Corrosion behaviour of nitrogen implanted titanium in simulated body fluid

Abstract

Titanium is one of the most important materials for medical applications, as a result of its uniquely high biocompatibility. The effect of nitrogen implantation on the biocompatibility and the corrosion resistance of cp titanium are reported. Grazing incidence X-ray diffraction studies showed that implantation formed a δ-TiN_x phase. Electrochemical tests in HBSS showed an optimal decrease in corrosion current density for specimens implanted with 3 × 10¹⁷ ions cm^-2 at 25 keV, compared with unimplanted titanium. Following implantation and immersion in a commercial physiological solution, phases are precipitated which are rich in calcium and phosphorus, and these hydroxyapatite precursors indicate that this implantation regime confers optimal properties of corrosion resistance and biocompatibility.     

Wear and corrosion properties of plasma-based low-energy nitrogen ion implanted titanium

Plasma-based low-energy nitrogen ion implantation, including plasma source ion nitriding/carburizing and plasma source low-energy ion enhanced deposition, has emerged as a low-temperature surface engineering technique for metal and alloy. In this paper, the pure metal Ti samples have been modified by the plasma source ion nitriding process at a process temperature of 700 °C for a processing time of 4 h. The nitrided Ti surfaces were constructed of a continuous and dense Ti₂N compound layer about 2 μm thick and a 7-8 μm diffused layer. During tribological test on a ball on disk tribometer against the Si₃N₄ ceramic counterface, a low friction coefficient of about 0.3 and the faint wear volume were obtained for the nitrided Ti samples. The cyclic polarization curves of the nitrided Ti samples in 3.5% and 6.0% NaCl solutions showed that the improved pitting corrosion resistance with an increase of corrosion potential and a decrease of passive current, compared with that of the unnitrided Ti sample. The plasma source ion nitriding of the Ti samples provided the engineering surfaces for the functional applications with the combined improvement in wear and corrosion resistance.     

Effect of nitrogen ion implantation on the localized corrosion behavior of titanium modified type 316L stainless steel in simulated body fluid

Nitrogen ion implantation on titanium-modified type 316L stainless steel (SS) at the energy of 70 keV was carried out at different doses ranging from 1×10¹⁵ to 2.5×10¹⁷ ions/cm². These samples were subjected to open circuit potential (OCP)—time measurement, cyclic polarization, and accelerated leaching studies—in order to discover the optimum dose that can provide good localized corrosion resistance in a simulated body fluid condition. The results showed that the localized corrosion resistance improved with an increase in doses up to 1×10¹⁷ ions/cm², beyond which it started to deteriorate. The results of the accelerated leaching studies showed that the leaching of the major alloying elements was arrested upon nitrogen ion implantation. Gracing incidence x-ray diffraction studies showed the formation of chromium nitrides at a dose of 2.5×10¹⁷ ions/cm². X-ray photoelectron spectroscopy studies revealed the presence of these chromium nitrides in the passive film, which was attributed to the decreased corrosion resistance at a higher dose. Secondary ion mass spectroscopy studies on the passive film showed the variation in the depth profile upon nitrogen ion implantation. Thus, nitrogen ion implantation can be effectively used as a method to improve the corrosion resistance of the orthopedic implant devices made of titanium-modified type 316L SS. The nature of the passive film and its influence on corrosion resistance are discussed in this article.     

微束等离子喷涂羟基磷灰石涂层的体外生物活性研究

采用微束等离子喷涂(MPS)方法在Ti6A14V基体上制备羟基磷灰石(HA)涂层.利用扫描电镜(SEM)和x射线衍射(XRD)分析技术对HA涂层的表面形貌、相组成和结晶度进行表征,并通过模拟体液进行体外生物活性试验.结果表明,微束等离子喷涂制备的HA涂层具有一定粗糙度,存在气孔以及微裂纹.涂层存在热分解现象,涂层中含有HA、α-TCP、β-TCP和非晶相,不含CaO等杂质相.模拟体液试验表明,微束等离子喷涂工艺制备的HA涂层具有较好的生物活性和稳定性.涂层表面均有较大比例的CaP沉积层,且涂层整体保持完整,没有出现明显的剥离.     

