Measurement of residual stresses by X-ray diffraction techniques in MoN and Mo2N coatings deposited by arc PVD on high-speed steel substrate

Polycrystalline MoN and Mo₂N films have promising physical and mechanical properties, which made them candidates for wear- and corrosion-resistant coatings and diffusion barriers in microelectronics. The residual stresses in MoN and Mo₂N films consist of thermal and growth stresses or intrinsic stress generated during deposition. Residual stresses in the MoN and Mo₂N coatings deposited by arc PVD techniques on HSS substrate were measured by XRD using the Rocking and the Fixed Incidence Multiplane (FIM) techniques. Residual stresses measured by both techniques in Mo₂N (face center cubic, f.c.c.) and in MoN (hexagonal) films were about 5 and 10 GPa (compressive), respectively. These results indicated that residual stresses in the MoN film was two times greater than the residual stresses in the Mo₂N film.     

Effect of Axial Magnetic Field on the Microstructure and Mechanical Properties of CrN Films Deposited by Arc Ion Plating

CrN films were deposited on the high-speed-steel substrates by arc ion plating. The effect of an axial magnetic field on the microstructure and mechanical properties was investigated. The chemical composition, microstructure, surface morphology, surface roughness, hardness and film/substrate adhesion of the film were characterized by X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscope(SEM), surface morphology analyzer, Vickers microhardness test and scratch test. The results showed that the magnetic field puts much effect on the microstructure,chemical composition, hardness and film/substrate adhesion of the Cr N films. The N content increases and Cr content decreases when the magnetic flux density increases from 0 to 30 m T. All of the Cr N films were found to be substoichiometric. With an increase in the magnetic flux density, the film structures change in such way: Cr_2N →Cr_(2-N)+CrN→CrN+Cr_2N→CrN.The SEM results showed that the number of macroparticles(MPs) on the film surface is significantly reduced when the magnetic flux density increases to 10 mT or higher. The surface roughness decreases with the magnetic field, which is attributed to the fewer MPs and sputtered craters on the film surface. The hardness value increases from 2074 HV_(0.025) at 0 mT(without magnetic field) and reaches a maximum value of 2509 HV_(0.025) at 10 m T.The further increase in the magnetic flux density leads to a decrease in the film hardness. The critical load of film/substrate adhesion shows a monotonous increase with the increase in magnetic flux density.     

非平衡磁控溅射沉积Ti-N薄膜色彩和性能调控研究

目的研究Ti-N薄膜颜色和硬度及其结合强度的影响因素。方法利用封闭磁场非平衡磁控溅射离子镀膜技术,该变溅射偏压、氮气流量等参数,分别在304不锈钢基体和载玻片基体上沉积多彩Ti-N薄膜。用努氏硬度、划痕法和球坑法分别评价Ti-N薄膜的显微硬度和结合强度等性能。结果当偏压和溅射电流分别为-60 V和2 A时,将反应气体氮气流量从3sccm逐渐增加到20sccm,Ti-N薄膜颜色依次发生从"淡黄-金黄-红黄-紫红-金黄"的循环变化趋势。薄膜的硬度随氮气流量的增加在601~700HK之间呈逐步上升的趋势。膜基结合普遍较好。当氮气流量和溅射电流分别为10sccm和2 A时,将负偏压从-50 V逐渐增加到-120 V,薄膜颜色从淡黄色变成金黄色,膜基结合强度较好。硬度随偏压的增加变化不明显。结论影响Ti-N薄膜颜色的主要因素为氮气流量,偏压也可以轻微地改变薄膜颜色,但对薄膜性能影响并不明显。     

氮气流量对反应磁控溅射TiN薄膜微结构与力学性能的影响

利用磁控溅射镀膜技术分别在硬质合金YG6X和单晶Si片表面制备TiN薄膜,分析N2流量对薄膜相组成、表面形貌、显微硬度和膜基结合力的影响。结果表明,N2流量对薄膜的微结构以及力学性能具有重要影响。随着N2流量的降低,TiN薄膜表面孔洞和台阶明显减少,表面平整度得到明显改善;薄膜的物相组成在N2流量为0.2sccm时为TiN和TiN0.61两相;N2流量的变化改变了薄膜表面的能量状态,因此,降低N2流量导致TiN薄膜的生长取向由(200)面向(111)面转变。同时,N2流量为2.4 sccm时TiN薄膜的膜基结合力最高,此时TiN薄膜也具有最高的显微硬度。     

