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The effects of annealing temperature on the microstructure, mechanical properties, and tribological properties of TiAlSiCN coatings with C contents of 9.24 at.% and 19.45 at.% are systematically investigated. The results show that all coatings maintain cubic structures with strongly preferential orientation of (200) planes, and the microstructure transforms from amorphous embedded in (Ti, Al)(C, N) nanocrystalline to amorphous encapsulated nanocrystalline with increasing C content. Elevating annealing temperature to 800 °C leads to a continuous decline in hardness, whereas the elastic strain resistance H/E increases first and then decreases. Release of H 2 formed by the breaking of the C–H bonds at 400 °C induces a local stress transformation from compressive to tensile. The toughness and hardness decreases dramatically at 600 °C by conversion of sp3 to sp2. The wear mechanisms of the coating against Si 3 N 4 counterballs are adhesive and oxidative wear. The coefficient of friction (COF) and wear rate initially decrease followed by an increase. The coatings with a-C structure exhibit lower COF and the wear process is smoother, but showing higher wear rate. Thus, the annealed TiAlSiCN coatings with preferred C content could improve the mechanical and tribological properties. [ABSTRACT FROM AUTHOR]

This article investigates the plasma‐enhanced chemical vapor deposition of a‐C:H:SiOx coatings in a non‐self‐sustaining arc discharge plasma with a hot cathode in combination with a low‐frequency (200 kHz) inductively coupled plasma. It is shown that increasing the inductor power from 0 to 600 W leads to a twofold increase in the ion current density on the substrate. An increase in ion bombardment intensity results in a 1.3‐fold reduction in the coating's growth rate due to the resputtering phenomenon, a 1.5‐fold reduction in surface roughness, and an improvement in the mechanical properties of the coatings. The hardness of the coating is increased by 9–11%, the plasticity index by 10–17%, and the resistance to plastic deformation by 32–49%. [ABSTRACT FROM AUTHOR]

In this study, a NiCoCrAlY + lanthanum zirconate multilayer thermal barrier coating was deposited on Inconel 738 through the thermal plasma spray technique. The coated samples subjected to hot corrosion testing at 900 °C for 240 h after coating them with 90 wt.% Na2SO4 + 5 wt.% NaCl + 5 wt.% V2O5. The corroded samples were evaluated using SEM, SED, XRD, microhardness and electrochemical study. The dominance of vanadium was observed in the form of LaVO4 phase formation at the plates on the coating surface. The as-received coating sample, sample after the electrochemical test, sample after hot corrosion and hot-corroded sample after electrochemical test were tested for hardness. A significant decrease of 23.8% in hardness was measured after the electrochemical test of the corroded sample. [ABSTRACT FROM AUTHOR]

DLC coatings are well known for their high fracture toughness, however, often exhibit poor adhesion properties on metallic substrates. The use of interlayers and metallic doping can be used to overcome such challenge. In this study duplex CrN/DLC and nano-multilayer DLC-W coatings were both deposited on hydraulic valve tappet using a hybrid PVD/PECVD deposition system. Microhardness measurements were taken for the uncoated valve tappet, duplex CrN/DLC and nano-multilayer DLC-W coated valve tappet at loads of 0.98 N, 1.96 N, 2.94 N, 4.9 N, 9.8 N and 19.6 N for 15 seconds using a Shimadzu hardness tester. The fracture toughness was evaluated using the Vickers indentation method from microhardness indents on the surface of the coatings. The fracture toughness for duplex CrN/DLC and nano-multilayer DLC-W coatings indented at 4.9 N, 9.8 N and 19.6 N, reveals that the fracture toughness for the duplex CrN/DLC were 20.24 ± 0.97 MPa.m1/2, 17.18 ± 0.86 MPa.m1/2 and 6.6 ± 0.28 MPa.m1/2 respectively. While the fracture toughness for nano-multilayer DLC-W was calculated as 3.75 ± 0.41 MPa.m1/2 and 4.67 ± 0.38 MPa.m1/2 at 9.8 N and 19.6 N respectively. [ABSTRACT FROM AUTHOR]

Fe‐0.3C‐15Cr‐1Ni high hardness corrosion‐resistant alloy coating is prepared on the surface of 3Cr13 by laser cladding technology. The effects of scanning speeds on the microstructure, microhardness, and corrosion resistance of the coating are studied. The results show that the microstructure of the cladding layer is mainly composed of intracrystalline martensite and carbides distributed along the grain boundaries. When scanning speed increases from 3 to 5 mm s−1, the grain is obviously fined, and the number of carbides increases, further increasing scanning speed, the grain refinement degree decreases and the carbide quantity decreases gradually. When scanning speed is 5 mm s−1, the microhardness reaches the maximum, the corrosion resistance is significantly improved at 5 and 7 mm s−1, and the pitting potential and passivation zone width increase by 180–219% and 69–78%, respectively, compared with 3 mm s−1 sample, but further increases scanning speed to 9 mm s−1, the hardness and corrosion resistance significantly reduce. This is because scanning rate affects the component undercooling degree of the dynamic molten pool and the temperature gradient at the solidification interface front, which affects the growth of dendrites, the number of carbides, and further affects the alloying elements in the carbide and matrix. [ABSTRACT FROM AUTHOR]

The wear resistance of hard anodic coatings fabricated on 5005 and 6061 aluminum alloys was determined. The Taber abrasion test, ball-on-disc tribological test, and scratch test at constant load were conducted. The wear resistance of the hard coating fabricated on the 6061 alloy was found to be higher compared to the coating on the 5005 alloy. This is related to the lower nanoscale porosity of the former, and the higher hardness of the 6061 alloy compared to 5005. The specific wear rates for the load of 4.905 N were equal to 1.70 × 10−5 and 1.02 × 10−5 mm3 N−1 m−1 for the coatings on 5005 alloy and 6061 alloy, respectively. In the case of the hard anodized 5005 alloy, the specific wear rate increased with increasing load to 4.56 × 10−5 mm3 N−1 m−1 whereas for anodized 6061 alloy to 1.98 × 10−5 mm3 N−1 m−1. It was also found that the protective properties of the coating on 6061 alloy do not change significantly across the coating thickness. [ABSTRACT FROM AUTHOR]

