To improve the corrosion resistance of biodegradable Mg alloys,WE43 alloys were implanted with Fe,Ti,Zn and Zr ions at the same implantation dose.The surface morphology,valence state of elements,nano-hardness(NH),elas...To improve the corrosion resistance of biodegradable Mg alloys,WE43 alloys were implanted with Fe,Ti,Zn and Zr ions at the same implantation dose.The surface morphology,valence state of elements,nano-hardness(NH),elastic modulus(EM),degradation rate and in vitro cell experiments of the modified WE43 alloys were systematically studied.A modified layer composed of Mg,MgO,the implanted elements and their oxides was formed on the modified alloys.Since high-speed metal ions caused severe surface lattice damage,the surface hardness of the substrate considerable increased.Electrochemical tests demonstrated a substantial enhancement in the corrosion resistance of the modified alloys via the implantation of Ti and Zr ions,resulting in a reduction of the corrosion current density to 88.1±9.9 and 15.6±11.4μA cm^(−2),respectively,compared with the implantation of Fe and Zn ions.Biocompatibility tests showed that the implantation of Fe,Ti,Zn and Zr ions enhanced the anticoagulant and hemolytic resistance of the WE43 alloy.All surface-modified samples showed negligible cytotoxicity(0-1)at 12.5%extract concentration.Moreover,the alloys implanted with Fe,Ti and Zn ions significantly promoted proliferation of human umbilical vein endothelial cells(HUVEC)compared with the unmodified alloy.The results demonstrate that Ti ion implantation is the best choice for WE43 alloy modification to achieve outstanding corrosion resistance and biocompatibility.展开更多
Silicon Carbide (SiC) wafers have been widely used in micro- and nano-devices due to their excellent optical and material properties. However, polishing SiC wafers has been challenging and inefficient, tending to caus...Silicon Carbide (SiC) wafers have been widely used in micro- and nano-devices due to their excellent optical and material properties. However, polishing SiC wafers has been challenging and inefficient, tending to cause significant surface crack and subsurface damage. This work proposed modifying SiC surface properties by ion implantation to improve machining efficiency, suppress surface crack, and reduce damage. High-energy ion implantation disrupted the SiC crystal lattice, reducing hardness and elastic modulus while increasing brittle-ductile transition depth, thus changing the removal mode from brittle fracture to plastic removal. Theoretical models of material removal rate and surface roughness were established for abrasive polishing of the SiC wafers. Polishing experiments were conducted on ion-implanted, modified SiC samples. The improvement mechanisms of ion implantation on surface damage, removal rate, morphology, and residual stress were investigated. The effect of ion implantation on the polished surface quality of SiC was investigated through orthogonal experiments. The results showed that ion implantation can significantly improve the average material removal rate of the SiC samples. Additionally, the ion-implanted samples had exhibited remarkable reductions in surface roughness, surface damage, and tensile residual stress.展开更多
To enhance the corrosion resistance and electrical conductivity, the surface of 316L stainless steel was modified by the ion implantation of Mo. By investigating various accelerating voltages and implantation doses, i...To enhance the corrosion resistance and electrical conductivity, the surface of 316L stainless steel was modified by the ion implantation of Mo. By investigating various accelerating voltages and implantation doses, it was found that the corrosion resistance of stainless steel was enhanced by 50%-80% and the surface conductivity by 15%-28% at most. The minimum stabilized current density is 0.72 μA/cm^(2). This is due to the formation of a Cr and Mo riched modified layer on the surface of the stainless steel. Mo oxides synergize with Cr oxides in the form of a solid solution to enhance the corrosion resistance of passivation films on the stainless steel surface. The optimum parameters were Cr in the proportion of 6%-8% and Mo in the proportion of 4%-5%.展开更多
Ion implantation technology is a crucial strategy for modulating the degradation behavior of biomedical magnesium alloys.In this study,Ag,Ti,and Zr ions were implanted into the surface of pure Mg at varying doses to i...Ion implantation technology is a crucial strategy for modulating the degradation behavior of biomedical magnesium alloys.In this study,Ag,Ti,and Zr ions were implanted into the surface of pure Mg at varying doses to investigate their effects on the microstructure and properties of pure Mg.The results revealed that differences in the affinities of Mg and the implanted elements for reacting with oxygen led to the formation of implanted layers with distinct compositions and structures.Specifically,Ag ion implantation resulted in a layer predominantly composed of elemental silver,while Ti and Zr ion implantation promoted the formation of a denser layer containing Mg,MgO,the implanted elements,and their respective oxides.This layer significantly enhanced the corrosion resistance of pure Mg by reducing its susceptibility to corrosive media.Electrochemical assessments showed a substantial reduction in corrosion current density following Ti and Zr ion implantation.However,increasing doses of Ag ions induced heightened susceptibility to galvanic corrosion due to the electrode potential differences between Ag and Mg,thereby accelerating the degradation of the pure Mg substrate.Additionally,first-principles calculations of the work functions for both the (0001) basal plane and the(101 0) prism plane of Mg corroborated the observed electrochemical trends.展开更多
