Hard Protective Coatings Research Articles

Thermodynamic properties, interfacial adhesion energy and tribological properties between MCN (M = Hf, Ta, Cr, Nb) coating and Ti alloy substrates investigated by experiment and first-principles calculations

A series of MCN (M = Hf, Ta, Cr, Nb) coatings were prepared by double glow plasma surface alloying (DGPSA) as protective hard coatings for Ti60 (Ti-5.5Al-4.0Zr-4.0Sn), aiming to solve the problems of low bonding strength between the ceramic coating and the substrate as well as the poor wear resistant of ceramic alloy coatings. First principles calculation was used to study the elastic constant of MC0.5N0.5 solids, thermomechanical parameters and the interfacial adhesive strength of Ti(101)/MCN(220). The calculated results indicated the HfCN solids show excellent mechanical properties, lower thermal expansion coefficient α, lower Gibbbs values and higher values of entropy (S), superior adhesion strength Wad ∼ 5.7 J/m2. The high-temperature tribological performance tests show that the HfCN and TaCN coatings exhibited better wear resistance compared with the CrCN and NbCN coatings at 500 °C -700 °C. The wear rate of HfCN coatings at 500 °C and 700 °C is about 2 times and 5 times lower than that of CrCN, which is in accordance with the HfCN coating’s excellent thermal stability and high interfacial bonding strength with the Ti substrate. The adhesion wear mechanism of all coatings gradually intensified with increasing temperature.

Bilayer period and ratio dependent structure and mechanical properties of TiN/MoN superlattices

Transition metal nitrides are widely used in the hard materials and protective coatings industry, but are limited by their low fracture toughness. Encouraged by previous studies on remarkable simultaneous improvements in strength and ductility through superlattice (SL) architectures, various TiN/MoN SL thin films were developed on MgO (100) substrates. By varying their bilayer periods (Λ) between 2 and 23 nm with bilayer ratios (Γ = ℓMoN:ℓTiN) of 0.5, 1, 2, and 2.7, their individual effects on structure and mechanical properties can be revealed. All SLs—independent of Λ, Γ, and nitrogen-to-metal (N/Me) ratio (within the analysed variations)—exhibit a rocksalt structure with high-order satellite peaks in X-ray diffraction. While the SLs with Γ = 2 have the lowest hardness (H)—presumably due to their overall lowest N/Me ratio—the SLs with Γ = 2.7 are the hardest with a neat superlattice effect. The SLs with Γ = 1 and 2.7 have a comparable superlattice effect on fracture toughness (KIC), peaking at Λ = 9.9 and 9.3 nm, respectively. Of all the SLs investigated, those with Γ = 1 provide the best blend of mechanical properties and dry sliding coefficient of friction (µ), such as H = 34.8±1.6 GPa, KIC = 4.1±0.2 MPa√m, and µ = 0.27 when Λ = 9.9 nm. Deepening current understanding of superlattice effects in general—particularly the influence of bilayer periods and ratios—in relation to the nitrogen supply and heterogeneous microstructures, our study accelerates the design of nanolayered coatings with desired structure-property combinations.

Stripping process of TiAlN/TiSiN coating on WC-Co cemented carbide substrate by using the dry-electropolishing technique

Physical Vapor Deposition hard protective coatings are frequently applied to hardmetal cutting tools to extend their lifespan under service-like working conditions. However, these coatings may experience damage during their performance, such as wear. In addition, defective coatings during the production process can occur, requiring reconditioning. In this sense, provided that the coating has not chipped off, removing and recoating the tools is a crucial process for their reuse, ultimately reducing costs. This study investigates the stripping process of an industrial ternary system (TiAlN/TiSiN) coating deposited on WC-Co cemented carbide using the dry-electropolishing technique. X-ray photoelectron spectroscopy was used to analyze the electrochemical surface changes. Chemical analysis reveals that a layer of oxide is created during the stripping process, mainly composed of SiO2, TiO2, and Al2O3, as well as organic compounds (e.g.: pyrrodic group in aromatics C-(NH)-C) and nitrogen oxides (e.g.: pyrinidic O=N-C). The stripping process successfully removed the coating without damaging the WC-Co substrate or leaching metallic Co binder. Additionally, the process follows a linear trend, establishing a correlation between the time of dry-electropolishing applied and the remaining coating thickness.

