Fretting wear behavior of nitrogen ion implanted titanium alloys in bovine serum lubrication

Nitrogen ion implantation was performed on biomedical titanium alloys by using of the PBII technology to improve the surface mechanical properties for the application of artificial joints. The titanium nitride phase was characterized with X-ray photoelectron spectroscopy (XPS). The nanohardness of the titanium alloys and implanted samples were measured by using of in-situ nano-mechanical testing system (TriboIndenter). Then, the fretting wear of nitrogen ion implanted titanium alloys was done on the universal multifunctional tester (UMT) with ball-on-flat fretting style in bovine serum lubrication. The fretting wear mechanism was investigated with scanning electron microscopy (SEM) and 3D surface profiler. The XPS analysis results indicate that nitrogen diffuses into the titanium alloy and forms a hard TiN layer on the Ti6Al4V alloys. The nanohardness increases from 6.40 to 7.7 GPa at the normal load of 2 mN, which reveals that nitrogen ion implantation is an effective way to enhance the surface hardness of Ti6Al4V. The coefficients of friction for Ti6Al4V alloy in bovine serum are obviously lower than that in dry friction, but the coefficients of friction for nitrogen ion implanted Ti6Al4V alloy in bovine serum are higher than that in dry friction. Fatigue wear controls the fretting failure mechanism of nitrogen ion implanted Ti6Al4V alloy fretting in bovine serum. The testing results in this paper prove that nitrogen ion implantation can effectively increase the fretting wear resistance for Ti6Al4V alloy in dry friction, and has a considerable improvement for Ti6Al4V alloy in bovine serum lubrication.     

Instrument combining x-ray photoelectron spectroscopy and secondary ion mass spectrometry for surface studies

X-ray Photoelectron Spectroscopy (XPS) or (ESCA) and Secondary Ion Mass Spectrometry (SIMS) have been combined in the same ultrahigh vacuum system to facilitate a new approach to studying clean and reacted surfaces. The design philosophy is to connect two satellite vacuum systems via a set of magnetically driven sample transfer devices. The advantages and capabilities of this approach are discussed with respect to its flexibility and its ability to couple to other surface techniques. XPS and static SIMS spectra of an oxidized polycrystalline indium film are presented to exemplify the type of information which can be gleaned from a multitechnique investigation of surfaces. The additional ability to prepare sample surfaces in our system by ion implantation is demonstrated by a positive-ion SIMS analysis of a gold-implanted aluminum foil.     

天然产物的质谱研究 Ⅷ.寡糖甙与Na~ 加合离子的快原子轰击质谱和质量分离离子动能谱

研究了三种糖甙与Na~ 加合离子的快原子轰击质谱(FABMS)和质量分离离子动能谱(MIKES)。实验结果表明,当把这几种糖甙与氯化钠(NaCI)一起加到基质中时,在FAB谱中出现丰度相当高的[M Na]~ 加合离子,它的丰度比[M H]~ 要高得多。[M Na]~ 离子的MIKES为这些甙所连糖的序列分析提供了方便的方法。     

Influence of ion source configuration and its operation parameters on the target sputtering and implantation process

In the work, investigation of the features and operation regimes of sputter enhanced ion-plasma source are presented. The source is based on the target sputtering with the dense plasma formed in the crossed electric and magnetic fields. It allows operation with noble or reactive gases at low pressure discharge regimes, and, the resulting ion beam is the mixture of ions from the working gas and sputtering target. Any conductive material, such as metals, alloys, or compounds, can be used as the sputtering target. Effectiveness of target sputtering process with the plasma was investigated dependently on the gun geometry, plasma parameters, and the target bias voltage. With the applied accelerating voltage from 0 to 20 kV, the source can be operated in regimes of thin film deposition, ion-beam mixing, and ion implantation. Multi-component ion beam implantation was applied to α-Fe, which leads to the surface hardness increasing from 2 GPa in the initial condition up to 3.5 GPa in case of combined N(2)-C implantation. Projected range of the implanted elements is up to 20 nm with the implantation energy 20 keV that was obtained with XPS depth profiling.     