In vertical channel transistors(VCTs),source/drain ion implantation(I/I)represents a significant technical challenge due to inherent three-dimensional structural constraints,which induce complications such as difficul...In vertical channel transistors(VCTs),source/drain ion implantation(I/I)represents a significant technical challenge due to inherent three-dimensional structural constraints,which induce complications such as difficulties in dummy gate forma-tion and shadowing effects of I/I.This article systematically investigates the impact of different implantation conditions on the performance of VCTs with and without dummy gates through TCAD simulation.It reveals the significant role of the lightly doped regions(LDRs)naturally formed due to ion implantation in source/drain of VCTs.Furthermore,it was found that VCT with-out dummy gates can achieve an approximately 27%increase in on-state current(Ion)under the same implantation conditions,and can greatly simplify the process flow and reduce costs.Finally,N-type and P-type VCTs were successfully fabricated using this implantation method.展开更多
Various doses of nitrogen ions were implanted into the surface of pure titanium, Ti6Al7Nb and Ti6Al4V, by plasma immersion ion implantation. Torsional fretting wear tests involving flat specimens of no-treated and tre...Various doses of nitrogen ions were implanted into the surface of pure titanium, Ti6Al7Nb and Ti6Al4V, by plasma immersion ion implantation. Torsional fretting wear tests involving flat specimens of no-treated and treated titanium, as well as its alloys, against a ZrO2 ball contact were performed on a torsional fretting wear test rig using a simulated physiological medium of serum solution. The treated surfaces were characterized, and the effect of implantation dose on torsional fretting behavior was discussed in detail. The results showed that the torsional fretting running and damage behavior of titanium and its alloys were strongly dependent on the dose of the implanted nitrogen ions and the angular displacement amplitude. The torsional fretting running boundary moved to smaller angular displacement amplitude, and the central light damage zone decreased, as the ion dose increased. The wear mechanisms of titanium and its alloys were oxidative wear, abrasive wear and delamination, with abrasive wear as the most common mechanism of the ion implantation layers.展开更多
The biological effects during seed germination were investigated after the dry seeds of Stevia rebaudianum Bertoni were implanted with carbon ion beam of 75 keV and 10 14 ions/cm 2. The results showed that the g...The biological effects during seed germination were investigated after the dry seeds of Stevia rebaudianum Bertoni were implanted with carbon ion beam of 75 keV and 10 14 ions/cm 2. The results showed that the germination rate of carbon ion implanted seeds was slightly higher than that of the control, but the survival rate of the treated seedlings, on the contrary, was lower than that of the control (P<0.02), while the height of the treated seedlings was significantly higher than that of the control (P<0.01). On the 4th day after germination, the leaf cell wall in the treated group was thick, some high electron_dense substance deposited in the enlarged plasmodesma; Cell membrane creased with high electron_dense granules deposited on it. The plasma membrane protruded towards cell wall, and the granules shifted via plasmodesma or deposited onto cell wall. These phenomena may be related to the conveyance of implanted ions across cell wall, or be related to the accumulation of callose. In addition, the implantation of carbon ions could increase the lamellae of the chloroplast and cause high development of the chloroplast which sometimes contained two plastid centers in an individual chloroplast. Also, the highly developed cristae, abundant mitochondria and typical crystalloid structure in microbody could be found. All these results indicated that the anabolic and catabolic activities in the seedlings implanted with carbon ions before germination were obviously more active than those in the controls.展开更多
A high speed LIGBT with localized lifetime control by using high dose and low en ergy helium implantation(LC-LIGBT) is proposed.Compared with conventional LIGB Ts,particle irradiation results show that trade-off relat...A high speed LIGBT with localized lifetime control by using high dose and low en ergy helium implantation(LC-LIGBT) is proposed.Compared with conventional LIGB Ts,particle irradiation results show that trade-off relationship between turn- off time and forward voltage drop is improved.At the same time,the forward volta ge drop and turn-off time of such device are researched,when localized lifetime control region place near the p+-n junction,even in p+ anode.The results s how for the first time,helium ions,which stop in the p+ anode,also contribute to the forward voltage drop increasing and turn-off time reducing.展开更多
A1 and N were introduced into copper substrate using plasma immersion ion implantation （PIII） in order to enhance its hardness and oxidation resistance. The dosage of N ion is 5 × 1016 cm-2, and range of dosage...A1 and N were introduced into copper substrate using plasma immersion ion implantation （PIII） in order to enhance its hardness and oxidation resistance. The dosage of N ion is 5 × 1016 cm-2, and range of dosage of A1 ion is 5× 1016-2× 1017 cm-2. The oxidation tests indicate that the copper samples after undergoing PIII possess higher oxidation resistance. The degree of oxidation resistance is found to vary with implantation dosage of AI ion. The antibacterial tests also reveal that the plasma implanted copper specimens have excellent antibacterial resistance against Staphylococcus aureus, which are similar to pure copper.展开更多
To improve the total-dose radiation hardness,silicon-on-insulator （SOI） wafers fabricated by the separation-by-implanted-oxygen （SIMOX） method are modified by Si ion implantation into the buried oxide with a post ...To improve the total-dose radiation hardness,silicon-on-insulator （SOI） wafers fabricated by the separation-by-implanted-oxygen （SIMOX） method are modified by Si ion implantation into the buried oxide with a post anneal. The ID- VG characteristics can be tested with the pseudo-MOSFET method before and after radiation. The results show that a proper Si-ion-implantation method can enhance the total-dose radiation tolerance of the materials.展开更多
