TiN单层和TiN/Ti(C,N)多层涂层的结构和性能研究

借助XRD、SEM、纳米压痕和划痕仪研究了采用磁控溅射在硬质合金基体上沉积的TiN单层和TiN/Ti(C,N)多层涂层的组织结构和力学性能。研究表明:TiN与TiN/Ti(C,N)多层涂层的晶粒形貌均呈柱状晶结构,而TiN/Ti(C,N)多层涂层形成了TiN、Ti(C,N)交替的调制结构。由于界面强化作用,TiN/Ti(C,N)多层涂层表现出比TiN更高的硬度及与基体更好的结合力。     

Microstructure and Tribological Property of TiC-Mo Composite Coating Prepared by Vacuum Plasma Spraying

TiC-based composite coating using Mo as an additive has been fabricated by vacuum plasma-spraying, and then the phase composition and microstructure of TiC-Mo composite coating were investigated. Wear resistance of the TiC-Mo composite coating was comparatively studied with pure TiC coating. The experimental results showed that the microstructure of the TiC-Mo composite coating was relatively homogeneous and compact, exhibiting typical lamellar structure of plasma-sprayed coating. Orientated columnar grains of TiC can be found in the composite coating, and a (Ti, Mo)C transition phase was also observed. Due to the formation of (Ti, Mo)C transition phase, strong interface between TiC and Mo splats was obtained, which positively influenced the wear performance of the composite coating. As compared with pure TiC coating, the TiC-Mo composite coating exhibited improved wear resistance both at low and high loads. Wear mechanisms for the TiC coatings have been changed by adding Mo element.     

A comparative research on physical and mechanical properties of (Ti, Al)N and (Cr, Al)N PVD coatings with high Al content

Arc ion plating (Ti_0.34, Al_0.66)N and (Cr_0.28, Al_0.72)N coatings are deposited onto cemented carbide substrates at 350 °C. The crystal structure and microstructure of the deposited coatings are characterized by means of X-ray diffraction (XRD), electron probe microanalysis (EPMA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). XRD examination indicates that both (Ti_0.34, Al_0.66)N and (Cr_0.28, Al_0.72)N coatings are of fcc structure. The atomic ratios of Al against Ti (Cr) for the two coatings are approximately close to those of the alloy targets according to EPMA measurement. In accordance with SEM observation, the fractured cross-section of the (Cr_0.28, Al_0.72)N coating is composed of columnar crystallites repeatedly interrupted by a renucleation process. Based on SEM and TEM methods, the cross-sectional fracture of (Ti_0.34, Al_0.66)N coating is found to show nano-crystalline feature without appearance of the columnar structure. (Cr_0.28, Al_0.72)N coating exhibits better wear resistance, approximately equal adhesion with the substrate, but lower nano-hardness compared with (Ti_0.55, Al_0.45)N coating.     

Mechanical and tribological properties of TiN/Ti multilayer coating

A large area filtered arc deposition (LAFAD) technique was used to deposit TiN/Ti multilayer coatings with fixed TiN layer thickness and different Ti layer thickness. Nanoindention and pin-on-disk tribometer were used to characterize the hardness, elastic modulus, plasticity, friction coefficient, and wear rate of the multilayer coatings. The dependence of the mechanical and tribological properties of the coating on the Ti interlayer thickness was systematically studied. It was found that the increase in the Ti layer thickness resulted in a decrease in the effective hardness and elastic modulus, and an increase in the wear rate, plasticity, and toughness. The coatings with a Ti layer thicknesses of 0, 25 nm and 50 nm possess an excellent combination of high effective hardness (> 20 GPa), high plasticity (> 69%), low friction coefficient, and high wear resistance.     