AlCoCrFeNi2.1 eutectic high-entropy alloys (HEAs) are a new kind of alloy with high entropy and eutectic properties. Their advantages in terms of strength and shape matching can be fully exploited using extreme high-speed laser cladding (EHLA). In this paper, AlCoCrFeNi2.1 eutectic HEA coatings were prepared by conventional laser cladding (CLA) and EHLA. The microstructures and phase compositions of the two coatings were analyzed by scanning electron microscopy, x-ray diffraction, and electron backscatter diffraction. The microhardness and wear resistance values of the coatings were tested using a microhardness tester and a friction and wear tester, respectively. The results showed that the surface qualities of both the CLA and EHLA coatings were good and had no cracks or defects. Compared with those of the CLA coating, the EHLA coating had finer grains and a more uniform distribution. Both coatings contained face-centered cubic (FCC) and body-centered cubic (BCC) phases, but the BCC phase of the EHLA coating was less precipitated than the CLA coating. The higher microhardness and better wear resistance of the EHLA coatings occurred in the presence of Hall–Petch strengthening. [ABSTRACT FROM AUTHOR]

Conventional electroless Ni–B–Mo (ENB–Mo) deposits are formed using hazardous lead or thallium-containing solutions, which must be removed. In this study, ENB–Mo deposits were developed in a bath free of stabilizers and harmful heavy metals. This study estimates the effect of variation of coating bath temperature on tribological performance of ENB–Mo coating developed over AISI 1040 steel. The chosen bath temperatures were 8 5 ∘ C, 9 0 ∘ C, and 9 5 ∘ C to achieve ENB–Mo coating with varying B and Mo content. The 12–15 μ m thick coating was uniform. In comparison to steel substrate, all of the coatings show enhanced corrosion resistance. In the as-deposited state, coatings were mixed amorphous and nanocrystalline with peak of Fe overlapping with Ni. Moreover, TGA results revealed that inclusion of molybdenum enhanced coatings thermal stability. The worn specimens at 3 0 0 ∘ C reveal development of shielding tribo-oxide coatings and existence of microstructural changes. At high working temperatures (3 0 0 ∘ C), wear debris also has a major impact on tribological mechanisms of coatings. Correlation between microstructure, tribological behavior, and corrosion resistance have also been conducted for ENB–Mo coatings. [ABSTRACT FROM AUTHOR]

Due to their superior corrosion resistance at high temperatures, stainless steels have a wide range of applications in numerous industries (including chemistry, the petrochemical industry, the paper industry, and nuclear engineering), it is also utilized in the medical industry as an implant material. To enhance the outstanding qualities of stainless steel such as high temperature corrosion, surface coating methods are also used. Boronizing, nitriding, thermal spray coating, physical vapor deposition, chemical vapor deposition, and electro-spark deposition procedures are used to apply these coating processes to steel surfaces. The electro-spark deposition (ESD) coating technology is one of the most promising approaches in this area. Using high-frequency and high-current electric pulses, the ESD micro-welding procedure bonds electrode material to the surface of a metallic substrate. In this study, AISI 304 and AISI 316L stainless steels were coated with FeAl and NiAl intermetallics using the ESD method. First, suitable experimental parameters for ESD coating were established. Second, X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the microstructures and phases that formed on the coated surfaces. Then, the surface hardness of the resulting layers was determined. Finally, the corrosion properties of intermetallic-coated stainless steels were determined using electrochemical methods and compared with each other. As a result, both the hardness values and corrosion resistances of both stainless steel sheets have increased with intermetallic coatings. [ABSTRACT FROM AUTHOR]

Thermally sprayed ceramic coatings with varied weight percentages of carbon nanotube (CNT) reinforcement were examined. AISI 1020 steel was coated with yttria-stabilized zirconia (ZrO2 + 8% Y2O3) using the atmospheric plasma spraying (APS) method. The study examined the CNT dispersion in the coating microstructure and evaluated the porosity, bond strength, and corrosion resistance of the coating. In addition, the coating thicknesses were measured. The coatings were characterized using a variety of techniques, including optical microscopy, scanning electron microscopy, image analysis, bond strength testing, and corrosion analysis. According to the findings, adding CNTs to the coatings improved their mechanical characteristics, particularly their hardness and wear resistance. Notably, the best levels of hardness and wear resistance were seen in coatings with a 5 percent CNT reinforcement. Additionally, the coatings' corrosion resistance was enhanced by the inclusion of CNTs. The results of this work show that the mechanical and corrosion properties of thermally sprayed ceramic coatings can be successfully improved by the inclusion of CNTs. This means that these CNT-reinforced coatings have a lot of potential for a variety of applications, such as wear-resistant, corrosion-resistant, and thermal barrier coatings. [ABSTRACT FROM AUTHOR]

Chromium‐based coatings have been of interest to researchers for the last two decades because of their extraordinary properties like high hardness, high wear, and corrosion resistance properties. However, it is in practice and research to increase the properties of Cr‐based coatings for high‐temperature applications. Numerous dopants like silicon (Si), titanium (Ti), vanadium (V), aluminum (Al), and zirconium (Zr) have been used together with Cr to achieve enhanced properties. The plasma‐based sputtering process is one of the popular and reliable techniques to deposit thin film coatings. The substrate material, processed gas and pressure, substrate temperature, film thickness, and so on also play a significant role in varying the properties and microstructure of the deposited film. Several researchers have deposited Cr/CrN‐based thin films via the chemical vapor deposition technique (CVD) and physical vapor deposition technique (PVD) to study their properties and behavior at room temperature as well as for high‐temperature applications. This work reflects the review of work done to deposit Cr/CrN‐based coatings deposited via PVD: more specifically sputtering technique. The effect of doping in the CrN matrix and variation in sputtering parameters on the properties of CrN‐based coatings have also been studied. [ABSTRACT FROM AUTHOR]

The low toughness and high brittleness of hard coatings are common defects that seriously affect their application in various fields. In order to ensure high hardness while increasing the toughness of the coatings, an evaluation model for the mechanical properties of TiN/TiSiN coatings has been established and validated by the finite element method. The effects of modulation period and modulation ratio on the hardness and toughness of TiN/TiSiN nano-multilayer coatings are investigated. Subsequently, a modulation ratio gradient structure is introduced to optimize the coating structure and thus achieve the toughening effect. The results indicate that the load on the low modulation ratio coating is distributed over a larger surface area and can resist greater loads, and that this structure has higher hardness and deformation resistance. However, the low modulation ratio structure produces a higher shear stress concentration region inside the structure. The modulation ratio gradient structure can take into account the advantages of low and high modulation ratios, it can ensure the high hardness of 34 GPa while dramatically reducing the maximum principal stress by about 46 %, and the maximum shear stress by 14 %, which effectively inhibiting crack formation and enhancing the toughness of the nano-multilayer coatings. [ABSTRACT FROM AUTHOR]