The research on plasma immersion ion implantation has been conducted for a little over ten years. Much is needed to investigate including processing technlogy, plasma sheath dynamics, interaction of plasma and surface...The research on plasma immersion ion implantation has been conducted for a little over ten years. Much is needed to investigate including processing technlogy, plasma sheath dynamics, interaction of plasma and surface, etc. Of the processing methods elavated temperature technique is usually used in PIII to produce a thick modified layer by means of the thermal diffusion. Meanwhile plasma ion heating is more recently developed by Ronghua Wei et al[1]. Therefore the temeperature is a critical parameter in plasma ion processing. In this paper we present the theoretical model and analysize the effect of imlantation voltage, plasma density, ion mass,etc on the temperature rise.展开更多
Niobium ion implantation is found to significantly decrease the friction coefficient and improve wear resistance of NiTi shape memory alloy. Scanning electron microscope（SEM） observations indicate that surface groov...Niobium ion implantation is found to significantly decrease the friction coefficient and improve wear resistance of NiTi shape memory alloy. Scanning electron microscope（SEM） observations indicate that surface grooves formed on NiTi during the mechanical polishing are removed after Nb ion implantation. Dry friction tests show that Nb implanted NiTi samples exhibit a lower friction coefficient, narrower wear tracks, fewer wear debris generated, 46 %-62 % reduction in wear width, and29 %-49 % reduction in wear depth compared with the untreated NiTi. Wear resistance is related to the incident parameters, and the Nb implanted NiTi with the incident dose of 2.5 9 1017ionsácm-2, and incident current of2 mA behaves the best wear performance. The lubricating of Nb2O5, good oxidation resistance of Nb in NiTi, and increased micro-hardness of NiTi are responsible for the enhanced wear resistance.展开更多
Titanium carbide coatings are widely used as various wear-resistant material. The hydrogen erosion resistance of TiC-C films and the effect of hydrogen participation on TiC-C films were studied. Seventy-five percent T...Titanium carbide coatings are widely used as various wear-resistant material. The hydrogen erosion resistance of TiC-C films and the effect of hydrogen participation on TiC-C films were studied. Seventy-five percent TiC-C films are prepared on stainless steel surface by using ion mixing, where TiC-C films are deposited by rf magnetron sputtering followed by argon ion bombardment. The samples are then submitted to hydrogen ion implantation at 1.2 × 10^-3 Pa. Characterization for the 75% TiC-C films was done with SIMS, XRD, AES, and XPS. Secondary ion mass spectroscopy （SIMS） was used to analyze hydrogen concentration variation with depth, X-Ray diffraction （XRD） was used to identify the phases, and Auger electron spectra （AES） as well as X-ray photoelectron spectra （XPS） were used to check the effects of hydrogen on shifts of chemical bonding states of C and Ti in the TiC-C films. It is found that TiC-C films on stainless steel surface can prevent hydrogen from entering stainless steel.展开更多
In order to enhance the antibacterial ability of titanium components,an antibacterial coating was fabricated on Ti surface by micro-arc oxidation(MAO)and further nitrogen plasma immersion ion implantation(N-PIII).The ...In order to enhance the antibacterial ability of titanium components,an antibacterial coating was fabricated on Ti surface by micro-arc oxidation(MAO)and further nitrogen plasma immersion ion implantation(N-PIII).The XPS spectra demonstrated that nitrogen was incorporated into TiO2 coatings by N-PIII and the nitrogen content on the surface of TiO2 coatings increased as the N-PIII time increased.Nitrogen-incorporated samples exhibited remarkably increased absorbance in the visible region and the light absorption edge of nitrogen-incorporated samples showed a redshift compared to MAO samples.Escherichia coli and Staphylococcus aureus were seeded on the samples to assess their antibacterial ability.The bacterial experiment demonstrated that nitrogen-incorporated TiO2 could effectively reduce the bacterial viability in visible light.Thus,the antibacterial TiO2 coatings fabricated by MAO and further N-PIII might have large potential in the medical and marine fields.展开更多
As bearing parts, 12 Cr2 Ni4 A is expected to have high hardness and excellent fatigue strength, so carburizing is employed to improve the inherit properties of 12 Cr2 Ni4 A. However, the traditional carburizing is li...As bearing parts, 12 Cr2 Ni4 A is expected to have high hardness and excellent fatigue strength, so carburizing is employed to improve the inherit properties of 12 Cr2 Ni4 A. However, the traditional carburizing is limited by poor microstructure distribution and low rate of carburizing. The rare earth ion implantation is known to help improving the properties of tribology, corrosion resistance and oxidation resistance of metal. In this article, the RE implantation is employed to assist the carburizing. Lanthanum and cerium ion implantations are initially used to assist 12 Cr2 Ni4 A low pressure vacuum carburization.The microstructure, content of retained austenite, hardness, thickness of layer and carbon diffusion were analyzed by optical microscopy(OM), scanning electron microscopy(SEM), X-ray diffraction(XRD) and Rockwell/Vickers hardness tester, respectively. It was shown that lanthanum and cerium implantations can improve structure of the vacuum carburizing layer, and enhance the uniformity of carbon element distribution on the carburized surface. Meanwhile the RE implantation plays a positive role in promoting the surface hardness and carburized rate. The lanthanum element has more significant effect on surface hardness and content of retained austenite than cerium element. The surface hardness of lanthanum element implanted layer was 62.9 HRC with 9.6% content of retained austenite, while the carburizing rate of cerium implanted layer increased by 12.4%.展开更多
