Structural and mechanical properties of nano-crystal TiN coatings

The structural and mechanical properties of TiN coatings prepared by ion beam assisted deposition (IBAD) were studied. The coatings have a polycrystal structure with grain size of ～10 nm or less. The hardness of the coatings increases with increasing grain size of TiN crystallites. The coating with grain size of 10.3 nm even has a superhardness of 44.7GPa. The relationship between the hardness and the grain size in the nano-crystalline coatings was discussed on the basis of grain-boundary triple junctions.     

溅射压强对TiN/SiNx纳米多层膜微观结构及力学性能的影响

利用磁控溅射方法在不同溅射压强条件下制备了TiN/SiN_x纳米多层膜.多层膜的微观结构及力学性能分别用X射线衍射仪、原子力显微镜及纳米压痕仪来表征.结果表明随着溅射压强的增大,多层膜的界面变模糊,TiN层的择优取向由(200)晶面过渡到(111)晶面.与此同时,多层膜的表面粗糙度增大,硬度和弹性模量随溅射压强的增大而减小.多层膜力学性能的差异主要是由于薄膜的周期性结构及致密度存在差异所致. 关键词： x多层膜')" href="#">TiN/SiN_x多层膜 界面宽度 表面形貌     

Effects of pulsed bias duty ratio on microstructure and mechanical properties of TiN/TiAlN multilayer coatings

TiN/TiAlN multilayer coatings were deposited on M2 high speed steel by a pulsed bias arc ion plating system. The effect of pulsed bias duty ratio on the microstructure, mechanical and wear properties was investigated. The amount of macroparticles reduced with the increase of the duty ratio. The surface roughness was 0.0858 μm at duty ratio of 50%. TiN/TiAlN multilayer coatings were crystallized with orientations in the (1 1 1), (2 0 0) (2 2 2) and (3 1 1) crystallographic planes and the microstructure strengthened at (1 1 1) preferred orientation. At duty ratio of 20%, the hardness of TiN/TiAlN multilayer coatings reached a maximum of 3004 HV, which was 3.2 times that of the substrate. The adhesion strength reached a maximum of 77 N at 50% duty ratio. Friction and wear analyses were carried out by pin-on-disc tester at room temperature. Compared with the substrate, all the specimens coated with TiN/TiAlN multilayer coatings exhibited better tribological properties.     

Structural and photoluminescent properties of TiN thin films

Structural and photoluminescent properties of TiN thin films deposited by dc reactive magnetron sputtering are studied. It is found that TiN thin films are polycrystalline with a grain size of ～15 nm and have a NaCl-type cubic crystal structure with a lattice constant of 0.42 nm. The TiN films under study exhibit photoluminescence in the spectral range h _ν ≈ 2.1–3.4 eV at 300 K.     

Structural and elastic properties of TiN under high pressure

We have investigated the structural and elastic properties of TiN at high pressures by the first-principles plane wave pseudopotential density functional theory method at applied pressures up to 45.4 GPa. The obtained normalized volume dependence of the resulting pressure is in excellent agreement with the experimental data investigated using synchrotron radial x-ray diffraction (RXRD) under nonhydrostatic compression up to 45.4 GPa in a diamond-anvil cell. Three independent elastic constants at zero pressure and high pressure are calculated. From the obtained elastic constants, the bulk modulus, Young's modulus, shear modulus, acoustic velocity and Debye temperature as a function of the applied pressure are also successfully obtained.     

Structural and mechanical properties of multi-element (TiVCrZrHf)N coatings by reactive magnetron sputtering

In this study, (TiVCrZrHf)N multi-component coatings with quinary metallic elements were deposited by reactive magnetron sputtering system. The composition, structure, and mechanical properties of the coatings deposited at different N₂ flow rates were investigated. The (TiVCrZrHf)N coatings deposited at N₂ flow rates of 0, 1, and 2 SCCM showed an amorphous structure, whereas those deposited at N₂ flow rates of 4 and 6 SCCM showed a simple face-centered cubic solid solution structure. A saturated nitride coating was obtained for N₂ flow of 4 SCCM and higher. By increasing N₂ flow to 4 SCCM, the hardness and modulus reached a maximum value of 23.8 ± 0.8 and 267.3 ± 4.0 GPa, respectively.     