Thin coatings are subject to scratch and wear damage in tribological applications. Scratch hardness numbers are used to evaluate scratch and abrasive wear resistance. Few studies have measured the scratch hardness of thin films, and a proper scratch hardness measurement method for thin coatings is still lacking. In this study, the scratch hardness of these DLC coatings was measured at both micro-scale and nano-scale, respectively. The micro-scratch test using a 200 µm tip is an inapplicable method because the substrate effect has dominated the scratch hardness measurement. On the other hand, a nano-scratch hardness test using a sharper tip is an effective method to measure the scratch hardness of thin coatings. Although the scratch hardness introduces a lateral force compared with the indentation hardness, it well correlates with the nano-indentation hardness. The ratio of the scratch hardness to the indentation hardness is close to 1 for DLC coatings due to the amorphous structure. It proves that the tangential force induced by scratching does not influence the hardness property. In addition, a simple approach is proposed to obtain the scratch hardness of DLC coatings qualitatively without width measurement. [ABSTRACT FROM AUTHOR]

Deposition of high entropy alloy FeCoNiMnCu on SS-304 was carried out by microwave energy for application in "solid oxide fuel-cell (SOFC) interconnects". The ball-milling has been performed by taking "Fe, Co, Ni, Mn, and Cu" in equal 20 wt. % of before deposited on SS-304 substrate. The deposited steel with 20% Fe 20% Co 20% Ni 20% Mn 20% Cu high entropy alloy (HEA) was exposed to thermal-exposure in the air for up to 10 weeks at 800 °C. The uniform cladding distribution of 20% Fe 20% Co 20% Ni 20% Mn 20% Cu HEA particles can be apparently observed on SS-304 substrate by utilizing Scanning Electron Microscope (SEM), and Optical microscopy analysis. Homogeneity in the interfacial layer was evident by employing Scanning Electron Microscope (SEM) characterization. Results have indicated that after the thermal exposure of deposited steel with 20% Fe 20% Co 20% Ni 20% Mn 20% Cu in the air for up to ten weeks at 800 °C, a "protective Cr2O3 layer", and "high-entropy spinel coating" of (Fe, Co, Ni, Mn, Cu)3O4 have been formed. During microwave cladding, the emergence of harder-phases has contributed to the raised hardness. The wear behavior after coating of 20% Fe 20% Co 20% Ni 20% Mn 20% Cu HEA on SS-304 substrate has significantly enhanced due to the strengthened wear resistance and hardness of the coatings. Findings have exhibited that the formation of (Fe, Co, Ni, Mn, Cu)3O4 phase is a potential coating material for "SOFC interconnects" applications. Moreover, the cladding of SS304 with a composition of 20% Fe, 20% Co, 20% Ni, 20% Mn, and 20% Cu has demonstrated remarkable stability under thermal expansion studies. As the findings have revealed that the composite cladding has efficiently withstand significant variations in volume when subjected to elevated temperatures for a prolonged period of time, thus, exhibiting its superior thermal stability for SOFC-interconnect applications. Furthermore, the SEM images of the cladding surface, surface hardness, and tribocorrosion behavior of the coated material have been observed to identify the 20% Fe 20% Co 20% Ni 20% Mn 20% Cu HEA coating effect on SS-304 steel-substrate. [ABSTRACT FROM AUTHOR]

Coatings on a titanium alloy are prepared by electrospark deposition with a non-localized anode consisting of titanium and aluminum granules with addition of chromium diboride powder. With increase of the CrB2 concentration from 2 to 10 vol.%, the gain in the weight of the cathode increases monotonically from 4.10 to 9.56 mg/cm2. According to the data of polarization tests and electrochemical impedance spectroscopy, the Ti – Al – Cr – B coatings reduce the corrosion rate of the VT3-1 alloy. The highest oxidation resistance of the coatings is observed for a CrB2 concentration of 2 vol.%. Deposition of Ti – Al – Cr – B coatings makes it possible to increase the surface hardness of the VT3-1 alloy by a factor of 2.7 – 4. The deposited Ti – Al – Cr – B coatings increase the wear resistance of the surface of titanium alloy VT3-1 by up to a factor of 6. [ABSTRACT FROM AUTHOR]

A TiNiCoCrVSi high entropy alloy (HEA) coating was prepared on Ti–6Al–4V alloy by laser cladding. Then, the microstructure, phase composition, hardness, wear resistance and high-temperature oxidation resistance of the prepared coatings were investigated. The wear behavior of the TiNiCoCrVSi coating against a Si3N4 ball was evaluated under dry sliding conditions. The high-temperature oxidation resistance was tested at 800∘C. The results show that the phase structure of the TiNiCoCrVSi coating was mainly composed of a body-centered cubic (BCC) (Ni,Co)Ti2 and (Ti,V)5Si3. The TiNiCoCrVSi coating has a high hardness, and the highest surface hardness was 1357 HV. The wear volume of the coating was 1/7 of that of Ti–6Al–4V. The wear mechanism was abrasive wear and oxidative wear. The TiNiCoCrVSi coating exhibited good high-temperature oxidation resistance at 800∘C. A dense oxide film (TiO2, Cr2O3 and NiCr2O4) was formed on the surface of the coating. The dense oxide film prevented oxidation. The high-temperature oxidation resistance of the coating was 1/12 of that of the substrate. [ABSTRACT FROM AUTHOR]

Duplex Ni–P/Ni–Mo–P coating systems were developed using electroless dual bath technique with Ni–P and Ni–Mo–P as outer layers alternately. The coatings were subjected to heat treatment at temperatures from 200 to 800 °C and for 1–4 h. The effect of heat treatment on the microstructural characteristics of the coatings was investigated using field emission scanning electron microscopy, energy-dispersive X-ray analysis, and X-ray diffraction. The influence of heat treatment conditions on microhardness, friction, wear, and corrosion behavior was studied. Heat treatment has a beneficial impact on the coating with the detection of harder crystalline phases. In general, the duplex coating with Ni–Mo–P as the outer layer outperforms the coating where Ni–P was the outer layer. For Ni–Mo–P as the external layer coating, the highest microhardness, and lowest wear rate is obtained when heat treated at 600 °C temperature with an hour duration. This is due to the formation of hard crystalline phases like Ni3P and Ni–Mo. However, when heat treated at higher temperature of 800 °C with 4 h, Ni–Mo–P exterior layer exhibits cracks and plastic deformation together with few oxide patches. This deteriorated the wear performance of the coating system. The wear mechanism displayed by both coatings indicates the occurrence of both adhesive and abrasive wear. The corrosion performance of the coatings improved upon heat treatment and was enhanced with increasing temperature and duration. Sample (Ni–Mo–P as outer layer) heat treated at 800 °C for 4 h displayed the highest corrosion potential (Ecorr = − 241 mV) and also significantly higher charge transfer resistance (Rct = 20.8 Ω cm−2 × 105) than others. [ABSTRACT FROM AUTHOR]

