共查询到20条相似文献,搜索用时 78 毫秒
1.
C.X. Shan 《Surface & coatings technology》2008,202(11):2399-2402
Titanium dioxide (TiO2) films have been deposited onto stainless steel substrates using atomic layer deposition (ALD) technique. Composition analysis shows that the films shield the substrates entirely. The TiO2 films are amorphous in structure as characterized by X-ray diffraction. The electrochemical measurements show that the equilibrium corrosion potential positively shifts from − 0.96 eV for bare stainless steel to − 0.63 eV for TiO2 coated stainless steel, and the corrosion current density decreases from 7.0 × 10− 7 A/cm2 to 6.3 × 10− 8 A/cm2. The corrosion resistance obtained by fitting the impedance spectra also reveals that the TiO2 films provide good protection for stainless steel against corrosion in sodium chloride solution. The above results indicate that TiO2 films deposited by ALD are effective in protecting stainless steel from corrosion. 相似文献
2.
By a two-step fabrication process of electrolytic deposition and annealing treatment, an MgO/ZrO2 duplex-layer coating has been prepared on AZ91D magnesium alloy as a protective film against corrosion. Owing to the chemical bonding formed after the condensation of precursory hydroxides, the adhesion strength, thickness and compactness of MgO coating on the substrate are significantly enhanced by the intermediate ZrO2 layer which prevents the formation of corrosion product Mg2(OH)3Cl·4H2O. As a result, the MgO/ZrO2 duplex-layer coated specimen reveals relatively high corrosion resistance and superior stability in 3.5 wt% NaCl solution with respect to the MgO single-layer coated specimen. 相似文献
3.
Thermal stability behaviors of Cr(N,O)/CrN double-layered coatings by TGA/DTA analysis 总被引:1,自引:0,他引:1
In this study, Cr(N,O)/CrN double-layered coatings were synthesized using the cathodic arc deposition (CAD) process. CrN film was first deposited onto a substrate as an interlayer to ensure better adhesion, and Cr(N,O) film was subsequently deposited on top of the CrN layer as the surface layer. Variation in the Cr(N,O) coating composition was achieved through changing the O2/N2 flow ratio during the last stage of processing. Phase structure, chemical composition, and morphology of the resulting coatings were analyzed and observed using the X-ray diffractometer, Auger electron spectrometer and SEM. In addition, oxidation behavior of the coatings was investigated using TGA/DTA methods. The tests were carried out by increasing temperature up to 1000 °C in ambient air. With the introduction of oxygen gas during the CAD process, a superficial layer was produced in the Cr(N,O) constituent containing CrN and Cr2O3 phases. The formation of the oxide phase attributed to the reaction of chromium and oxygen was more favorable than that of chromium and nitrogen. The results also showed that Cr(N,O)/CrN double-layered coatings exhibited superior oxidation resistance at elevated temperature than that of CrN single-layer coated specimen (870 °C vs. 750 °C). 相似文献
4.
T. Dudziak H. L. Du P. K. Datta A. P. Ehiasarian C. Reinhard P. Eh. Hovsepian 《腐蚀工程科学与技术》2014,49(7):590-602
The high temperature sulphidation/oxidation behaviour of three multilayered coatings CrAlYN/CrN etched by Y+, CrAlYN/CrN etched by Cr+ and CrAlYN/CrN etched CrAl+ and the uncoated γ-TiAl (Ti–45Al–8Nb (at-%) used as reference sample was studied at 850°C for 675 h. Sulphidation/oxidation test was performed in the environment of H2/H2S/H2O, yielding pS2?=?10?1 Pa and pO2?=?10?18 Pa. Kinetic data obtained by discontinuous gravimetric method showed that the multilayered coatings effectively enhanced the sulphidation/oxidation resistance of γ-TiAl alloy. The corrosion resistance decreasing in order: CrAlYN/CrN etched by Y+>CrAlYN/CrN etched by CrAl+>CrAlYN/CrN etched by Cr+>γ-TiAl. Scale development studies using SEM, EDX and X-ray diffraction confirmed two regions of the coated materials: ‘affected,’ where coating cracked and developed non-protective TiO2 scale, and ‘unaffected,’ where protective (Al,Cr)2O3 scale formed. The uncoated γ-TiAl material, after exposure, showed a typical multilayered structure consisting of layers of TiO2 and Al2O3. 相似文献
5.