TiN/SiC纳米多层膜的生长结构与力学性能

研究了TiN/SiC纳米多层膜中立方SiC（B1cubic SiC）的形成及其对TiN/SiC多层膜力学性能的影响.结果表明：在TiN/SiC多层膜中，非晶态的SiC层在厚度小于0.6nm时形成立方结构并与TiN形成共格外延生长的超晶格柱状晶，使多层膜产生硬度和弹性模量显著升高的超硬效应，最高硬度超过60GPa.SiC随着层厚的增加转变为非晶相，从而阻止了多层膜的共格外延生长，使薄膜呈现TiN纳米晶和SiC非晶组成的层状结构特征，同时多层膜的硬度和弹性模量下降.TiN/SiC纳米多层膜产生的超硬效应与立方 关键词： 立方碳化硅 TiN/SiC纳米多层膜 外延生长 超硬效应     

Structure and mechanical properties of Ni-P electrodeposited coatings

The coatings with different phosphorus contents were obtained by varying the concentration of H₃PO₃ in the electroplating bath. With the increase of phosphorus content, the structure of the Ni-P electrodeposited coatings transformed from microcrystalline to a mixture of nanocrystalline and amorphous phases, then to amorphous phase. A high hardness value of 710 HV_0.1 of as-deposited Ni-P coating was obtained at 8.3 at.% phosphorus content, and high wear resistance was accordingly achieved. The refined nanocrystalline grains with average size of about 7 nm were found to be responsible for the high hardness and improved wear resistance of the as-deposited Ni-P electrodeposited coating.     

Ti-B-C-N纳米复合薄膜结构及力学性能研究

利用反应磁控溅射方法在单晶硅和高速钢(W18Cr4V)基片上制备出不同C含量Ti-B-C-N纳米复合薄膜. 使用X射线衍射和高分辨透射电子显微镜研究了Ti-B-C-N纳米复合薄膜的组织和微观结构,用纳米压痕仪测试了它们的硬度和弹性模量. 结果表明,利用往真空室通入C₂H₂气体的方法制备得到的Ti-B-C-N纳米复合薄膜中,在所研究成分范围内只发现TiN基的纳米晶. 当C₂H₂流量较小时,C元素的加入可以促进Ti-B-C 关键词： Ti-B-C-N薄膜 磁控溅射 微观结构 力学性能     

Structural and mechanical properties of compositionally gradient CrNx coatings prepared by arc ion plating

Compositionally gradient CrN_x coatings were fabricated using arc ion plating by gradually increasing N₂ flow rate during the deposition process. The effect of substrate bias, ranging from 0 to −250 V, on film microstructure and mechanical properties were systematically investigated with XRD, SEM, HRTEM, nanoindentation, adhesion and wear tests. The results show that substrate bias has an important influence on film microstructure and mechanical properties of gradient CrN_x coatings. The coatings mainly crystallized in the mixture of hexagonal Cr₂N, bcc Cr and fcc rock-salt CrN phases. N₂ flow rate change during deposition results in phase changes in order of Cr, Cr + Cr₂N, Cr₂N, Cr₂N + CrN, and CrN, respectively, along thickness direction. Phase fraction and preferred orientation in CrN_x coatings vary with substrate bias, exerting an effective influence on film hardness. With the increasing of bias, film microstructure evolves from an apparent columnar structure to a highly dense one. The maximum hardness of 39.1 GPa was obtained for the coatings deposited at a bias of −50 V with a friction coefficient of 0.55. It was also found that adhesion property and wear resistance of gradient CrN_x coatings were better than that of homogeneous CrN coatings.     

Laser ablation and micropatterning of thin TiN coatings

Laser ablation of thin TiN films deposited on steel substrates has been studied under wide-range variation of irradiation conditions (pulsewidth, wavelength, energy density and spot size). It has been demonstrated that both picosecond (150–300 ps) and nanosecond (5–9 ns) laser pulses were suitable for controllable ablation and microstructuring of a 1-μm-thick TiN film unlike longer 150-ns pulses. The ablation rate was found to be practically independent of the wavelength (270–1078 nm) and pulsewidth (150 ps–9 ns), but it increased substantially when the size of a laser spot was reduced from 15–60 μm to 3 μm. The laser ablation technique was applied to produce microstructures in the thin TiN films consisting of microcraters with a typical size of 3–5 μm in diameter and depth less than 1 μm. Tests of lubricated sliding of the laser-structured TiN films against a steel ball showed that the durability of lubricated sliding increased by 25% as compared to that of the original TiN film. Received: 28 July 1999 / Accepted: 17 April 2000 / Published online: 20 September 2000     

Microwave-absorbing and mechanical properties of carbonyl-iron/epoxy-silicone resin coatings