Structure and properties of selected (Cr–Al–N,TiC–C,Cr–B–N) nanostructured tribological coatings

The paper will present the state-of-art in the process, structure and properties of nanostructured multifunctional tribological coatings used in different industrial applications that require high hardness, toughness, wear resistance and thermal stability. The optimization of these coating systems by means of tailoring the structure (graded, superlattice and nanocomposite systems), composition optimization, and energetic ion bombardment from substrate bias voltage control to provide improved mechanical and tribological properties will be assessed for a range of coating systems, including nanocrystalline graded Cr_1−xAl_xN coatings, superlattice CrN/AlN coatings and nanocomposite Cr–B–N and TiC/a-C coatings. The results showed that the superlattice CrN/AlN coating exhibited a super hardness of 45 GPa when the bilayer period Λ was about 3.0 nm. Improved toughness and wear resistance have been achieved in the CrN/AlN multilayer and graded CrAlN coatings as compared to the homogeneous CrAlN coating. For the TiC/a-C coatings, increasing the substrate bias increased the hardness of TiC/a-C coatings up to 34 GPa (at −150 V) but also led to a decrease in the coating toughness and wear resistance. The TiC/a-C coating deposited at a −50 V bias voltage exhibited an optimized high hardness of 28 GPa, a low coefficient of friction of 0.19 and a wear rate of 2.37 × 10⁻⁷ mm³ N⁻¹ m⁻¹. The Cr–B–N coating system consists of nanocrystalline CrB₂ embedded in an amorphous BN phase when the N content is low. With an increase in the N content, a decrease in the CrB₂ phase and an increase in the amorphous BN phase were identified. The resulting structure changes led to both decreases in the hardness and wear resistance of Cr–B–N coatings.     

TiC–VC–Co: a study on its sintering and microstructure

In this work a preliminary reassessment of the TiC–VC–Co system has been made by studying seven compositions designed according to the formula 90 wt% [(1−x)TiC−xVC]–10 wt% Co with x=0, 0.2, 0.4, 0.5, 0.6, 0.8 and 1.0; pressureless sintered in the 1250–1450 °C range. The sintering behavior was correlated to the microstructural parameters of carbide grain size, contiguity and binder mean free path. The results showed an extensive densification in the solid state stage and increase in the γ-(Ti,V)C_1−x phase grain size with the VC contents. The mechanical properties of hardness and toughness were also evaluated but no correlation between them and the TiC:VC ratio could be established. Hardness values between 16.5 and 18 GPa and Vickers indentation toughness in the 5.4–6.4 MPa range were obtained for the compositions with 18–54 wt% vanadium carbide.     

Effect of interlayers on the structure and properties of TiAlN based coatings on WC-Co cemented carbide substrate

Two interlayers (Ti and Cr) have been evaluated with respect to their influence on the structure and growth of TiAlN based coatings on WC-Co cemented carbide by a non-commercial hybrid PVD (physical vapor deposition) coater by Sichuan University in China. The structure and the growth morphology were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The diffusion of interlayer was tested by Energy Diffraction Spectrum (EDS). Nanoindentation techniques and Rockwell HRC indentations were carried out to investigate the mechanical properties. The results show that the structure and the growth style change in the coatings on Cr interlayer, and this can be explained by thermodynamic theories. Cr interlayer exhibits a better diffusion compared with Ti interlayer, partly resulting in the transition from columnar crystal to equiaxed crystal. Columnar crystals disappear with the addition of Si, too. Due to the diffusion of Cr interlayer and the growth style changes in the coating, a transition zone is formed, and it is estimated to improve the adhesion. Good adhesion occurs in the coating with Cr interlayer. The hardness of TiAlN on Cr interlayer increases, and the Ti/(Ti,Si,Al)N coating shows the hardness as high as 40.0Gpa.     

C/Ti/Cu interfacial reaction in SiC<Subscript>f</Subscript>/Cu composites

Continuous SiC fiber reinforced copper matrix(SiCf/Cu) composites were prepared by fiber coating method,and Ti6Al4V interlayer was introduced as an interfacial modification coating to improve the interfacial bonding strength.The interfacial reaction characteristics were investigated by transmission electron microscopy(TEM).The results show that nearly all the titanium atoms reacted with the carbon coating of SiC fibers to form two layers of TiC.Also,a thin copper layer that is sandwiched between these two layers was detected.No Ti-Cu interfacial reaction product was observed.The formation process of the interfacial reaction along with its mechanism was discussed.     