The tribology behaviors of Ti6Al7Nb,its alloy with N-ion implantation,and its alloy with diamond-like carbon(DLC)coating were investigated in artificial saliva.Fretting wear tests of untreated,N-ion implanted and DLC ...The tribology behaviors of Ti6Al7Nb,its alloy with N-ion implantation,and its alloy with diamond-like carbon(DLC)coating were investigated in artificial saliva.Fretting wear tests of untreated,N-ion implanted and DLC coated Ti6Al7Nb alloys plate against a Si3N4ball were carried out on a reciprocating sliding fretting wear test rig.Based on the analysis of X-ray diffraction,Raman spectroscopy,3-D profiler,SEM morphologies and frictional kinetics behavior analysis,the damage behavior of surface modification layer was discussed in detail.The results indicated that the fretting wear behavior of Ti6Al7Nb alloy with N-ion implantation was increased with the dose increase of the implanted nitrogen ions.Moreover,the DLC-coated Ti6Al7Nb alloy with low ion implantation could improve the fretting wear behavior greatly.In addition,the Ti6Al7Nb with DLC coating had better ncorrosion resistance due to the special compact structure.All results suggested that the Ti6Al7Nb with DLC coating had better wear resistance than that with N-ion implantation in artificial saliva.展开更多
With ion implantation (N+, energy 10 keV and dosage 1.56×1015 N+cm-2), a high xylanase-producing strain Aspergillus niger N212 was selected. Based on an orthogonal experiment, an optimal fermentation condition wa...With ion implantation (N+, energy 10 keV and dosage 1.56×1015 N+cm-2), a high xylanase-producing strain Aspergillus niger N212 was selected. Based on an orthogonal experiment, an optimal fermentation condition was designed for this high-yield strain. The suitable medium was composed of 8% corncob; 1.0% wheat bran; 0.1%TWEEN20; 0.5% (NH4)2SO4; 0.5%NaNO3; 0.5%FeSO4, 7.5 × 10-4; MnSO4·H2O, 2.5 × 10-4; ZnSO4, 2.0 × 10-4; CoCl2, 3.0 × 10-4. At present, under our experiment condition, xylanase activity of Aspergillus niger N212 reached a level of 600 IU/ml, almost increased by 100% in xylanase production and the time of yielding xylanase was largely reduced to 12 h at 28℃.展开更多
Magnesium alloys have a wide range of applications in industry; however, their corrosion resistance, wear resistance, and hardness are rather poor, which limit their applications. Ti ion was implanted into the AZ31 ma...Magnesium alloys have a wide range of applications in industry; however, their corrosion resistance, wear resistance, and hardness are rather poor, which limit their applications. Ti ion was implanted into the AZ31 magnesium alloy surface by metal vapor vacuum arc （MEVVA） implanter. This metal arc ion source has a broad beam and high current capabilities. The implantation energy was fixed at 45 keV and the dose was at 9×10^17 cm^-2. Through ion implantation, Ti ion implantation layer with approximately 900 um in thickness was directly formed on the surface of AZ31 magnesium alloy, by which its surface property greatly improved. The chemical states of some typical elements of the ion implantation layer were analyzed by means of X-ray photoelectron spectroscopy （XPS）, while the cross sectional morphology of the ion implantation layer and the phase structure were observed by means of scanning electron microscopy （SEM） and X-ray diffraction （XRD）. The property of corrosion resistance of the Ti ion implanted layer was studied by the CS300P electrochemistry corrosion workstation in 3.5% NaCl solution. The results showed that the property of corrosion resistance was enhanced remarkably, while the corrosion velocity was obviously slowed down.展开更多
This paper reports that ion implantation to a dose of 1 ×10^17 ions/cm^2 was performed on c-axis-orientated ZnO thin films deposited on （0001） sapphire substrates by the sol-gel technique. After ion implantatio...This paper reports that ion implantation to a dose of 1 ×10^17 ions/cm^2 was performed on c-axis-orientated ZnO thin films deposited on （0001） sapphire substrates by the sol-gel technique. After ion implantation, the as-implanted ZnO films were annealed in argon ambient at different temperatures from 600 - 900 ℃. The effects of ion implantation and post-implantation annealing on the structural and optical properties of the ZnO films were investigated by x-ray diffraction （XRD）, photoluminescence （PL）. It was found that the intensities of （002） peak and near band edge （NBE） exitonic ultraviolet emission increased with increasing annealing temperature from 600- 900 ℃. The defect related deep level emission （DLE） firstly increased with increasing annealing temperature from 600 - 750 ℃, and then decreased quickly with increasing annealing temperature. The recovery of the intensities of NBE and DLE occurs at ～850℃ and ～750℃ respectively. The relative PL intensity ratio of NBE to DLE showed that the quality of ZnO films increased continuously with increasing annealing temperature from 600 - 900 ℃.展开更多
Plasma-immersion ion implantation (PIII) is a technique for implanting ions into conducting, semiconducting and insulating objects. In PIII, the object being treated is immersed in a plasma and pulsed to a large negat...Plasma-immersion ion implantation (PIII) is a technique for implanting ions into conducting, semiconducting and insulating objects. In PIII, the object being treated is immersed in a plasma and pulsed to a large negative voltage (=-1 to-100 kV). The resulting sheath expands into the ambient plasma, extracting ions and accelerating them to the target. PIII has advantages over beam-line implantation in that large surfaces can be rapidly implanted, irregularly-shaped objects can be implanted without target manipulation, and surfaces that are not line-of-sight accessible can be treated. A two-dimensional, self-consistent model of plasma dynamics appropriate for PIII is described. The model is a hybrid, with Boltzmann electrons and kinetic ions, where the ion Vlasov equation is solved using the particle-in-cell (PIC) method. Solutions of the model give the time dependence of the ion flux, energy and impact angle at the target surface, together with the evolution of the sheath.展开更多
基金supported by National Natural Science Foundation of China(52271117)Educational Commission of Hunan Province of China(23A0107)High Technology Research and Development Program of Hunan Province of China(2022GK4038).
