CrTiAlN Coatings Research Articles

NANOHARDNESS AND MODULE OF ELASTICITY OF CR-BASED NITRIDE COATINGS DEPOSITED AT TEMPERATURES BELOW 200°C

Sets of Cr-based hard coatings were prepared via reactive closed field unbalanced magnetron sputtering (CFUBMS). Substrate temperature was kept in range of 150 to 200ºC during deposition. Nanohardness (H) andeffective modulus of elasticity (E*) of the CrN, CrAlN, CrTiN and CrTiAlN coatings were examined using depth-sensing indentationmethod. The results from the combined examination of the research ratios showed that the triple and quaternary hard coatings have superior mechanical properties and they strongly depend on the deposition conditions

Application of Multiple Nitrogen-based Coatings for Cemented Carbide Tools: A Review

As the main-stream of the machining coating, nitrogen-based coatings have irreplaceable advantages, such as high hardness, high strength, and good oxidation resistance recently. This paper introduces common multiple nitrogen-based coatings which including TiAlN, CrAlN, TiAlSiN, CrAlSiN and CrTiAlN coatings for cemented carbide tools. The microstructure and property of coating is depended on its chemical composition. Generally, compounds of different structures are formed between the various elements of the coating, and these have different forms of existence and properties: titanium and chromium exist in nitrides (face-centered cubic structure), aluminium solubilizes in TiN/CrN, and amorphous Si3N4 can make difference in fine grain strengthening. The Al2O3 and SiO2 can improve oxidation resistance.

Microstructure and indentation hardness study of CAE-PVD (Cr,Ti,Al)N solid solution coatings deposited using a combinatorial multitarget approach

In this study we have analysed the indentation hardness and modulus of cathodic arc deposited CrTiAlN coatings as a function of the stoichiometric variables Ti/Cr, Al content and cation mix. The coatings have been prepared using a combinatorial cathode composition approach, leading up to 14 different stoichiometries produced in 5 batches. The coatings have been inspected by glow discharge optical emission spectroscopy, scanning electron microscopy, X-ray diffraction and nanoindentation techniques. The coatings develop crystalline structures compatible with solid solutions of face–centered cubic unit cells for all the compositions produced. Such unit cells exhibited a downwards lattice parameter dependency on the aluminum concentration of the coatings (from 0.417 nm down to 0.413 nm). The indentation hardness as a function of the Ti/Cr is compatible with other previous studies reported. The films hardnesses and moduli also increase as the aluminum concentration increases (21 GPa up to 34 GPa). Both indentation responses upon Ti/Cr and Al are attributed to solid solution strengthening. However in order to prove this statement, the indentation hardness and modulus were studied as a function of the mixing term of the cations, as this term is well representative of the solid solution compositional map. The observed results unambiguously evidence that the solid solution strengthening effect is confirmed on the basis of the dependency between the indentation hardness and the so called degree of mixing. • CrTiAlN arc coatings deposited using a multi-cathode combinational approach. • CrTiAlN coatings form solid solutions of decreasing lattice parameter as the Al content increases. • The absolute aluminum concentration increases the hardness and modulus of the quaternary solid solution. • Solid solution strengthening constituted the as main mechanism of the coating indentation hardness and modulus evolution.

Ti- and Cr-based hard coatings obtained at low temperatures by unbalanced magnetron sputtering

We prepared a set of Ti- and Cr-based ternary and quaternary hard coatings at low deposition temperatures (< 200 °C) by closed-field unbalanced magnetron sputtering in a gas mixture of Ar + N2. The morphological, structural and mechanical properties of the coatings were characterized by means of atomic force microscopy, scanning electron microscopy, X-ray photoelectron spectrometry, a micro-scratch tester and a nanoindentation tester. The results of the analyses performed revealed that the surface of the deposited ternary Ti-Al-N coatings was rougher than that of the CrTiAlN coatings. The metallic elements in the coatings react with nitrogen to form CrN, TiN and AlN nitride phases, as no Cr2N phase was detected in the Cr-based coatings. The optimized quaternary coating demonstrated mechanical properties superior to those of the ternary ones in terms of hardness; adherence strength of 32 GPa and elastic modulus of 418 GPa were measured for the multicomponent coating of composition Cr0.68Ti0.19Al0.13N.