An assessment of machining performance of CAPVD-coated carbide tools in face milling of Ti-6Al-4V

The present study aims to extend the life of tungsten carbide (WC) cutting tools utilized in face milling operations of Ti-6Al-4V by applying hard protective coatings developed using the cathodic-arc physical vapor deposition (CAPVD) technique. Box-Behnken design with 15 experimental runs and response surface methodology were used to mathematically model the relationships between input parameters and output responses to determine the optimal cutting parameters resulting in maximum material removal rate and minimum tool wear. Additionally, the performance of uncoated and coated carbide tools was assessed under dry and wet conditions to identify the best machining conditions. Intriguingly, the tool life of an uncoated WC tool in dry conditions was up to threefold more than that in wet conditions. The tool life of the coated tools was 33% to 166% longer than that of their uncoated counterparts. An analysis of their performance revealed an inverse relationship between the amount of Al in the coating and the tool life. The results from sliding wear tests suggest that Al-deficient coatings have a low coefficient of friction. This study sheds light on the effectiveness of CAPVD-coated carbide tools for improving the tool life during face milling of Ti-6Al-4V.

High-power-density sputtering of industrial-scale targets: Case study of (Al,Cr)N

Large-scale sputter-deposition of hard protective coatings has not been prevalent as the large dimensions of the industrial targets posed an enormous technological challenge: only relatively low power (and plasma) densities could be achieved, resulting ultimately in poor performance of such coatings. Here, we introduce a novel sputtering technology allowing to reach high power densities for industrial tubular targets. This is realised on the principle of a longitudinal movement of a reduced-size magnetron inside the target. In doing so, peak power densities of 840 W/cm2 have been achieved for the overall power of 25 kW and the target dimensions of Ø110 × 510 mm. To demonstrate the effectiveness of the solution, we produced a series of cubic (Al,Cr)N coatings by sputtering an Al60Cr40 target. Most of the coatings have a stoichiometric composition, smooth surface and a moderate amount of growth defects. Significant improvements through recipe optimisation could be achieved resulting in mechanical properties (hardness, fracture toughness, wear resistance) being equal to and even exceeding those of the benchmark coatings produced by means of conventional sputtering and cathodic arc evaporation. Our results open up great potential of this novel sputtering technique for the coating industry.

Oxidation properties of quaternary Zr-based diboride thin films grown by hybrid high-power impulse/DC magnetron co-sputtering

Sputter-deposited transition metal diborides are subject of increasing attention for protective hard coatings. However, they suffer from high brittleness and rapid oxidation. Alloying with Ta increases their toughness, but their oxidation resistance requires further enhancement. Here, the influence of adding Si on the microstructure, mechanical, and oxidation properties of quaternary Zr1−(x + y)TaxSiyBz thin films grown by hybrid high-power impulse/DC magnetron co-sputtering (ZrB2-DCMS/Ta-HiPIMS/Si-DCMS) is studied. The layers are deposited at two different conditions of Ta-target HiPIMS powers and frequencies (30 W/100 Hz and 60 W/200 Hz series) with Si-target DCMS powers PSi = 0, 10, 15, and 20 W, while the ZrB2-target DCMS power is maintained constant at 200 W. For the 30 W/100 Hz series, x decreases from 0.20 to 0.15, y increases from 0 to 0.22, and z decreases from 2.0 to 1.8 by increasing PSi. The Ta/metal ratio remains constant at x = 0.3 for the 60 W/200 Hz series, while y increases from 0 to 0.1, and z decreases from 1.7 to 1.4. All layers show columnar growth and crystallize in a hexagonal-diboride structure, but crystal orientations change by increasing PSi. The 60 W/200 Hz series have much denser microstructure than the 30 W/100 Hz series. The 60 W/200 Hz series have high hardness values (≥35 GPa), while the hardness of the 30 W/100 Hz series significantly decreases from ∼37 to ∼21 GPa as a function of PSi. Zr0.7Ta0.3B1.7 has markedly better high-temperature oxidation resistance than Zr0.8Ta0.2B2.0 due to the formation of protective B-containing oxide scales. Alloying with Si considerably decreases the oxidation rate of the 30 W/100 Hz series owing to the formation of oxide scales containing a ZrSiO4 phase with a thin Si oxide top layer; however, the oxidation rate increases for the 60 W/200 Hz series as these quaternary alloys do not contain sufficiently high B and Si to form oxidation protective barriers.