纯镁在模拟体液中的腐蚀机理

考察纯镁浸泡于模拟体液（SBF）中所发生的化学和物理过程，实验材料为扩散退火态，浸泡时间3-21d。结果发现，镁的腐蚀速率随时间增加而降低，同时溶液pH递增；裂纹和腐蚀坑是材料损伤的主要形貌特征，而MgCl2的局部富积是形成腐蚀坑的重要原因；随着浸泡时间延长，Mg（OH）2沉积于试样表面并逐步增长，成为Ca、P在Mg表面沉积的屏障，因此抑制Mg（OH）2的形成和生长是诱导磷酸钙陶瓷在Mg表面沉积的必要条件。     

Microstructure and in vitro bioactivity of laser-cladded bioceramic coating on titanium alloy in a simulated body fluid

In order to obtain bioactivity on the surface of titanium alloy, the bioceramic coating on Ti–6Al–4V was designed and fabricated by laser cladding. The microstructure and bioactivity of laser-cladded bioceramic coating were investigated in vitro via soaking in a simulated body fluid (SBF). The results indicated that the laser-cladded bioceramic coating was metallurgically bonded to the substrate and contained such bioactive phases as hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP). A bone-like apatite layer was spontaneously formed on the surface of laser-cladded coating merely soaked in SBF for 7 days. And the appearance of flake-like and cotton-like morphology, which is the characteristic morphology of apatite, offered an advantageous condition for osseo-connection. The formation ability of apatite was remarkably accelerated on the surface of laser-cladded bioceramic coating compared with the untreated titanium alloy substrate.     

Comparative corrosion resistance of plasma-based low-energy nitrogen ion implanted austenitic stainless steel

A high nitrogen face-centered-cubic phase (γ_N) was obtained on the nitrided surface of 1Cr18Ni9Ti austenitic stainless steel by plasma-based low-energy nitrogen ion implantation. No pitting corrosion for the γ_N phase was confirmed by electrochemical polarization measurement in 3% NaCl solution. The protective passive film with a duplex character, iron hydroxide/oxides in the outer region and chromium hydroxide/oxides and iron oxides accompanying chromium and iron nitrides in the inner region, was by 2-3 times thicker than that of original stainless steel. The thick iron hydroxide/oxides region formed on the chromium hydroxide/oxides region due to the increase of alkalinity in the solution, leading to barrier against penetration of localized attack of the aggressive ions. The equivalent general corrosion resistance for the γ_N phase was observed in 0.5 mol/l H₂SO₄ solution relative to the original stainless steel. The passive film formed on the γ_N phase in 0.5 mol/l H₂SO₄ solution was similar to that of original stainless steel. The different role of nitrogen was proposed in pitting corrosion resistance and general corrosion resistance of austenitic stainless steel.     

Tribological properties of 2024 aluminum alloy plasma-based ion implanted with nitrogen then titanium

1　INTRODUCTIONOwingtolowdensityandhighspecificstrength ,aluminumanditsalloysareextensivelyusedinmanyfields ,especiallyinaviationandspaceindustry .Butlowhardnessandlowwearresistanceoftenlimittheirengineeringapplications .Surfacemodificationforalu minumanditsalloysbyionimplantationoffersthepossibilityofwideningtheirapplicationswherehighwearresistanceandlowdensityarerequired[15] .Sincenitrogenionisconvenienttoobtainandeasytocontrol,andAlNhasexcellentmechanicalproperties ,nitrogenionimplant…     

Numerical simulations study of the localized corrosion resistance of AISI 316L stainless steel and pure titanium in a simulated body fluid environment

The resistance of both AISI 316L stainless steel (AISI 316L SS) and commercially pure titanium (cpTi) to localized corrosion in a simulated body fluid solution was investigated using numerical simulations. The resulting model, based on transport equations in dilute solutions, is designed to predict the susceptibility of these two biomaterials to crevice corrosion initiation. The results show that cpTi and AISI 316L SS alloy are very resistant to the initiation of crevice corrosion in 0.9% NaCl solution and AISI 316L SS alloy is more susceptible to corrosion initiation over the long term than cpTi.     

Effect of alloyed molybdenum on corrosion behavior of plasma immersion nitrogen ion implanted austenitic stainless steel

Plasma immersion ion implantation (PIII) of nitrogen has been performed on two austenitic stainless steels (with and without Mo addition) at three different temperatures namely, 250, 380 and 500 °C for 3 h. Grazing angle X-ray diffraction (GXRD) was carried out on the surface of the steels (both PIII treated and untreated). GXRD results suggest that PIII is more effective in Mo containing stainless steel (SS). The electrochemical corrosion studies examined through both by DC polarization and EIS technique in 3.5 wt.% NaCl reveals that, 3 h N-implantation at 250 and 380 °C improves the corrosion and pitting resistance of both the austenitic stainless steels under investigation. The effect N implantation on pitting resistance is seen more in the presence of Mo, than when it is not present in the SS. It is further emphasized that the pitting resistance of the alloys significantly deteriorates, when they are implanted at 500 °C.     