Interest in composite thick coatings with an intermetallic matrix stimulates the development of new deposition techniques like the co-milling of pre-alloyed NiAl powder with platelet-shaped substrates. Obtained coatings were up to several micrometers thick as cold-welding of intermetallic particles was effective only at the start of this process, while later, chipping prevailed over added material. The present experiment covered the co-milling in the planetary ball mill of Ni and Al elemental powders (1:1 molar ratio) with AISI 304 steel platelets for 32 h at 300 rpm. Next, this process was repeated with an admixture of 15 wt.% of CrB2 powder. In both cases, their milling succeeded in producing up to a 200 μm coating after 4 h. The use of light, scanning and transmission electron microscopy (LM/SEM/TEM) helped to establish that the coatings had gradient microstructures with more refined crystallites of NiAl, Al3Ni2 and CrB2 closer to the surface. With the addition of a ceramic phase, the coatings presented higher hardness and lower friction during dry wear tests both at RT and at 500 °C. [ABSTRACT FROM AUTHOR]

The V-O-N coating set was produced at different relative oxygen concentrations of O2(x) = O2/(N2 +O2) using cathodic arc evaporation. The aim of the research was to determine the effect of oxygen on coating properties. The coatings' composition and structural properties (X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX)) and mechanical properties—hardness, adhesion, and wear resistance (nano-indenter, scratch tester, ball-on-disc tester)—were extensively investigated. EDX and XRD analyses indicate that in coatings formed with a relative oxygen concentration in the range of 20–30%, the oxygen concentration in the coating increases dramatically from approximately 16 at.%. to 63 at.%, and the nitrogen concentration drops from about 34 at.% up to 3 at.%. This may indicate greater activity of oxygen compared to nitrogen in forming compounds with vanadium. The occurrence of the V5O9 phase belonging to the Magnéli phases was observed. Microscopic observations indicate that the number of surface defects increases with the oxygen concentration in the coating. The opposite effect is characterized by mechanical properties—hardness, adhesion, and wear resistance decrease with increasing oxygen concentration in the coating. [ABSTRACT FROM AUTHOR]

Rare earth oxides have been proven for their ability to refine grains and have high melting points. In this paper, different contents of rare earth oxide La2O3 were added into the Ni60/WC-Ni composite coating, in order to study its effect on the coating properties. SEM observation confirmed that the grain was refined significantly after the addition of La2O3. Energy Dispersive Spectroscopy (EDS) was applied to investigate the composition and X-Ray Diffraction (XRD) was used to measure the residual stress in the coating samples. In addition, the microhardness and wear resistance of the samples were tested. The results showed that the dilution ratio of coatings with different additions of La2O3 was in the range of 2.4 to 9.8%, and the sample with 1.0% addition of La2O3 exhibited the highest hardness of 66.1 HRC and best wear resistance with a wear volume of 9.87 × 106 μm3, and the residual stress increased from 159.4 MPa to 291.0 MPa. This implies that the performance of the coating has been obviously improved after the addition of La2O3. [ABSTRACT FROM AUTHOR]

In this study, two layers of NiCrAlY (Meto 81VF) and YSZ (Metco 204NS) were applied by laser cladding method on IN713 LC superalloy and the effect of laser parameters (pulse frequency, pulse duration and scanning speed) was investigated on the microstructure and the hardness. The results show that with increasing the heat input, the dilution ratio of coating increases. This causes important elements such as Cr and C to segregate from the substrate due to K<1 and the physical and mechanical properties of the coating, including the hardness, reduce by decreasing the Cr7C3 carbides in the coating. However, by reducing the heat input and consequently the decrease of dilution ratio, in addition to the eutectic structure (Cr7C3+γ), the Cr7C3 carbides are also formed in the clad zone. The second layer, which is applied as a thermal barrier coating to reduce the working temperature of its substrate, has a thickness of 14 μm and equiaxed grains. Porosity, which is the most important challenge of laser cladding, decreases significantly with increasing the heat input to 61.3 J/mm. This can be attributed to the excessive fluidity of the melt and the consequent increase in its backfilling capacity in the created cavities. As the dilution ratio decreases, the hardness of the clad zone raises. This can be attributed to the presence of Cr7C3 inter-dendritic carbides in the cladding zone. [ABSTRACT FROM AUTHOR]

This paper is devoted to the influence of substrate preheating on the structure of cermet coatings made of TI–6AL–4V alloy reinforced with B4C particles using direct metal deposition. Coatings with a 15% mass fraction of B4C were obtained for the first time. It is shown that substrate preheating makes it possible to produce cermet coatings without cracks. In tribological tests, the wear scar volume of the cermet coating decreased by a factor of eight compared to the coating with a 10% mass fraction of B4C. [ABSTRACT FROM AUTHOR]

In the present study, the deposition of silicon nitride (Si3N4) coating on Inconel 738 through plasma spray has been investigated. For producing the Si3N4 coating, different times (6, 8 and 10 s), different distances of the plasma spray torch from the substrate (30, 35 and 40 mm) and different currents for plasma spraying (3000, 3250 and 3500 A) were employed. For the characterisation of the coatings, SEM (thickness), XRD, micro-hardness and adhesion of the samples were measured. The coatings' surface morphology was investigated through SEM. Based on the experimental results, by using a spraying time of 10 s, a distance of the torch of 40 mm and a current of 3500 A, high microhardness and adhesion of the coatings are obtained. On the other hand, the thickness of the coating increased by reducing the distance and increasing spray time and current. [ABSTRACT FROM AUTHOR]

