Influence of aluminum ions implanted on corrosion behavior of zirconium in 1 M H2SO4

In order to study the effect of aluminum ion implantation on the aqueous corrosion behavior of zirconium, specimens were implanted with aluminum ions with fluence ranging from 1 × 10¹⁶ to 1 × 10¹⁷ ions/cm², using a metal vapor vacuum arc source (MEVVA) at an extraction voltage of 40 kV. The valence states and depth distributions of elements in the surface layer of the samples were analyzed by X-ray photoelectron spectroscopy (XPS) and auger electron spectroscopy (AES), respectively. Transmission electron microscopy (TEM) was used to examine the microstructure of the aluminum-implanted samples. Glancing angle X-ray diffraction (GAXRD) was employed to examine the phase transformation due to the aluminum ion implantation. The potentiodynamic polarization technique was employed to evaluate the aqueous corrosion resistance of implanted zirconium in a 1 M H₂SO₄ solution. It was found that a significant improvement was achieved in the aqueous corrosion resistance of zirconium implanted with aluminum ions. Finally, the mechanism of the corrosion behavior of aluminum-implanted zirconium was discussed.     

Studies on the corrosion behavior of yttrium-implanted zircaloy-4

In order to study the effects of yttrium ion implantation on the aqueous corrosion behavior of zircaloy-4, specimens were implanted with yttrium ions using a MEVVA source at an energy of 40 keV, with a dose range from 1 × 10¹⁶ to 1 × 10¹⁷ ions/cm² at about 150°C. Transmission electron microscopy (TEM) was used to obtain the structural character of the yttrium-implanted zircaloy-4. The valence of the yttrium ions in the surface layer was analyzed by X-ray photoemission spectroscopy (XPS). Three-sweep potentiodynamic polarization measurement was employed to evaluate the aqueous corrosion behavior of zircaloy-4 in a 1 N H₂SO₄ solution. It was found that a significant improvement was achieved in the aqueous corrosion resistance of zircaloy-4 compared with that of the as-received zircaloy-4. The mechanism of the corrosion resistance improvement of the yttrium-implanted zircaloy-4 is probably due to the addition of the yttrium oxide dispersoid into the zirconium matrix.     

Studies on the corrosion behavior of cerium-implanted zircaloy-4 with GAXRD

In order to study the influence of cerium ion implantation on the aqueous corrosion behavior of zircaloy-4, specimens were implanted by cerium ions with a fluence range from 1×10¹⁶ to 1×10¹⁷ ions/cm² at maximum 150°C, using MEVVA source at an extracted voltage of 40 kV. The valence and elements penetration distribution of the surface layer were analyzed by X-ray photoelectron spectroscopy (XPS) and auger electron spectroscopy (AES) respectively. Glancing angle X-ray diffraction (GAXRD) was employed to examine the phase transformation due to the cerium ion implantation in the oxide films. Three-sweep potentiodynamic polarization measurement was employed to value the aqueous corrosion resistance of zircaloy-4 in a 1 N H₂SO₄ solution. It was found that a significant improvement in the aqueous corrosion behavior of zircaloy-4 implanted with cerium ions compared with that of the as-received zircaloy-4. The improvement effect will declined with raising the implantation fluence. The bigger is the fluence, the less is the improvement. Finally, the mechanism of the corrosion behavior of the cerium-implanted zircaloy-4 is discussed.     

Surface analysis of argon-implanted zircalloy-2 and influence of bubble formation on the corrosion behavior

In order to simulate the irradiation damage, argon ions were implanted into zircalloy-2 alloy with a fluence ranging from 1×10¹⁶ to 1×10¹⁷ ions/cm², using an implanter at an extraction voltage of 190 kV, at liquid nitrogen temperature. Then the effect of argon ion implantation on the aqueous corrosion behavior of zircalloy-2 alloy was studied. The valence states of elements in the surface layer of the samples were analyzed by X-ray photoelectron spectroscopy (XPS). Transmission electron microscopy (TEM) was used to examine the microstructure of the argon-implanted samples. Glancing angle X-ray diffraction (GAXRD) was employed to examine the phase transformation due to the argon ion implantation. The potentiodynamic polarization technique was employed to evaluate the aqueous corrosion resistance of implanted zircalloy-2 alloy in a 1 M H₂SO₄ solution. It was found that the bubbles were formed on the surface of implanted samples; the bubbles grew larger with increasing argon fluence. The microstructure of argon-implanted samples changed from amorphous to partial amorphous, then to polycrystalline and finally to amorphous. The bubble forming and changing and microstructure changes affected the corrosion properties of implanted samples. Finally, the mechanism of the corrosion behavior of argon-implanted zircalloy-2 alloy is discussed.     