On the correlations between mechanical properties, oxidation behaviors and high temperature wear resistance of AlCrSiTiN coatings: A combinatorial study

Pinpointing the critical influencing factors of the high temperature tribological properties has always been the critical issues for hard protective coatings used in high temperature applications. The synergistic effect of simultaneous chemical attack and mechanical damage to the coatings would make it difficult to predict the performance and the durability of the protective coatings. In this study, a systematical investigation of the effect of chemical composition on the mechanical properties, oxidation resistance, and high temperature tribological properties is conducted through combinatorial approach for AlCrSiTiN coatings. It is found that in addition to the properties of the coatings, the whole system of wearing counterpart/coating/substrate plays a vital role in the high temperature tribological behaviors. However, a general observation of the inferior high temperature wear resistance for the coatings with poor mechanical properties and oxidation resistance still holds.Overall, this study provides a general guideline for designing protective hard coatings with superior high temperature tribological properties.

Effects of duty cycle and nitrogen flow rate on the mechanical properties of (V,Mo)N coatings deposited by high-power pulsed magnetron sputtering

(V,Mo)N is theoretically predicted to have high hardness and fracture toughness and is a promising material for the application on protective hard coatings. However, the toughness enhancement of (V,Mo)N coatings deposited by dc-unbalanced magnetron sputtering (dc-UBMS) was not as remarkable as expected. The issue could be due to insufficient energy delivery to the plasma species in the deposition process such that nitrogen and metal atoms were not fully reacted and led to the degradation of coating quality. Since high-power pulsed magnetron sputtering (HPPMS) can provide high peak power density, the method was selected to deposit (V,Mo)N coatings in this research. The objective of this study was to investigate the effects of duty cycle and nitrogen flow rate on the microstructure and mechanical properties of (V,Mo)N coatings deposited on Si substrates by HPPMS. Four sets of (V,Mo)N coatings were deposited by HPPMS at different durations with two duty cycles, 5% and 3%, and two nitrogen flow rates, 6.0 and 12.0 SCCM. The results showed that the N/metal ratio was mainly affected by the nitrogen flow rate, ranging from 0.70 to 0.96 with increasing nitrogen flow rate. The lattice parameter of the samples linearly increased with the N/metal ratio. The x-ray diffraction (XRD) patterns revealed that all samples tended to approach (200)-preferred orientation with increasing deposition duration. The glancing incident XRD patterns indicated that the samples deposited at 6 SCCM nitrogen flow rate and 3% duty cycle have multiphases. Transmission electron microscopy analysis confirmed that phase separation from (V,Mo)N to (V-rich,Mo)N and (V,Mo-rich)N occurred in those samples. The hardness of the (V,Mo)N coatings decreased with increasing N/metal ratio, which may be related to the N-vacancy hardening effect. The sample deposited at 6 SCCM nitrogen flow rate and 3% duty cycle for 36 h showed the highest hardness of 28.4 GPa, which was possibly associated with the phase separation, and hence plastic deformation became difficult. The fracture toughness (Gc) of the (V,Mo)N coatings was evaluated using the internal energy-induced cracking method. The resultant Gc of the (V,Mo)N coatings, ranging from 36.1 to 43.7 J/m2, was higher than that of the coatings deposited by dc-UBMS in our previous study. The toughness enhancement could be caused by a higher fraction of Mo–N bonding due to the adequate reaction energy provided by the HPPMS process.