Junhua Hu Guan Shaokang Caili Zhang Cuilian Wen Li Peng 《Surface & coatings technology》2009,203(14):2017-2020
TiO2 layer was prepared as a protective coating for AZ31 magnesium alloy by the liquid phase deposition (LPD) method followed by an annealing treatment. The structural evolution and crystallization of coating brought by annealing were investigated by field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD), respectively. The corrosion protection performance was evaluated in a three-electrode electrochemical examination system. The anatase TiO2 layer shows evident corrosion resistance. With the increase of the annealing temperature and prolongation of annealing time, the anticorrosion property was improved. The improvements of the anticorrosion properties were related with the structural evolution of the coating brought by the annealing treatment. 相似文献
6.
The present study explored the in-situ deposition of hard and adherent nanocrystalline protective coatings on NiTi/PZT/TiOx thin film heterostructure prepared by dc/rf magnetron sputtering. Protective layers (AlN, CrN and TiCrN) of approximate thickness (~ 200 nm) were used to improve the surface, mechanical and corrosion properties of NiTi/PZT/TiOx heterostructure without sacrificing the shape memory effect and ferroelectricity of the NiTi and PZT layers, respectively. The influence of the protective layer on structural, electrical and mechanical properties of NiTi/PZT/TiOx heterostructure was systematically investigated and the results were compared. Nanoindentation studies were performed at room temperature to determine the hardness and reduced modulus. The surface modified NiTi/PZT/TiOx heterostructures were found to exhibit high hardness, high elastic modulus and thereby better wear resistance as compared to pure NiTi/PZT/TiOx films. From the results of potentiodynamic polarization test conducted in 1 M NaCl solution, the CrTiN coated NiTi/PZT/TiOx heterostructure showed the best corrosion resistance with the lowest corrosion current density (1.52 × 10? 8 A cm? 2) and the highest protective efficiency (96.8%). The results presented here prove the potential of a surface modified NiTi/PZT/TiOx heterostructure to be used in various microelectromechanical (MEMS) applications. 相似文献
7.
A CrN/Cr1?xAlxN coating comprised of an inner layer of CrN and an outer layer of Cr1?xAlxN with a gradient distribution of Al was deposited on two different alloys by a reactive sputtering method. Oxidation and hot‐corrosion tests of the gradient CrN/Cr1?xAlxN coating were performed at different temperatures. The phase compositions and morphologies of the as‐deposited coating and the corrosion products were investigated by using XRD and SEM/EDS. The results showed that the gradient CrN/Cr1?xAlxN coating exhibited good oxidation resistance at temperatures above 1000 °C owing to the formation of an α‐Al2O3‐rich oxide scale. The coating possessed good hot‐corrosion resistance in molten sulfate because the inner CrN layer could supply enough Cr to form a relatively protective Cr2O3 after the Al2O3‐enriched scale failed due to its dissolution in the molten sulfate. 相似文献
8.
Enhancing Biocompatibility and Corrosion Resistance of Ti-6Al-4V Alloy by Surface Modification Route
Tejinder Pal Singh Sarao Harpreet Singh Hazoor Singh 《Journal of Thermal Spray Technology》2018,27(8):1388-1400
Titanium (Ti) and its alloys are widely used as candidate materials for biomedical implants. Despite their good biocompatibility and corrosion resistance, these materials suffer from corrosion after implantation in biological environments. The aim of this research work is to study the effect of two coatings on biocompatibility and corrosion behavior of Ti-6Al-4V biomedical implant material. Hydroxyapatite (HA) and hydroxyapatite/titanium dioxide (HA/TiO2) coatings were thermal-sprayed on Ti-6Al-4V substrates. In the latter case, TiO2 was used as a bond coat between the substrate and HA top coat. The corrosion behavior of coated and un-coated samples in Ringer’s solution was studied by potentiodynamic and linear polarization techniques. Before and after corrosion testing, XRD and SEM/EDS techniques were used for the analysis of phases formed and to investigate microstructure/compositional changes in the coated specimens. The cellular response was analyzed by the MTT (microculture tetrazolium) assay. The results showed that both the HA, as well as, the HA/TiO2 coatings significantly increased the corrosion resistance of the substrate material. The HA coating was found to be more biocompatible as compared to the un-coated and HA/TiO2-coated Ti-6Al-4V alloy. 相似文献
9.