Characterisation of cathodic arc evaporated CrTiAlN coatings: Tribological response at room temperature and at 400 °C

In this work, cathodic arc evaporation CrTiAlN coatings have been deposited on H13 hot work steel and the tribological behavior investigated at room temperature and at 400 °C. The microstructure, composition, roughness, indentation hardness and lattice parameter have been measured as a function of the deposition conditions, mainly given by the different Cr and TiAl vapour fluxes coming from the cathode arrangement in the vacuum reactor. The coating microstructures showed dense, compact columnar growth and a good film adhesion. The lattice parameter measured over the (002) diffraction peaks exhibited a quasi lineal correlation with the Ti/Cr+Al atomic ratio of the samples. In addition, the indentation hardness also increased as the lattice parameter increased. The coefficients of friction unveiled the different tribological behavior of the samples depending on the stoichiomentry and the temperature. At 400 °C, the coefficients of friction showed high dispersion, in contrast to the coherent evolution observed at room temperature. The wear damage at 400 °C was more intense than that observed at room temperature in agreement with the friction evolution observed. The coating with a stoichiometry of Cr0.23Ti0.13Al0.22N0.42 showed a good wear performance at 400 °C.

Evaluating mechanical properties and crack resistance of CrN, CrTiN, CrAlN and CrTiAlN coatings by nanoindentation and scratch tests

Abstract CrN, CrTiN, CrAlN and CrTiAlN coatings were deposited on Si (100) wafers, and their microstructure, mechanical properties, fracture toughness and adhesive strength were investigated via X-ray diffraction (XRD), nanoindentation and micro-scratch tests. Besides an F.C.C. crystal structure, TiN0.3 (004) and AlN (222) phases were found in the CrTiN and CrAlN coatings while the crystallinity of the CrTiAlN coating decreased. The hardness of the CrN (14.5 GPa), CrTiN (13.9 GPa) and CrAlN (17.7 GPa) coatings was determined by their grain sizes while the CrTiAlN coating with the most compact morphology exhibited the highest hardness of 22.0 GPa. In addition, CrTiN (KIc = 2.73 MPa· m ), CrAlN (KIc = 2.70 MPa· m ) and CrTiAlN coatings showed a stronger crack resistance than the CrN coating (KIc = 1.06 MPa· m ), especially the CrTiAlN coating without any radial cracks. However, the CrTiAlN coating encountered circumferential cracks and premature delamination (Adhesive energy Gc = 70 J/m2) because of its highest compressive stress (4.64 GPa). Based on the results here, it is concluded that a decent compressive stress of 3.0 GPa is expected to help thin films prevent from radial and circumferential cracks simultaneously.

The structure, oxidation resistance, mechanical and tribological properties of CrTiAlN coatings

CrxTiyAlzN coatings (x+y+z=1) with low Al contents were deposited using hybrid high power impulse magnetron sputtering (HiPIMS) and pulsed dc magnetron sputtering (PDCMS). The Ti fraction (fTi=Ti/(Cr+Ti+Al)) was increased from 5 to 64% to produce coatings with different chemical compositions varied from Cr-rich to Ti-rich. The microstructure of the coatings was studied using X-ray diffraction and scanning electron microscopy. Mechanical properties of the coatings were analyzed by nanoindentation. The oxidation behavior of the coatings was evaluated in the ambient air at 900°C and 1000°C. The high temperature wear resistance of the coatings was measured using a high temperature pin-on-disc tribometer in the ambient air from 600°C to 900°C. The CrTiAlN coatings showed a (111) preferred orientation when the fTi is less than 10%. The orientation of the coatings changed from (111) to (311) as the fTi increased. The addition of a small amount of Ti (e.g., fTi=5–10%) effectively improved the mechanical properties and the wear resistance of the Cr0.66Al0.34N baseline coating. The Cr0.61Ti0.10Al0.29N coating exhibited the highest hardness of 40GPa, the lowest coefficient of friction of 0.4 and the lowest wear rate of 7×10−7mm3N−1m−1 at room temperature. The Cr0.61Ti0.10Al0.29N coating also showed excellent oxidation resistance after annealing at 1000°C and good wear resistance from 600°C to 800°C. These enhanced properties can be attributed to multiple factors including solid solution strengthening, the dense microstructure, and the strong (111) orientation. However, as the fTi increased from 20% to 64%, the oxidation resistance, mechanical properties, and wear resistance of the CrTiAlN coatings decreased.

