Effect of transition layer on the performance of hydroxyapatite/titanium nitride coating developed on Ti-6Al-4V alloy by magnetron sputtering

A gradient transition multilayer hydroxyapatite/titanium nitride (HA/TiN) coating was prepared on the Ti-6Al-4V alloy by magnetron sputtering. The composition, surface topography, microstructure, adhesion strength and electrochemical properties of the as-deposited coatings were characterized by SEM/EDS, AFM, XRD, FT-IR and electrochemical workstation. The experimental results showed that the single TiN coating deposited at a partial pressure of nitrogen (N₂) of 0.08?Pa had the best internal stress and tribological performance, and its volume loss was only 0.89% of that of Ti-6Al-4V alloy. The introduction of the TiN transition layer greatly improved the wear resistance of the Ti-6Al-4V alloy, and the adhesion strength of the HA layer to the substrate increased from 6.50?±?0.5?N to 11.70?±?1.2?N, an increase of 56%. The HA/TiN coating surface consisted of uniform hemispherical particles with dense structure and invisible defects (micro-cracks and pores). For the HA surface layer, the crystal structure and active hydroxyl (-OH) group was restored after heat treatment. Potentiodynamic polarization experiments indicated that the HA/TiN coating achieved the lowest corrosion current density and the most positive corrosion potential compared to the single TiN layer and Ti-6Al-4V alloy. In summary, it can be conclude that the gradient transition layer can well improve the mechanical properties and electrochemical behavior of the titanium alloy, and largely ensuring the stability of the surface bioactive coating.     

Tribomechanical and microstructural properties of cathodic arc-deposited ternary nitride coatings

Sintered carbides are promising materials for surfaces that are exposed to extreme wear. Owing to their high service load, ceramic-based thin films are coated on carbides using different techniques. In this study, non-toxic and cobalt-free powder metallurgy-sintered carbide samples were coated with TiN, TiAlN, CrAlN, and TiSiN ceramic-based thin film coatings by cathodic arc physical vapor deposition. The microstructure (phase formation, coating thickness, surface roughness, and topography), mechanical properties (hardness, modulus of elasticity, and plasticity indices), and tribological properties (nanoscratch and wear behavior) of the thin film coatings were investigated. No cracks or defects were detected in these layers. The ceramic-based ternary nitride thin film coatings exhibited better mechanical performance than the TiN coating. The TiN thin film coating had the highest average surface roughness, which deteriorated its tribological performance. The ternary nitride thin film coatings exhibited high toughness, while the TiN thin film coating exhibited brittle behavior under applied loads when subjected to nanoscratch tests. The wear resistance of the ternary nitride coatings increased by nearly 9–17 times as compared to that of the TiN coating and substrate. Among all the samples investigated, the substrate showed the highest coefficient of friction (COF), while the TiSiN coating exhibited the lowest COF. The TiSiN thin film coating showed improved mechanical and tribological properties as compared to other binary and ternary nitride thin film coatings.     

PVD hard coatings on ceramic tiles for aesthetic applications: surface characterisation and corrosion properties

The development of innovative ceramic tiles looks for materials with improved mechanical and tribological properties as well as a higher corrosion resistance (high relative humidity, daily watering, household chemical cleaners). In addition, a greater durability leads to lower environmental impact. Along with their improved functionality and recyclability, ceramic tiles should also provide aesthetic properties. Ceramic tiles can be treated to modify the physico-chemical properties of the surface by metal coatings or metallic compounds, also providing an attractive metallic sheen appearance. In the present paper, titanium nitride (TiN) and zirconium nitride (ZrN) coatings were deposited on glazed porcelain stoneware by an industrial PVD multicathode arc deposition system under a reactive nitrogen atmosphere. After the process, the tiles showed a gold-like colour, a smooth surface and a coating thickness between 0.7 and 1.6 μm. The coating composition, scratch resistance and corrosion behaviour have been evaluated. It can be concluded that both coatings are suitable for use in domestic environments due to their stability and resistance to aggressive conditions. Few references have been found regarding these coatings on ceramic tiles for domestic and industrial applications, but it has been proved that they bring added value to traditional ceramics, giving new functional properties of ceramics both decorative and highly corrosion and mechanical resistance.     