文摘To improve the corrosion resistance of biodegradable Mg alloys,WE43 alloys were implanted with Fe,Ti,Zn and Zr ions at the same implantation dose.The surface morphology,valence state of elements,nano-hardness(NH),elastic modulus(EM),degradation rate and in vitro cell experiments of the modified WE43 alloys were systematically studied.A modified layer composed of Mg,MgO,the implanted elements and their oxides was formed on the modified alloys.Since high-speed metal ions caused severe surface lattice damage,the surface hardness of the substrate considerable increased.Electrochemical tests demonstrated a substantial enhancement in the corrosion resistance of the modified alloys via the implantation of Ti and Zr ions,resulting in a reduction of the corrosion current density to 88.1±9.9 and 15.6±11.4μA cm^(−2),respectively,compared with the implantation of Fe and Zn ions.Biocompatibility tests showed that the implantation of Fe,Ti,Zn and Zr ions enhanced the anticoagulant and hemolytic resistance of the WE43 alloy.All surface-modified samples showed negligible cytotoxicity(0-1)at 12.5%extract concentration.Moreover,the alloys implanted with Fe,Ti and Zn ions significantly promoted proliferation of human umbilical vein endothelial cells(HUVEC)compared with the unmodified alloy.The results demonstrate that Ti ion implantation is the best choice for WE43 alloy modification to achieve outstanding corrosion resistance and biocompatibility.
基金support from the China Postdoctoral Science Foundation(No.2023M742735)the Postdoctoral Fellowship Program of CPSF,China(No.GZC20232029)+5 种基金the National Natural Science Foundation of China(No.52475530)the Shaanxi Postdoctoral Science Foundation,China(No.2023BSHEDZZ175)the Innovation Capability Support Program of Shaanxi Province,China(No.2021TD-23)the Key Industrial Chain Core Technology Research Project in Xi’an,China(No.23LLRH0029)the Natural Science Basic Research Program of Shaanxi,China(No.2024JC-YBQN-0490)the Fundamental Research Funds for the Central Universities,China(No.ZYTS24023).
文摘Silicon Carbide (SiC) wafers have been widely used in micro- and nano-devices due to their excellent optical and material properties. However, polishing SiC wafers has been challenging and inefficient, tending to cause significant surface crack and subsurface damage. This work proposed modifying SiC surface properties by ion implantation to improve machining efficiency, suppress surface crack, and reduce damage. High-energy ion implantation disrupted the SiC crystal lattice, reducing hardness and elastic modulus while increasing brittle-ductile transition depth, thus changing the removal mode from brittle fracture to plastic removal. Theoretical models of material removal rate and surface roughness were established for abrasive polishing of the SiC wafers. Polishing experiments were conducted on ion-implanted, modified SiC samples. The improvement mechanisms of ion implantation on surface damage, removal rate, morphology, and residual stress were investigated. The effect of ion implantation on the polished surface quality of SiC was investigated through orthogonal experiments. The results showed that ion implantation can significantly improve the average material removal rate of the SiC samples. Additionally, the ion-implanted samples had exhibited remarkable reductions in surface roughness, surface damage, and tensile residual stress.
基金supported by the National Natural Science Foundation of China(22005140)Scientific Research Foundation for the Introduction of Talents by Nanjing Institute of Technology(YKJ201996)Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX22_1370).
文摘To enhance the corrosion resistance and electrical conductivity, the surface of 316L stainless steel was modified by the ion implantation of Mo. By investigating various accelerating voltages and implantation doses, it was found that the corrosion resistance of stainless steel was enhanced by 50%-80% and the surface conductivity by 15%-28% at most. The minimum stabilized current density is 0.72 μA/cm^(2). This is due to the formation of a Cr and Mo riched modified layer on the surface of the stainless steel. Mo oxides synergize with Cr oxides in the form of a solid solution to enhance the corrosion resistance of passivation films on the stainless steel surface. The optimum parameters were Cr in the proportion of 6%-8% and Mo in the proportion of 4%-5%.
