPa and 286–381 GPa, respectively, whereas the hardness and Young’s modulus of the amorphous Ta7W33Si20N40 films exhibited low levels of 18.2 and 229 GPa, respectively. The oxidation behavior of TaWSiN films was investigated after annealing at 600 °C in a 1%O2–Ar atmosphere, and cone-like Ta0.3W0.7O2.85 oxides formed and extruded from the TaWSiN films.

WSiN films were produced through hybrid pulse direct current/radio frequency magnetron co-sputtering and evaluated as diffusion barriers for Cu metallization. The Cu/WSiN/Si assemblies were annealed for 1 h in a vacuum at 500–900 °C. The structural stability and diffusion barrier performance of the WSiN films were explored through X-ray diffraction, Auger electron spectroscopy, and sheet resistance measurement. The results indicated that the Si content of WSiN films increased from 0 to 9 at.% as the power applied to the Si target was increased from 0 to 150 W. The as-deposited W76N24, W68Si0N32, and W63Si4N33 films formed a face-centered cubic W2N phase, whereas the as-deposited W59Si9N32 film was near-amorphous. The lattice constants of crystalline WSiN films decreased after annealing. The sheet resistance of crystalline WSiN films exhibited a sharp increase as they were annealed at 800 °C, accompanied by the formation of a Cu3Si compound. The failure of the near-amorphous W59Si9N32 barrier against Cu diffusion was observed when annealed at 900 °C.

In this study, the feasibility of using ZrO2 coatings, fabricated through the atmospheric pressure plasma jet technique, as top coats in thermal barrier systems was explored. Inconel 617 was used as the substrate material, and sputtered laminated RuAl/RuAlZr/Ru was used as the bond coat. >20-μm-thick ZrO2 coatings were deposited through several iterations of deposition at 500 °C and annealing at 600 °C; here, ZrO2 existed in the tetragonal phase. The tetragonal ZrO2 was stable after annealing at up to 700 °C but transformed into a mixture of tetragonal and monoclinic ZrO2 phases when annealed at >800 °C. The thermal stability of the ZrO2/RuAl/RuAlZr/Ru/Inconel 617 assembly was evaluated at 800–900 °C in air. The variations in volumetric fractions of the tetragonal and monoclinic ZrO2 phases were recorded; 44% of the tetragonal phase remained after 100 h of annealing at 800 °C, whereas 80% of the tetragonal phase had transformed into the monoclinic phase after 4 h of annealing at 900 °C. Observation of BC after annealing at 800 °C indicated that a dense thermally grown oxide scale, comprising O and Al, formed between the ZrO2 and RuAl layers, which impeded the inward diffusion of O. The inhibition of O diffusion declined with the crystallization of the thermally grown oxide scale into the δ-Al2O3 phase when the annealing time was extended.

Monolithic and multilayered W N and W–Si–N coatings were fabricated through direct current magnetron cosputtering at substrate holder rotation speeds of 0 and 5 rpm. The mechanical properties, structural evolutions, and oxidation behaviors of the W N and W–Si–N coatings were investigated through nanoindentation, X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy. The mechanical properties of crystalline W N coatings correlated to their textures and residual stresses. The monolithic W77N23 samples located closest to the W target exhibited a high deposition rate of 18.0 nm/min, a strong (200) texture coefficient, a high nanoindentation hardness of 32.7 GPa, a high Young's modulus of 392 GPa, and a high residual stress of −3.2 GPa. The addition of Si into the W N matrix transformed the monolithic W–Si–N coating into an X-ray amorphous phase dominated structure that comprised Si3N4, W2N, and W constituents. Ion bombardment caused the formation of multilayered W78N22 samples with high residual stress and mechanical properties. The mechanical properties and residual stresses of the multilayered W–Si–N coatings decreased due to the preferential formation of Si3N4. By contrast, oxidation resistance was improved by adding Si content higher than 24 at.% with annealing at 600 °C in a 1% O2–99% Ar atmosphere.

In this study, TaWN films were fabricated through co-sputtering. The effects of W addition on the structural variation and mechanical properties of these films were investigated. TaWN films formed face-centered cubic (fcc) solid solutions. With the increase in the W content, the fcc phase varied from TaN-dominant to W2N-dominant, which was accompanied by a decrease in the lattice constant and alterations in material characteristics, such as the chemical bonding and mechanical properties. The phase change was further correlated with the bonding characteristics of films examined by X-ray photoelectron spectroscopy. The hardness increased from 21.7 GPa for a Ta54N46 film to 23.2–31.9 GPa for TaWN films, whereas the Young’s modulus increased from 277 GPa for the Ta54N46 film to 302–391 GPa for the TaWN films. The enhancement in films’ mechanical properties was attributed to the strengthening of the solid solution and the phase change. The wear behavior of the fabricated TaWN films was evaluated using the pin-on-disk test. The Ta17W55N28 and Ta36W24N40 films exhibited an abrasive wear behavior and low wear rates of 4.9–7.6 × 10−6 mm3/Nm.