Corrosion protection of ion vapor deposition (IVD) Al-coated Al alloys by low-temperature plasma interface engineering Part II. DC cathodic polymerization under conditions of IVD (without using anode assembly)

DC cathodic polymerizations of trimethylsilane (TMS) were carried out in a bell-jar reactor without using an anode assembly, i.e., under the conditions similar to ion vapor deposition (IVD) operation. In order to initiate the DC glow discharge, a negative potential was applied to IVD Al-coated aluminum panels, the cathode, and grounded reactor wall, the anode. TMS plasma coatings obtained under such operation was studied in terms of refractive indices, linear polarization resistance, and adhesion performance to subsequent spray paint primers. Experimental results indicated that the TMS plasma coatings obtained without anode assembly have similar coating characteristics to those obtained by anode magnetron plasmas as used in Part I of this series, which showed excellent corrosion protection of IVD Al-coated aluminum alloys. As a result, the plasma interface engineered coating systems of IVD/plasma polymer/non-chromated primer obtained under such operation showed excellent corrosion protection of IVD Al-coated aluminum alloys, which outperformed the chromate conversion-coated IVD controls after 4 weeks of SO₂ and 12 weeks prohesion salt spray tests.     

Structural characterization and adhesion appraisal of TiN and TiCN coatings deposited by CAE-PVD technique on a new carbide composite cutting tool

A new composite matrix was developed for a cutting tool based on tungsten carbide ligated with cobalt (WC-Co) using sintering technique. The admixtures of niobium carbide, tantalum carbide, and titanium carbide with the WC-Co matrix aim to inhibit the grain growth of WC and to promote covalent bonding at the interface. The modified WC-Co tools were coated with titanium nitride and titanium carbonitride layers by CAE-PVD technique. To substantiate the performances of the new coating-substrate systems, we have performed X-ray diffraction, atomic force microscopy, and scratch test measurements to estimate: phase content, average crystallite size, average texture coefficient, residual stress level, coating thickness, average roughness, square mean root, fractal dimension, cohesive adhesion, and adhesive adhesion. The results enable the in-depth understanding of the coating growth mechanisms and provide an objective evaluation of the coatings adhesion to the new cutting tools matrix. The results provide evidence to support the potential of TiN and TiCN coatings to enhance the working performances of the composite WC-Co cutting tools and to differentiate their properties. TiCN coating is shown to be superior to TiN coating in terms of adhesion and thus represents a better alternative for coating the modified WC-Co composite matrix.     

3类光热转换涂层的力学、光学和集热性能研究

制备了3种不同类型的光热转换涂层──喷涂高分子涂层、电镀黑铬涂层和物理气相沉积氮氧化钛涂层,测试了涂层的力学性能和光学性能。将不同涂层试样做成平板板芯,装配成平板集热器,测试了3种平板集热器的集热性能。结果表明,物理气相沉积氮氧化钛涂层集热器的集热性能最好,电镀黑铬涂层次之,但静电喷涂高分子涂层集热器在低温使用时性价比更高。     

A novel biomedical TiN-embedded TiO2 nanotubes composite coating with remarkable mechanical properties,corrosion, tribocorrosion resistance,and antibacterial activity

Tribocorrosion is a severe problem in dental implants, artificial joints, and other implants, and it will affect the long-term safety of the implants. To improve the deficiencies of titanium alloys, we combined physical vapor deposition technology and anodic oxidation to prepare TiN to embed TiO₂ nanotube composite coatings (NTNTs-TiN). Results show that the hardness of the NTNTs-TiN composite coatings reaches 33.2 ± 0.6 GPa, and the grains of the composite coatings were further refined. The NTNTs-TiN coating has the smallest average coefficient of friction (0.22) during tribocorrosion. The tribocorrosion resistance of NTNTs-TiN coating in SBF is increased by ∼44 and ∼2 times compared with Ti6Al4V alloy and TiN coating, respectively. The capillarity effect of the lower contact angle of NTNTs-TiN can form a continuous water-lubrication film at the interface between the counter-ball and coating and produce a lubrication film composed of Ca, Mg, and P, which reduces the coefficient of friction significantly. The NTNTs/TiN composite coating exhibits the best synergistic effect of wear and corrosion. In addition, the NTNTs-TiN coating also exhibits excellent antimicrobial and corrosion properties, which provides a new solution for the long-term safe use of implants in the human body.     

钛纳米聚合物涂料在NaCl溶液中的电化学阻抗谱

采用电化学阻抗谱方法对钛纳米聚合物涂料的防腐性能进行了研究,并通过与环氧树脂清漆、环氧玻璃鳞片涂料的对比,说明钛纳米聚合物涂料的防腐性能显著优于上述两种涂料的防腐性能。     

38DD350型电解槽阳极流场分布对钛板点蚀的影响

应用CFD软件建立38DD350型电解槽阳极流场的物理模型和数值模型,模拟出了电解槽阳极室中气液混合物液相和气相的整体分布。用涡街理论分析了钛板凸起部分气相的分布原因,认为钛板圆锥凸起部分出现的点蚀与Cl2在该部位的富集有关。     

Evaluation techniques and improvements of adhesion strength for TiN coating in tool applications: a review