The introduction of high-entropy alloys, notable for their increased hardness and thermal stability, gave impetus to the study of their properties in coatings. High-entropy metal coatings are characterized by high hardness, ranging from 7 to 19 GPa. The general laws governing the influence of various parameters on the mechanical properties of high-entropy metal coatings were analyzed. Single-layer metal, nitride, oxide, and carbide coatings and multilayer nitride coatings from high-entropy alloys produced by different deposition techniques were examined. The phase composition, structure, hardness, elastic modulus, and friction coefficient of the coatings were determined. The mechanical properties of high-entropy coatings, along with those of cast alloys, depend on the lattice parameter. With increase in the lattice parameter in bcc metal coatings, the elastic modulus and hardness decrease. The increased hardness of vacuum high-entropy coatings contributes to decrease in their friction coefficient compared to the cast state. The influence of pressure in the sputtering chamber and the voltage applied to the substrate on properties of the nitride coatings was established. The capabilities of producing thick (up to 80 μm) coatings combining metal and nitride interlayers from high-entropy alloys and determining their properties were shown. For the high-entropy carbide in the TiZrNbVTaHf system, the influence of the lattice parameter on hardness was revealed. The lowest friction coefficient (0.05) was observed in high-entropy oxide coatings. The high-entropy coatings showed high hardness. A hardness level of 19 GPa was reached for a metal coating based on the TiZrNbTaHfCr alloy, 63 GPa for a nitride coating based on the TiZrNbVHf alloy, and 48 GPa for a carbide coating based on the TiZrNbVHfTa alloy. The analysis showed that nitride coatings were the hardest, while the lowest friction coefficient was possessed by oxide coatings. [ABSTRACT FROM AUTHOR]

In this work, functionally graded material (FGM) coating that uses three powders with WC-10 wt% Co-4 wt% Cr (designated as P1), WC-12 wt% Co (designated as P2), and Ni-25 wt% Cr (designated as P3) are proposed for use over the liners of CI engines. Scanning electron microscopy and energy dispersive x-ray spectroscopy are conducted to analyze the microstructural properties, composition, and quality of the powder and the prepared coating. Results shows that the porosity of powder P3 is the highest of all three powders used in this work, and the porosity of powder P2 is smallest, whereas the porosity of powder P1 lies between P1 and P3. In addition, the hardness of the FGM coating, measured using Vicker's test, containing a combination of P1 and P2 (designated as sample 1), is higher than that of the FGM prepared with a combination of P2, P3 and P1, P3. The findings of the present work have potential implications for improving the performance and durability of CI engine liners by using an appropriate FGM coating. [ABSTRACT FROM AUTHOR]

The surfaces of 316L stainless steels, which are frequently used in the industry due to their mechanical properties, were coated with HVOF method in order to improve their properties. Two different powders for steel surfaces; Diamalloy 2002 (Tungsten Carbide, chromium based) and Metco 7202 (chromium based) powders were prepared in different concentrations. Group A specimens were coated with a mixture of 50% Diamalloy 2002 and 50% Sulzer Metco and Group B specimens were coated with a mixture of 100% Sulzer Metco 7202 by HVOF method. These powders produce coatings that provide wear resistance due to their content. The surface properties of the coated samples were analysed by some methods. Optical and SEM images of all samples were taken and XRD analyses were performed. The coating layer is clearly visible. Some porosity formation was observed. Microhardness values were measured. As a result of hardness measurements, it was determined that the surface hardness increased 4-7 times with the coating. Linear abrasion tests were performed with CSM abrasion tester. It was observed that the abrasion resistance increased. After the abrasion test, roughness measurements and SEM-EDS analyses of the abraded surfaces were performed. Abrasive and adhesive wear formations are present on the worn surfaces. [ABSTRACT FROM AUTHOR]

The FeCrMoSi amorphous coatings were fabricated on the surface of a 304 stainless steel (SS) base material using atmospheric plasma spraying. A comprehensive investigation was carried out to evaluate the structure, morphology, adhesion to base material, hardness, hydrophobicity, interfacial contact resistance, and corrosion resistance of the coatings. The results show a remarkable hardness of 1180.1 HV, a strong bond strength of up to 64.3 N/mm2, and excellent hydrophobicity with a water contact angle reaching 141.2°. Additionally, in an acidic environment with fluoride ions (0.5 M H2SO4 + 2 ppm HF, 80 °C), the FeCrMoSi amorphous coating demonstrated superior corrosion resistance compared with 304 SS while maintaining similar electroconductibility. Detailed analysis of the structural characteristics and corrosion resistance of FeCrMoSi amorphous coatings provided valuable insights into their mechanics. These promising results signify a bright future for FeCrMoSi amorphous coatings in various industrial sectors, including transportation, petroleum, and electric power industries. [ABSTRACT FROM AUTHOR]

Coatings from WC–Co–Cr AMPERIT®554.074 powder were deposited using a multichamber detonation device. Investigations of coating microstructure and phase composition were conducted, using scanning electron microscopy and X-ray structural analysis. Dense coatings form at spraying by this method which consist of inclusions of tungsten carbide phases, uniformly distributed in Co–Cr matrix. Coating porosity is equal to ~0.2 %, microhardness is – 10.4 ± 1.2 GPa. Experience of application of multichamber detonation device for deposition of wear-resistant coatings from WC–Co–Cr powder is shown, both at the stage of part reconditioning and at design of components of various mechanisms. [ABSTRACT FROM AUTHOR]

An iron alloy coating with gradient transition was sprayed on F304 stainless steel substrate by plasma spraying method and with a gradient material obtained by the material performance simulation software, and the effect of gradient transition on the microstructure, hardness and wear resistance of the coating was analyzed by comparing with the non gradient transition coating. The results show that both the gradient coating and the non gradient coating have wavy layered structure and are formed by highly flattened deformed particles overlapping each other. Micro metallurgical bonding was observed between the coating particles, and oxides were observed between the coating and the substrate, between the flat particles and inside the flat layer. The coating microstructure includes austenite phase, ferrite phase and carbides. The surface hardness of the gradient coating and the non gradient transition coating are basically similar, but there are obvious steep drop steps between the section hardness of the non gradient coating and the substrate hardness, while the section hardness of the gradient coating and the substrate hardness change gently, and the section hardness of the gradient coating is slightly lower than that of the non gradient coating. The wear rate of gradient coating is similar to that of non gradient coating at 400 °C, but it is lower than that of non gradient transition coating at 350 °C. The reason for reducing hardness changes and improving wear resistance of the coating may be related to the improvement of the microstructure and plasticity of the coating by the gradient layer, but more research is needed. [ABSTRACT FROM AUTHOR]