基金financially supported by the National Natural Science Foundation of China(Nos.52271117 and 52401064)Hunan Provincial Natural Science Foundation of China(Nos.2021JJ30646 and 2023JJ10020)+2 种基金Educational Commission of Hunan Province of China(No.23A0107)Scientific Research Fund of Hunan Provincial Education Department(No.24B0172)Shaanxi Provincial Key R&D Program(No.2024CY2-GJHX-71)
文摘Ion implantation technology is a crucial strategy for modulating the degradation behavior of biomedical magnesium alloys.In this study,Ag,Ti,and Zr ions were implanted into the surface of pure Mg at varying doses to investigate their effects on the microstructure and properties of pure Mg.The results revealed that differences in the affinities of Mg and the implanted elements for reacting with oxygen led to the formation of implanted layers with distinct compositions and structures.Specifically,Ag ion implantation resulted in a layer predominantly composed of elemental silver,while Ti and Zr ion implantation promoted the formation of a denser layer containing Mg,MgO,the implanted elements,and their respective oxides.This layer significantly enhanced the corrosion resistance of pure Mg by reducing its susceptibility to corrosive media.Electrochemical assessments showed a substantial reduction in corrosion current density following Ti and Zr ion implantation.However,increasing doses of Ag ions induced heightened susceptibility to galvanic corrosion due to the electrode potential differences between Ag and Mg,thereby accelerating the degradation of the pure Mg substrate.Additionally,first-principles calculations of the work functions for both the (0001) basal plane and the(101 0) prism plane of Mg corroborated the observed electrochemical trends.
文摘In vertical channel transistors(VCTs),source/drain ion implantation(I/I)represents a significant technical challenge due to inherent three-dimensional structural constraints,which induce complications such as difficulties in dummy gate forma-tion and shadowing effects of I/I.This article systematically investigates the impact of different implantation conditions on the performance of VCTs with and without dummy gates through TCAD simulation.It reveals the significant role of the lightly doped regions(LDRs)naturally formed due to ion implantation in source/drain of VCTs.Furthermore,it was found that VCT with-out dummy gates can achieve an approximately 27%increase in on-state current(Ion)under the same implantation conditions,and can greatly simplify the process flow and reduce costs.Finally,N-type and P-type VCTs were successfully fabricated using this implantation method.
基金Projects(U1530136,51375407)supported by the National Natural Science Foundation of China
文摘Various doses of nitrogen ions were implanted into the surface of pure titanium, Ti6Al7Nb and Ti6Al4V, by plasma immersion ion implantation. Torsional fretting wear tests involving flat specimens of no-treated and treated titanium, as well as its alloys, against a ZrO2 ball contact were performed on a torsional fretting wear test rig using a simulated physiological medium of serum solution. The treated surfaces were characterized, and the effect of implantation dose on torsional fretting behavior was discussed in detail. The results showed that the torsional fretting running and damage behavior of titanium and its alloys were strongly dependent on the dose of the implanted nitrogen ions and the angular displacement amplitude. The torsional fretting running boundary moved to smaller angular displacement amplitude, and the central light damage zone decreased, as the ion dose increased. The wear mechanisms of titanium and its alloys were oxidative wear, abrasive wear and delamination, with abrasive wear as the most common mechanism of the ion implantation layers.
文摘The biological effects during seed germination were investigated after the dry seeds of Stevia rebaudianum Bertoni were implanted with carbon ion beam of 75 keV and 10 14 ions/cm 2. The results showed that the germination rate of carbon ion implanted seeds was slightly higher than that of the control, but the survival rate of the treated seedlings, on the contrary, was lower than that of the control (P<0.02), while the height of the treated seedlings was significantly higher than that of the control (P<0.01). On the 4th day after germination, the leaf cell wall in the treated group was thick, some high electron_dense substance deposited in the enlarged plasmodesma; Cell membrane creased with high electron_dense granules deposited on it. The plasma membrane protruded towards cell wall, and the granules shifted via plasmodesma or deposited onto cell wall. These phenomena may be related to the conveyance of implanted ions across cell wall, or be related to the accumulation of callose. In addition, the implantation of carbon ions could increase the lamellae of the chloroplast and cause high development of the chloroplast which sometimes contained two plastid centers in an individual chloroplast. Also, the highly developed cristae, abundant mitochondria and typical crystalloid structure in microbody could be found. All these results indicated that the anabolic and catabolic activities in the seedlings implanted with carbon ions before germination were obviously more active than those in the controls.
文摘A high speed LIGBT with localized lifetime control by using high dose and low en ergy helium implantation(LC-LIGBT) is proposed.Compared with conventional LIGB Ts,particle irradiation results show that trade-off relationship between turn- off time and forward voltage drop is improved.At the same time,the forward volta ge drop and turn-off time of such device are researched,when localized lifetime control region place near the p+-n junction,even in p+ anode.The results s how for the first time,helium ions,which stop in the p+ anode,also contribute to the forward voltage drop increasing and turn-off time reducing.
基金Project(9231083) supported by Yunnan Aerospace Industry Corporation Contract Research,ChinaProject(9220061) supported by City University of Hong Kong Donation Research Grant,China
文摘A1 and N were introduced into copper substrate using plasma immersion ion implantation （PIII） in order to enhance its hardness and oxidation resistance. The dosage of N ion is 5 × 1016 cm-2, and range of dosage of A1 ion is 5× 1016-2× 1017 cm-2. The oxidation tests indicate that the copper samples after undergoing PIII possess higher oxidation resistance. The degree of oxidation resistance is found to vary with implantation dosage of AI ion. The antibacterial tests also reveal that the plasma implanted copper specimens have excellent antibacterial resistance against Staphylococcus aureus, which are similar to pure copper.