Torsional fretting wear of a biomedical Ti6Al7Nb alloy for nitrogen ion implantation in bovine serum

Ti6Al7Nb is a high-strength titanium alloy used in replacement hip joints that possesses the excellent biocompatibility necessary for surgical implants. Ti6Al7Nb treated with nitrogen gas (N₂) plasma immersion ion implantation–deposition (PIII–D) was investigated. Torsional fretting wear tests of untreated and nitrogen-ion-implanted Ti6Al7Nb alloys against a Zr₂O ball (diameter 25.2 mm) were carried out under simulated physiological conditions (serum solution) in a torsional fretting wear test rig. Based on the analyses of the frictional kinetics behavior, the observation of 3D profiles, SEM morphologies and surface composition analyses, the damage characteristics of the surface modification layer and its substrate are discussed in detail. The influence of nitrogen ion density on the implantation and torsional angular displacement amplitudes were investigated. The results indicated that ion implantation layering can improve resistance to torsional fretting wear and thus has wide potential application for the prevention of torsional fretting damage in artificial implants. The damage mechanism prevented by the ion implantation layer on the Ti6Al7Nb alloy is a combination of oxidative wear, delamination and abrasive wear. An increase in ion implantation concentration inhibited detachment by delamination.     

Alloy liquid metal ion sources and their application in mass separated focused ion beams

For special purposes like writing ion implantation or ion mixing in the micrometer- or sub-micrometer range different ion species are needed. Therefore alloy liquid metal ion sources (LMISs) are used. The energy distribution of the ions from an alloy LMIS is one of the determining factors for the performance of a FIB column. Different source materials like Au(73)Ge(27), Au(82)Si(18), Au(77)Ge(14)Si(9), Co(36)Nd(64), Er(69)Ni(31), and Er(70)Fe(22)Ni(5)Cr(3) were investigated with respect to the energy spread of the different ion species as a function of emission current, ion mass and emitter temperature. The alloy LMISs discussed above have been used in the Rossendorf FIB system IMSA especially for writing implantation to fabricate sub-micrometer pattern without any lithographic steps. A Co-FIB was applied for the ion beam synthesis of CoSi(2) micro-structures. Additionally, the possibility of varying the current density with the FIB by changing the pixel dwell time was used for radiation damage investigations in Si and SiC at elevated implantation temperatures. Furthermore, a broad spectrum of ions was employed to study the sputtering process depending on temperature, angle of incidence and ion mass on a couple of target materials using the volume-loss method. Especially this technique was used for the fabrication of various kinds of micro-tools.     

Focused ion beam fabrication of solidified ferritin into nanoscale volumes for compositional analysis using atom probe tomography

The purpose of this investigation was to conduct atom probe tomography (APT) analyses on ferritin specimens prepared with focused ion beam (FIB) to assess whether this approach can be used to effectively characterize biomaterials. Soft matter is particularly sensitive to ion beam exposure which can induce physical and chemical changes. We employ protective metal films and low-energy ion fluence to mitigate potential problems that may be introduced by FIB. This study had two major objectives: (1) to qualitatively assess the viability of the specimens when subjected to the unique physical conditions of APT analysis, namely ultrahigh vacuum, high electric field, and thermal pulsing using a laser and (2) to quantitatively assess the data from such specimens under various experimental parameters and compare the results with appropriate control specimens. For the first objective, a range of experimental parameters were determined that met the basic criteria necessary to validate that ferritin-based specimens prepared with FIB can retain structural integrity during APT analysis. Initial field evaporation time-of-flight mass spectrometry (TOF-MS) data show that the specimens fabricated with FIB are capable of emitting ions under various laser pulsing conditions with a high electric field applied. For the second objective, the experimental parameter space was narrowed to a range that yielded data quality sufficient to produce meaningful comparison between the ferritin-based specimens and the salt-only controls.     