The article describes the influence of a solid lubricant such as graphite on the coating-substrate adhesion, susceptibility to cracking during three-point bending tests and tribological properties of the cermet coating-substrate systems. Two types of deposits Cr3C2-25(Ni20Cr) and (Cr3C2-25(Ni20Cr))-5(Ni25C), cold-sprayed on the Al 7075 alloy substrate, were analyzed. The Cr3C2-25(Ni20Cr) coatings showed a homogeneous microstructure with evenly distributed ceramic particles in a Ni20Cr matrix. The (Cr3C2-25(Ni20Cr))-5(Ni25C) deposits also contained graphite placed both between metallic particles and near the crushed ceramic Cr3C2 particles. The force required for the crack that appeared in the coating-substrate system during the three-point bending test under constant velocity was significantly higher in the case of (Cr3C2-25(Ni20Cr))-5(Ni25C) deposit than in that without the solid lubricant. The cracks were observed perpendicular to the coating-substrate interface. The graphite embedded in the cermet coating structure prevented the formation of crack nuclei during three-point bending test under cyclic load at room temperature and reduced the size of cracks in the deposit at 200 °C. Both cermet coatings revealed the same adhesion. The addition of graphite not only did not deteriorate the adhesion of the deposits and thus their quality but also improved their other properties, such as flexural strength and wear resistance. Coatings containing the solid lubricant showed a lower wear index than the Cr3C2-25(Ni20Cr) deposits examined at both room and elevated temperatures. This recommends their use in industry as deposit working in heavy wear conditions. The presented results of mechanical tests effectively fill the gap regarding the properties of the cold-sprayed cermet coatings. [ABSTRACT FROM AUTHOR]

The future scope of work lies in the development and comprehensive assessment of advanced coatings to resist wear, corrosion and abrasion of engineering components in harsh environments. Among them, thermal spray especially HVAF coatings occupy an important place in coating huge and complex parts which become techno-economically viable. Such exercise may not be possible in the traditional coating procedures including the powder metallurgy route. In general, a choice of the spray process, material selection, and design is as significant to benchmark thermal spray coatings. In most cases, thermally sprayed hard metal coatings are mechanically attached to substrates with thicknesses ranging from 100 to 500 microns. The current study gives an overview of the literature concerning HVAF coatings for tribological applications. It comprises HVAF coating developments and mechanisms followed by their application to different types of tribological performance such as sliding wear, erosion, abrasion, fretting and corrosion. HVAF coatings override other thermal spray coatings including HVOF and offer distinct advantages with respect to adherence and strength coupled with hardness so as to have strong resistance to wear, and corrosion integrated with deformation. The ingredients used in the process like metal carbides and metal alloys coated with combustible powders have a particle size in the range of a few nanometers to 60 microns. The researchers are now concentrating on the development and recognition of dense HVAF coatings so that they perform reliably and suitably in the field with good attributes. This article covers in-depth the deployed materials which are suitable for the HVAF process followed by an evaluation of physical, chemical, mechanical, and metallurgical characterization with the main focus on adhesive, abrasive, erosive, fretting and corrosive wear phenomena. [ABSTRACT FROM AUTHOR]

Steel is the most widely used structural material in engineering applications. It has high strength and elasticity. But the major problem with steel is that it corrodes when comes in contact with the atmosphere. To avoid corrosion many techniques have been developed over the years. Coating the surface of steel with a non-corrosive element is the most common method. However, the currently used methods are expensive and need very controlled environmental conditions. In this paper, the dip coating method for coating zinc on mild steel is studied. The hardness of the surface after coating in measured and immersion tests was conducted. It was observed that the zinc coating done through the dip coating process could reduce the corrosion. This proves that the dip coating is an effective method to apply coating on mild steel. This method also has the advantage of lesser expenses. [ABSTRACT FROM AUTHOR]

In the present work, two mathematical diffusion models have been used to estimate the growth of the iron monoboride and diiron boride coating formed on AISI 420 steel. The boronizing of the steel was carried out with the solid diffusion packing method at a boronizing temperature of 1123 K–1273 K. Experimental results show the two-coating system consists of an outer monoboride and an inner diiron boride coating with a predominantly planar structure at the propagation front. The depth of the boride coating increases according to temperature and treatment time. A parabolic curve characterizes the propagation of the boride coatings. The two proposed mathematical models of mass transfer diffusion are founded on the solution corresponding to Fick's second fundamental law. The first is based on a linear boron concentration–penetration profile without time dependence, and the second model with time dependence (exact solution). For both models, the theoretical law of parabolic propagation and the average flux of boron atoms (Fick's first fundamental law) at the growth interfaces (monoboride/diiron boride and diiron boride/substrate) are considered to estimate the propagation of the boride coatings (monoboride and diiron boride). To validate the mathematical models, a programming code is written in the MATLAB program (adaptation 7.5) designed to simulate the growth of the boride coatings (monoboride and diiron boride). The following parameters are used as input data for this computer code: (the layer thicknesses of the FeB and Fe2B phases, the operating temperature, the boronizing time, initial formation time of the boride coating, the surface boron concentration limits, FeB/Fe2B and Fe2B/Fe growth interfaces, and the mass transfer diffusion coefficient of boron in the iron monoboride and diiron boride phases). The outputs of the computer code are the constants ε F e B and ε F e 2 B . The assessment of activation energies of AISI 420 steel for the two mathematical models of mass transfer is coincident ( Q F e B = 221.9 kJ∙mol−1 and Q F e 2 B = 209.1 kJ∙mol−1). A numerical analysis was performed using a standard Taylor series for clarification of the proximity between the two models. SEM micrographs exhibited a strong propensity toward a flat-fronted composition at expansion interfaces of the iron monoboride and diiron boride coating, confirmed by XRD analysis. Tribological characterizations included the Vickers hardness test method, pin-on-disc, and Daimler–Benz Rockwell-C indentation adhesion tests. After thorough analysis, the energies were compared to the existing literature to validate our experiment. We found that our models and experimental results agreed. The diffusion models we utilized were crucial in gaining a deeper understanding of the boronizing behavior of AISI 420 steel, and they also allowed us to predict the thicknesses of the iron monoboride and diiron boride coating. These models provide helpful approaches for predicting the behavior of these steels. [ABSTRACT FROM AUTHOR]

The potential in assessing the hardness of the thin film of a coated material using indentation tests has drawn much attention, since this method is vital for predicting its performance characteristics. Modeling is used to investigate the spherical indentation tests with emphasis on the influence of the coating thickness on the composite hardness. An expression for the hardness of the thin film of the coated material has been obtained by geometrical and mathematical modeling of the imprint size of the monolayer coating on the film and substrate using spherical-tip indentation. The expression for the hardness of the thin film of the coated material is theoretically studied together with surface modeling, indentation depth, and size effect of indentation tests on the thin film and the coated system. [ABSTRACT FROM AUTHOR]

