Plasma Spray Deposition Enhancement of Titanium Nitride Layer Using Nitrogen-Contained Plasma Irradiation of Titanium Substrate as a Pre-spraying Method

Reactive plasma spray of TiN ceramic coating attracts much attention over the years because of its ability to deposit thick layers on various metal surfaces. However, some mechanical properties of the coating such as its hardness should be improved. In this study, initially a thin layer of titanium nitride was prepared on a titanium substrate during irradiation of titanium substrate by a thermal DC nitrogen-contained plasma jet. Then, during reactive plasma spraying, Ti particles were injected into plasma jet, converted to titanium nitride and huddled on to the substrate. This new hybrid method (primary plasma irradiation and post-reactive plasma spraying) for deposition of TiN coatings would combine the advantages of both plasma-enhanced chemical vapor deposition and reactive plasma spraying methods in part. It resulted in a thick and hard layer of titanium nitride film. Sample produced by this method was analyzed with x-ray diffraction confirming titanium nitride production. Vickers hardness was measured using optical microscopy which was around 1319 H_v300g. To study the cross section of the layer, optical microscopy and scanning electron microscopy (SEM) were used.     

Prevention of hydrogen degradation in titanium by deposition of TiN thin film

This paper describes the effects of using a TiN film as a possible protection layer for titanium in an aggressive chemical environment. The TiN film as a barrier of hydrogen permeation into the material was evaluated by electrochemical cathodic charging of the specimens in solutions with different pH values and temperatures. Results revealed that the thickness of hydride on the surface of the uncoated titanium increased with the increase of charging time. Higher charging temperature and lower pH value promoted the formation of hydride phases. For titanium coated with a TiN film, it effectively retarded the permeation of hydrogen into the titanium substrate. However, this was at the sacrifice of the TiN film itself.     

离子辅助沉积TiN/Ti复合膜提高TC17钛合金高温微动疲劳抗力

为提高钛合金高温微动疲劳抗力,利用离子辅助电弧沉积技术在TC17钛合金表面制各了TiN/Ti复合膜层,研究了膜层的剖面成分分布、膜基结合强度、膜层显微硬度、韧性、常规摩擦学性能以及抗高温微动疲劳性能.结果表明:利用离子辅助电弧沉积技术可以获得硬度高、韧性好、膜基结合强度和承载能力优异的TiN/Ti复合膜层,该膜层具有良好的抗磨和减摩性能,能够显著地提高TC17钛合金在350℃高温环境下的常规磨损和微动疲劳抗力.然而,TC17钛合金表面喷丸强化后进行离子辅助沉积TiN/Ti复合膜,由于喷丸层残余压应力的显著松弛以及膜层易于开裂和脱落的缘故,微动疲劳抗力则不及喷丸强化或TiN/Ti复合膜单独作用.     

Surface engineering with light alloys—Hard coatings, thin films, and plasma nitriding

Light alloys have been attracting increasing attention over the past decade, since they can be used to reduce weight and save energy. For many years, light metals such as titanium and aluminum have also been used to synthesize hard compound coatings such as physically vapor deposited (PVD) TiN, (Ti,Al)N, and chemically vapor deposited (CVD) Al₂O₃. The coatings field is developing rapidly. Combining plasma-aided coating and diffusion processes has led to the development of so-called “duplex treatment,” consisting of plasma nitriding and subsequent hard coating. Another interesting development is TiN coating of aluminum vacuum parts, such as pumps, to reduce degassing and make the cleaning of the surfaces easier. Despite the many advantageous properties of light alloys, their surface properties sometimes cause problems. For example, galling may be a severe problem with titanium parts, and plasma nitriding has been applied successfully to combat it. However, due to adherent oxide scale, plasma nitriding of aluminum has proven to be more difficult. In this paper, we discuss some recent trends in the application of plasma-aided coating, thin film deposition, and diffusion processes, and give practical examples of industrial applications.     