Structure and Mechanical Properties of CrTiAlN/TiAlN Composite Coatings Deposited by Multi-Arc Ion Plating

CrTiAlN/TiAlN composite coatings were deposited on cemented carbide by using a home-made industrial scale multi-arc ion plating system. The samples were studied by X-ray diffraction, scanning electron microscopy (SEM), microhardness and ball-on-disk testing. The properties of the CrTiAlN/TiAlN coatings were significantly influenced by the microstructure and the deposition time ratio of TiAlN over CrTiAlN layers. With the increase of deposition time ratio, the microhardness of CrTiAlN/TiAlN increased from 28.6 GPa to 37.5 GPa, much higher than that of CrTiAlN coatings. The friction coefficients of the CrTiAlN/TiAlN coatings were higher than those of CrTiAlN coatings against a cemented carbide ball. The microhardness of the CrTiAlN/TiAlN coatings was changed after annealing at 800°C, and the friction coefficients of the annealed coatings were increased against the cemented carbide ball.

Research on Microstructure and Tribological Properties of Cr-Based Hard Coatings

In this paper, three kinds of Cr-based hard coatings have been studied for its structural, mechanical and tribological properties at room temperature. By the technology of closed field unbalanced magnetron sputter ion plating (CFUMSIP), CrN CrAlN and CrTiAlN hard coatings were deposited onto DC53 cold die steel and silicon (100) substrate. The coatings were characterized by means of field emission scanning electron microscopy (FESEM), X-ray diffractometer (XRD), microhardness tester, optical microscope and ball-on-disc tribometer, in order to check their structural, as well as to determine the mechanical and tribological properties. The experimental results showed that the CrTiAlN coating performed better than the CrN coating and the CrAlN coating in terms of mechanical and tribological properties. The wear resistances of CrN, CrAlN and CrTiAlN coatings have been significantly improved compared with DC53 steel substrate.

Effect of CrTiAlN Coatings on High-Temperature Oxidation Behavior of H13 Steel

CrTiAlN hard coatings have been deposited on H13 steel for improving the oxidation resistance by Closed Field Unbalanced Magnetron Sputter Ion Plating (CFUMSIP). The phase components, surface and section morphology of H13 steel before and after oxidation were analyzed by XRD and SEM. The results showed that the columnar crystal film possesses three major parts, i.e., the internal Cr bonding layer, the intermediate CrN transition layer, the external CrTiAlN gradient coating. The selective oxidation of Cr element was found on the surface of uncoated H13 steel while oxidation, but a continuous protective layer was not formed because of low Cr content, finally a lot of alpha Fe2O3 particles took place on the surface of H13 steel owing to the oxidation of the matrix element. O element can diffuse much more easily through the coating and oxide scales at 800 °C, and spallation and cracks were not found during the oxidation. These results indicated that the CrTiAlN coating have excellent high-temperature oxidation resistance at 800 °C.

Effect of plasma nitriding on adhesion strength of CrTiAlN coatings on H13 steels by closed field unbalanced magnetron sputter ion plating

A duplex treatment, i.e. plasma nitriding followed by closed field unbalanced magnetron sputter ion plating, is used to strengthen the bonding of CrTiAlN coatings to H13 steels in the paper. A nitride layer is first formed on H13 steel samples by plasma nitriding and then two chromium transition layers are prepared on the surface of the nitrided H13 steels using closed field unbalanced magnetron sputter ion plating. The adhesion between the substrate and the coating is evaluated using the Rockwell indentation and scratch tests. Meanwhile, the composition, phase structure and the morphologies for CrTiAlN coatings as well as the worn surfaces are characterized by EDX, SEM and XRD, respectively. Dry sliding wear behavior of the duplex-treated H13 steels is analyzed by using ball-on-disk wear tests compared with those of untreated and plasma-nitrided H13 steels. The results show that the adhesion strength and wear resistance for duplex-treated coatings increase significantly due to a gradient-hardness support, one favorable gradient of chemical composition, an intermediate hardening effect and a diffusion reaction of the nitrided layer-coating interface.