Studies on the corrosion behavior of lanthanum-implanted zircaloy

In order to study the effects of the lanthanum ion implantation on the aqueous corrosion behavior of zircaloy, specimens were implanted with lanthanum ions using a MEVVA source at an energy of 40 keV, with a dose range from 5 × 10¹⁶ to 2 × 10¹⁷ ions/cm² at about 150°C. The surface structure was investigated by X-ray Diffraction (XRD) and the valence of the lanthanum ions in the surface layer was analyzed by X-ray Photoemission Spectroscopy (XPS). Three-sweep potentiodynamic polarization measurement was employed to evaluate the aqueous corrosion behavior of zircaloy in a 0.5 M H₂SO₄ solution. It was found that a significant improvement was achieved in the aqueous corrosion resistance of zircaloy compared with that of the as-received zircaloy. The mechanism of the corrosion resistance improvement of the lanthanum-implanted zircaloy is probably due to the addition of the lanthanum oxide dispersoid into the zircaloy matrix.Financed by Institute of Low Energy Nuclear Physics, Radition Beam and Materials Laboratory, Beijing Normal University     

Experimental investigation on corrosion and hardness of ion implanted AISI 316L stainless steel

The AISI 316L stainless steel has been widely used both in artificial knee and hip joints in bio-medical applications. In the present study AISI 316L SS was implanted with two different ions: nitrogen and helium at 100 keV with a dose of 1 × 10¹⁷ ions/cm² at room temperature. The crystallographic orientation and surface morphology were studied using X-ray diffraction (XRD) and scanning electron microscope (SEM). The effects of ion implantation on the corrosion performance of AISI 316L stainless steel was evaluated in 0.9% NaCl solution using electro chemical test both on the virgin and implanted samples. The subsequent Tafel analysis shows that the ion implanted specimens were more corrosion resistant when compared to the bare specimens. Microhardness was also measured by Vickers method by varying the loads. The results of the studies indicated that there was a significant improvement in both corrosion resistance and hardness of implanted samples.     

Properties of implanted PET by W ion using MEVVA implantation

Polyethylene terephthalane (PET) has been modified with W ions from a metal vapour arc source (MEVVA). W ions were implanted at 136 keV to doses ranging from 5×10¹⁵ to 2×10¹⁷/cm². The surface of the implanted PET darkened with increasing ion dose, when the metal ion dose is greater than 1×10¹⁷ cm⁻² the colour changed to metallic bright. The surface resistance obviously decreases with increasing dose. The resistivity is stable after long-term storage. TEM photos revealed the presence of W nanometer particles on the surface resulting from the high does implantation. The depth of implanted layer is approximately between 180 and 100 nm for W-implanted PET to doses of 2×10¹⁷/cm² and 5×10¹⁶/cm², respectively. The conductivity and wear resistance have been improved significantly due to W ion implantation. It can be seen that nanometer particles of W precipitation, and carbides have been formed in the implanted layer. The nano-hardness of the implanted PET has been measured by a nano-indenter. The results show that the surface hardness, modulus and wear resistance could be increased.     

Effect of Titanium ion implantation on the oxidation behaviour of zircalloy-4 at 500 °C

The beneficial effect of titanium ion implantation on the oxidation behaviour of zircalloy-4 at 500 °C was investigated. Titanium ions were implanted by a MEVVA source at an energy of 40 keV with dose 5×10¹⁶, 1×10¹⁷, and 2×10¹⁷ ion/cm² at the maximum temperature 130 °C. Weight gain curves of the as-received and implanted zircalloy-4 were measured after oxidation in air at 500 °C for 100 min. It was found that improvement was achieved in the oxidation behaviour of titanium ion implanted samples compared with that of the as-received one. The valence of the oxides in the scale was analyzed by X-ray photoemission spectroscopy. Glancing angle X-ray diffraction was used to examine the phase transformation in the oxide films and is showed that the addition of titanium transformed the phase from monoclinic zirconia to hexagonal zirconia. Finally, the mechanism of improvements oxidation behaviour is discussed.     