The dependence of hardness and corrosion protection power of ion- beam-assisted deposition TiN coatings on the ion beam impact angle

Hard coatings such as titanium nitride are often porous and therefore not necessarily very corrosion resistant. Possibilities for reducing the film porosity are densification and multilayer structures. These methods are studied in our laboratories at present.

Ion-beam-assisted deposition (IBAD) TiN films were deposited changing the angle between the substrate normal and the ion beam incidence direction.

The films were characterized by transmission electron microscopy, scanning electron microscopy and X-ray diffraction analyses, the hardness was determined by means of a dynamic Vickers hardness tester and the corrosion behaviour was evaluated using current-potential measurements in a multicycle voltammogram mode.

The results are strongly dependent on the changes in the crystal orientation induced by the ion flux under different angles. Careful optimization may lead to coatings with high hardness and excellent corrosion protection potential. These results are compared with Ti/TiN multilayers deposited by IBAD and magnetron sputtering and with a sputtered TiN single layer.     

High thickness Ti/TiN multilayer thin coatings for wear resistant applications

Hard coatings like titanium nitride (TiN) normally contain a high degree of internal stress (usually compressive in-plane parallel with the surface) owing to growth defects developed during the deposition process and thermal mismatch effects after final cooling; it is, therefore, difficult to produce single-layer TiN coatings thicker than 6-7 μm, without adhesion problems. In the present study, thick coatings (i.e. > 10 μm) have been achieved by alternate multilayering of TiN with Ti interlayers, leading to a tougher and less-stressed film. However, having a constant distribution of titanium interlayer thickness is not necessarily the best solution to achieve maximum performance in terms of wear resistance and hardness. The residual stress distribution along the thickness is unlikely to be constant with the inner layers being more stressed due to a greater amount of thermal differential strain. Following this guideline, a series of numerical simulations was performed in order to calculate the residual stress through thickness distribution due to the deposition process. Three sets of multilayered Ti/TiN coatings having both constant and variable Ti interlayer thickness were modelled and deposited, using a reactive arc PVD process. Mechanical and tribological properties were characterized using static and depth sensing Vickers micro-hardness indentation tests, rotating wheel (dimpling grinder) abrasive wear tests and Rockwell C adhesion tests. Coating interface characterizations were made by SEM-EDS. Results showed that adhesion can be significantly improved by adopting a titanium through thickness quantity increasing towards the interface: an optimized distribution allows also higher hardness and wear resistance to be obtained, as it requires a lower total amount of titanium to obtain good adhesion properties.     

Spraying TiN by a Combined laser and low-pressure plasma spray system

The formation of a TiN-Ti composite coating by thermal spraying of titanium powder with laser processing of the subsequent coating in a low-pressure N₂ atmosphere was examined. A low-pressure plasma spray system was used in combination with a CO₂ laser. First, the coating was plasma sprayed onto a mild steel substrate using a N₂ plasma jet and titanium powder in a controlled low-pressure N2 atmosphere. The coating was then irradiated with a CO₂ laser beam in a N₂ atmosphere, and the coating was heated with a N₂ plasma jet. The amount of TiN formed in the coating was characterized by X-ray diffraction analysis. The influence of plasma spraying conditions such as plasma power, flow of plasma operating gases, chamber pressure, and laser irradiating conditions on the formation of TiN was investigated. The effect of TiN formation in the titanium coating on Vickers hardness of the coatings was examined. It was evident that coating hardness increased with an increase in TiN content in the coating and that a TiN-Ti composite coating with a hardness of more than 1200 H V can be obtained with the use of laser irradiation processing.     