ZrNx (x = 0.67&ndash, 1.38) films were fabricated through direct current magnetron sputtering by a varying nitrogen flow ratio [N2/(Ar + N2)] ranging from 0.4 to 1.0. The structural variation, bonding characteristics, and mechanical properties of the ZrNx films were investigated. The results indicated that the structure of the films prepared using a nitrogen flow ratio of 0.4 exhibited a crystalline cubic ZrN phase. The phase gradually changed to a mixture of crystalline ZrN and orthorhombic Zr3N4 followed by a Zr3N4 dominant phase as the N2 flow ratio increased up to &gt, 0.5 and &gt, 0.85, respectively. The bonding characteristics of the ZrNx films comprising Zr&ndash, N bonds of ZrN and Zr3N4 compounds were examined by X-ray photoelectron spectroscopy and were well correlated with the structural variation. With the formation of orthorhombic Zr3N4, the nanoindentation hardness and Young&rsquo, s modulus levels of the ZrNx (x = 0.92&ndash, 1.38) films exhibited insignificant variations ranging from 18.3 to 19.0 GPa and from 210 to 234 GPa, respectively.

Nb–Si–N coatings with Si contents of 0–30 at% were fabricated through reactive direct current magnetron cosputtering. The processing parameters were various sputtering powers, substrate holder rotation speeds, and nitrogen flow ratio (N2/(N2 + Ar)). Three phase regions, namely face-centered cubic (f.c.c.) NaCl structure, X-ray amorphous, and nanocrystalline phases, were identified and related to the chemical compositions of the coatings. Low-Si-content (0–13 at%) and middle-N-content (39–45 at%) Nb–Si–N coatings exhibited an f.c.c. structure, high-Si-content (17–30 at%) and high-N-content (45–53 at%) Nb–Si–N coatings exhibited an X-ray amorphous structure, and low-Si-content (6 at%) and low-N-content (26–30 at%) Nb–Si–N coatings exhibited a nanocrystalline structure. Examining the bonding characteristics of the Nb–Si–N coatings by using X-ray photoelectron spectroscopy indicated that NbN tended to form preferentially and was followed by Si3N4, which is consistent with the laws of thermodynamics. The correlations between the mechanical properties, residual stresses, and structures of the Nb–Si–N coatings were investigated using nanoindentation, a curvature method, and X-ray diffraction. The oxidation behaviors of the Nb–Si–N coatings annealed in air at 400–600 °C were also examined.

Nanocomposite CrSiN films with a Si content of 14 at.% were fabricated through reactive direct current magnetron cosputtering. The Si content was determined based on the superior mechanical properties and oxidation resistance for CrSiN films reported in a previous study. Substrate bias voltage (Vb) and temperature (Ts) were the process variables for sputtering CrSiN films. The results indicated that the chemical composition (Cr34–37Si14N49–52) and crystalline phase (CrN) of CrSiN films were not affected by Vb or Ts. The application of Vb and Ts significantly increased the hardness of the films from 13.4 to 22.2 GPa, and Young's modulus increased from 223 to 299 GPa. The oxidation behavior of the films annealed at 800 °C in ambient air was identical, which was accompanied by the formation of an amorphous oxide layer and extruded Cr2O3 precipitations.

Ta Si N coatings with a Si content of 19–21 at.% were fabricated through reactive direct current magnetron cosputtering; the sputter power was set at 100 W for each target, and the coatings were X-ray amorphous in the as-deposited state. The N contents of the Ta Si N coatings increased from 31 to 47 at.% as the N 2 /(N 2 + Ar) flow ratio was increased from 0.1 to 0.4; additionally, nanoindentation hardness decreased from 20 to 14 GPa, and the Young's modulus decreased from 220 to 196 GPa. The oxidation resistance of the Ta Si N coatings was evaluated through annealing at 600 °C and 800 °C in ambient air, which revealed notable oxidation resistance related to the TaN coatings. The oxidation behavior of the X-ray amorphous Ta Si N coatings was examined through transmission electron microscopy and X-ray photoelectron spectroscopy.

Zr–Si–N coatings with cyclic gradient concentration were fabricated using reactive direct current magnetron cosputtering. The low-Si-content coatings, Zr60N40 and Zr58Si2N40, exhibited a face-centered cubic (f.c.c.) structure, accompanied with a nanohardness of 21.0–23.6 GPa and a Young's modulus of 248–267 GPa, whereas the medium-Si-content coatings, Zr54Si6N40 and Zr52Si8N40, exhibited a mixture of f.c.c. and near-amorphous structures, accompanied with a nanohardness of 19.7–18.4 GPa and a Young's modulus of 204–207 GPa. When the Si content ranged from 14 to 19 at.%, the structures of Zr–Si–N coatings were X-ray amorphous; those coatings exhibited lower nanohardness levels of 13.7–10.3 GPa and Young's modulus values of 196–148 GPa. The high-Si-content coatings, Zr28Si24N48 and Zr22Si30N48, exhibited an amorphous structure, accompanied with a nanohardness of 13.7–16.2 GPa and a Young's modulus of 196–217 GPa, which were higher than those of the coatings with a Si content of 14–19 at.%. Coatings formed by adding Si into the Zr–N matrix and performing annealing at 600 °C in a 1% O2–99% Ar atmosphere showed notably high oxidation resistance because Si–Zr–O oxide scales formed on the surfaces. The mechanical properties of crystalline Zr–Si–N coatings declined after annealing, whereas near-amorphous Zr–Si–N coatings retained high levels of mechanical properties after annealing.