TiC–Fe gradient coating on pure titanium fabricated by in-situ solid-phase diffusion: toward superior hardness and interfacial adhesion strength

Protective hard coatings can significantly improve the bottleneck problem of low hardness and poor wear resistance on titanium alloy surface. However, hardness and adhesive strength usually exhibit an inverse relationship, which greatly limits its widespread use. In this work, TiC–Fe gradient coating with high hardness and adhesion was successfully fabricated by in-situ solid-phase diffusion method (ISDM) on pure titanium at 1000 °C for 2 h. The average thickness of the coating was approximately 5 μm, and the volume fraction of TiC in the coating was greater than 95 vol%. The grain size of TiC gradually increased from 200 nm at the coating surface to 2 μm towards the substrate. The phase interface and the coating/substrate interface exhibited excellent interfacial bonding at the atomic scale. The novel TiC–Fe gradient coating can simultaneously achieve superior hardness (42.9 ± 2.6 GPa) and elastic modulus (557.4 ± 10.3 GPa) that is mainly dominated by in situ synthesised high volume fraction TiC, as well as high adhesion strength (>225 ± 10 MPa). The increased adhesion strength was attributed to the excellent macro/micro interfaces and gradient transition of the microstructure. The use of ISDM to fabricate TiC–Fe gradient coating on titanium alloy may provide a new strategy to improve the comprehensive properties including hardness, elastic modulus, interfacial adhesion strength, and wear resistance for wider applications.

Microstructure and bond strength of niobium carbide coating on GCr15 prepared by in-situ hot press sintering

The hardness and adhesion of protective hard coatings to the substrate are the most important parameters that influence the performance of the tool. Herein, we propose an effective strategy, by in-situ hot press sintering, to fabricate a novel niobium carbide coating with high hardness and excellent interfacial bond strength on GCr15. The coating is composed of Nb2C, NbC, and α-Fe phases. The volume fraction of niobium carbide (Nb2C and NbC) phases reaches 93%. Along the direction of coating thickness, the grain morphology of niobium carbide changes from equiaxed (Nb2C) to columnar (NbC), and then to equiaxed (NbC), presenting a gradient microstructure. The coating/substrate interface displays an excellent macro/micro interface. The formation of the gradient microstructure is attributed to the nucleation-growth process controlled by the carbon concentration gradient diffusion. The novel gradient coating can simultaneously achieve superhardness (20.2 ± 0.3 GPa) and excellent bond strength (>210 ± 20 MPa). The excellent bond strength is mainly attributed to the in-situ formation of the coating and the gradient microstructures. The tensile test results show that the fracture mechanism of the niobium carbide coating on GCr15 is mainly a brittle fracture of niobium carbide coating and a small amount of coating debonding.

Microstructure, mechanical and tribological behavior of CrHfNbTaTiCxNy high-entropy carbonitride coatings prepared by double glow plasma alloy

A series of CrHfNbTaTiCxNy high-entropy carbonitride coatings were prepared as protective hard coatings for Ti60, aiming to solve the problems of high density and poor wear resistant of high-entropy alloy coatings. The coatings were deposited by double glow plasma metallurgy alloy and the microstructure, mechanical and tribological properties were detected. The XRD analysis exhibited that all the coatings show a single NaCl-type structure. The CrHfNbTaTiCxNy coating with a content of 34 at.% C and 10 at.% exhibited relatively excellent wear resistant and low wear rate at different temperature (RT, 300 °C and 500 °C), although the CrHfNbTaTiC have the highest hardness. It can be attributed to the CrHfNbTaTiC0.34N0.1 coating have excellent toughness, plastic deformation resistance, as well as the formation of dense and stable tribo-layer on wear surface during friction, and the wear rate reduce 40.6% compared with 300 °C and 57.3% compared with the CrHfNbTaTiC coating at 500 °C. Accordingly, the main wear mechanism transfer from abrasion wear (at 300 °C) to adhesion wear.