DLC、TiN涂层对TC4钛合金抗砂尘冲蚀性能的影响

为提高TC4钛合金的抗砂尘冲蚀性能,采用金属蒸汽真空弧(MEVVA)离子源注入与磁过滤真空阴极弧(FCVA)沉积复合技术、磁控溅射技术在TC4钛合金表面制备DLC、TiN涂层。采用SEM、Raman、XRD、纳米压痕仪和划痕仪等方法对涂层的物相结构、硬度、弹性模量以及与基体的结合力进行表征。在冲蚀试验平台上考核试样在不同入射角度条件下的抗砂尘冲蚀性能。结果表明:DLC涂层表面结构致密,含有大量sp3键,硬度为62.1 GPa,弹性模量为391.64 GPa,结合力达80.4 N;TiN涂层表面存在许多熔滴颗粒及空穴,硬度为22.72 GPa,弹性模量为383.18 GPa,结合力达34.7 N。30°冲蚀条件下,涂层主要是通过提高基体表面硬度来抵抗砂尘粒子的微切削作用,从而提高TC4钛合金的抗砂尘冲蚀性能。90°冲蚀条件下,涂层通过延缓基体的塑性变形来实现TC4钛合金抗砂尘冲蚀性能的提高。     

工业纯钛TA2激光气体氮化表面硬度的研究

激光气体氮化可以有效地提高钛合金表面硬度，从而改善钛合金耐磨损性能。通过金相组织观察和硬度测试分析了钛合金激光气体氮化时．激光气体氮化参量和激光光束分布对钛合金氮化后表面硬度的影响。结果表明，氮化区域内生成硬质相TiN是TA2钛合金表面硬度得到提高的主要原因，有利于硬质相TiN形成的激光气体氮化参量都会提高钛合金表面的硬度。而采用带式积分镜进行激光光束变换可以有效提高激光氮化处理的效率，钛合金平均表面硬度是原来的1.3倍。     

Dependence of Microstructure and Hardness of Nanocomposite Coatings of nc-(Ti_(1-x)Al_xN)/a-Si_3N_4 on Aluminum Contents

HARD COATINGS are finding a widely applicationin machining industries as tools and moulds since1980s[1].Hard coatings consisting of a variety of thetransition metal nitrides,for instance,TiN,TiC,TiCN,TiBN,TiAlN,CrN etc,usually service as a protectioncoatings that requires some better properties ofwear-resistance,corrosion-resistance and also highfatigue-strength especially at elevated temperature(formore details see Ref.2-6).The generic concept for the design of novelsuper-hard(>40G…     

Structure and properties of cathodic vacuum arc deposited NbN and NbN-based multi-component and multi-layer coatings

Binary Nb-N coatings, ternary Ti-Nb-N and Zr-Nb-N, and multi-layer TiN/NbN coatings consisting of up to 100 alternating TiN and NbN layers, were deposited onto WC-Co substrates, using two different vacuum arc deposition (VAD) systems: with and without magnetic guiding of the metal plasma flow. Binary Nb-N coatings were fabricated by deposition of metal plasma produced by a Nb cathode in a background of reactive nitrogen gas at different pressures, P. Ternary coatings were fabricated at co-deposition of plasmas originating from two different cathode materials. Multilayer coatings were fabricated by alternatively depositing plasmas of Ti and Nb in reactive nitrogen gas. The crystalline coating structure, phase composition, hardness and critical load for coating failure were studied.For binary Nb-N coatings fabricated using both deposition systems, the phase composition, the Vickers hardness, HV, and the critical load strongly depended on the deposition pressure. Using VAD with magnetic plasma guiding, the highest HV of ∼ 42 GPa was measured for coatings deposited at low nitrogen pressure. These coatings contained a hexagonal β-Nb₂N phase and had a relatively low critical load. The highest critical load and HV ∼ 38 GPa were obtained for coatings consisted of a single phase NaCl-type cubic δ-NbN structure, deposited at a higher nitrogen pressure. The structure and properties of Nb-N coatings deposited using VAD without magnetic plasma guiding had a similar correlation with the deposition pressure, however, their hardness values were lower.Ternary Ti-Nb-N and Zr-Nb-N coatings fabricated by both deposition processes had a single phase cubic NaCl-type structure and the hardness higher than that of the binary nitrides TiN, ZrN and NbN. The hardest coatings, HV ∼ 51.5 Pa, deposited with magnetic plasma guiding had a single-phase cubic δ-(Ti,Nb)N structure and a Ti:Nb ratio of ∼ 50:50 (at.%).Multilayer coatings TiN/NbN consisting of 20-40 alternating TiN and NbN layers with total thickness of 4-5 μm increased the life time of cemented carbide cutting inserts at turning tough Ni-base alloys by 2-7 times relative to uncoated cutting tools, while conventional vacuum arc deposited TiN coatings were not effective in machining of these alloys.     