The adhesion between coating-substrate systems is an important factor in determining the performance and durability of coated engineering components. This paper reviews the microstructures and adhesion strength of titanium nitride (TiN) coating produced using two different processing methods: chemical vapor deposition and physical vapor deposition. Three methods to evaluate the adhesion strength of the coatings, namely the indentation test, laser spallation technique, and scratch test are presented and discussed in terms of their working principles, their advantages and disadvantages. The extrinsic and intrinsic factors influencing the adhesion strength of coating-substrate system, particularly for TiN coating, are also elaborated. The mechanisms and modes of coating failures in adhesion evaluation techniques are discussed with respect to the variation of coating-substrate system combination such as brittle, ductile, soft, and hard. Possible improvements on the adhesion strength of coating-substrate systems, focusing on the processing methods, compositions, and structures of coatings, are also reported.     

The lifetime assessment of low infrared emissivity composite coatings in chloride environments

The microstructural-electrochemical model is employed to predict the lifetime of low infrared emissivity composite coatings in chloride environments. Electrochemical data collected in 3.5 wt.% NaCl solution is presented for the low infrared emissivity coating, and these values are used as inputs for a mechanistic-based corrosion model which yields the salt spray life of the coating. To check the calculated results, the model predictions were compared with the results of salt spray tests. The current work showed that the model was able to predict lifetime of low infrared emissivity coating under salt spray, but tended to under-predict lifetime at short times and over-predict at long times. Under-prediction may be associated with corrosion protection of metallic pigment particles by polymer. Over-prediction by the model at longer exposure times may be associated with the fact that an influence of porosity is not included as a part of this simple model.     

The lifetime assessment of low infrared emissivity composite coatings in chloride environments

The microstructural-electrochemical model is employed to predict the lifetime of low infrared emissivity composite coatings in chloride environments. Electrochemical data collected in 3.5 wt.% NaCl solution is presented for the low infrared emissivity coating, and these values are used as inputs for a mechanistic-based corrosion model which yields the salt spray life of the coating. To check the calculated results, the model predictions were compared with the results of salt spray tests. The current work showed that the model was able to predict lifetime of low infrared emissivity coating under salt spray, but tended to under-predict lifetime at short times and over-predict at long times. Under-prediction may be associated with corrosion protection of metallic pigment particles by polymer. Over-prediction by the model at longer exposure times may be associated with the fact that an influence of porosity is not included as a part of this simple model.     

化学镀镍层封孔新工艺的研究

利用溶胶-凝胶法在化学镀镍层表面制备出TiO2、TiO2、-SiO2膜，研究了热处理温度和涂覆次数对涂层表面成分及其耐蚀性、抗氧化性和耐磨性的影响，结果表明，经四次涂覆后，TiO2、TiO2-SiO2溶胶-凝膜层具有很好的耐蚀性和抗高温氧化性，少量钼、铬元素的加入可提高TiO2溶胶-凝胶膜的耐磨性。     

Characterization of reactive magnetron sputtered nanocrystalline titanium nitride (TiN) thin films with brush plated Ni interlayer

Thin nanocrystalline Titanium nitride (TiN) films were deposited on mild steel (MS) substrates using reactive direct current magnetron sputtering. With the aim of improving the corrosion resistance an additional Nickel interlayer of about 5 μm thick was brush plated on to the steel substrates. X-ray diffraction analysis showed the polycrystalline nature of the sputtered TiN films. SEM analysis showed uniform surface morphology with dense columnar structure. Laser Raman spectroscopy revealed the presence of characteristic peaks of TiN at 320, 440 and 570 cm⁻¹. The optical quality of the film was confirmed from the photoluminescence (PL) spectrum recorded at room temperature. The corrosion behavior of the coatings in 3.5% NaCl solution was studied using electrochemical techniques.     

Electrochemical oxidation of ethanol in acid media on titanium nitride supported fuel cell catalysts

In the present study, titanium nitride, TiN that possesses good electronic conductivity, high corrosion resistance combined with the ability to support metallic particles, has been used to anchor Pt catalysts and subsequently used for ethanol oxidation. Platinum deposited on TiN (Pt–TiN) surface is contrasted with the conventional support material, Vulcan carbon for the electrochemical oxidation of ethanol in acidic medium. Though the comparison is not straight forward due to different morphology/particle size of the Pt catalyst on the two supports, the present investigations reveal that the TiN support lead to surface Ti–OH type functional groups that help in reducing the accumulation of carbon monoxide on the catalyst surface. The Tafel slopes are similar but the exchange current density on Pt–TiN is approximately twice that of the value observed on Pt–C. X-ray photoelectron spectroscopy data support the long term stability and electrocatalytic activity of Pt–TiN electrocatalyst.     