Effect of titanium ions on the ion release rate and uptake at the interface of silica based xerogels with simulated body fluid

The dissolution and surface layer changes of new xTiO₂(100 − x)[4SiO₂·CaO·0.3P₂O₅] sol–gel derived xerogels (0 ⩽ x ⩽ 20 mol%) have been investigated in Kokubo’s simulated body fluid (SBF). The ionic leaching rate was analysed by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES). ICP-AES results showed a relatively fast dissolution of titanium free sample, with a high release of phosphorous and calcium ions in the first hour of incubation while the release of silicon ions continuously increased up to 6 h of immersion. The titanium dioxide addition up to 20 mol% differently influences the release of phosphorus, calcium and silicon ions, i.e. TiO₂ strongly stabilises the phosphorus ions, to a lesser extent the calcium ions, and has almost no effect on the silicon ions release. The structural changes were evaluated using X-ray powder diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). The XRD results show that all samples remain mainly amorphous after immersion in SBF. The changes occurred in the surrounding of phosphorous and silicon ions are well reflected in FTIR spectra and they were correlated with the samples stability in SBF.     

Effect of heat treatment on corrosion behaviour of magnesium alloy AZ91D in simulated body fluid

The research explored ways of improving corrosion behaviour of AZ91D magnesium alloy through heat treatment for degradable biocompatible implant application. Corrosion resistance of heat-treated samples is studied in simulated body fluid at 37 °C using immersion and electrochemical testing. Heat treatment significantly affected microgalvanic corrosion behaviour between cathodic β-Mg₁₇Al₁₂ phase and anodic α-Mg matrix. In T4 microstructure, dissolution of the β-Mg₁₇Al₁₂ phase decreased the cathode-to-anode area ratio, leading to accelerated corrosion of α-Mg matrix. Fine β-Mg₁₇Al₁₂ precipitates in T6 microstructure facilitated intergranular corrosion and pitting, but the rate of corrosion was less than those of as-cast and T4 microstructures.     

铝合金表面氮和钛等离子体基离子注入改性层XPS研究

用XPS(X射线光电子能谱 )和GXRD(小掠射角X射线衍射 )研究了铝合金等离子体基离子注入氮再注入钛最后复合注入氮和钛改性层的成分分布及相结构 ,并用Gaussian Lorentzion峰位拟合方法分析了改性层中不同深度处各元素的化学态及其在相结构中的分布。结果表明 ,复合改性层的表层有较高浓度的氮和钛 ,次表层有较高浓度的钛及一定浓度的氮 ,铝 /钛界面有较宽的过渡区 ,基体中氮呈高斯分布。改性层主要由TiN ,TiO2 ,α Ti,TiAl3 ,Al2 O3 和AlN等组成 ,氮和氧还以固溶态的形式存在。最表层含有大量TiN及部分TiO2 ;次表层含有大量α Ti及许多TiN ;过渡层由TiO2 ,TiN ,TiAl3 ,Al2 O3 和AlN等组成 ;注氮层包括AlN ,Al2 O3 及α(Al)。各元素在相应相结构中的浓度分布与其成分深度分布基本相似。     

Friction and wear properties of UHMWPE against ion implanted titanium alloy

In this study, a new two-step plasma immersion ion implantation technique was developed and applied for the modification of Ti6Al4V alloy; firstly ion implanting with nitrogen at high temperature and followed with oxygen in high dose. A graded titanium oxide-titanium nitride film was obtained on the surface of the Ti6Al4V alloy. The contact angle and the microhardness of the modified alloys were measured. The friction and wear properties of UHMWPE rubbing against the modified alloys under lubrication of distilled water were investigated using a pin-on-disc tribometer. The wettability and the microhardness of the alloy surfaces were found to be increased significantly after ion implantation. The friction coefficient decreased by nearly 5 times and the wear resistance of UHMWPE increased by about 40 times against the ion implanted Ti6Al4V alloy. Many deep furrows were found on the surface of the un-implanted alloy and were absent in the ion implanted surfaces of the alloy.     

Effects of plastic strain of diamond-like carbon coated stainless steel on the corrosion behavior in simulated body fluid environment

We have investigated the effect of plastic deformation of diamond-like carbon (DLC) coated and uncoated stainless steel on the corrosion resistance in a simulated body fluid environment to measure its protective efficiency as a biomedical coating material. We deposited the DLC film on 304 stainless steel specimens by radio frequency plasma assisted chemical vapor deposition(R.F.-PACVD) method, followed by a tensile test to apply plastic strain on the coated specimen. Corrosion behavior in the simulated body fluid environment was studied by a potentiodynamic polarization test. As the tensile deformation progressed, the cracks of the film were observed to be perpendicular to the tensile axis. Further deformation increased both cracking and the spallation. Estimated porosity and corrosion current density increased, and thus the protective efficiency decreased at a strain of 2%. In spite of the degradation, the anti-corrosion properties were significantly improved relative to the uncoated stainless steel. However, a significant increase in porosity and corrosion current density was observed at a strain of 4%. This study showed that increasing the thickness of the Si interlayer of film improved the corrosion resistance with reduction of spallations and cracks.     