柔性钛电极电火花合成TiN涂层

文中提出一种利用柔性钛电极在钛合金TC4表面合成TiN涂层以改善工件表面性能的新方法.在加工中利用柔性钛电极与钛合金TC4表面进行电火花放电,同时通过钛电极内部向加工区域通入氮气,利用电火花放电能量在工件表面反应生成TiN涂层.测量其表面硬度并利用SEM,XRD等手段对其涂层微观形貌和组分进行测试.结果表明,在TC4工件表面制备出了TiN强化涂层,涂层致密、均匀、连续;TiN涂层厚度超过1 mm;涂层主要由TiN强化相组成,显微硬度高达1859.6 MPa;涂层表面的放电坑大而浅且存在刮削痕迹,柔性钛电极丝对TiN涂层有较强的刮削涂覆作用;TiN涂层与基体之间相互渗透形成冶金结合.     

氮化钛薄膜二次电子发射特性研究

目的研究氮化钛薄膜的部分物理特性及真空中的电子发射特性,验证氮化钛薄膜具有相对较好的电导特性及较低的电子发射系数,证明氮化钛薄膜在空间大功率微波器件表面处理中有良好的应用前景。方法使用射频磁控溅射技术在单晶硅及玻璃片表面制备氮化钛薄膜,实验中通过调节溅射过程中氮气与氩气的气体流量比控制薄膜中的氮钛原子比。使用SEM对氮化钛薄膜的表面形貌及厚度进行表征。使用超高真空二次电子发射特性研究平台对氮化钛薄膜的二次电子发射特性进行表征。结果通过调节溅射过程中的氮气氩气流量比,能够有效控制薄膜中氮钛两种元素的含量,进而改变氮化钛薄膜的结晶方式和其他物理特性。当氮氩气体流量比约为10:15时,薄膜中氮钛原子比约为1:1。电阻率测试结果表明,薄膜中氮钛原子比越接近1:1,薄膜的电阻率越低。二次电子产额(SEY)测试结果表明,所制备氮化钛薄膜的最小SEY峰值约为1.46,低于平滑金(~1.8)、银(~2.2)表面的SEY。结论氮化钛薄膜具有较好的电导特性及较低的SEY,且其在真空环境中有良好的稳定性,能在不影响微波器件表面损耗的情况下,有效降低器件表面发生电子倍增的风险。     

直流PCVDTi（CxN1—X）硬质膜及其应用

对不同成分的PCVD－Ti（CXN1－X）膜的组织结构及性能进行了研究。结果表明，Ti（CN）膜的高硬度、高致密组织和膜表面因吸附氧而形成的与TiN不同的表面结构是Ti（CN）膜性能优于TiN膜的重要因素。在冷挤压模上应用结果也表明，用PCVD法制备的Ti（CN）膜和TiC膜的使用效果要比TiN膜好得多。     

TC4钛合金表面沉积CrAlSiN涂层的组织与性能

为了提高TC4钛合金表面硬度和耐磨性能,通过等离子渗氮技术和多弧离子镀技术相结合的方法对TC4钛合金进行表面改性处理。通过扫描电镜、维氏显微硬度计、三维轮廓仪、高速往复摩擦磨损试验仪和电化学工作站,对比研究了TC4钛合金、渗氮层和CrAlSiN涂层的显微组织、硬度、耐磨性能和耐腐蚀性能。结果表明,经渗氮处理后,TC4合金表面渗氮层硬度提高了约2倍,在此基础上制备的CrAlSiN涂层的平均硬度高达3222 HV0.025,涂层表面存在少许大颗粒和凹坑;CrAlSiN涂层平均摩擦因数为0.22,磨损机理主要为粘着磨损,对磨副的材料粘着到涂层表面,而涂层几乎无磨损,耐磨性能显著提高。CrAlSiN涂层的自腐蚀电位为-0.542 V,比TC4钛合金基体的自腐蚀电位-0.747 V正移了0.205 V,表明在渗氮层基础上沉积CrAlSiN涂层显著提高了合金的耐电化学腐蚀性能。     