TC4合金表面氩弧熔覆TiCp/Ti基复合涂层组织及耐磨性

利用氩弧熔覆技术在TC4合金表面制备出TiC增强的Ti基复合涂层。利用SEM、XRD和EDS分析了熔覆涂层的显微组织;利用显微硬度仪测试了复合涂层的显微硬度;利用摩擦磨损试验机测试了涂层在室温干滑动磨损条件下的耐磨性能。结果表明:氩弧熔覆涂层组织均匀致密,熔覆层与基体呈冶金结合,涂层中有大量的TiC树枝晶和条块状TiC颗粒;复合涂层明显改善了TC4合金的表面硬度,HV平均硬度可达9GPa;复合涂层室温干滑动磨损机制为磨粒磨损和轻微粘着磨损。     

反应火焰喷涂TiC/Fe复合涂层组织及形成机理

以TiFe粉和碳的前驱体（石油沥青）为原料通过前驱体碳化复合技术制备了Ti-Fe-C系反应喷涂复合粉末,并用普通火焰喷涂技术制备了TiC/Fe陶瓷金属复合涂层.观测了喷涂粉末、淬熄实验获取的飞行粒子以及涂层的形态、相和组织结构.结果表明：前驱体碳化复合Ti-Fe-C系喷涂粉末有非常紧密的结构;可有效的解决反应喷涂过程中原料粉末分离的问题.在反应火焰喷涂过程中,每一个喷涂粉末颗粒构成独立的微小反应单元,原料之间反应充分.在整个喷涂过程中喷涂粉末经历了熔化扩散、物相形成、碰撞后快速凝固三个阶段.所得涂层由TiC和Ti2O3共生聚集片层和细小TiC颗粒弥散分布于金属基体所形成的内晶型复合强化片层交替叠加而成.     

Microstructure and cutting performance of CrTiAlN coating for high-speed dry milling

Using a closed field unbalanced magnetron sputtering system, the cemented carbide end mills were coated with a CrTiAlN hard coating, which consisted of a Cr adhesive layer, a CrN interlayer and a CrTiAlN top layer. The microstructure and mechanical properties of the coating were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), micro indentation and scratch test. The cutting performance of the coated end mills were conducted by high-speed dry milling hardened steel (P20, HRC 45). The results indicates that the coating is composed of (Cr, Ti, Al)N columnar grains with nanolayers. The coating exhibits good adhesion to cemented carbide substrate and high microhardness of around 30 GPa. The coated end mills show significant improvement on tool life and much lower cutting force as compared to the uncoated ones. And the related mechanisms were discussed.     

Effect of pretreatment, seeding and interlayer on nucleation and growth of HFCVD diamond films on cemented carbide tools

The direct deposition of diamond on carbide tools is difficult because formation of graphitization and thus leading to poor adhesion, due to presence of cobalt on the surface. Various methods were adopted to suppress the effect of cobalt during deposition. One of them was by putting an interlayer. In this study, carbide substrates with coatings of Ti, TiN and TiC were used. Ti coating has a strong tendency to form intermediate carbide leading to the highest nucleation density of diamond. A comparison was made on nucleation and growth of diamond crystals on various interlayers by hot filament CVD method. At the same time, the variations of diamond film growth morphology have been studied on unseeded and seeded carbide inserts. The SEM pictures revealed that among interlayer, Ti coating gave highest nucleation density compared to TiN and TiC coatings. At the same time, diamond seeded inserts, pretreated by Treat 1 [HCl + HNO₃ + H₂O (1:1:1)] for 15 min ultrasonically resulted in the highest nucleation density, compared to Treat 2 [K₃[Fe(CN)₆] + KOH + H₂O] solution in (1:1:10) for 15 min, at constant process parameters.     