Cr–W–N coatings were prepared through reactive direct current magnetron cosputtering at nitrogen flow ratios of 0.1–0.5. The feasibility of the surveyed Cr–W–N coatings as protective coatings on glass molding dies was evaluated by studying their mechanical properties, tribological characteristics, surface roughness, and oxidation resistance. Crystalline Cr–W–N coatings with a (200) orientation, namely Cr29W40N31, Cr24W46N30, and Cr16W57N27, were found to be suitable candidates for protective coatings.

A direct current magnetron cosputtering system was used to deposit Nb–Ru coatings with various chemical compositions onto silicon wafers. The Nb–Ru coatings exhibited distinct nanolaminated structures because of the cyclical gradient concentration deposition. The oxidized Nb–Ru coatings formed oxide and metal multilayers when they experienced internal oxidation at 400–600 °C in a 1% O2–99% Ar atmosphere. A two-stage parabolic-rate law was obeyed for the Nb0.49Ru0.51 coatings oxidized at 350–550 °C in 1% O2–99% Ar. The activation energies in the two-stage oxidation, dominated by oxygen dissolution and oxide formation, were calculated at 88 and 127 kJ/mol, respectively.

Ta–Al–N coatings were prepared using reactive magnetron cosputtering on silicon substrates. The coatings with a high Ta content exhibited a face-centered-cubic structure, whereas the coating with a high Al content exhibited a near-amorphous phase. To determine the oxidation resistance of the Ta–Al–N coatings, annealing treatments were conducted in air at 600–800 °C. Adding Al into a TaN structure increased the oxidation resistance to endure 8-h annealing at 600 °C. Moreover, the Ta35Al15N50 coating exhibited a superior oxidation resistance at 700 °C for 4 h. The material characteristics of the annealed Ta–Al–N coatings were examined through Auger electron spectroscopy and transmission electron microscopy and by using a nanoindentation tester.

In this study, Ta Al multilayer films were cosputtered on Inconel 617 through cyclical gradient concentration deposition. The oxidation behavior of the Ta Al films and the interdiffusion between the Ta Al films and Inconel 617 were evaluated through thermogravimetric analysis, X-ray diffraction, transmission electron microscopy, and Auger electron spectroscopy after the films were annealed in air at 400–800 °C. The results indicated that the Ta0.79Al0.21 multilayer films had a low O content even though O diffused inward through the entire film thickness after 8 h of annealing at 800 °C, which was attributed to the formation of an Al oxide scale due to the outward diffusion of Al in the initial oxidation stage. This under-stoichiometric Al2O3/Ta2O5 structure caused the produced films to exhibit a high hardness of 23.2 GPa and a high Young's modulus of 316 GPa. Moreover, the outward diffusion of Inconel 617 elements, namely Ni and Cr, was restricted by the oxidized films. However, the high Ta content in the Ta Al films deteriorated the film adherence to the substrates due to a high volume ratio of Ta2O5/Ta. Furthermore, laminated Ta0.79Al0.21/Ta0.34Al0.66/Ti films were fabricated to improve the film–substrate adhesion. These films exhibited a high hardness of 17.1 GPa after annealing at 800 °C for 24 h.

The reactive gas flow ratio and substrate bias voltage are crucial sputtering parameters for fabricating transition metal nitride films. In this study, W&ndash, N films were prepared using sputtering with nitrogen flow ratios (f) of 0.1&ndash, 0.5. W&ndash, N and W&ndash, Si&ndash, N films were then prepared using an f level of 0.4 and substrate bias varying from 0 to &minus, 150 V by using sputtering and co-sputtering, respectively. The variations in phase structures, bonding characteristics, mechanical properties, and wear resistance of the W&ndash, N films were investigated. The W&ndash, N films prepared with nitrogen flow ratios of 0.1&ndash, 0.2, 0.3, and 0.4&ndash, 0.5 displayed crystalline W, amorphous W&ndash, N, and crystalline W2N, respectively. The W&ndash, N films prepared using a nitrogen flow ratio of 0.4 and substrate bias voltages of &minus, 50 and &minus, 100 V exhibited favorable mechanical properties and high wear resistance. The mechanical properties of the amorphous W&ndash, N films were not related to the magnitude of the substrate bias.