基体对氮化钛膜的微力学和摩擦性能的影响

采用等离子电弧沉积法分别在GT35和40CrNiMo钢上沉积厚约为0．5μm的TiN膜。为了检测成膜质量，在较宽的载荷范围内分别使用显微硬度、纳米压痕和纳米划痕技术表征钢基材和TiN／基材的微力学和摩擦性能。同TiN／40CrNiMo相比，TiN／GT35的硬度高和固体润滑效果显著，GT35是较为理想的基体材料。对这种亚微米厚的膜，纳米压痕技术和纳米划痕技术能提供丰富的近表面的弹塑性变形、断裂和摩擦等的信息。     

Room-temperature growth of high-purity titanium nitride by laser ablation of titanium in a nitrogen atmosphere

Thin films of titanium nitride (TiN) were deposited on glass substrates by KrF excimer laser ablation of titanium over a very broad nitrogen pressure range with different target–substrate distances at room temperature. The as-deposited TiN thin films were analyzed by X-ray diffraction and transmission electron microscopy. It was found that the as-deposited thin films are normally a mixture of TiN and metallic titanium, and the TiN-to-Ti ratio of the as-deposited thin film depends on both the nitrogen pressure and the target–substrate distance. High-purity TiN thin films can be obtained only in a very narrow deposition parameter range. A compound parameter (the product of the nitrogen pressure and the target–substrate distance) is proposed to optimize the deposition of high-purity TiN thin films, and the possible mechanism is also discussed. It was also revealed that the as-deposited TiN thin films are polycrystalline with an average grain size of about 20 nm.     

The microstructural characterization of the nitrided layers prepared by direct current nitrogen arc

The characteristics of nitrided layers prepared on commercially pure titanium substrates by direct current nitrogen arc are presented by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) micrographs as well as X-ray diffraction (XRD). The titanium nitride (TiN) dendrites were fully developed with interconnected cellular morphologies at the top surface but grew almost perpendicular to the interface with coarser arms in the middle area. Also less TiN was found near the interface. The energy inputs had an obvious effect on the microstructures and the hardness of the nitrided layers. The maximum micro-hardness was 2 500 HV at the top surface which was over 9 times higher than that of the substrate.     

氮电弧制备陶瓷表面层中TiN相形态及生长机制

利用氮电弧熔化纯钛基体表面,原位制备氮化钛（TiN）陶瓷表面层,研究陶瓷表面层的形成机理、TiN相的生长形态及其生长机制．结果表明,氮电弧熔化过程为非平衡快速冷却凝固过程,冷却速度可达10^2～10^3 K／s,表面层中TiN相的微观生长方式具有多样性．在熔池中过冷度较小的位置,TiN晶体为螺型位错侧面长大方式,而熔池...     

Effect of TiN/Ti multilayer on fretting fatigue resistance of Ti-811 alloy at elevated temperature

The TiN/Ti multilayer was deposited on Ti-811 alloy surface by magnetron sputtering(MS) technique for improving fretting fatigue(FF) resistance of the titanium alloy at elevated temperature. The element distribution, bonding strength, micro-hardness and ductility of the TiN/Ti multilayer were measured. The effects of the TiN/Ti multilayer on the tribological property and fretting fatigue resistance of the titanium alloy substrate at elevated temperature were compared. The results indicate that by MS technique a TiN/Ti multilayer with high hardness, good ductility and high bearing load capability can be prepared. The MS TiN/Ti multilayer, for its good toughness and tribological behavior, can significantly improve the wear resistance and FF resistance of the Ti-811 alloy at 350 ℃.