直流溅射沉积CrN薄膜组织结构与摩擦性能分析研究

采用直流反应溅射在304不锈钢表面沉积CrN薄膜。利用X射线衍射仪（XRD）,扫描电子显微镜（SEM）,原子力显微镜（AFM）,显微硬度计,磨损试验机与三维轮廓仪等表征氮气流量对CrN薄膜组织结构与摩擦性能的影响。研究结果表明,随着氮气流量的增加,CrN (200)晶面呈择优取向,薄膜的沉积速率随着氮气流量的增加逐渐降低。另外,薄膜的表面粗糙度随着氮气流量的增加呈先降低后增加的趋势。随着氮气流量从15 sccm增加至30 sccm时,薄膜的显微硬度先从527.34 HV增加至1042.26 HV,当氮气流量再增加至35 sccm时,薄膜的显微硬度却降低至918 HV。磨损试验表明,当氮气流量为30 sccm 时薄膜具有最小的摩擦系数0.93和磨损率2.02×10-15m3·(N·m)-1,显示最佳的磨损性能。     

Composite TiN–Ni thin films deposited by reactive magnetron sputter ion-plating

Composite TiN–Ni thin films were deposited by direct-current (DC) magnetron sputter ion-plating from an alloy Ti–48 at% Ni target in a mixture of argon and nitrogen gases at a total pressure of 0.1 Pa onto glass and stainless steel substrates heated to temperatures higher than 250 °C. The films deposited at the nitrogen flow Q_N2≥6.4 sccm consisted of a mixture of δ-TiN and fcc nickel phases. The effects of negative substrate bias and substrate temperature on the crystal structure of the films were studied. The substrate bias of −200 V resulted in improved crystallization of films and a smaller difference in size between the TiN and nickel grains, as compared with films deposited onto substrates at floating potential. It was possible to vary the crystal grain size of both phases by varying the substrate temperature in the range 270–430 °C. The maximum hardness measured in the films was 10.5 GPa. It is expected that the hardness can be increased by decreasing the content of nickel.     

Laser ablation synthesis and characterization of nitride coatings

Thin film nitride coatings were deposited on Si (100) substrates by the pulsed laser deposition (PLD) technique. The PLD method is a unique process for depositing high quality thin films with novel microstructure and properties. Boron nitride (BN) films deposited on Si (100) substrates have a higher percentage of c-BN phases when processed in higher nitrogen partial pressure. Titanium nitride films deposited on Si (100) substrates at a higher temperature (600 °C) have better quality crystallinity and higher hardness and Young’s modulus values than films deposited at lower temperatures. Nanoindentation technique was used to measure the mechanical properties of thin films. The film orientation was determined by x-ray diffraction. Atomic force microscopy (AFM) technique was used to understand the growth structure of the films.     

Study of Electrical,Mechanical, and Tribological Properties of CrN x Thin Films as a Function of Sputtering Conditions

The influences of chemical composition and deposition power on the electrical, mechanical, and tribological properties of sputtered chromium nitride (Cr-N) thin films that can be used for development of cryogenic temperature sensor are investigated. Cr-N thin films were deposited by DC reactive magnetron sputtering technique under various nitrogen gas flows (5-20 sccm) and deposition powers (200 and 250 W). Results of chemical composition showed that films produced with 5 and 10 sccm flow of nitrogen gas were substoichiometric, while at higher flows they were overstoichiometric. The surface morphology investigation showed that grains size and surface roughness increase with nitrogen gas flow, whereas deposition power has an inverse effect on both of these parameters. The electrical results demonstrated that the substoichiometric films had a positive temperature coefficient of resistivity, and the overstoichiometric films showed a negative temperature coefficient of resistivity. The films produced at higher deposition power of 250 W showed higher hardness and lower friction coefficient and scratch volume, while variation of nitrogen gas flow in the range of 5-20 sccm did not affect these properties, significantly.     