Hard yet tough thermodynamics-driven nanostructured (AlCrNbSixTi)N multicomponent nitride hard coating

Breaking the hardness-toughness trade-off has always been a critical issue for hard protective coatings. Rational materials design, which simultaneously incorporate multiple strengthening and toughening mechanisms, could provide pathways toward hard yet tough materials.In this study, (AlCrNbSixTi)N multicomponent nitride coatings with various Si content are fabricated via magnetron co-sputtering. Multi-dimensional strengthening and toughening mechanisms are found in thermodynamics-driven nanostructured (AlCrNbSixTi)N. Enhanced atomic packing, nanostructure formation, and microstructural modification originate from spinodal decomposition contribute to multiple strengthening and toughening mechanisms after Si incorporation. From atomic-level packing, spinodal-decomposed nanostructure, to microstructure, the evolutions are quantitatively characterized and correlated to mechanical properties. With the addition of 4.4 at% of Si, maximum hardness of 27.2 GPa is achieved while maintains high fracture toughness of 3.66±0.37MPam. On the other hand, the maximum fracture toughness is found for (AlCrNbSi7.6Ti)N and is attributed to the featureless microstructure, nanostructure formation and non-complete amorphization.

Microstructure, mechanical properties, and oxidation behavior of arc-evaporated Cr–Al–O–N coatings with various Cr/Al ratios

Cr–Al-based oxynitride materials have attracted significant attention as hard protective coatings for decades. However, knowledge of the influence of the constituents on oxidation behavior is limited. Here, Cr–Al–O–N coatings with various Cr/Al ratios prepared using cathodic arc evaporation were studied with respect to their microstructure, mechanical properties, and oxidation behavior. With a decrease in the Cr/Al ratio, the coatings yielded a phase evolution from face-centered cubic CrN to rock salt-type cubic (Cr, Al)2O3 to a wurtzite-type hexagonal AlN structure. The cubic structured coatings showed a comparable indentation hardness, much higher than that of the Cr-free Al–O–N coating with a wurtzite structure. Thermogravimetric together with differential scanning calorimetric (TG-DSC) analysis revealed that the ternary Cr–O–N and Al–O–N coatings were more susceptible to oxidation than the quaternary Cr–Al–O–N coatings. Moreover, isothermal oxidation experiments indicated that the addition of 66 at.% Al within the metallic species gives rise to the growth of an Al-rich oxide scale on top of the Cr–Al–O–N coating. However, this oxide scale containing substantial voids cannot prevent the underlying coating from oxidation. Oxidation kinetics study illustrates that the oxidation activation energies of (CrxAl1−x)–O–N coatings with x = 1.00, 0.76, 0.58, 0.33, and 0 are 252.3, 305.2, 370.7, 303.8, and 297.7 kJ/mol, respectively. The best oxidation resistance was obtained by the (Cr0.58Al0.42)–O–N coating, whereas the Al-containing (Cr0.33Al0.67)–O–N coating showed inferior oxidation resistance owing to its high intrinsic oxygen fraction.

Dense and hard TiWC protective coatings grown with tungsten ion irradiation using WC-HiPIMS/TiC-DCMS co-sputtering technique without external heating

Titanium tungsten carbide (TiWC) coatings are deposited by a combined high-power impulse and dc magnetron co-sputtering (HiPIMS/DCMS) technique. No external heating is applied during deposition phase, instead, the thermally driven adatom mobility is substituted by heavy ion irradiation. DCMS sources equipped with titanium carbide targets provide constant neutral fluxes to establish the predominant coating structures, whereas tungsten carbide target in HiPIMS mode serves as the source of heavy metal-ions. Substrate bias of −60 V is synchronized to W+ ion-rich time domains of HiPIMS pulses to minimize the contribution from working gas ions. The influence of W+ ion flux intensity, controlled by varying peak target current density (JT), on film properties is investigated. X-ray photoelectron spectroscopy reveals the presence of over stoichiometric carbon forming an amorphous phase, the amount of which can be fine-tuned by varying JT. Changes in film composition as a function of JT are explained based on the in-situ ion mass spectroscopy analyses. Dense TiWC coatings by hybrid process exhibit hardness higher than 30 GPa, which are comparable to TiWC films deposited by DCMS with dc substrate bias and external heating. The relative energy consumption in the hybrid process is reduced by 77 % as compared to high-temperature DCMS processing.