TiC生成方式对激光熔覆镍基涂层组织和性能的影响

分别以TiC粉和Ti+C粉为原料,采用外加法和原位法制备了TiC/Ni激光熔覆涂层,分析了TiC生成方式对涂层物相组成、微观组织、硬度和磨损性能的影响。结果表明,涂层的物相组成不受生成方式的影响;但Ti+C质量分数高于30%时,原位法涂层无法成型,而外加法可获得40%TiC的涂层。外加法涂层中TiC以原料TiC为主,少量溶解析出的结晶TiC;而原位法涂层中TiC全部为结晶析出,分布更加均匀,颗粒细小,枝晶数量增多。原位法涂层的平均硬度和耐磨性均优于相同TiC含量的外加法涂层;涂层中TiC含量(质量分数)由20%增至30%时,涂层硬度升高,耐磨性下降,生成方式引起的磨损性能差异由5%降至0.6%。     

Effects of Post-spray Heat Treatment on Hardness and Wear Properties of Ti-WC High-Pressure Cold Spray Coatings

In this research, the effects of post-spray heat treatment at 550 and 650 °C for 1 h on a cermet Ti-WC nanostructured coating deposited onto AISI 304 stainless steel substrates by high-pressure cold spray was observed. A metallic Ti interlayer was further used to compensate for stresses resulting from subsequent heat treatment on the developed coating. Microstructural analysis of the as-deposited coating by scanning electron microscopy (SEM) showed mostly fine WC grain (below 1 µm) present in the coating with a few larger 4 µm grains dispersed homogeneously throughout. X-ray diffraction analysis of the as-sprayed coating showed no noticeable evidence of WC decarburization. Heat treatment of the coating caused porosity to decrease from above 1.7% to below 0.5%, traced by SEM image analysis. Post-spray heat treatment promotes the formation of new carbide phases caused by the reactions between the Ti binder and WC grains, resulting in significant increases to Vickers microhardness. Evidence of an SHS reaction that produces TiC with heat treatment is confirmed with SEM image analysis as well as (S)TEM area mapping techniques, further supported by selected area electron diffraction analysis. Three-body sliding wear/abrasion tests have shown that wear resistance of Ti-WC cold spray coatings increases with heat treatment as well. In all, the effect of post-spray heat treatment behavior of nanostructured Ti-WC coating will be compared with that of as-sprayed behavior and WC-Co cold spray coatings.     

Microstructure, morphology and electrochemical property of RuO270SnO230 mol% and RuO230SnO270 mol% coatings

The DSA anodes based on RuO₂–SnO₂ oxides are most employed in chlorine-alkali cells. Their properties are strongly influenced by the mixed-oxide coating structures. In this paper, two RuO₂–SnO₂/Ti DSA anodes with different Ru and Sn molar ratios were prepared through a sol–gel technique. The nano-structure, morphology, grain structure and composition of the coatings were investigated by means of XRD, SEM and TEM. XRD analysis indicates two rutile-type solid solutions are formed. Peak profile analysis shows that in the solid solution where SnO₂ is the major component smaller crystallites (about 20–30 nm) are formed than in those where RuO₂ is the major component (about 100–200 nm). The SEM images reveal the coating with high level of SnO₂ possesses more accumulated and compact structures. The EDS analysis indicates that two DSA anodes coatings in which SnO₂ is similar to the designed concentration are prepared by the sol–gel method. TEM characterization shows the polygonal crystallites are present in the obtained RuO₂–SnO₂ coatings. The voltages of Cl₂-evolution and O₂-evolution suggest both RuO₂–SnO₂/Ti DSA anodes have a good electrochemical performance and can be used for the chlorite industrial productions.     

(Ti,Al)N涂层的织构特征和切削性能研究

借助EPMA、XRD、SEM、EDX、纳米压痕和切削实验研究了采用磁控溅射在硬质合金基体上沉积的(Ti,Al)N涂层的微观组织结构和切削性能。研究表明:(Ti,Al)N涂层为面心立方的的平直的柱状晶;(Ti,Al)N涂层因其高的硬度和良好的抗氧化性能大大地提高切削寿命。     

纳米CrNx涂层相组成、结构及力学性能研究

采用高功率调制脉冲磁控溅射(modulated pulsed power magnetron sputtering, MPPMS)和脉冲直流磁控溅射(pulsed direct current magnetron sputtering, PDCMS)复合沉积CrN_x涂层,通过调节氮气流量比及溅射功率,研究了氮气/氩气流量比、PDCMS溅射功率及MPPMS溅射功率等工艺参数对CrN_x涂层成分、相组成、微结构和力学性能的影响。通过电子探针(EPMA)、X射线衍射仪(XRD)、扫描电子显微镜(SEM)、纳米压痕仪及维氏硬度计等,分别对CrN_x涂层的成分、相组成、微结构、形貌、硬度及断裂韧性等进行表征。结果表明,当PDCMS溅射功率从700 W增加到1000 W,MPPMS峰值功率增加43.5%,涂层中Cr含量(原子分数)由61.0%增加到65.4%,N含量由39.0%减少到34.6%,而CrN_x涂层主要由Cr₂N相组成。随着溅射功率的增大,CrN_x涂层硬度变化不...     