Coatings with flake carbonyl-iron particles as absorber and epoxy-silicone resins as matrix were prepared. The complex permittivity, complex permeability and microwave-absorbing properties were investigated in the frequency range of 2-18 GHz. Both the real part of permittivity and permeability were increased with carbonyl-iron weight concentration. The minimum reflection loss shifts to the low-frequency region with increase in carbonyl-iron weight concentrations. The minimum reflection loss value of −42.5 dB was obtained at 10.6 GHz for the coatings with 55 wt% carbonyl-iron. The values of adhesive power and impact strength are up to 24 MPa and 50 kg cm, respectively. These results show that the coatings possess good microwave-absorbing and mechanical properties.     

Porosity and effective mechanical properties of plasma-sprayed Ni-based alloy coatings

The aim of this paper was to address the relationship between the porosity and micro-mechanical properties of the Ni-based alloy coatings which were prepared by a novel plasma-spraying system. The porosity and the mechanical properties of the coatings varied through changing the spraying parameters. Experimental results showed that the measured data of porosity, Young’s modulus and micro-hardness of the coating exhibited high scattering and followed the Weibull distribution. From statistic trend, the micro-hardness and Young’s modulus of the coating decreased with increasing the porosity of the coating. Moreover, generally, with increasing the micro-hardness of the coating, Young’s modulus of the coating increased.     

TiN/TiB2异结构纳米多层膜的共格生长与力学性能

采用多靶磁控溅射法制备了一系列具有不同TiB2调制层厚度的TiN/TiB2纳米多层膜.利用x射线衍射仪、高分辨电子显微镜和微力学探针研究了TiB2层厚变化对多层膜生长结构和力学性能的影响.结果表明,在fcc-TiN层(111)生长面的模板作用下,原为非晶态的TiB2层在厚度小于2.9nm时形成hcp晶体态,并与fcc-TiN形成共格外延生长;其界面共格关系为{111}TiN∥{0001}TiB2,〈110〉TiN∥〈1120〉TiB.由于共格界面存在晶格失配度,多层膜中形成拉、压交变的应力场,导致多层膜产生硬度和弹性模量升高的超硬效应,最高硬度和弹性模量分别达到46.9GPa和465GPa.继续增加TiB2层的厚度,TiB2形成非晶态并破坏了与TiN层的共格外延生长,多层膜形成非晶TiN层和非晶TiB2层交替的调制结构,其硬度和弹性模量相应降低.     

Microstructure and mechanical properties of reactive magnetron sputtered Ti-B-C-N nanocomposite coatings

Ti-B-C-N nanocomposite coatings with different C contents were deposited on Si (1 0 0) and high speed steel (W18Cr4V) substrates by closed-field unbalanced reactive magnetron sputtering in the mixture of argon, nitrogen and acetylene gases. These films were subsequently characterized ex situ in terms of their microstructures by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM), their nanohardness/elastic modulus and facture toughness by nano-indention and Vickers indentation methods, and their surface morphology using atomic force microscopy (AFM). The results indicated that, in the studied composition range, the deposited Ti-B-C-N coatings exhibit nanocomposite based on TiN nanocrystallites. When the C₂H₂ flow rate is small, incorporation of small amount of C promoted crystallization of Ti-B-C-N nanocomposite coatings, which resulted in increase of nano-grain size and mechanical properties of coatings. A maximum grain size of about 8 nm was found at a C₂H₂ flux rate of 1 sccm. However, the hardness, elastic modulus and fracture toughness values were not consistent with the grain size. They got to their maximum of 35.7 GPa, 363.1 GPa and 2.46 MPa m^1/2, respectively, at a C₂H₂ flow rate of 2 sccm (corresponding to about 6 nm in nano-grain size). Further increase of C content dramatically decreased not only grain size but also the mechanical properties of coatings. The presently deposited Ti-B-C-N coatings had a smooth surface. The roughness value was consistent with that of grain size.     