Ru–Al–Zr multilayer coatings with a Ru interlayer were fabricated through cyclical gradient concentration deposition by using direct current magnetron cosputtering on Inconel 617 substrates. The thermal stability of these Ru–Al–Zr coatings after annealing at 800 °C in ambient air was investigated through X-ray diffraction, Auger electron spectroscopy, and transmission electron microscopy. A multilayered structure of the Ru–Al–Zr coatings was maintained, transformed to small grains, and grew into large grains as the annealing duration was increased from 30 min to 4 h, and then to 12 h, which was accompanied with the outward diffusion of Ni, Cr, and Co from Inconel 617 substrates. Moreover, the Ru–Al–Zr coatings could not prevent the inward diffusion of oxygen. With the deposition of a Ru–Al top coating, the laminated Ru–Al/Ru–Al–Zr coatings restricted the inward diffusion of oxygen by forming a continuous Al2O3 scale.

Glass molding is widely used for manufacturing high-precision optical elements. Nitride coatings are recommended as protective coatings on glass molding dies. In a die-fixed glass molding system, the molding dies undergo rapid thermal shocks. In this study, near-amorphous Cr–Si–N, Ta–Si–N, and Zr–Si–N coatings with a Si concentration of >14 at.% were prepared. The feasibility of these coatings in the glass molding process was evaluated through rapid thermal cycling annealing in a 15-ppm O2–N2 atmosphere. The cycling annealing test was performed at 270 °C and 580 °C or 600 °C. The heating, holding, and cooling times in the annealing process were 1 min each. The results indicated that Zr–Si–N coatings exhibited superior anti-sticking against SiO2–B2O3–BaO-based glass. The reactions between the nitride coatings and glass were investigated.

HfNx (x = 0.81–2.07) films were fabricated through direct current magnetron sputtering by varying nitrogen flow ratio [N2/(Ar + N2)] from 0.1 to 1.0. The structural evolution, mechanical properties, and bonding characteristics of the as-deposited HfNx films were investigated for various values of the stoichiometric variable x. The results indicated that the films prepared using nitrogen flow ratios lower than 0.2 and higher than 0.4 exhibited crystalline and near-amorphous structures, respectively. The highest level of the nanoindentation hardness of the near-stoichiometric Hf51N49 films prepared using a nitrogen flow ratio of 0.2 was 26.0 GPa. Further increases to the x value of HfNx films decreased the hardness levels, which could be attributed to higher Hf3N4 content. The bonding constitutions comprised metallic Hf, Hf N bonds of HfN and Hf3N4, and Hf O bonds. The amounts of Hf N bonds in Hf3N4 structure increased as x increased. The thermal stability values of the HfNx films at 500 and 600 °C in a 15-ppm O2–N2 atmosphere were evaluated.

Monolithic Hf&ndash, Si&ndash, N coatings and multilayered Hf&ndash, N coatings with cyclical gradient concentration were fabricated using reactive direct current magnetron cosputtering. The structure of the Hf&ndash, N coatings varied from a crystalline HfN phase, to a mixture of HfN and amorphous phases and to an amorphous phase with continuously increasing the Si content. The multilayered Hf48Si3N49 coatings exhibited a mixture of face-centered cubic and near-amorphous phases with a maximal hardness of 22.5 GPa, a Young&rsquo, s modulus of 244 GPa and a residual stress of &minus, 1.5 GPa. The crystalline phase-dominant coatings exhibited a linear relationship between the hardness and compressive residual stress, whereas the amorphous phase-dominant coatings exhibited a low hardness level of 15&ndash, 16 GPa, this hardness is close to that of Si3N4. Various oxides were formed after annealing of the Hf&ndash, N coatings at 600 &deg, C in a 1% O2&ndash, 99% Ar atmosphere. Monoclinic HfO2 formed after Hf54N46 annealing and amorphous oxide formed for the oxidation-resistant Hf32Si19N49 coatings. The oxidation behavior with respect to the Si content was investigated by using transmission electron microscopy and X-ray photoelectron spectroscopy.

Zr&ndash, Si&ndash, N films were fabricated through the co-deposition of high-power impulse magnetron sputtering (HiPIMS) and radio-frequency magnetron sputtering (RFMS). The mechanical properties of the films fabricated using various nitrogen flow rates and radio-frequency powers were investigated. The HiPIMS/RFMS co-sputtered Zr&ndash, N films were under-stoichiometric. These films with Si content of less than 9 at.%, and N content of less than 43 at.% displayed a face-centered cubic structure. The films&rsquo, hardness and Young&rsquo, s modulus exhibited an evident relationship to their compressive residual stresses. The films with 2&ndash, 6 at.% Si exhibited high hardness of 33&ndash, 34 GPa and high Young&rsquo, s moduli of 346&ndash, 373 GPa, which was accompanied with compressive residual stresses from &minus, 4.4 to &minus, 5.0 GPa.