The corrosion resistance of Ti-5%Ta-2%Nb alloy and DOCTOR (double oxide coating on titanium for reconditioning) coated titanium by O5+ ion irradiation were compared and investigated for their corrosion behaviour. O5+ ion irradiations were carried out at a dose rate of 1 × 1017, 1 × 1018 and 1 × 1019 ions/m2 at 116 MeV. The surface properties and corrosion resistance were evaluated by using scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-ray (EDX), glancing-angle X-ray diffraction (GXRD) and electrochemical testing methods. The results of electrochemical investigations in 11.5 N HNO3 indicated that the open circuit potential (OCP) of DOCTOR coated titanium is nobler than Ti-5%Ta-2%Nb alloy. The potentiodynamic polarization study of Ti-5%Ta-2%Nb alloy and DOCTOR coated specimen indicated decrease in passive current density with increase in ion doses (1 × 1017 to 1 × 1019 ions/m2) indicating decrease in anodic dissolution. Nyquist arc behaviour in the electrochemical impedance study substantiated the enhancement in oxide layer stability by O5+ ion irradiation. AFM results revealed that the DOCTOR coated Ti surface was dense without gross voids, and the surface roughness decreased by O5+ ion irradiation, but increased after corrosion test. EDX and GXRD patterns of DOCTOR coated Ti sample indicated that the coating was mainly composed of rutile TiO2. Based on the above results, the O5+ ion irradiation effect on corrosion behavior of Ti-5%Ta-2%Nb alloy and DOCTOR coated titanium are discussed in this paper. 相似文献
10.
以恒压阳极氧化方法在钛基体上制备TiO2氧化膜,使用水热釜模拟深海热液区的条件研究其耐腐蚀性能。采用XRD、SEM、接触角测定仪对氧化膜以及腐蚀试样产物进行晶型、表面结构、化学成分和亲疏水性能测定,使用动电位扫描方法对其进行极化曲线测试。结果表明,钛试样和阳极氧化钛试样在模拟深海环境条件下,经过腐蚀反应在表面都生成了一层非致密的TiO2 膜,对基体并不能起到保护作用,而阳极氧化生成的致密TiO2 膜对基体能够起到很好的保护作用。经腐蚀后钛试样表面有TiH2相的形成,腐蚀电位负移0.45 V。而阳极氧化钛试样表面没有TiH2相的形成,且腐蚀电位负移较小,表现出良好的耐腐蚀性能。 相似文献
11.
U. C. Chung B. M. Lim I. M. Park Y. H. Park K. M. Cho I. B. Kim 《Metals and Materials International》2005,11(2):149-156
The corrosion behavior and resistance of hot-dip Al and Al−Cr coated steel sheets (SS) were investigated via scanning electron
microscopy (SEM), energy dispersive X-ray spectrometry (EDX), electron probe micro analysis (EPMA), glow discharge light spectroscopy
(GDLS), and X-ray diffraction patterns (XRD). The Al−Cr coated layer was composed of the following three phases. Al phase
comprised the surface layer, Al13Cr2 the middle layer, and Al13Fe4 and Al5Fe2 phases the interfacial layer between the Fe substrate and the coated layer. The corrosion behavior of the Al−Cr coated layer
showed different aspects compared with the Al coated layer. In the Al−Cr coated layer, Cr was observed at an intermediate
layer having a band shape. From the analysis of the polarization curve, the initial corrosion current of the Al−Cr coated
SS was 10 times lower than that of Al in the early stage, and the corrosion resistance was superior to that of Al. The Al
coated SS formed an Al−Fe−Si IMC layer, and the coated layer was almost destroyed. Many cracks were produced, and the corroded
parts were enlarged from the cracks. The upper part of the Al−Cr coated SS, an Al−Si coated layer, was corroded. In contrast,
the Cr-rich intermediate layer was not destroyed. Consequently, the high corrosion resistance was attributed to the densely
covered Al(OH)3 and the intermetallic compound layer of Al13Cr2. These results significantly contribute toward attaining a detailed understanding of the corrosion behavior and resistance
Al−Cr coated steel sheets. 相似文献
12.
Yusuf Kayali Osman Aslan Muhammet Karabaş Şükrü Talaş 《Protection of Metals and Physical Chemistry of Surfaces》2016,52(6):1079-1085
AISI316L stainless steel is extensively used in orthopedic and dental applications. However, this alloy exhibits low integration behaviour when it comes in contact with surrounding bone tissue and implant healing duration can be as much as few months. The aim of this study is the fabrication of biocompatible hydroxyapatite (HA) coatings on stainless steel substrate in order to accelerate the process of osseointegration of implants. The biocompatible single layer of Titania (TiO2), Hydroxyapatite and bi-layer TiO2/HA coatings were deposited by atmospheric plasma spray on 316L stainless steel. Coated and uncoated stainless steel specimens were incubated in simulated body fluids and 0.9% NaCl solutions for 1h and 7 days. In vitro electrochemical-corrosion evaluation of coated and uncoated stainless steel specimens have been investigated by Tafel extrapolation and linear polarization methods. Results indicates that corrosion resistance of single layer HA coated stainless steel specimens are superior to single layer TiO2 and bi-layer HA/TiO2 coated stainless steel specimens. 相似文献
13.