TiCN/TiNbCN multilayer coatings with enhanced mechanical properties

Enhancement of mechanical properties by using a TiCN/TiNbCN multilayered system with different bilayer periods (Λ) and bilayer numbers (n) via magnetron sputtering technique was studied in this work. The coatings were characterized in terms of structural, chemical, morphological and mechanical properties by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nanoindentation. Results of the X-ray analysis showed reflections associated to FCC (1 1 1) crystal structure for TiCN/TiNbCN films. AFM analysis revealed a reduction of grain size and roughness when the bilayer number is increased and the bilayer period is decreased. Finally, enhancement of mechanical properties was determined via nanoindentation measurements. The best behavior was obtained when the bilayer period (Λ) was 15 nm (n = 200), yielding the highest hardness (42 GPa) and elastic modulus (408 GPa). The values for the hardness and elastic modulus are 1.6 and 1.3 times greater than the coating with n = 1, respectively. The enhancement effects in multilayer coatings could be attributed to different mechanisms for layer formation with nanometric thickness due to the Hall-Petch effect; because this effect, originally used to explain the increase in hardness with decreasing grain size in bulk polycrystalline metals, has also been used to explain hardness enhancements in multilayers taking into account the thickness reduction at individual single layers that make the multilayered system. The Hall-Petch model based on dislocation motion within layers and across layer interfaces, has been successfully applied to multilayers to explain this hardness enhancement.     

Microstructure and mechanical characteristics of hydroxyapatite coatings on Ti/TiN/Si substrates synthesized by pulsed laser deposition

We synthesized by pulsed laser deposition a bilayer of Ti/TiN on Si(100) wafers which was coated in a next step with hydroxyapatite (samples labelled HA-1). Some of the structures were further thermally treated in a water vapour jet (samples labelled HA-2). In SEM, the HA surface looked rough, with micronic droplets. TEM and SAED investigations revealed a compact organization of HA crystals in the case of the HA-1 sample, while two regions (one compact and one porous) were identified for the HA-2 sample, with triclinic HA crystals within the 500 nm range. In XTEM, at the Si/TiN border, a 2–3 nm SiO₂ layer was visible, whereas at the TiN/Ti border there was a smooth transition from fcc (111) TiN to hcp (100) Ti. The HA crystals were elongated normal to the surface. According to Berkovich indentation qualitative analyses, the sample HA-1 was more homogeneous and harder but brittle. Scratch tests confirmed quantitatively that HA-1 was more resistant and adherent than HA-2 films. In the first case, the big droplets only were removed by the indenter, while the HA-2 films were delaminated on large areas as a result of wedge spallation failure.     

Microstructure, mechanical properties, and oxidation resistance of nanocomposite Ti-Si-N coatings

Ti-Si-N coatings with different silicon contents (0-12 at.%) were deposited onto Si(1 0 0) wafer, AISI M42 high speed steel, and stainless steel plate, respectively. These coatings were characterized and analyzed by using a variety of analytical techniques, such as XRD, AES, SEM, XPS, nanoindentation measurements, Rockwell C-type indentation tester, and scratch tester. The results revealed that the hardness was strongly correlated to the amount of silicon addition into a growing TiN film. The maximum hardness of 47.1 GPa was achieved as the Si content was 8.6 at.%. In the mechanical and oxidation resistance measurements, the Ti-Si-N coatings showed three distinct behaviors. (i) The coatings with Si contents of no more than 8.6 at.% performed good adhesion strength quality onto the HSS substrates. (ii) The fracture toughness of the coatings decreased with the increase in Si content. (iii) The Ti-Si-N coating with 8.6 at.% Si showed the excellent oxidation resistance behavior. The cutting performance under using coolant conditions was also evaluated by a conventional drilling machine. The drills with Ti-Si-N coatings performed much better than the drills with TiN coating and the uncoated drills.     

TiN/TiB2异结构纳米多层膜的共格生长与力学性能

采用多靶磁控溅射法制备了一系列具有不同TiB₂调制层厚度的TiN/TiB_{2纳米多层膜.利用x射线衍射仪、高分辨电子显微镜和微力学探针研究了TiB2层厚变化对多层膜生长结构和力学性能的影响.结果表明，在fcc-TiN层(111)生长面的模板 作用下，原为非晶态的TiB2层在厚度小于2.9nm时形成hcp晶体态，并与fcc-TiN 形成共格外延生长；其界面共格关系为{111}TiN//{0001}TiB2，〈110〉TiN//〈1120〉TiB2.由于共格界面存在晶格失配 度，多层膜中形成拉、压交变的应力场，导致多层膜产生硬度和弹性模量升高的超硬效应， 最高硬度和弹性模量分别达到46.9GPa和465GPa.继续增加TiB2层的厚度，TiB2形成非晶态并破坏了与TiN层的共格外延生长，多层膜形成非晶TiN层和非晶TiB< sub>2层交替的调制结构，其硬度和弹性模量相应降低. 关键词： 2}纳米多层膜')" href="#">TiN/TiB₂纳米多层膜 共格生长 晶体化 力学性能