Cr基及其化合物过渡层对TiCN涂层性能的影响

为研究过渡层材料及结构对TiCN涂层性能的影响,设计3种Cr基及其化合物过渡层,利用多弧离子镀技术制备TiCN涂层。膜系分别为Cr/TiCN、Cr/CrN/TiCN和Cr/CrN/CrCN/TiCN。利用SEM、XRD、纳米压痕仪、划痕仪、摩擦磨损试验机和球磨仪对涂层的微观结构和性能进行表征。结果表明:随着过渡层由单层Cr依次加入CrN和CrCN,涂层原有的柱状晶生长被抑制并最终消除。与具有Ti过渡层的TiCN相比,涂层不再具有明显择优取向,(111)峰强度大大减弱而(200)峰发生宽化。具有CrN和CrCN过渡层的样品硬度和附着力明显高于以单层Cr为过渡层的样品,Cr/CrN/CrCN/TiCN膜系硬度和附着力最高,分别为(30.11±0.34)GPa和(37.21±0.46)N。摩擦磨损试验结果表明:CrCN过渡层的引入显著提升了涂层耐磨性,其对应样品摩擦因数最低,达到0.111,并在球磨测试中表现稳定,而其它膜系均出现不同程度的磨损形貌。     

SiC颗粒增强铝基复合材料基材上制备(Ti,Al)N涂层的研究

利用电弧离子镀技术在SiCp／2024Al基体上制备(Ti，Al)N涂层．研究了偏压对涂层的相组成、晶格常数和成分的影响及不同过渡层对涂层与基体结合性能的影响．结果表明，在较小偏压下，(Ti，Al)N涂层呈(111)择优取向；偏压在-150V时，涂层无择优取向；但随偏压继续升高，出现(200)和(220)择优取向．在添加Ti过渡层时，涂层与基体形成致密均匀的良好结合．同时通过设计梯度涂层，获得了厚度达105um的无裂纹(Ti，Al)N涂层．     

Modelling, production and characterisation of duplex coatings (HVOF and PVD) on Ti-6Al-4V substrate for specific mechanical applications

Titanium and its alloys are extensively used in aerospace and mechanical application because of their high specific strength and high fracture toughness. On the other hand, titanium alloys often show low hardness, very low load bearing capacity and poor resistance to sliding wear, so that surface properties improvement is in many cases recommended, often by PVD processes.Present work deals with design, production and experimental characterisation of a duplex coating for Ti-6Al-4V components, consisting of a thick WC-Co interlayer deposited by High Velocity Oxygen Fuel (HVOF), followed by a Ti/TiN multilayer (two layer pairs, including the Ti bond layer) deposited by Cathodic Arc Evaporation (CAE) PVD.Before deposition, a preliminary coating design was carried out, based on finite element simulation of residual stress fields on the PVD coating for a range of configurations of its multilayered structure (Ti buffer layer position and thickness).Morphological properties of the produced coatings (thickness, grain size, surface defect size distribution, roughness) were measured by means of Digital Optical (DOM), Scanning Electron (SEM), Atomic Force (AFM) and Focused Ion Beam (FIB) microscopy techniques.Coatings mechanical properties were investigated by micro-scratch testing, Rockwell C adhesion test, nano-indentation techniques, Vickers/Knoop micro-hardness testing and composite hardness modelling.Results showed that the use of a CAE-PVD multilayer Ti/TiN top layer, whose thicknesses and Ti distribution were suggested by finite element modelling optimisation, leads to a significant increase (45%) in adhesion of PVD coating to the HVOF layer and load bearing capacity of the coated system, compared to monolayered TiN, without reduction in superficial hardness and load bearing capacity.