Young-Jin Kim Ik-Beom Kim Mok-Soon Kim Byung-Don You Jeong-Whan Han Woon-Suk Hwang 《Metals and Materials International》2000,6(5):455-459
In order to investigate the role of chlorine in the oxidation resistance of Ti-45at.%Al-1.6at.%Mn intermetallic compounds,
specimens with and without chlorine were prepared by a reactive sintering and a remelting process, respectively, and then
isothermally oxidized at temperatures of 800 to 1000°C. The oxidation resistance of reactive-sintered Ti-45at.%Al-1.6at.%Mn
containing 0.02 wt.%Cl was superior to that of remelted specimens due to the formation of a protective Al2O3, layer. From the results of an EPMA line scan of a cross-section of the oxide layer, carbon and chlorine peaks were detected
on the TiO2 layer of the reactive-sintered specimens suggesting that TiO2 can decompose to TiCl4 through the reaction with Cl2 and C (or CO). As a result of the chlorination of TiO2, the growth of TiO2 could be constrained and a protective A12O3 scale was easily formed on the reactive-sintered alloy. 相似文献
14.
Attempts have been made to improve the high-temperature corrosion behavior of an intermetallic alloy, Ti–46.7Al–1.9W–0.5Si, in an H2/H2S/H2O atmosphere at 850°C using AlTiN coating with and without CrN and NbN diffusion barriers. The oxidation and sulfidation behavior of the uncoated Ti–46.7Al–1.9W–0.5Si alloy followed protective kinetics with a parabolic rate constant of 6×10–11 g2/cm4/s. A multi-layered scale developed: an outer rutile (TiO2) layer, a continuous layer of -Al2O3 beneath the rutile layer, and an inner TiS layer, in which pure W was scattered. Fast outward diffusion of Ti within the substrate resulted in the formation of a zone of high concentration of aluminum (TiAl3 and TiAl2) between the scale and substrate.The use of an AlTiN coating greatly increased the oxidation and sulfidation resistance of Ti–46.7Al–1.9W–0.5Si. The use of NbN and CrN diffusion barriers further enhanced its corrosion resistance. The protection of the double-layer coatings persisted even after 240 hr exposure. However the mismatch of thermal expansion coefficients between the coating and substrate led to the development of cracks in some locations within the coatings. A 2.5 m thick AlTiN coating on the Ti–46.7Al–1.9W–0.5Si substrate with an embedded defect was modeled using the general finite element (FE) program ABAQUS. The modeling results showed rapid mode I failure of the coating at a temperature of 774°C. The through-fracture of the nitride film caused the nitride coating to shrink back leading to delamination around the crack in the nitride coating. The cracks formed acted as diffusion paths, for the ingress of oxygen and sulfur species and the outward diffusion of substrate elements, which resulted in the formation of nodular corrosion products with similar morphologies and microstructures to the uncoated alloy in those locations where cracks developed. 相似文献
15.
Jin-Young CHO Duck-Young HWANG Dong-Heon LEE Bongyoung YOO Dong-Hyuk SHIN 《中国有色金属学会会刊》2009,19(4):824-828
The effect of potassium pyrophosphate in the electrolyte on plasma electrolytic oxidation (PEO) process for AZ91 Mg alloy was investigated. The morphologies and chemical compositions of the coating layer on the AZ91 Mg alloy were evaluated and corrosion resistance was also estimated by potentiodynamic polarization analysis. The coating layer on AZ91 Mg alloy coated from the Bath 2 containing 0.03 mol/L of potassium pyrophosphate for 360 s exhibited considerably dense structure and contained 11%–18% (mass fraction) of phosphorous. The higher content of phosphorous of coating layer coated from Bath 2 could be detected at the bottom of oxide layer, which strongly implied that the phosphorous ion might be concentrated at the barrier layer. Corrosion potential of coating layer of AZ91 Mg alloy increased and corrosion current density decreased with increasing the concentration of potassium pyrophosphate. The polarization resistance (Rp) of coating layer of AZ91 Mg alloy coated from Bath 2 was 4.65×107 Ω/cm2, which was higher than that (Rp=3.56×104 Ω/cm2) of the sample coated from electrolyte without potassium pyrophosphate. The coating layer coated from Bath 2 containing 0.03 mol/L potassium pyrophosphate exhibited the best corrosion resistance. 相似文献
16.