Phase formation and modification of corrosion property of nitrogen implanted Ti-Al-V alloy

In the present investigation, polished samples were implanted with nitrogen ion at an energy of 60 keV and implantation doses were 1×10¹⁶, 5×10¹⁶, 1×10¹⁷ and 6×10¹⁷ ions/cm². Glancing incidence X-ray diffraction was employed on the implanted specimens to understand the phases formed with increasing dose. The valence states of nitrogen, titanium and carbon on the sample surfaces were analyzed by X-ray photoemission spectroscopy. The corrosion resistance was examined by the electrochemical methods in a solution with pH=10 at room temperature in order to determine the optimum dose that can give good corrosion resistance in a simulated nuclear reactor condition. Scanning electron microscopy was used to observe the topographies of nitrogen-implanted Ti-Al-Zr after potentiodynamic measurement. It was found that implanted nitrogen dissolved in titanium matrix with increasing dose and the resultant nitrides such as TiN and Ti₂N precipitated. Implantation of nitrogen ions into the surface of Ti-Al-V alloy improves its corrosion resistance, and the increase of the corrosion resistance depends on the nitrogen dose employed; the maximum improvement of the corrosion resistance was observed at a dose of 1×10¹⁷ N⁺/cm².     

Influence of aluminum ions implanted on oxidation behavior of ZIRLO alloy at 500 °C

The beneficial effect of aluminum ion implantation on the oxidation behavior of ZIRLO alloy at 500 °C has been studied. ZIRLO alloy specimens were implanted with aluminum ions with fluence range from 1×10¹⁶ to 1×10¹⁸ ion/cm², using a MEVVA source at an extraction voltage of 40 kV at maximum temperature of 380 °C. The weight gain curves were measured after being oxidized in the air at 500 °C for 120 min, which showed that a significant improvement was achieved in the oxidation behavior of ZIRLO alloy implanted with aluminum compared with that of the virgin ZIRLO alloy. It has been obviously found that when the fluence is 1×10¹⁸ ion/cm², the oxidization of the implanted ZIRLO alloy is reduced into 30% of the virgin ZIRLO alloy.     

Effect of ion bombardment on the optical properties of LDPE/EPDM polymer blends

Ion bombardment is a suitable tool to improve the physical properties of polymers. In the present study, the effect of ion bombardment on the optical properties of low density polyethylene (LDPE)/Ethylene propylene diene monomer (EPDM) blend (LDPE/EPDM) was studied. Polymer samples was bombarded with 130 keV He and 320 keV Ar ions at fluencies levels ranging from 1 × 10¹³ to 2 × 10¹⁶ ions/cm². The untreated and ion beam bombarded samples were investigated using ultraviolet-visible (UV-Vis) spectrophotometry. The optical band gap (E_g), was decreased from ∼2.9 eV for the pristine sample down to 1.7 eV for the samples bombarded with He and Ar ions at the highest fluences. Change in the optical gap indicates the presence of a gradual phase transition for the polymer blends. Activation energy has been investigated as a function of the ion fluences. With increasing ion fluence, a decrease in both the energy gap and the activation energy was observed. The number of carbon atoms (N) in a formed cluster is determined according to the modified Tauc's equation.     

Effect of sodium-ion implantation on the properties of the surface layers formed on CoCrMo alloy (Endocast SL)

This paper is concerned with the surface modification of a cobalt alloy (Endocast) by sodium-ion implantation and with the effect of this modification on its corrosion resistance. The Na ions were implanted at doses of 1×10¹⁷ and 2×10¹⁷ ions/cm² at energy of 25 keV. The chemical composition of the surface layers formed during the implantation was examined by secondary ion mass spectrometry (SIMS) and X-ray photoelectron spectroscopy (XPS), and their microstructure by transmission electron microscopy (TEM). The corrosion resistance was determined by electrochemical methods in a simulated body fluid (SBF) at a temperature of 37 °C. Prior to the measurements, the samples were exposed to the test conditions for 13 h to allow the corrosion potential E_corr to stabilize, and for 181, 733 and 2200 h to investigate how the long-time exposures affect the corrosion resistance. The surfaces of the samples were examined by optical microscopy and by SEM-EDS. The TEM results indicate that the surface layers formed during the Na-implantation are amorphous. The results of the electrochemical examinations obtained for the Na-implanted Endocast samples indicate that the corrosion resistance of the alloy is reduced.     