This study explores the internal oxidation of laminated Hf–Ta coatings with a cyclically gradient chemical concentration distribution along the growth direction. The oxidation behavior was examined by annealing the coatings at 400–600 °C in a 15 ppm O 2 –N 2 atmosphere for 30 min. The variations in crystalline structure, nanohardness, chemical states, and chemical composition profiles in depth after various annealing conditions were investigated. The results indicate that all the Hf–Ta coatings maintain a laminated structure after annealing at 400–600 °C. Internal oxidation conducts during 500 and 600 °C annealing, but part of the outmost layers exhibits complex oxides after annealing at 600 °C. The nanohardness of annealed Hf–Ta coatings related to the formation of HfO 2 , Hf 6 Ta 2 O 17 , and amorphous Ta-oxide were studied.

Researchers have observed the internal oxidation phenomenon in binary alloy coatings when developing refractory alloy coatings for protective purposes by conducting annealing at high temperatures and in oxygen-containing atmospheres. The coatings were assembled using cyclical gradient concentration deposition during cosputtering by employing a substrate holder rotating at a slow speed. The internally oxidized zone demonstrated a laminated structure, comprising alternating oxygen-rich and oxygen-deficient layers stacked in a general orientation. In the current study, Ru–Ta–Zr coatings were prepared with various stacking sequences during cosputtering. The Ru–Ta–Zr coatings were annealed at 600 °C in an atmosphere continuously purged with 1% O2–99% Ar mixed gas for 30 min. A transmission electron microscope was used to examine the periods of the laminated layers and crystallinity of the annealed coatings. Depth profiles produced using an Auger electron spectroscope and X-ray photoelectron spectroscope were used to certify the periodic variation of the related constituents and chemical states of the elements, respectively. The results indicate that the internally oxidized ternary coatings are stacked of Ru-, Ta2O5-, and ZrO2-dominant sublayers and that the stacking sequences of the sublayers affect the crystalline structure of the coatings. Zr is oxidized preferentially in the Ru–Ta–Zr coatings, increasing the surface hardness of the oxidized coatings.

Ta1 − xZrxNy coatings were fabricated using reactive direct-current magnetron cosputtering on silicon and cemented carbide substrates. The oxidation resistance of the Ta1 − xZrxNy coatings was evaluated by annealing the samples in a 15-ppm O2–N2 atmosphere at 600 °C. The variations in crystalline structure, mechanical properties, and surface roughness values after annealing were investigated. One commercial moldable glass material, a SiO2–B2O3–BaO-based glass, was used to evaluate the chemical inertness of Ta1 − xZrxNy coatings, applied as protective coatings in glass molding processes. Thermal cycling annealing at 270 and 600 °C, with the temperature strictly maintained at 600 ± 10 °C for 1 min/cycle, was conducted in a quartz tube furnace to simulate a glass molding process in a continuous flow of 15 ppm O2–N2. Up to 500 thermal cycling annealing tests were conducted for the glass and coating assemblies.

Glass molding can be employed to fabricate high-quality lenses with a lower cost and higher process rate than those of the traditional glass lens production method. Glass molding is widely employed in manufacturing precision optical elements with aspheric surfaces. In this study, amorphous Ta–Si–N coatings with a Ti interlayer were sputtered on cemented carbide substrates to evaluate their potential as protective coatings on glass molding dies. Commercial moldable SiO2–B2O3–BaO-based and B2O3–ZnO–La2O3-based glasses were used to evaluate the chemical inertness of Ta–Si–N coatings in glass molding. Thermal cycle annealing, which involves annealing at 270 °C and 600 °C and maintaining the glasses at 600 °C ± 10 °C for 1 min/cycle, was conducted in a quartz tube furnace to simulate glass molding in a continuous flow of a 15-ppm O2–N2 atmosphere. The glass and coating assemblies were subjected to up to 1000 thermal cycles. The variations in the crystalline structure and surface roughness after various annealing durations were investigated.

In this study, Cr–Ta–Si–N coatings were prepared using reactive magnetron co-sputtering on silicon wafers and cemented carbide substrates to evaluate their feasibility for protective purposes on glass molding dies. The nitrogen gas flow-rate ratio (N 2 /(N 2 + Ar)) was set at 0.4 to fabricate the Cr–Ta–Si–N coatings with an overstoichiometric ratio, N/(Cr + Ta + Si) > 1, for the rock salt structure. The as-deposited Cr–Ta–Si–N coatings, with Cr and Si contents in the ranges of 1–15 at.% and 9–15 at.%, respectively, exhibited a nanohardness of 14.6–21.6 GPa and a surface roughness of 0.4–1.0 nm. The coatings with a Si content between 11 and 15 at.% exhibited X-ray amorphous. Annealing treatments were conducted in a 1% O 2 –99% Ar atmosphere at 600 °C for 500 min, which is an oxidation-accelerating condition, and thermal cycling annealing was conducted at 270 °C and 600 °C in a 15 ppm O 2 –N 2 atmosphere, which is a realistic glass molding atmosphere for mass production. The outward diffusion of Si resulted in the formation of a Si-oxide scale 12–14 nm thick, thus maintaining a surface roughness of approximately 1 nm and confirming the thermal stability of the Cr–Ta–Si–N coatings. The chemical inertness of the Cr 6 Ta 25 Si 11 N 58 coating during the molding of B 2 O 3 –ZnO–La 2 O 3 -based and SiO 2 –B 2 O 3 –BaO-based glasses was evaluated.