Enabling macroscopic superlubricity in TaC/a-C nanocomposite film by atomic-level Au

Endowing the hard protective coating systems with macroscopic superlubricity can adequately minimize unnecessary material consumption and energy waste caused by friction and wear. Herein, a novel scheme for realizing superlubricity-protective bifunction is demonstrated, namely introducing atomic-level dispersed Au atoms (∼1.4 at.%) into the TaC / amorphous carbon (a-C) nanocomposite structure consisting of the TaC-nanoparticles-based network backbone and the a-C filler. With the aid of the atomic-level dispersed Au atoms reducing the ordered transformation barrier of a-C, the in-situ formation of graphite-like carbon (GLC) flakes during the sliding process wrap the TaC grains to form TaC@GLC nanoscrolls in the shearing layer for multi-contact configuration and incommensurate contact, thereby obtaining the robust macroscopic superlubrication with the friction of coefficient of ∼0.002 and the ultra-low wear rate of ∼8.80 × 10−10 (mm−3/Nm). This strategy of triggering in-situ self-assembled nanoscrolls from hard protective coatings provides a new avenue to enable macroscopic superlubricity for robust engineering applications.

Investigation of the microstructure of a graded ZrN/Ti0.33Al0.67N multilayer coating using cross-sectional characterization methods

An approach to enhance the performance of protective hard coatings for cutting applications is to modify the coating architecture by combining two inherently different materials in a multilayer. Besides the choice of the materials, the thickness of the individual layers strongly influences the coating microstructure and consequently also its properties. Within this work, a graded ZrN/Ti0.33Al0.67N multilayer coating with constant Ti0.33Al0.67N and stepwise increasing ZrN layer thickness was investigated in detail by a combinatorial approach of cross-sectional X-ray nanodiffraction, electron backscatter diffraction and transmission electron microscopy. The primary aim was to obtain a profound understanding of the microstructure of the coating as well as of the residual stress state. (Semi-)coherent grain growth was observed independently of the ZrN layer thickness. Changes in the multilayer architecture were found to affect not only the grain size, but also the residual stress state of the coating. While the grain size increased with increasing ZrN layer thickness, the residual stress decreased. This work contributes to a deeper understanding of the influence of the multilayer architecture on the microstructure and stress state of heteroepitactic multilayer coatings.

Microstructure and high-temperature tribological characteristics of self-lubricating TiAlSiN/VSiN multilayer nitride coatings

In recent years, self-lubricating hard protective coatings operated at elevated temperature have drawn great amount of attentions. It has been found that alloying certain elements such as vanadium is an effective method to reduce the friction coefficient, since the Magnéli phase formed at elevated temperature provides a self-lubricious surface during the wear process. However, the formation kinetics of the Magnéli phase should be appropriately controlled. Insufficient or excessive amount of Magnéli phase formation may result in high friction coefficient or severe oxidation of coatings. This study reports an architectural design strategy to engineer the mechanical and high temperature tribological properties of TiAlSiN/VSiN multilayer.In this study, the multilayer system exhibited a low friction coefficient of 0.28 and the lowest wear rate of 7.01 × 10−6mm3N−1m−1 was revealed at multilayer with bilayer period of 16 nm during the wear test at 700 °C. The existence of the Magnéli phase, V2O5, was observed by XPS and its high-temperature lubricating effect was revealed as compared to the wear test at room temperature. It is demonstrated that a particular architectural design of TiAlSiN/VSiN multilayer coating provides a potential candidate for high-speed cutting tools due to their mechanical and lubricious properties.