Microstructural characterisation of alumina with Ti ion implantation

The microstructure of alumina after Ti ion implantation has been investigated. A metal vapourvacuum arc (MEVVA) ion source was employed to implant Ti ions into alumina with doses of7.6 × 10¹⁶ and 3.1 × 10¹⁷ ions/cm² at 40 kV. Scanning electronmicroscopy (SEM) of the irradiated surfaces revealed topographical changes, which were dependent ondose. The implanted layer was also characterised by Rutherford backscattering (RBS) andcross-sectional transmission electron microscopy (XTEM) which showed the lower Ti dose resulted in ahighly defective surface layer. In contrast, TiO₂ precipitates in anamorphous matrix were observed at the higher dose.     

Correlation between surface damage and micro-defects in Si covered with insulating layer by implantation of He and H ions

Cz n-type Si (100) wafers covered with a 220 nm SiO₂ layer or a 170 nm Si₃N₄ layer were singly implanted with 160 keV He ions at a dose of 5 × 10¹⁶/cm² or successively implanted with 160 keV He ions at a dose of 5 × 10¹⁶/cm² and 110 keV H ions at a dose of 1 × 10¹⁶/cm². Surface morphologies together with defect microstructures have been studied by means of several techniques, including optical microscopy, atomic force microscopy, and cross-sectional transmission electron microscopy (XTEM). Only surface blistering has been observed for He and H sequentially implanted SiO₂/Si samples after annealing in temperature range up to 1000 °C. However, as for the He and H implanted Si₃N₄/Si samples, surface features including blistering and the localized exfoliation of both the top Si₃N₄ layer and the implanted Si layer have been well demonstrated during subsequent annealing. XTEM observations reveal quite different defect morphologies in two kinds of materials under the same implantation and annealing conditions. The possible mechanisms of surface damage in two kinds of materials have been discussed and presented based on the XTEM results.     

100 keV nitrogen ion beam implanted polycarbonate: A possibility for UV blocking devices

Polycarbonate samples were implanted with 100 keV N⁺ ions at fluences 10¹⁵, 10¹⁶ and 5 × 10¹⁶ ions cm⁻². Drastic alterations in UV-Visible transmittance spectra were observed which are interrelated with change in surface color and optical absorption of the implanted samples. UV-Visible transmission studies show that at ion fluence of 10¹⁶ ions cm⁻², transmission approaches to zero at about λ = 427 nm and below up to 200 nm. Optical band gap (E_OPT) reduces with increase in fluence and at maximum ion fluence of 5 × 10¹⁶ N⁺ cm⁻², E_OPT was determined to be 1.56 eV whereas for pristine its value was 3.00 eV. Raman analysis indicates the formation of amorphous carbon on the surface of polycarbonate at an ion fluence of 10¹⁶ N⁺ cm⁻². Rise in fluence to 5 × 10¹⁶ N⁺ cm⁻² results in enhancement in disorder on the surface of the host polymer. Modifications in the structural arrangements were found to be in strong association with changes in optical properties with increase in ion fluence and the same is discussed.     

HI-ERDA, Micro-Raman and HRXRD studies of buried silicon oxynitride layers synthesized by dual ion implantation

Silicon oxynitride (Si_xO_yN_z) buried insulating layers were synthesized by dual implantation of nitrogen (¹⁴N⁺) and oxygen (¹⁶O⁺) ions sequentially into single crystal silicon in the ratio 1:1 at 150 keV to ion-fluences ranging from 1 × 10¹⁷ to 5 × 10¹⁷ cm⁻². Heavy ion elastic recoil analysis (HI-ERDA) studies of as implanted samples show Gaussian like distributions of nitrogen and oxygen. After annealing at 800 °C, both the nitrogen and oxygen distributions appear as flat plateau like regions near projected range showing the formation of a continuous buried oxynitride layer. Micro-Raman study of as implanted samples shows a broad peak at 480 cm⁻¹ for all fluences. It signifies a complete amorphization of silicon due to high fluence implantation. The annealing at 800 °C results in the reduction of the intensity of the broad peak observed at 480 cm⁻¹ and also gives rise to an additional peak at 517 cm⁻¹. It shows partial recrystallization of damaged silicon due to annealing. The X-ray rocking curves studies from high-resolution X-ray diffraction (HRXRD) of the samples implanted with different fluences have also further confirmed partial recrystallization of damaged silicon on annealing.     