The feasibility of applying Ta-containing nitride protective coatings on glass molding dies was examined by conducting thermal cycling annealing. TaN, CrTaN, TaSiN, and CrTaSiN coatings are prepared by reactive co-sputtering. The thermal cycling annealing was performed at 270 °C and 600 °C in a 15-ppm O 2 –N 2 atmosphere, a realistic glass molding atmosphere for mass production. This study investigated variations in crystalline structure, surface oxide scale, mechanical properties, surface roughness, and residual coating stress after thermal cycling annealing up to 2000 cycles. The results indicated that the near-amorphous Cr 6 Ta 25 Si 11 N 58 coating exhibited a nanohardness of 19 GPa, a Young's modulus of 230–240 GPa, a surface roughness of 1 nm, and a consistent residual stress during the 2000 thermal cycles of annealing. The Cr 6 Ta 25 Si 11 N 58 coating is proposed as an appropriate coating for molding glass.

B 2 O 3 –ZnO–La 2 O 3 -based glasses with a high refractive index are widely used as optical glass materials for lenses. To evaluate the feasibility of applying protective coatings on glass molding dies, Ir–Re and Ta–Ru coatings were sputtered on cemented tungsten carbide or silicon substrates. B 2 O 3 –ZnO–La 2 O 3 -based glasses were placed on the surface of the coatings and heat-treated in a glass molding atmosphere of 15-ppm O 2 –N 2 at a molding temperature of 600 °C. Up to 1000 thermal cycling annealing tests were performed at 270 °C and 600 °C. The holding time at the molding temperature was set at 1 min for each cycle. The variations in chemical inertness, residual stress, and coating characteristics after annealing were investigated.

Ta–Si–N coatings were prepared using reactive direct current magnetron co-sputtering on silicon substrates. When the sputtering powers and N 2 flow ratio were varied, Ta–Si–N coatings exhibited various chemical compositions and crystalline characteristics. The high-Si-content Ta–Si–N coatings exhibited an amorphous phase in the as-deposited states, whereas the low-Si-content coatings exhibited a face-centered cubic phase or an amorphous phase depending on the N content. This study evaluated the application of amorphous Ta–Si–N coatings, such as the protective coatings on glass molding dies, in high-temperature and oxygen-containing atmospheres for longed operation durations. To explore the oxidation resistance and mechanical properties of the Ta–Si–N coatings, annealing treatments were conducted in a 1%O 2 –99%Ar atmosphere at 600 °C for 4–100 h. The material characteristics and oxidation behavior of the annealed Ta–Si–N coatings were examined using atomic force microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and a nanoindentation tester. The Si oxidized preferentially in the Ta–Si–N coatings. The in-diffusion of oxygen during 600 °C annealing was restricted by the formation of an amorphous oxide scale consisting of Si and O.

Ta&ndash, Al multilayer coatings were fabricated through cyclical gradient concentration deposition by direct current magnetron co-sputtering. The as-deposited coatings presented a multilayer structure in the growth direction. The oxidation behavior of the Ta&ndash, Al multilayer coatings was explored. The results specified that Ta-rich Ta&ndash, Al multilayer coatings demonstrated a restricted oxidation depth after annealing at 600 &deg, C in 1% O2&ndash, 99% Ar for up to 100 h. This was attributed to the preferential oxidation of Al, the formation of amorphous Al-oxide sublayers, and the maintenance of a multilayer structure. By contrast, Ta2O5 formed after exhausting Al in the oxidation process in an ambient atmosphere at 600 &deg, C which exhibited a crystalline Ta2O5-amorphous Al-oxide multilayer structure.

Zr&ndash, Si&ndash, N films with atomic ratios of N/(Zr + Si) of 0.54&ndash, 0.82 were fabricated through high-power impulse magnetron sputtering (HiPIMS)&ndash, radio-frequency magnetron sputtering (RFMS) cosputtering by applying an average HiPIMS power of 300 W on the Zr target, various RF power levels on the Si target, and negative bias voltage levels of 0&ndash, 150 V connected to the substrate holder. Applying a negative bias voltage on substrates enhanced the ion bombardment effect, which affected the chemical compositions, mechanical properties, and residual stress of the Zr&ndash, N films. The results indicated that Zr&ndash, N films with Si content ranging from 1.4 to 6.3 atom % exhibited a high hardness level of 33.2&ndash, 34.6 GPa accompanied with a compressive stress of 4.3&ndash, 6.4 GPa, an H/E* level of 0.080&ndash, 0.107, an H3/E*2 level of 0.21&ndash, 0.39 GPa, and an elastic recovery of 62&ndash, 72%.