Optical properties and corrosion behaviour of sputtered Zr-B and Zr-B-N coatings

In this paper, we present results on the structure, optical properties and corrosion behaviour of Zr-B and Zr-B-N coatings employing non-reactive and reactive d.c. magnetron sputter deposition. The addition of nitrogen reduced the grain size—coatings deposited at nitrogen flow rates f(N₂) of less than approximately 14 sccm (standard cm³ min^-1) were extremely fine grained, while nitrogen flow rates of more than 14sccm led to fracture-amorphous coatings with a very smooth surface. The hardness and abrasion resistance decreased with the increase in nitrogen content. Pure Zr-B coatings are silver-greyish with metallic brilliance but nitrogen changes the colour from dark grey or black at low contents to interference colours in the amorphous state. Ellipsometric measurements of the refractive index n and adsorption coefficient k supported the results derived from electron microscopy, colour measurements and mechanical testing. The transition point between the fine-grained and fracture-amorphous structure lies in the range of f(N₂) around 10 sccm. The black coatings deposited with such nitrogen levels showed good corrosion and abrasion resistance combined with a satisfying hardness. In some cases, increasing the nitrogencontent improved the corrosion resistance. In potentio- dynamic experiments, more positive free corrosion and pitting potentials were demonstrated. However, in salt spray testing and immersion testing using an artificial sweat solution, no beneficial effect of high nitrogen additions was noticed. Zr-B-N coatings deposited with nitrogen flow values in the range 10–20 sccm offer an excellent choice for decorative purposes, owing to their dark grey or intense black colour and good corrosion resistance.     

氮含量对Mo-Ta-W-N多主元合金氮化物薄膜的影响

目的 探究氮含量对MoTaW多主元合金薄膜的微观组织和力学性能的影响,并提高Mo-Ta-W多主元合金薄膜的力学性能。方法 采用反应多靶磁控溅射技术在单晶硅片上制备出了具有不同氮含量的Mo-Ta-W-N多主元合金氮化物薄膜,通过X射线光电子能谱仪、掠入射角X射线衍射、场发射扫描电子显微镜、原子力显微镜对薄膜的成分、组织结构、表面及截面微观形貌、厚度和粗糙度进行了表征分析,并采用纳米压痕仪对薄膜的硬度和弹性模量进行了测试。结果 Mo-Ta-W-N多主元合金氮化物薄膜中的氮含量随着溅射过程中氮气流量的增加而增加,当氮气流量达到50%时,薄膜中的氮含量升至49%,而钽含量则随之降低至12%。形成氮化物后,Mo-Ta-W多主元薄膜由BCC结构转变成了单相FCC固溶体结构,表面由层片状结构转变为花椰菜状团簇结构,随着氮含量的增加,表面的粗糙度先降低后升高,厚度则不断降低。与Mo-Ta-W多主元合金薄膜相比,Mo-Ta-W多主元合金氮化物薄膜的力学性能有所提高,但随着氮含量的增加而下降,当氮气流量为10%时,Mo-Ta-W-N多主元合金氮化物薄膜的硬度和弹性模量分别为34.3 GPa和327.5 GPa。结论 氮化物的形成对Mo-Ta-W多主元合金薄膜的相结构、表面形貌等有影响,可有效提高薄膜的力学性能。     

Effect of hydrogen flow on the properties of hydrogenated amorphous carbon films fabricated by electron cyclotron resonance plasma enhanced chemical vapor deposition

The hydrogenated amorphous carbon films (a-C:H, so-called diamond-like carbon, DLC) have exceptional physical and mechanical properties and have wide applications. In the present study, amorphous hydrogenated carbon films (a-C:H) have been deposited on a Si (100) substrate at different hydrogen flow using electron cyclotron resonance chemical vapor deposition (ECR-CVD). The flow of hydrogen changed from 10 sccm to 40 sccm and the flow of acetylene was fixed at 10 sccm. The microstructure and properties of the a-C:H were measured using visible Raman spectra, Fourier transform infrared (FTIR) spectroscopy, UV-VIS spectrometer,surface profilometer and nano-indentation. The results showed that the sp³ content and sp³-CH₂ structure in the amorphous hydrogenated carbon films increased with the hydrogen flow. The deposition rate decreased with the hydrogen flow. The residual stress and the nano-hardness of the amorphous hydrogenated carbon films increased with the hydrogen flow. Consequently, the a-C:H film become more diamond-like with the increase of hydrogen flow.     

Effects of nitrogen content on structure and mechanical properties of multi-element (AlCrNbSiTiV)N coating

AlCrNbSiTiV metallic and nitride films were deposited by reactive radio-frequency unbalanced magnetron sputtering. The composition, microstructure and mechanical properties of the coatings deposited at different nitrogen flow rates were evaluated. The deposited AlCrNbSiTiV metallic film has an amorphous structure. The nitride films, regardless of the nitrogen flow ratio, were found to have only an FCC structure register on the XRD profiles. A Stoichiometric nitride ratio, i.e. (Al,Cr,Nb,Si,Ti,V)₅₀ N₅₀ is attained for a nitrogen flow ratio (R_N) of 10% and higher. At the lowest nitrogen flow ratio there is a preferred (200) orientation; however the films become less textured at higher nitrogen flow ratios. Nano-grained structures are obtained for all flow ratios, with grain sizes ranging from 8.7 to 12.3 nm. At the highest nitrogen flow rates the coatings have a compressive stress of around 4.5 GPa. The (Al,Cr,Nb,Si,Ti,V)₅₀ N₅₀ nitride coatings have both a high hardness and elastic modulus of 41 and 360 GPa, respectively. The maximum H/E ratio occurs at a nitrogen flow ratio of 20%.     