High coating hardness and toughness are mutually contradicting properties and are challenging to be achieved simultaneously. Combining the vast component space of high entropy systems and the powerful high-dimensional data processing tools is expected to be the best solution to this problem. In this paper, high-entropy nitride coatings data for quinary and hexagonal systems were collected and machine learning prediction models were trained. Using a new material system combined with multi-objective optimization, high-entropy nitride coatings with the optimal hardness and elastic modulus combination were successfully obtained and verified by experiments. In addition, the partial dependence heatmaps were used to visualize how elemental content affects mechanical properties prediction in this system. This approach helped to better interpret the optimization results and discover the unknown mapping relationships between elemental content and the mechanical properties of high-entropy nitrides in machine learning models. [ABSTRACT FROM AUTHOR]

Biomedical applications of diamond-like carbon (DLC) coatings are continuously increasing due to their superior mechanical properties, low friction coefficient, antiwear characteristics, and biocompatibility. The mechanical and tribological characteristics of DLC coatings have been comprehensively investigated on various substrate systems as a function of their deposition parameter dependant features for various biomaterial applications. However, the relationship between biocompatibility and resulting hardness of DLC coatings as a function of their bias voltage driven intrinsic features like sp2 and sp3 bonds remains largely unexplored. In this work, a series of DLC coatings are prepared as a function of varying bias voltage from 0 to −120 V, and characterised for their atomic structure, physical, and mechanical properties, and biocompatibility. The contact angle and surface roughness of the DLC coatings reduce while hardness increases from 7.8 to 20.3 GPa with increasing bias voltage from 0 to −120 V. A relatively soft DLC coating is shown to retain excellent biocompatibility which is approximately 38% higher than the harder DLC coatings following exposure of their leached extracts to L929 mouse fibroblast cells. This work demonstrates the complex interdependence of biocompatibility and hardness of DLC coatings and the outcomes will support correct material selection with an appropriate balance of these key properties for specific biomedical applications such as load-carrying and non-load carrying devices. [Display omitted] [ABSTRACT FROM AUTHOR]

In this work AlSi nanocomposite coating were deposited by RF magnetron sputtering in Ar/N 2 reactive atmosphere. AlSi alloy target of composition 86:14 wt % have been used to deposit the coating on float glass substrate by varying the deposition time: starting from 0.5 h to 2 h. The substrate temperature and target power were fixed at 250 °C and 100 W respectively. The effect of deposition time on microstructure, mechanical and optical property were studied by usingX-ray Diffraction (XRD), Stylus profiler, Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-ray Spectroscopy (EDS), Transmission Electron Microscopy (TEM), UV–Visible Spectrometer and Nanoindentation techniques. The XRD shows the formation h-AlN phase for film deposited for 2 h which shows that with increase in deposition time, the film structure changes from amorphous to polycrystalline, the coating deposited for 2 h develops wurtzite-AlN nanocrystalline structure. The thickness of the coating increases with respect to the increasing deposition time which was confirmed from stylus profiler. The FESEM study shows the uneven and randomly oriented grains present in the coating. TEM study confirms the amorphous and polycrystalline nature of the films with low and high thickness respectively. The elemental composition was confirmed by EDS. UV–Visible Spectrometer delivers the optical transparency of the film which is >90% for all the coatings in the visible range spectra. The roughness of the samples was also measured from scanning probe microscope image, which showed average roughness (R ã) value below 2 nm. The maximum hardness obtained is 31 GPa for the coating deposited 2 h with 490 nm thickness, it has an elastic recovery of 92% which suggest its resistance to elasticity as well as plastic deformation. [Display omitted] [ABSTRACT FROM AUTHOR]

The high-purity MAX phase coatings with thickness lower than 10 μm are mainly deposited by physical vapor deposition. Still, they typically fail to meet the long-term stability demand of heavy load and high-temperature applications. In the present study, a process for in situ synthesis of Cr2AlC MAX phase coating based on plasma transferred arc cladding directly from pure Cr, Al and Cr3C2 powder has been proposed for the first time. The as-received powders were mixed at a molar ration Cr:Al:C = 2:1.1:1 in a mortar manually for 1800s. To reveal the possible in situ synthesis mechanism, the effects of the plasma gas flux on the phase formation and microstructure evolution of coatings were investigated. The results indicated that a Cr2AlC gradient coating with a 1 mm high-purity Cr2AlC top layer was formed on low-carbon steel by plasma gas flux 0.03 and 0.04 L/s. If plasma gas flux continued to increase to 0.05 L/s, no Cr2AlC MAX phase was observed in the coating. The study proved the possibility of in situ synthesis of Cr2AlC coating by plasma transferred arc cladding and revealed the in situ synthesis mechanism. [ABSTRACT FROM AUTHOR]

In order to continuously update the prediction model based on the ever-expanding data set solely, this study established a continual learning model, i.e. the elastic weight consolidation (EWC)-based artificial neural network (ANN) model to predict the hardness of Ni–Cu–CrBN coating that could be used in tribology field. The results showed that after being trained by the ever-expanding dataset, the determination coefficient R 2 of the normal ANN model on old data decreased to 0.8421 while that of the EWC-based ANN model was still 0.9836. It was indicated that the EWC-based ANN model presented good performance on both new and old data after being trained by the ever-expanding dataset solely, which saved time and was more in line with practical application. [ABSTRACT FROM AUTHOR]

This paper presents the results of studies on AlMgB14-based ceramic coatings deposited on WC-Co hard alloy substrates using RF plasma sputtering. The aim of this work is to study the structure, phase composition, and mechanical properties of AlMgB14-based coatings depending on the sputtering mode. According to the results of the microstructural study, the bias voltage applied to the substrate during the sputtering process significantly contributed to the formation of the coating morphology. Based on the results of compositional and structural studies by energy dispersive X-ray spectroscopy, X-ray diffraction, and Raman spectroscopy, it was found that the coatings are composed of nanocrystalline B12 icosahedrons distributed in an amorphous matrix consisting of Al, Mg, B, and O elements. The nanohardness of the coatings varied from 24 GPa to 37 GPa. The maximum value of the hardness together with the lowest coefficient of friction (COF) equal to 0.12 and wear resistance of 7.5 × 10−5 mm3/N·m were obtained for the coating sputtered at a bias voltage of 100 V. Compared with the COF of the original hard alloy substrate, which is equal to 0.31, it can be concluded that the AlMgB14-based coatings could reduce the COF of WC-based hard alloys by more than two times. The hardness and tribological properties of the coatings obtained in this study are in good agreement with the properties of AlMgB14-based materials obtained by other methods reported in the literature. [ABSTRACT FROM AUTHOR]