Cr&ndash, Si&ndash, N coatings were prepared through reactive direct current magneton sputtering using a high N2/Ar flow ratio of 1. The addition of Si to improve the mechanical properties and oxidation resistance of Cr&ndash, N coatings was examined. The results indicated that the Cr&ndash, N coatings with an Si content of &lt, 12 at % and an N content of &gt, 50 at % exhibited a cubic CrN phase with a columnar structure, whereas the coatings with 14 at % Si comprised of a nanocomposite structure, and the coatings with 16&ndash, 18 at % Si were near-amorphous. The nanocomposite Cr32Si14N54 coating possessed hardness and Young&rsquo, s modulus values of 17 and 209 GPa, respectively, accompanied with a hardness to effective Young&rsquo, s modulus (H/E*) value of 0.077 and an elastic recovery (We) level of 55%&mdash, all the properties were highest within the as-deposited coating. The addition of Si was also beneficial to reduce the surface roughness and improve the oxidation resistance.

Ir–Re coatings are widely applied as protective coatings on glass molding dies. Because the glass molding process in mass production is conducted in an oxygen-containing atmosphere at a high temperature, the protective coatings must endure cyclic annealing treatments. Oxidation and thermal stability of Ir–Re coatings has received scant attention. In this study, Ir–Re coatings were prepared using co-sputtering. Constant-temperature annealing treatments were conducted at 600 °C under a 1% O 2 –Ar atmosphere, which is an oxidation-accelerating atmosphere. The thermal cyclic test was performed at 270 and 600 °C under atmospheres of 1% O 2 –Ar and 15 ppm O 2 –N 2 , respectively. The 15 ppm O 2 –N 2 atmosphere is glass molding atmosphere suitable for mass production. The variations in crystalline structure, nanohardness, surface roughness, and residual stress after various annealing treatments were investigated. The more elevated Ir content coating, namely, Ir 0.77 Re 0.23 , displays superior thermal stability compared with the lower Ir content coating, namely, Ir 0.53 Re 0.47 .

This study investigates the internal oxidation of Nb–Ru multilayer coatings with a cyclically gradient chemical concentration distribution along the growth direction after annealing in a 1% O 2 –Ar atmosphere at 600 °C for 1 h. X-ray photoelectron spectroscopy and transmission electron microscopy were used to analyze the oxidation behavior of Nb–Ru coatings. The results show that Nb oxidized preferentially in a Nb–Ru coating and partial Nb atoms oxidized to Nb 5 + , Nb 4 + , and Nb 2 + , but Ru remained in a metallic state. After annealing, the microstructure evolved to a laminated structure consisting of alternative crystalline Nb 2 O 5 and Ru layers.

Refractory metal alloy coatings, such as Mo–Ru and Ta–Ru coatings, have been developed to protect glass molding dies. Forming intermetallic compounds in the coatings inhibits grain growth in high temperature environments when mass producing optical components. After annealing in oxygen containing atmospheres, a surface roughening of the Mo–Ru coatings and a soft oxide layer on the Ta–Ru coatings have been observed in our previous works. Oxidation resistance becomes critical in high-temperature applications. In this study, Ta–Zr coatings were deposited with a Ti interlayer on silicon wafers using direct current magnetron sputtering at 400 °C. The as-deposited Ta–Zr coatings possessed nanocrystallite or amorphous states, depending on the chemical compositions. The annealing treatments were conducted at 600 °C under atmospheres of 50 ppm O 2 –N 2 or 1% O 2 –Ar, respectively. After the annealing treatment, this study investigated variations in crystalline structure, hardness, surface roughness, and chemical composition profiles. Preferential oxidation of Zr in the Ta–Zr coatings was verified using X-ray photoelectron spectroscopy, and the microstructure was observed using transmission electron microscopy.

This paper proposes Ta–Zr multilayer coatings fabricated by using magnetron co-sputtering, achieving high nanohardness and low roughness after annealing, as appropriate protective coatings for die materials. The as-deposited nanolaminated Ta–Zr coatings exhibited nanocrystalline or amorphous phases, depending on the chemical compositions. The Zr oxidized preferentially when annealed in oxygen-containing atmospheres. The nanohardness increased in relation to the oxygen content in the coating, which was attributed to the formation of a crystalline tetragonal ZrO2 phase. To serve as a protective coating when applied in high-temperature conditions with an appropriate nanohardness, such as coatings on glass molding dies, the coating must endure an annealing treatment in an oxygen-containing atmosphere at 600 °C. In this study, the periods of nanolaminated coatings were controlled by the rotation speed of the substrate-holder. The annealing treatments were conducted at 600 °C in atmospheres of 20-ppm and 50-ppm O2–N2. The variations in crystalline structure, nanohardness, and in-depth chemical composition profiles after various annealing durations were investigated. The feasibility of a protective Ta–Zr coating was improved by annealing the coating in a 1% O2–Ar environment for 30 min at 600 °C to achieve a nanohardness of 10 GPa, which is higher than the hardnesses of molded glasses, and by being subsequently exposed to a 10-ppm O2–N2 atmosphere, which is a realistic glass molding atmosphere.