Exceptions to the microstructure zone model revealed by the reactive d.c. magnetron sputter deposition of δ-TiNx thin films

This paper deals with the influence of the nitrogen flow rate on the microstructure of δ-TiN_x films prepared by d.c. magnetron sputtering. The δ-TiN_x films were prepared under decreasing nitrogen flow rates to obtain nitrogen contents in the films ranging from x=0.99 to 0.95. Ion bombardment of the films was negligible in these experiments.

Some films prepared under deposition conditions which typically result in a fine-grain (about 0.1 μm) transition zone microstructure exhibit a “large”-grain (about 1 μm) zone III microstructure. It has been demonstrated that there exists a narrow area of nitrogen flow rate for which the microstructure of the films does not agree with the zone model. The large-grain films are stress free. The nitrogen content in the films containing large grains is x=0.97. All deposition conditions except the nitrogen flow rate were kept constant in this experiment. Chemical energy dissipated during the reactive process can explain the observed effects.     

Relationship Between Crystalline Structure and Hardness of Ti-Si-N-O Coatings Fabricated by dc Sputtering

Ti-Si-N-O coatings were deposited on AISI D2 tool steel and silicon substrates by dc reactive magnetron co-sputtering using a target of Ti-Si with a constant area ratio of 0.2. The substrate temperature was 400 °C and reactive atmosphere of nitrogen and argon. For all samples, argon flow was maintained constant at 25 sccm, while the flow of the nitrogen was varied to analyze the structural changes related to chemical composition and resistivity. According to results obtained by x-ray diffraction and stoichiometry calculations by x-ray energy dispersive spectroscopy the Ti-Si-N-O coatings contain two solid solutions. The higher crystalline part corresponds to titanium oxynitrure. Hardness tests on the coatings were carried out using the indentation work model and the hardness value was determined. Finally, the values of hardness were corroborated by nanoindentation test, and values of Young’s modulus and elastic recovery were discussed. We concluded that F2TSN sample (F _Ar = 25 sccm, F _N = 5 sccm, P = 200 W, and P _W = 8.9 × 10⁻³ mbar) presented the greatest hardness and the lowest resistivity values, due to its preferential crystalline orientation.     

Physical properties of Mo6−xRuxTe8 and Mo6Te8−xSx

A series of the Chevrel phases, Mo_6−xRu_xTe₈ and Mo₆Te_8−xS_x (x=0, 1, 2), has been prepared and the various physical properties, such as the elastic modulus, Debye temperature, and electrical resistivity, have been evaluated. The relationships between several properties of the compounds have also been studied. Young’s modulus and Debye temperature of Mo_6−xRu_xTe₈ and Mo₆Te_8−xS_x increase with increasing x value. The relationship between the Vickers hardness and Young’s modulus shows ceramic characteristics for Mo_6−xRu_xTe₈, while they show glass-like characteristics for Mo₆Te_8−xS_x. The electrical resistivities of Mo_6−xRu_xTe₈ and Mo₆Te_8−xS_x increase with increasing x value.     

Deposition of thick TiAlN coatings on 2024 Al/SiCp substrate by Arc ion plating

Aluminum-matrix composites with particulate SiC ceramic reinforcements (Al/SiC_p) have received much attention for space and aircraft propulsion applications. It is imperative to deposit thick hard coatings on these composites for protection. TiAlN coatings with a Ti interlayer were deposited by arc ion plating (AIP) on 2024 Al/SiC_p substrates at various nitrogen flow rates. It was found that when the nitrogen flow rate is increased from 100 sccm to 250 sccm, the deposition rate decreases, the coating hardness increases and the adhesion strength decreases. Based on the above results and the principle of gradient materials, the thick gradient TiAlN coatings with a Ti interlayer were successfully deposited on a 2024 Al/SiC_p substrate to a thickness of 60 μm by continuously increasing the nitrogen flow rate during deposition. Such an achievement can be attributed to the gradient distribution of elements, hardness, and stresses across the coating thickness.     