Influence of Negative Bias Voltage on the Microstructure and Tribological Properties of CrTiAlN Composite Films

By using the multi-ion plating,the CrAlTiN composite films were made on the suface of piston rings to improve its tribological properties and increase service life. The effects of negative bias voltage on morphology, hardness, adhesion strength, microstructure and tribological properties were studied. The results show that the morphology, phases, hardness, adhesion and wearability of the films were varied with negative bias voltage. When the negative bias voltage was at -200V, the hardness, adhesion strength of CrTiAlN coatings reaches maximum and the surface roughness, weightlessness for CrTiAlN composite coatings reaches minimum. And the conclusion can be obtained that the key factor which influences the wearability of the films are the function of the crystal size and adhesion strength together.

Study on Wear and Friction Resistance of CrTiAlMoN Coatings Deposited by Magnetron Sputtering

The present research aims to synthesize a nanoscale multilayer CrTiAlMoN hard coating for the modification of wear and friction performance, as compare to CrTiAlN coatings. CrTiAlMoN coatings were deposited on 1045 carbon steel substrates by magnetron sputtering at different Mo target current. The wear and friction resistance were characterized by pin-on-disc test. When a WC-Co ball was used as the counterpart, the coefficients of friction of CrTiAlMoN coatings were found to decrease with the increase of Mo target current, with the lowest value (0.34) being only one half that of CrTiAlN coating (0.76). The combination of high hardness above 36GPa and low coefficients of friction reduces the specific wear rate of the CrTiAlMoN coatings to only 10% of CrTiAlN coatings. When tested against a bearing steel ball, results demonstrate that the effect of Mo on reducing friction of the CrTiAlMoN coatings is not significant and even negative due to adhesive wear.

Structure and Tribological Properties of CrTiAlN Coatings Deposited by Multi-Arc Ion Plating

CrTiAlN coatings were prepared by using a home-made industrial scale multi-arc ion plating system. The coatings were found to be composites of face-center-cubic CrN and TiN. The surface roughness, microhardness, and tribological properties of the films were significantly affected by the nitrogen pressure and dc-pulsed bias voltage applied to the substrate. The CrTiAlN coatings with the smoothest surfaces were obtained at optimum conditions of nitrogen pressure of 5.0 Pa and bias voltage of −200 V. The samples were found to exhibit a hardness of 2900 HV0.05 with an average friction coefficient of 0.16 and wear rate of 1.5×10-16 m3/N·m against cemented carbide.

Mechanical and Tribological Properties of Multi-Element CrTiAlN Coatings for Dry Cutting Deposited by Magnetron Sputtering Technologies

Multi-element CrTiAlN coatings are deposited onto YT14 cemented carbide milling cutter by magnetron sputtering in an Ar+N2 mixture. The nano-indenter, scanning electron microscopy, X-ray diffraction and Rockwell indentations were used to investigate the mechanical property, microstructure and adhesion strength of CrTiAlN coatings. And the tribological properties and dry cutting performance of the CrTiAlN coatings were compared with TiN and TiAlN coatings. The experimental results showed that the phase structures of the composite films include Cr, CrN, Cr2N and TiN phases. And the surface crystal grain of CrTiAlN coatings is relative small and the section structure of CrTiAlN coatings was columns crystal structure. It showed better for CrTiAlN coatings on nano-hardness and adhesion compared with TiN and TiAlN coatings. And the friction coefficient of above three kind coatings was about 0.12-0.15. The friction coefficient and wear volume of CrTiAlN coatings appeared lowest among these three kind coatings. Dry cutting experimental results showed that the sequence of cutting life for these coated tools were CrTiAlN＞TiAlN＞TiN.

Bias effects on the tribological behavior of cathodic arc evaporated CrTiAlN coatings on AISI 304 stainless steel

In this study, CrTiAlN coatings were deposited on AISI 304 stainless steel by cathodic arc evaporation under a systematic variation of the substrate bias voltage. The coating morphology and properties including surface roughness, adhesion, hardness/elastic modulus ( H/ E) ratio, and friction behavior were analyzed to evaluate the impact of the substrate bias voltage on the coating microstructure and properties. The results suggest that for an optimized value of the substrate bias voltage, i.e. − 150 V, the CrTiAlN coatings showed increased Cr content and improved properties, such as higher adhesion strength, hardness, and elastic modulus in comparison to the coatings deposited by other substrate bias voltage. Moreover, the optimum coatings achieved a remarkable reduction in the steel friction coefficient from 0.65 to 0.45.