文摘To improve the total-dose radiation hardness,silicon-on-insulator （SOI） wafers fabricated by the separation-by-implanted-oxygen （SIMOX） method are modified by Si ion implantation into the buried oxide with a post anneal. The ID- VG characteristics can be tested with the pseudo-MOSFET method before and after radiation. The results show that a proper Si-ion-implantation method can enhance the total-dose radiation tolerance of the materials.
文摘The research on plasma immersion ion implantation has been conducted for a little over ten years. Much is needed to investigate including processing technlogy, plasma sheath dynamics, interaction of plasma and surface, etc. Of the processing methods elavated temperature technique is usually used in PIII to produce a thick modified layer by means of the thermal diffusion. Meanwhile plasma ion heating is more recently developed by Ronghua Wei et al[1]. Therefore the temeperature is a critical parameter in plasma ion processing. In this paper we present the theoretical model and analysize the effect of imlantation voltage, plasma density, ion mass,etc on the temperature rise.
基金financially supported by the National Basic Research Program of China(No.2012CB619403)the National Natural Science Foundation of China(No.51171009)the Tan Chin-Tuan exchange fellowship funding in Nanyang Technological University
文摘Niobium ion implantation is found to significantly decrease the friction coefficient and improve wear resistance of NiTi shape memory alloy. Scanning electron microscope（SEM） observations indicate that surface grooves formed on NiTi during the mechanical polishing are removed after Nb ion implantation. Dry friction tests show that Nb implanted NiTi samples exhibit a lower friction coefficient, narrower wear tracks, fewer wear debris generated, 46 %-62 % reduction in wear width, and29 %-49 % reduction in wear depth compared with the untreated NiTi. Wear resistance is related to the incident parameters, and the Nb implanted NiTi with the incident dose of 2.5 9 1017ionsácm-2, and incident current of2 mA behaves the best wear performance. The lubricating of Nb2O5, good oxidation resistance of Nb in NiTi, and increased micro-hardness of NiTi are responsible for the enhanced wear resistance.
基金Item Sponsored by National Natural Science Foundation of China (98061001)Foundation of the Institute of Engineering Physics of China(9603025)
文摘Titanium carbide coatings are widely used as various wear-resistant material. The hydrogen erosion resistance of TiC-C films and the effect of hydrogen participation on TiC-C films were studied. Seventy-five percent TiC-C films are prepared on stainless steel surface by using ion mixing, where TiC-C films are deposited by rf magnetron sputtering followed by argon ion bombardment. The samples are then submitted to hydrogen ion implantation at 1.2 × 10^-3 Pa. Characterization for the 75% TiC-C films was done with SIMS, XRD, AES, and XPS. Secondary ion mass spectroscopy （SIMS） was used to analyze hydrogen concentration variation with depth, X-Ray diffraction （XRD） was used to identify the phases, and Auger electron spectra （AES） as well as X-ray photoelectron spectra （XPS） were used to check the effects of hydrogen on shifts of chemical bonding states of C and Ti in the TiC-C films. It is found that TiC-C films on stainless steel surface can prevent hydrogen from entering stainless steel.
基金Projects(51831011,31670980)supported by the National Natural Science Foundation of ChinaProject(51525207)supported by the National Natural Science Foundation for Distinguished Young Scholars of ChinaProjects(18YF1426900,18410760600)supported by the Science and Technology Commission of Shanghai Municipality,China.
文摘In order to enhance the antibacterial ability of titanium components,an antibacterial coating was fabricated on Ti surface by micro-arc oxidation(MAO)and further nitrogen plasma immersion ion implantation(N-PIII).The XPS spectra demonstrated that nitrogen was incorporated into TiO2 coatings by N-PIII and the nitrogen content on the surface of TiO2 coatings increased as the N-PIII time increased.Nitrogen-incorporated samples exhibited remarkably increased absorbance in the visible region and the light absorption edge of nitrogen-incorporated samples showed a redshift compared to MAO samples.Escherichia coli and Staphylococcus aureus were seeded on the samples to assess their antibacterial ability.The bacterial experiment demonstrated that nitrogen-incorporated TiO2 could effectively reduce the bacterial viability in visible light.Thus,the antibacterial TiO2 coatings fabricated by MAO and further N-PIII might have large potential in the medical and marine fields.
基金The National Natural Science Foundation of China(51575118,51375106)National Basic Research Program of China(973 Program)(No.61328303)+1 种基金China Postdoctoral Science Foundation(2017T100225)Fundamental Research Funds for the Central Universities(No.HEUCFP201608)
文摘As bearing parts, 12 Cr2 Ni4 A is expected to have high hardness and excellent fatigue strength, so carburizing is employed to improve the inherit properties of 12 Cr2 Ni4 A. However, the traditional carburizing is limited by poor microstructure distribution and low rate of carburizing. The rare earth ion implantation is known to help improving the properties of tribology, corrosion resistance and oxidation resistance of metal. In this article, the RE implantation is employed to assist the carburizing. Lanthanum and cerium ion implantations are initially used to assist 12 Cr2 Ni4 A low pressure vacuum carburization.The microstructure, content of retained austenite, hardness, thickness of layer and carbon diffusion were analyzed by optical microscopy(OM), scanning electron microscopy(SEM), X-ray diffraction(XRD) and Rockwell/Vickers hardness tester, respectively. It was shown that lanthanum and cerium implantations can improve structure of the vacuum carburizing layer, and enhance the uniformity of carbon element distribution on the carburized surface. Meanwhile the RE implantation plays a positive role in promoting the surface hardness and carburized rate. The lanthanum element has more significant effect on surface hardness and content of retained austenite than cerium element. The surface hardness of lanthanum element implanted layer was 62.9 HRC with 9.6% content of retained austenite, while the carburizing rate of cerium implanted layer increased by 12.4%.