ZM61-0.5Ca镁合金组织对其在仿生溶液中耐蚀性能的影响

对挤压态ZM61-0.5Ca镁合金以不同的工艺进行热处理,改变合金微观组织结构,研究合金成分分布、析出相等对其在仿生溶液中(SBF)耐蚀性能的影响.通过光学金相显微镜、SEM扫描电镜、XRD观察测试其组织成分,通过浸泡腐蚀、析氢、电化学测试研究其耐腐蚀性能.结果表明合金在退火态时,其细小的析出相以球状沿晶界均匀分布,腐蚀过程均匀,耐蚀性能最优.     

The aqueous corrosion behaviour of an ion implanted 12% chromium steel

Ion implantation has shown beneficial effects in the field of wear and oxidation. This paper is a study of the influence of ion implantation on the corrosion performance of a 12% chromium ferritic steel, 3CR12. 80 keV ions were implanted at concentrations of 5 × 10¹² to 1 × 10¹⁷ ions cm^?2. The effect of implantation of 4 ion types (Mo, V, Ph, N) each at 4 dosages was studied potentiostatically in 1 N H₂SO₄ and 0.1 N NaCl solutions. Uniform corrosion loss calculations would imply that the effect of implantation is not long lasting in 1 N H₂SO₄. This could imply that changes in the potentiostatic curves are brought about by ions in solution. Pb-Implanted 3CR12 showed increased pitting resistance with increasing dosage, whereas Pb-implanted 3CR12 showed poorer pitting resistance. Mo and V implantation showed similar behaviour for the lower doses in that both species enhanced pitting resistance but the results showed poorer pitting resistance for the higher doses. The most important limitation of ion implantation is the shallow depth of penetration and whether or not implantation effects last over sufficent periods of time for practical application is still in question.     

Corrosion of biomaterials: anodic treatment and evaluation of 316L stainless steel in simulated body fluid

The influence of electropolishing at different conditions on the electrochemical behaviour of 316L stainless steel (316L SS) in simulated body fluid (SBF) was investigated. Accordingly, 316L SS samples were electropolished in several electropolishing baths of H₃PO₄ and H₂SO₄ at 2–6 applied volts and 50–110°C for different time intervals. The corrosion behaviour then was studied by means of potentiodynamic polarisation technique and electrochemical impedance spectroscopy in SBF at 37°C. The surface morphology was also investigated by scanning electron microscopy. The results proved that the treated samples had better corrosion resistance than nonpolished one. The highest corrosion resistance was observed for the treated sample at 5?V and 90°C in 10:90 ratio of acidic electrolyte (H₃PO₄:H₂SO₄) for 15?min. Moreover, the corrosion resistances of anodically treated samples were found to be dependent greatly on applied volt, bath temperature, polishing time and phosphoric to sulphuric acids ratio.     

Microstructure and corrosion resistance of tantalum after nitrogen ion implantation

This paper investigates the effect of nitrogen ion implantation on surface structure as well as resistance against tantalum corrosion. Bulk Ta surface was implanted with 30?keV nitrogen ions at a temperature of 100°C with doses between 1?×?10¹⁷ and 1?×?10¹⁸?ions/cm². The implanted samples were characterised by atomic force microscopy, X-ray diffraction analyses and the corrosion test to identify structural, compositional and electrochemical changes at various doses. The experimental results indicate the formation of hexagonal tantalum nitride (TaN_0.43), in addition to the fact that by increasing the ion dose, nitrogen atoms occupy more interstitial spaces in the target crystal, a case which can significantly improve corrosion resistance. The maximum extent in the improvement of the micro hardness was 75% and the reduction in the corrosion current was 83%. According to scanning electronic microscopy and corrosion results, in the dose of 1?×?10¹⁸?ions/cm² the highest corrosion resistance was received against the H₂SO₄ corroding media.     

Corrosion behavior of Mg and Mg-Zn alloys in simulated body fluid

The corrosion behavior of Mg and Mg-Zn in simulated body fluid was studied.The mass loss of pure Mg,Mg-Zn-Zr and Mg-Zn-Zr-Y in simulated body fluid was measured using photovoltaic scale meter.Corrosion rate was determined through electrochemical tests.Finally,the corrosion mechanism was tbermodynamically studied.The results show that the corrosion rate decreases with the lapse of time for both pure Mg and Mg alloys.The purer the alloy,the borer the corrosion resistance exhibits.The corrosion behavior of Mg alloy is improved by the addition of trace Y.