约束式热丝CVD法制备金刚石的研究

为提高热丝CVD法沉积金刚石薄膜的生长速率,以丙酮和氢气作为反应气源,利用自制的半封闭式空间约束装置,将热丝、衬底、反应气体聚集在狭小空间内,研究不同气体流速条件下的金刚石薄膜沉积情况;使用SEM和Raman光谱表征所合成的薄膜。结果表明:采用约束式沉积法可以显著提高沉积速率,本实验在230 cm3/min（标况）气体流速下获得最大沉积速率6.31 μm/h,比未约束时增大了近一倍。随着气体流速增大,沉积速率先增大后减小;气体流速86~115 cm3/min（标况）时,晶粒尺寸为微米级;气体流速115~575 cm3/min（标况）时,晶粒尺寸减小至纳米级。Raman光谱检测显示:约束式沉积所得薄膜总体质量较好,但随气体流速增大而逐渐降低。      

Effect of C2H2 gas flow rate on synthesis and characteristics of Ti–Si–C–N coating by cathodic arc plasma evaporation

The influences of C₂H₂ gas flow rate on the synthesis, microstructure, and mechanical properties of the Ti–Si–C–N films were investigated. Quaternary Ti–Si–C–N coatings were deposited on WC-Co substrates using Ti and TiSi (80:20 at.%) alloy target on a dual cathodic arc plasma evaporation system. The Ti–Si–C–N coatings were designed with Ti/TiN/TiSiN as an interlayer to enhance the adhesion strength between the top coating and substrate. The Ti–Si–C–N coatings were deposited under the mixture flow of N₂ and C₂H₂. Composition analysis showed that as the C₂H₂ gas flow increased, the Ti, Si and N contents decreased and the carbon content increased in the coatings. The results showed the maximum nanohardness of approximately 40 GPa with a friction coefficient of 0.7 was obtained at the carbon content of 28 at.% (C₂H₂ = 15 sccm). However, as the C₂H₂ gas flow rate increased from 15 to 40 sccm (carbon content from 25.2 to 56.3 at.%), both the hardness and friction coefficient reduced to 20 GPa and 0.3, respectively. Raman analysis indicated the microstructure of the deposited coating transformed from Ti–Si–C–N film to TiSi-containing diamond-like carbon films structure, which was strongly influenced by the C₂H₂ flow rate and is demarcated at a C₂H₂ flow of 20 sccm. The TiSi-containing diamond-like carbon films reveal low-friction and wear-resistant nature with an average friction coefficient between 0.3 and 0.4, lower than both TiSiN and Ti–Si–C–N films.     

Effect of N2 flow on low carbon TiAlNC coatings

TiAlNC coatings were prepared under various N₂ flows by reactive dc magnetron sputtering. The composition, microstructure and hardness of TiAlNC coatings were investigated by energy dispersive spectroscopy, X-ray diffraction, scanning electron microscopy and micro Vicker tester. By increasing the N₂ flow, the Al/Ti ratio and the nitrogen content of the coatings increased. It was found that hexagonal AlN phase precipitated under relatively high N₂ flow (e.g. 8 sccm). The increase in the N₂ flow also changed the preferred orientation of fcc Ti(Al)N(C) phase from random to [111], and then to [200]. The coating deposited at low N₂ flow (e.g. 2 sccm) exhibited [111] preferred orientation with porous structure and relatively low hardness. However, when the N₂ flow was relatively high (e.g. 8 sccm), the hcp AlN phase precipitation and N₂-induced grain refinement resulted in a denser multiphase structure, which improved the hardness and toughness of the TiAlNC coating.     

Mechanical properties of nano-structured Ti-Si-N films synthesized by cathodic arc evaporation

Ti_1−xSi_xN coatings were synthesized by cathodic arc evaporation with plasma-enhancing filter duct, using Ti₈₀Si₂₀ alloy target as cathodes. Optical emission study revealed that excitation, ionization and charge transfer reactions of the Ti-Si-N plasma occurred during the Ti_1−xSi_xN deposition process. The chemical content of Si varied from 3.3 to 6.0 at% in Ti_1−xSi_xN depending on the nitrogen partial pressure of the reaction chamber. All the Ti_1−xSi_xN coatings displayed a NaCl structure and a preferred (2 0 0) orientation parallel to the substrate surface. Among the studied Ti_1−xSi_xN coatings, the Ti_1−xSi_xN with 6 at.% Si possessed the highest hardness of 45 GPa and H³/E*² ratio of 0.527 GPa, indicating the best resistance to plastic deformation. We found that the structure and mechanical properties of the Ti_1−xSi_xN films were correlated with the nitrogen pressure and silicon content of the coatings.