文摘The tribology behaviors of Ti6Al7Nb,its alloy with N-ion implantation,and its alloy with diamond-like carbon(DLC)coating were investigated in artificial saliva.Fretting wear tests of untreated,N-ion implanted and DLC coated Ti6Al7Nb alloys plate against a Si3N4ball were carried out on a reciprocating sliding fretting wear test rig.Based on the analysis of X-ray diffraction,Raman spectroscopy,3-D profiler,SEM morphologies and frictional kinetics behavior analysis,the damage behavior of surface modification layer was discussed in detail.The results indicated that the fretting wear behavior of Ti6Al7Nb alloy with N-ion implantation was increased with the dose increase of the implanted nitrogen ions.Moreover,the DLC-coated Ti6Al7Nb alloy with low ion implantation could improve the fretting wear behavior greatly.In addition,the Ti6Al7Nb with DLC coating had better ncorrosion resistance due to the special compact structure.All results suggested that the Ti6Al7Nb with DLC coating had better wear resistance than that with N-ion implantation in artificial saliva.
文摘With ion implantation (N+, energy 10 keV and dosage 1.56×1015 N+cm-2), a high xylanase-producing strain Aspergillus niger N212 was selected. Based on an orthogonal experiment, an optimal fermentation condition was designed for this high-yield strain. The suitable medium was composed of 8% corncob; 1.0% wheat bran; 0.1%TWEEN20; 0.5% (NH4)2SO4; 0.5%NaNO3; 0.5%FeSO4, 7.5 × 10-4; MnSO4·H2O, 2.5 × 10-4; ZnSO4, 2.0 × 10-4; CoCl2, 3.0 × 10-4. At present, under our experiment condition, xylanase activity of Aspergillus niger N212 reached a level of 600 IU/ml, almost increased by 100% in xylanase production and the time of yielding xylanase was largely reduced to 12 h at 28℃.
基金This work was financially supported by the Scientific Research Common Program of Beijing Municipal Commission of Education (No. KM200510017005).
文摘Magnesium alloys have a wide range of applications in industry; however, their corrosion resistance, wear resistance, and hardness are rather poor, which limit their applications. Ti ion was implanted into the AZ31 magnesium alloy surface by metal vapor vacuum arc （MEVVA） implanter. This metal arc ion source has a broad beam and high current capabilities. The implantation energy was fixed at 45 keV and the dose was at 9×10^17 cm^-2. Through ion implantation, Ti ion implantation layer with approximately 900 um in thickness was directly formed on the surface of AZ31 magnesium alloy, by which its surface property greatly improved. The chemical states of some typical elements of the ion implantation layer were analyzed by means of X-ray photoelectron spectroscopy （XPS）, while the cross sectional morphology of the ion implantation layer and the phase structure were observed by means of scanning electron microscopy （SEM） and X-ray diffraction （XRD）. The property of corrosion resistance of the Ti ion implanted layer was studied by the CS300P electrochemistry corrosion workstation in 3.5% NaCl solution. The results showed that the property of corrosion resistance was enhanced remarkably, while the corrosion velocity was obviously slowed down.
文摘This paper reports that ion implantation to a dose of 1 ×10^17 ions/cm^2 was performed on c-axis-orientated ZnO thin films deposited on （0001） sapphire substrates by the sol-gel technique. After ion implantation, the as-implanted ZnO films were annealed in argon ambient at different temperatures from 600 - 900 ℃. The effects of ion implantation and post-implantation annealing on the structural and optical properties of the ZnO films were investigated by x-ray diffraction （XRD）, photoluminescence （PL）. It was found that the intensities of （002） peak and near band edge （NBE） exitonic ultraviolet emission increased with increasing annealing temperature from 600- 900 ℃. The defect related deep level emission （DLE） firstly increased with increasing annealing temperature from 600 - 750 ℃, and then decreased quickly with increasing annealing temperature. The recovery of the intensities of NBE and DLE occurs at ～850℃ and ～750℃ respectively. The relative PL intensity ratio of NBE to DLE showed that the quality of ZnO films increased continuously with increasing annealing temperature from 600 - 900 ℃.
文摘Plasma-immersion ion implantation (PIII) is a technique for implanting ions into conducting, semiconducting and insulating objects. In PIII, the object being treated is immersed in a plasma and pulsed to a large negative voltage (=-1 to-100 kV). The resulting sheath expands into the ambient plasma, extracting ions and accelerating them to the target. PIII has advantages over beam-line implantation in that large surfaces can be rapidly implanted, irregularly-shaped objects can be implanted without target manipulation, and surfaces that are not line-of-sight accessible can be treated. A two-dimensional, self-consistent model of plasma dynamics appropriate for PIII is described. The model is a hybrid, with Boltzmann electrons and kinetic ions, where the ion Vlasov equation is solved using the particle-in-cell (PIC) method. Solutions of the model give the time dependence of the ion flux, energy and impact angle at the target surface, together with the evolution of the sheath.