A review of tribological properties and deposition methods for selected hard protective coatings

Surface modification is widely adopted as a viable solution for surface damage under sliding or impacting conditions. Various coatings can be manufactured using different techniques and it has been applied on various substrates in previous studies which results in different characteristics. This review presents the anti-wear techniques with a focus on the most recent coatings of superior properties. Hard protective coatings may consist of various compositions; however, based on the hardness and the resistance to wear, some of the frequently used elements are Titanium (Ti), Nickel (Ni), carbides, Zirconium (Zr), Boron (B) and the Diamond Like Carbon (DLC). The deposition methods such as Chemical Vapor Deposition (CVD), Physical Vapor Deposition (PVD) as well as the cutting-edge coating hybrid-deposition methods such as Pulsed DC Magnetron Sputtering (PDCMS), High Power impulse (HiPIMS) and Arc Ion Plating (AIP) are reviewed and the resulted significant differences in the coating properties are discussed. In this review, listing the most important findings from previous studies in a table for each group of coatings make it easy to compare between various techniques and coatings. Some of the listed factors affecting the coating properties, such as the substrate, and others affecting the coefficient of friction, such as the counter body, were not been sufficiently highlighted before despite their importance in analyzing the tribological behavior for the coatings investigated. Although the focus was on the most recent studies, a wide range of studies was covered in order to accumulate and integrate the knowledge toward a complete analysis and discussion. Coating hardness is essential for better wear resistance; however, coating bonding, thickness and roughness may be equally important. Various techniques are used to improve the bonding. For some coatings, the Coefficient of Friction (CoF) increases with increasing the wear resistance where the counter body plays a major role. For most of the deposition techniques, the controlling parameters are the cleaning treatment, arc current, pressure, time, and gas supply. It was found that diamond-like carbon coatings are among the hardest coatings and the Plasma-Assisted Chemical Vapor Deposition (PACVD) is frequently reported as one of the most promising deposition techniques. Many coatings including the diamond-like carbon coating were not been investigated for their erosion wear resistance by solid particles despite the importance of such investigations for many applications.

Characterization and Evaluation of Engineered Coating Techniques for Different Cutting Tools-Review.

Coatings are now frequently used on cutting tool inserts in the metal production sector due to their better wear resistance and heat barrier effect. Protective hard coatings with a thickness of a few micrometers are created on cutting tools using physical or chemical vapor deposition (PVD, CVD) to increase their application performance. Different coating materials are utilized for a wide range of cutting applications, generally in bi-or multilayer stacks, and typically belong to the material classes of nitrides, carbides, carbonitrides, borides, boronitrides, or oxides. The current study examines typical hard coatings deposited by PVD and CVD in the corresponding material classes. The present state of research is reviewed, and pioneering work on this subject as well as recent results leading to the construction of complete “synthesis–structure–property–application performance” correlations of the different coatings are examined. When compared to uncoated tools, tool coatings prevent direct contact between the workpiece and the tool substrate, altering cutting temperature and machining performance. The purpose of this paper is to examine the effect of cutting-zone temperatures on multilayer coating characteristics during the metal-cutting process. Simplified summary and comparisons of various coating types on cutting tools based on distinct deposition procedures. Furthermore, existing and prospective issues for the hard coating community are discussed.

Fabrication of High-κ Dielectric Metal Oxide Films on Topographically Patterned Substrates: Polymer Brush-Mediated Depositions.

Fabrication of ultrathin films of dielectric (with particular reference to materials with high dielectric constants) materials has significance in many advanced technological applications including hard protective coatings, sensors, and next-generation logic devices. Current state-of-the-art in microelectronics for fabricating these thin films is a combination of atomic layer deposition and photolithography. As feature size decreases and aspect ratios increase, conformality of the films becomes paramount. Here, we show a polymer brush template-assisted deposition of highly conformal, ultrathin (sub 5 nm) high-κ dielectric metal oxide films (hafnium oxide and zirconium oxide) on topographically patterned silicon nitride substrates. This technique, using hydroxyl terminated poly-4-vinyl pyridine (P4VP-OH) as the polymer brush, allows for conformal deposition with uniform thickness along the trenches and sidewalls of the substrate. Metal salts are infiltrated into the grafted monolayer polymer brush films via solution deposition. Tailoring specific polymer interfacial chemistries for ion infiltration combined with subsequent oxygen plasma treatment enabled the fabrication of high-quality sub 5 nm metal oxide films.