Laser cladding technology is used to fabricate CoCrFeNi HEA/WC composite coatings with different mass fractions of WC on the surface of 316L stainless steel. The microstructures of HEA/WC composite coatings were analyzed by combining multiple characterization techniques. The results show that the HEA/WC composite coatings have good surface formation without pores and hot cracks, and the metallurgical bonding is well formed between the coating and the 316L SS substrate. Under the action of a laser beam and molten pool, WC particles partially or slightly melt and diffuse to the matrix, which hinders the orderly growth of grains and forms multiple strengthening. The phase structure of the HEA/WC composite coatings is composed of a main phase with FCC. The hardness and corrosion resistance of the HEA/WC composite coatings are clearly enhanced, and the HEA/WC composite coating with 5% WC has optimum properties. [ABSTRACT FROM AUTHOR]

The TiC–Ti 5 Si 3 –Ti 3 SiC 2 –SiC ceramic composite coatings were prepared with in-situ reaction by plasma spraying annealed Ti–SiC–C composite powders. The effect of SiC content in the annealed composite powders at 1200 °C on the microstructure and properties of the coatings was studied. With the increase of SiC content, the phases in the annealed Ti–SiC composite powders changed from Ti, SiC, TiC and Ti 5 Si 3 to SiC, TiC, Ti 5 Si 3 and Ti 3 SiC 2. The phases of the sprayed coatings were mainly composed of TiC, Ti 5 Si 3 , Ti 3 SiC 2 and a small amount of residual Si, and their content were closely related to SiC. The coating hardness first increased and then decreased, while their mass loss showed an opposite trend to that of hardness. The T1SCC (molar ratio of Ti-SiC-C is 3:1:1) coating had the highest hardness of HV 1509 and the lowest mass loss of 0.0019 g, whereas its fracture toughness was 3.51 MPa m−2. [ABSTRACT FROM AUTHOR]

High-velocity air–fuel (HVAF) is a combustion process that allows solid-state deposition of metallic particles with minimum oxidation and decomposition. Although HVAF and cold spray are similar in terms of solid-state particle deposition, a slightly higher temperature of HVAF may allow further particle softening and because of it, more particle deformation upon impact. The present study aims to produce dense Ti-6Al-4V coatings by utilizing an inner-diameter (ID) HVAF gun. The ID gun is considered a scaled-down version of the standard HVAF with a narrower jet, beneficial for near-net-shape manufacturing. To explore the potential of the ID gun in the solid-state deposition of Ti-6Al4V, an investigation was made into the effect of spraying parameters (i.e., spraying distance, fuel pressure, feeding rate, traverse speed, and nozzle length) on the characteristics of in-flight particles and the attributes of the as-fabricated coatings such as porosity, phases, and hardness. For studying in-flight particles characteristics, using online diagnostics is challenging due to the exothermic oxidation reaction of fine particles, while larger particles are too cold to be detected from their thermal emission. However, DPV diagnostic system was successfully employed to differentiate the non-emitting solid particles from the burning ones. It was found that increasing air and fuel pressure of the ID-HVAF jet as well as increasing the nozzle length led to an increase in the velocity of the in-flight particles and resulted in improved density and hardness of the as-sprayed samples. However, increasing the spraying distance had a negative effect on the density and hardness of the manufactured coatings. [ABSTRACT FROM AUTHOR]

The paper suggests dependences of the energy flux and specific energy onto the substrate on the pulse duty cycle during the dual magnetron-sputter deposition of the TiAlN coating. It is shown that the energy flux at the substrate increases by 20–30% with decreasing duty cycle from 40 to 6% at the constant average discharge power. Together with a decrease in the deposition rate at the high pulsed power, the specific energy grows sixfold on the substrate during the coating growth. The duty cycle can be thus considered as a way to control the energy flux onto the deposited coating, which affects its structure and properties. It is found that the TiAlN coating obtained at low duty cycle and high energy flux onto the substrate, possesses the high hardness and wear resistance. [ABSTRACT FROM AUTHOR]

The structure of molybdenum coatings deposited by electr oexplosion on titanium alloy VT6 is studied. Such properties of the coatings as the hardness, the modulus of elasticity, the wear resistance and the friction factor are determined. It is shown that the absence of aluminum and vanadium atoms in the coating can lower substantially the negative effect of implants from titanium alloy VT6 on the organism of the carrier. [ABSTRACT FROM AUTHOR]

This paper aims to explore the mechanism of an ultrasonic applied field on the microstructures and properties of coatings, and clarify the evolution of the molten pool under different ultrasonic frequencies. The Taguchi experimental design method was adopted in this paper. NbC-reinforced Ni-based coatings were in situ synthesized by laser cladding to investigate the effects of ultrasonic vibration process parameters on the microstructure, pore area, microhardness, and wear resistance of the cladding layer. The results show that the pore area decreases first and then increases as ultrasonic power increases from 600 to 900 W and ultrasonic frequency from 23 to 40 kHz. On the contrary, the hardness and wear resistance increase at first and then decrease. The pore area is minimized at 800 W ultrasonic power and 32 kHz ultrasonic frequency, and the hardness is maximized at 600 W ultrasonic power and 40 kHz ultrasonic frequency. Meanwhile, the highest wear resistance can be obtained when ultrasonic power is 700 W and ultrasonic frequency is 32 kHz. Based on the phase structure analysis, the cladding layer mainly consists of FeNi3, NbC, B4C, and CrB2. Ultrasonic vibration will not change the phase composition of the layer. Combined with the varying G/R value and cooling rate, the reasons for the change in grain morphology in different areas were analyzed to reveal the evolution mechanism of the molten pool under the influence of ultrasound. [ABSTRACT FROM AUTHOR]

We study the effect of nitrogen content on functional properties, thermal stability and oxidation resistance of hard and optically transparent amorphous Hf-Y-Si-B-C-N coatings prepared by pulsed magnetron sputtering. Ab-initio simulations are performed to link the experimentally obtained properties with the atomic and electronic structures of the fabricated materials. It is shown that the content of N in the material, varied from subsaturation 46 at.% to saturation 51 at.%, is of significant importance for the optimization of thermal stability and tuning the refractive index and extinction coefficient. We identify an optimum N 2 content in the plasma and in turn N content in the coatings which outperform the previously introduced high-temperature material Hf 6 Y 2 Si 29 B 12 C 2 N 45. The results constitute a progress in the efforts to combine multiple functional properties with exceptional (above 1300 °C) thermal stability and oxidation resistance. [ABSTRACT FROM AUTHOR]