As a protective hard coating on glass molding dies, Cr–Ta coatings were fabricated on binderless tungsten carbide substrates with a Ti interlayer by RF magnetron sputtering. The nanocrystalline Cr–Ta coatings were deposited at 550 °C, which revealed one nanocrystalline phase for the Ta-rich coating and two nanocrystalline phases for the Cr-rich coating. Annealing treatment was conducted at 600 °C in a 12 ppm O2–N2 atmosphere to evaluate the coating performance in a realistic glass molding environment. Both Auger electron spectroscopy and X-ray photoelectron spectroscopy depth profiles verified the outward diffusion of Cr, which formed a protective coating for the Cr-rich coatings. A scale of Cr2O3 and a Cr-depleted transition zone near the surface were identified by conducting a transmission electron microscopy investigation on the annealed Cr0.71Ta0.29 coating. The Cr-rich coating absorbed a smaller amount of oxygen, exhibited greater hardness, and maintained nanoscale surface roughness after annealing in the glass molding atmosphere, thus making it an appropriate protective coating for the die material.

Cr–Ru alloy coatings with Cr content ranging from 47 to 83 at.% were deposited at 400 °C by direct current magnetron co-sputtering with a Ti interlayer on silicon substrates. With a total input power of 300 W, the Cr content in the Cr–Ru coatings increased linearly with the increasing input power of Cr. The intermetallic compound phase Cr 2 Ru with columnar structure was identified for the as-deposited Cr 56 Ru 44 and Cr 65 Ru 35 coatings, resulting in an increase of hardness up to 15–16 GPa. To evaluate the performance of Cr–Ru coatings as a protective coating on glass molding dies, the annealing treatment was conducted at 600 °C in a 50 ppm O 2 –N 2 atmosphere. The outward diffusion and preferential oxidization of Cr in the Cr–Ru coatings resulted in the variations of the crystalline structure, chemical composition distribution, and surface hardness after annealing. X-ray diffraction and transmission electron microscopy (TEM) proved that an oxide scale consisting of Cr 2 O 3 formed on the free surface. Scanning electron microscopy and TEM observed the surface morphology and structural variation. The chemical composition depth profiles were analyzed by Auger electron microscopy, verifying the presence of a Cr-depleted zone beneath the oxide scale. The hardness of Cr 56 Ru 44 and Cr 65 Ru 35 coatings decreased to 11–12 GPa after annealing, accompanied by the replacement of the Cr 2 Ru phase by the Ru phase.

To prevent Co diffusion from cemented carbides at high working temperatures, we fabricated CrTaN coatings by reactive direct current magnetron co-sputtering onto 6 wt.% cobalt cemented carbide substrates, to form diffusion barrier layers. The nitrogen flow ratio, N 2 /(Ar + N 2 ), during the sputtering process was set at 0.4. The deposition rates of CrTaN coatings varied from 23 to 27 nm/min. The CrTaN coatings crystallized into a columnar structure, without heating the substrates during the sputtering process and exhibited surface hardness and Young's modulus values of 16–27 and 211–383 GPa, respectively. The CrTaN coatings were annealed at 500 and 600 °C for 4 h in air to evaluate the oxidation resistance and diffusion barrier performance. We also investigated oxidation resistance of the CrTaN coatings under a 50 ppm O 2 –N 2 atmosphere, to assess the fabricated layers effectiveness as a protective coating for glass molding dies.

Ta–Ru and Mo–Ru alloy coatings with phases of intermetallic compounds are often used as protective coatings on die materials. After annealing under an oxygen containing atmosphere, the internal oxidation phenomenon resulted in the preferential oxidation of Ta or Mo in the coatings. This process created a phase separated structure consisting of continuous and alternative oxygen rich and deficient layers with a nano scale period beneath the free surface. The experiments in this study deposited Ta–Ru and Mo–Ru coatings with a Cr interlayer by direct current magnetron co-sputtering at 400 °C. Annealing treatments were conducted at 600 °C for short durations under controlled atmospheres consisting of 50 or 10,000 ppm oxygen with residual nitrogen or argon gas. The internal oxidation behavior in the initial stage was determined by evaluating the variations in crystalline structure, surface morphology and chemical composition. The laminated structure was examined by transmission electron microscopy. Results show distinct oxidation behaviors for Ta47Ru53 and Mo46Ru54 coatings. Internal oxidation phenomena appeared in Ta47Ru53 coatings annealed in both 50 and 10,000 ppm O2 containing atmospheres. The Mo46Ru54 coatings exhibit external oxidation at 50 ppm O2 containing atmosphere, and internal oxidation at 10,000 ppm O2 containing atmosphere. Finally, this study proposes an internal oxidation mechanism for alloy coatings with an orientated structure.