Microstructure and electrochemical properties of Zircaloy-4 under Fe ion irradiation

To investigate the microstructure and electrochemical properties of Zircaloy-4 induced by Fe ion irradiation with the energy of 150 keV at liquid nitrogen temperature, transmission electron microscope analysis (TEM) was employed to analyze the surface layer of the samples irradiated at a dose ranging from 1×10¹³ to 1×10¹⁶ ions/cm², and potentiodynamic polarization measurements were used to evaluate the corrosion resistance of Zircaloy-4 in a 1 N H₂SO₄ solution at room temperature. TEM analyses show that Fe ion irradiation lead to a structural change and amorphous phase formation on the surface of the samples. Moreover, it is indicated from the corrosion tests that with an increase of the irradiation dose, the passive current density increases at first and then decreases rapidly, while the natural corrosion potential goes down at first and then up rapidly. The critical point, where the corrosion properties are transformed from a damaging stage to protecting stage, is at the damage level of 3.19 dpa. Finally, the mechanism for the change of corrosion resistance of the Zircaloy-4 samples is discussed.     

Annealing behavior of single mode planar waveguide in YVO4 produced by He ion implantation

We report, for the first time to our knowledge, the formation of single mode planar waveguide in z-cut YVO₄ by 400 keV, 500 keV He ion implantation in fluence of 3 × 10¹⁶ ions/cm² at room temperature or at liquid nitrogen temperature (77 K). We investigated annealing behavior of the guiding mode and near-field image in the waveguide by prism-coupling method and end-face coupling method respectively. We found that the effective refractive index of the TE₀ mode was different before and after annealing for the samples implanted at room temperature, while, annealing had nearly no influence on the effective refractive index of the TE₀ mode of the samples implanted at liquid nitrogen temperature (77 K). After annealing at 600 K for 1 h, no guiding mode was observed in the sample implanted by 400 keV He ion in fluence of 3 × 10¹⁶ ions/cm² at room temperature. The Rutherford backscattering/channeling technique was used to investigate the damage reduction after annealing treatments. The minimum yield of the implanted, annealed sample was 5.43%. We reconstructed the refractive index profiles in the waveguide under different condition by applying intensity calculation method.     

Concentration profiles of Zn ions implanted with 60 keV for nanoparticle formation in silica glass

Surface recession due to sputtering under low-energy and high-fluence heavy-ion implantation makes shallower and broader depth profile of implanted ions than those calculated by conventional ion-range simulation-codes such as SRIM. Depth profiles of Zn atoms in silica glasses (SiO₂) implanted with Zn⁺ ions of 60 keV up to 1.0×10¹⁷ ions/cm² were evaluated using both experimental methods as Rutherford backscattering spectrometry (RBS), sputtering depth-profiling by X-ray photoelectron spectroscopy (XPS), and an advanced numerical simulation code TRIDYN, which includes the sputtering loss effects. The TRIDYN code predicts the shallowing of the projectile range from ∼46 to ∼27 nm with increasing the fluence up to 1×10¹⁷ ions/cm², and very high-concentration (∼20 at%) of Zn atoms close to the surface. However, RBS and XPS results exclude such high concentration close to the surface. These results suggest remarkable redistribution of Zn atoms from the nearer surface to the deeper region during the implantation. In fact, Zn-atom concentration near the surface and that near the projectile range are, respectively, lower and higher than those by the SRIM code predictions.     

Implantation of silicon ions into a surface layer of the Ti6A14V titanium alloy and its effect upon the corrosion resistance and structure of this layer

The effect of silicon ion implantation upon the corrosion resistance and structure of the surface layers formed during the implantation in the Ti6A14V titanium alloy was examined. The silicon doses were 0.5, 1.5, 3.0 and 4.5 × 10¹⁷Si⁺/cm², and the ion beam energy was 100 keV. The corrosion resistance of the samples exposed to a 0.9% NaCl solution at a temperature of 37 °C was measured using electrochemical methods. The structure of the surface layers formed during the implantation was examined by a transmission electron microscope (TEM). The results of the corrosion resistance examinations have shown that the unimplanted and 0.5 × 10¹⁷Si⁺/cm² implanted samples undergo uniform corrosion. At higher silicon doses, the samples show pitting corrosion. The highest corrosion resistance was shown by the alloy implanted with 0.5 × 10¹⁷Si⁺/cm². It has been found that, after a long-term (1200 h) exposure to a 0.9% NaCl solution, the corrosion resistance of the samples is greater than that observed after a short-term exposure. TEM examinations have shown that, beginning from a dose of 1.5 × 10¹⁷Si⁺/cm², the surface of the Ti6A14V alloy samples becomes amorphous. Heating of the 1.5 × 10¹⁷Si⁺/cm² implanted samples at 200 and 500 °C does not change their structure, whereas after heating at 650 °C, the amorphous phase vanishes.