Electrochemical corrosion and materials properties of reactively sputtered TiN/TiAlN multilayer coatings

TiN/TiAlN multilayers of 2 μm thickness were successfully prepared by reactive DC magnetron sputtering method. XRD pattern showed the (1 1 1) preferential orientation for both TiN and TiAlN layers. XPS characterization showed the presence of different phases like TiN, TiO₂, TiON, AlN and Al₂O₃. Cross sectional TEM indicated the columnar growth of the coatings. The average RMS roughness value of 4.8 nm was observed from AFM analysis. TiN/TiAlN coating showed lower friction coefficient and lower wear rate than single layer coatings. The results of electrochemical experiments indicated that a TiN/TiAlN multilayer coating has superior corrosion resistance in 3.5% NaCl solution.     

A reactive-sputter-deposited TiSiN nanocomposite coating for the protection of metallic bipolar plates in proton exchange membrane fuel cells

To meet the needs of corrosion resistance and electrically conductivity for metallic bipolar plates that are employed in proton exchange membrane fuel cells (PEMFCs), a TiSiN nanocomposite coating was fabricated on to a Ti–6Al–4V substrate using reactive sputter-deposition through the double cathode glow discharge plasma technique. The microstructure of the TiSiN coating comprised nanocrystallite TiN grains embedded in an amorphous Si₃N₄ matrix. Electrochemical measurements were employed to investigate the corrosion behavior of the TiSiN coating in the simulated operating environments of a PEMFC, specifically 0.5 M H₂SO₄ solution containing different HF concentrations (namely 2, 4 and 6 ppm) at 70 °C pumped with H₂ at the anode and air at the cathode. With increasing HF concentration, a higher corrosion current density and lower corrosion potential were observed from both the coating and the uncoated substrate, indicating that the addition of HF accelerated their corrosion rates under these conditions. Compared to the uncoated substrate, the TiSiN coating showed a markedly higher corrosion resistance at all HF concentrations. The passive film that formed on the TiSiN coating, with a resistance of the order of magnitude of ~10⁷ Ω cm², displayed good electrochemical stability and was less affected by changes in HF concentration. For the TiSiN coating, the values of interfacial contact resistance (ICR) were 14.7 mΩ cm⁻² and 18.3 mΩ cm⁻², respectively, before and after 2.5 h potentiostatic polarization with 6 ppm HF under cathodic conditions under a compaction pressure of 140 N cm⁻². Both values are much lower than those for the bare substrate. Moreover, the TiSiN coating was shown to improve the hydrophobicity of Ti–6Al–4V that would help facilitate water management in the PEMFC operating environment. This coating, which exhibited excellent corrosion resistance, electro-conductivity and hydrophobicity, is therefore a promising material for protecting metallic bipolar plates from corrosive attack.     

靖边气田汽水分离器腐蚀机理与防护技术研究

靖边气田中分离器污水水质分析和垢样检测表明,其腐蚀主要由CO2-H2O(Cl-)-H2S系统作用引起的电化学腐蚀及SRB微生物腐蚀。采用Φ819 mm×60 mm×30 mm×51 mm的镯式铝牺牲阳极和45 mg/L氮氚杀菌剂联合防护,腐速由1.673 mm/a降到0.097 mm/a,符合国家标准<0.125 mm/a的要求。现场应用表明,运行1年后,再检时未发现明显腐蚀现象,防护效果良好。     

Enhancing corrosion resistance of aluminum composites in 3.5% NaCl using pigmented epoxy fluoropolymer

The corrosion protection performance of AA6061 T6–10% Al₂O₃ composite, coated with four different fluoropolymer paint systems, were investigated in 3.5% NaCl aqueous solutions under uniform and scratched conditions. A comparison between epoxy-treated clear and pigmented fluoropolymer coatings with newly developed vanadate-based fluoropolymer coatings was performed from corrosion protection, adhesion and durability points of view. The corrosion rates of epoxy-treated clear FLBZ 1074 increased dramatically after less than one month of exposure in 3.5% NaCl aqueous solutions. The addition of iron oxide or titanium oxide as pigments to the fluoropolymer decreased the porosity of epoxy and hence, improved the corrosion resistance. The newly developed vanadate based-clear FLBZ 1074 system showed outstanding corrosion resistance even after two months of immersion in 3.5% NaCl aqueous solutions under scratched coating conditions. The durability of such new coating based on salt spray test results was very promising (>2000 h without any sign of corrosion). The vanadate-pigmented FLBZ 1074 showed a dramatic increase in the corrosion rates. Moreover, the presence of pigments affected negatively the adhesion performance as well as the durability of the coating. A general model has been used to analyze the impedance data in terms of reactions occurring during the interaction of the coated metal with the environment. It was found that the vanadate-treated specimens not only improve the protective power against filiform corrosion as a factor of time, but also maintain the adhesion performance within the acceptable ranges.