The corrosion behavior of polycrystalline Ti3SiC2 was studied in the presence of Na2SO4 deposit and water vapor at 900°C and 1000°C. The mass gain per unit area of the samples superficially coated with Na2SO4 exposed to water vapor was slightly lower than that of the samples corroded without water vapor. The microstructure and composition of the scales were investigated by SEM/EDS and XRD. Pores were observed in the corroded sample surfaces. The main corrosion phases on the sample surface were identified by XRD as TiO2, Na2Si2O5 and Na2TiO3. After Ti3SiC2 corroded in the presence of the Na2SO4 deposit and water vapor, the scale had a three-layer microstructure, which was different from the duplex corrosion scale formed on Ti3SiC2 beneath the Na2SO4 film without water vapor. Because water vapor penetrated the corrosion layer and then reacted with SiO2 to form volatile Si(OH)4, an intermediate porous and TiO2-enriched layer formed in the corrosion layer. 相似文献
17.
In the present study, hydroxyapatite (HAP) coating along with HAP/TiO2 coating has been deposited by high-velocity flame spray (HVFS) technique onto 316LSS. Titania was used as a bond coat and HAP as top coat in HAP/TiO2 coating. The main aim of the study is to investigate the corrosion behavior of thermal spray coating of HAP and HAP/TiO2 on steel. Electrochemical corrosion testing was carried out using potentiodynamic polarization test. The corrosion behavior of bare and as-sprayed specimens was analyzed in simulated body fluid known as Hank’s solution. As-sprayed specimens along with corroded specimens were further characterized by XRD, SEM/EDS, and x-ray mapping analysis. It was observed that the HAP/TiO2 coating possessed higher microhardness (280 Hv) as compared to HAP coating (254 Hv). Surface roughness also got enhanced in case of HAP/TiO2 coating (9.35 μm) as compared to pure HAP coating (7.37 μm). The porosity of the HAP coating was found to be higher than the bond coating. It was observed that the Ca/P ratio almost resembled that of the natural bone composition. The corrosion resistance of steel increased after the deposition of HAP and HAP/TiO2 coatings. The maximum corrosion resistance was exhibited by HAP/TiO2 coating. 相似文献
18.
Nanostructured Al2O3–13?wt-% TiO2 was prepared on AZ91D magnesium alloy surface by laser surface alloying to improve its corrosion resistance. The microstructure of the laser surface alloyed specimens before and after corrosion tests was characterised by scanning electron microscope and optical microscope (OM). The phase and element composition were investigated by X-ray diffractometer and energy-dispersive spectrometry. An electrochemical workstation was used to evaluate the corrosion behaviour of the specimens. Results showed that the laser surface alloyed layer was primarily composed of Mg and Mg17Al12. Al2O3 and TiO2 existed in the form of agglomerated particles. The corrosion resistance was improved after laser surface alloying. 相似文献
19.
Anti‐corrosive composite cerium oxide/titanium oxide (CeO2/TiO2) thin films were successfully prepared on an AZ91D magnesium alloy substrate by applying cerium oxide (CeO2) thin films as the inner layer with a sol–gel process. Composition and surface morphology of the thin films were analyzed using X‐ray diffraction (XRD) and scanning electron microscope (SEM). XRD showed that the composite films consisted of cerianite and anatase phases. The wettability of the thin films was evaluated by water contact angles measurements. Potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) tests were used to evaluate the corrosion behavior of the bare substrate and coated samples in 3.5 wt% sodium chloride solution (3.5 wt% NaCl). The results demonstrated that titanium oxide (TiO2) thin film mainly dominated the corrosion resistance of samples and the composite films with excellent hydrophilicity could significantly improve the corrosion resistance of AZ91D magnesium alloy. 相似文献
20.
Tejinder Pal Singh Harpreet Singh Hazoor Singh 《Journal of Thermal Spray Technology》2012,21(5):917-927
The main aim of this study is to evaluate corrosion and biocompatibility behavior of thermal spray hydroxyapatite (HA) and hydroxyapatite/titania bond (HA/TiO2)-coated 316L stainless steel (316L SS). In HA/TiO2 coatings, TiO2 was used as a bond coat between HA top coat and 316L SS substrate. The coatings were characterized by x-ray diffraction and scanning electron microscopy/energy dispersive spectroscopy, and corrosion resistance determined for the uncoated substrate and the two coatings. The biological behavior was investigated by the cell culture studies using osteosarcoma cell line KHOS-NP (R-970-5). The corrosion resistance of the steel was found to increase after the deposition of the HA and HA/TiO2 bond coatings. Both HA, as well as, HA/TiO2 coatings exhibit excellent bond strength of 49 and 47?MPa, respectively. The cell culture studies showed that HA-coated 316L SS specimens appeared more biocompatible than the uncoated and HA/TiO2-coated 316L SS specimens. 相似文献