Oxidation Resistance of Multicomponent CrTiAlN Hard Coatings at Elevated Temperatures

Quaternary CrTiAlN hard coatings were deposited by closed field unbalanced magnetron sputtering ion plating technique onto steel substrates, and their structural, mechanical, and tribological properties after heat treatment in air at different temperatures (500-900 oC) were studied and compared by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), micro-indentation, and pin-on-disc (POD) tribometer, etc. The onset temperature of oxidation was determined by thermogravimetric analyser (TGA). The compositional depth profiles before and after the heat treatments were examined by X-ray photoelectron spectroscopy (XPS) in order to study the oxidation mechanism. The experimental results indicate that the CrTiAlN coatings have excellent oxidation resistance and thermal stability, and outperform the traditional hard coatings like TiN and TiAlN in terms of higher oxidation temperature, hardness, adhesion, and wear resistance. It is expected that the CrTiAlN coatings with superior properties should have better performance in dry high speed machining.

High temperature oxidation of CrTiAlN hard coatings prepared by unbalanced magnetron sputtering

The present research aims to synthesize a multi-component CrTiAlN hard coating for the modification of high-temperature performance, as compared to the traditional TiN and TiAlN coatings. In this work, the quaternary CrTiAlN coatings were deposited on AISI M42 steel substrates by reactive unbalanced magnetron sputtering technique from Cr, Ti and Al elemental targets in Ar + N 2 mixture atmosphere, and their high-temperature oxidation behaviours as well as the oxidized structure were studied after static oxidation tests in air at different temperatures (500–900 °C). The structural, mechanical and tribological properties of the coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), micro-indentation and pin-on-disc tribometer. The composition and depth profiles of the coatings after oxidation were investigated by X-ray photoelectron spectroscopy (XPS) with sputter profiling. The experimental results show that the CrTiAlN coatings outperform the other two conventional hard coatings (TiN and TiAlN) in terms of high-temperature oxidation resistance, structural stability, as well as wear resistance. The higher oxidation resistance is likely related to the formation of dense protective oxide layer consisting of Cr 2O 3 and Al 2O 3, suppressing the further diffusion and penetration of oxygen inside the coatings. After oxidation at 900 °C, the CrTiAlN coatings still retain basically their crystalline structure, surface morphology, hardness and wear resistance. It is expected that the CrTiAlN coating is a good candidate for industrial applications under harsh environments, such as dry high-speed machining.

Structural and tribological properties of CrTiAlN coatings on Mg alloy by closed-field unbalanced magnetron sputtering ion plating

In this paper, a series of multi-layer hard coating system of CrTiAlN has been prepared by closed-field unbalanced magnetron sputtering ion plating (CFUBMSIP) technique in a gas mixture of Ar + N 2. The coatings were deposited onto AZ31 Mg alloy substrates. During deposition step, technological temperature and metallic atom concentration of coatings were controlled by adjusting the currents of different metal magnetron targets. The nitrogen level was varied by using the feedback control of plasma optical emission monitor (OEM). The structural, mechanical and tribological properties of coatings were characterized by means of X-ray photoelectron spectrometry, high-resolution transmission electron microscope, field emission scanning electron microscope (FESEM), micro-hardness tester, and scratch and ball-on-disc tester. The experimental results show that the N atomic concentration increases and the oxide on the top of coatings decreases; furthermore the modulation period and the friction coefficient decrease with the N 2 level increasing. The outstanding mechanical property can be acquired at medium N 2 level, and the CrTiAlN coatings on AZ31 Mg alloy substrates outperform the uncoated M42 high speed steel (HSS) and the uncoated 316 stainless steel (SS).

Substrate Bias Effects on Mechanical and Tribological Properties of Nanoscale Multilayer CrTiAlN Coatings Prepared by Closed Field Unbalanced Magnetron Sputtering Ion Plating Method

Substrate Bias Effects on Mechanical and Tribological Properties of Nanoscale Multilayer CrTiAlN Coatings Prepared by Closed Field Unbalanced Magnetron Sputtering Ion Plating Method