A study on development of advanced environmental-resistant materials using metal ion processing

The development of the oxidation, wear and corrosion resistant materials that could be used in severe environmental conditions is needed. The elementary technologies for surface modification include ion implantation and/or thin film coating. Furthermore, in order to develop ion implantation technique to the specimens with three-dimensional shapes, plasma-based ion implantation (PBII) techniques were investigated. As a result, it was found that the ion implantation and/or thin film coating used in this study were/was effective for improving the properties of materials, which include implantations of various kinds of ions into TiAl alloy, TiN films formed on surface of base material and coatings in high-temperature steam. The techniques proposed in this study provide useful information for all of the material systems required to use at elevated temperature. For the practical applications, several results will be presented along with laboratory test results.     

用XPS研究Na_2S钝化的GaAs(100)表面

本文用Na_2S·9H_2O的水溶液及乙醇和异丙醇溶液对GaAs表面进行了钝化处理;用X射线光电子能谱仪(XPS)对钝化表面的化学组成和价态以及钝化层的厚度进行了研究。结果表明,经不同的Na_2S溶液处理后GaAs表面的自然氧化层会被除去,表面生成硫化镓和硫化砷;硫化物的含量与硫化层厚度与所用溶液的极性有关;并对钝化机理进行了探讨。     

Cryo-X-ray analysis-A novel tool to better understand the physicochemical reactions at the bioglass/biological fluid interface

The present study deals with the short-term physicochemical reactions at the interface between bioactive glass particles [55SiO(2)-20CaO-9P(2)O(5)-12Na(2)O-4MgO. mol%] and biological fluid (Dulbecco Modified Eagle's Medium (DMEM)). The physicochemical reactions within the interface are characterized by scanning transmission electron microscopy (TEM) (STEM) associated with Energy-dispersive X-ray spectroscopy (EDXS). Microanalysis of diffusible ions such as sodium, potassium, or oxygen requires a special care. In the present investigation the cryo-technique was adopted as a suitable tool for the specimen preparation and characterization. Cryosectioning is essential for preserving the native distribution of ions so that meaningful information about the local concentrations can be obtained by elemental microanalysis. The bioglass particles immersed in biological fluid for 24 h revealed five reaction stages: (i) dealkalization of the surface by cationic exchange (Na(+), Ca(2+) with H(+) or H(3)O(+)); (ii) loss of soluble silica in the form of Si(OH)(4) to the solution resulting from the breakdown of Si--O--Si bonds (iii); repolymerization of Si(OH)(4) leading to condensation of SiO(2)); (iv) migration of Ca(2+) and PO(4) (3-) to the surface through the SiO(2)-rich layer to form CaO-P(2)O(5) film; (v) crystallization of the amorphous CaO-P(2)O(5) by incorporating OH-- or CO(3) (2-) anions with the formation of three different surface layers on the bioactive glass periphery. The thickness of each layer is approximately 300 nm and from the inner part to the periphery they consist of Si--OH, which permits the diffusion of Ca(2+) and PO(4) (3-) ions and the formation of the middle Ca--P layer, and finally the outer layer composed of Na--O, which acts as an ion exchange layer between Na(+) ions and H(+) or H(3)O(+) from the solution.     

The Preparation and Tribological Investigation of Ni–P Amorphous Alloy Nanoparticles

Amorphous Ni–P alloy nanoparticles were synthesized by chemical reduction of nickel acetate in water reacted with sodium hypophosphite under stirring. The nanoparticles were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Results of XRD and TEM showed that nanoparticles have an average diameter 100 nm. And XPS analysis indicated that part of the surface of Ni–P amorphous alloy nanoparticles was oxidized. The tribological properties of the prepared Ni–P nanoparticles as an additive in lithium grease were evaluated with a four-ball friction and wear tester. The worn surfaces of the lubricated GCr15 steel were analyzed by means of XPS and scanning electron microscopy (SEM). The lubricating mechanisms were discussed on the basis of XPS and SEM analyses of the worn steel surfaces. The results show that these nanoparticles as a grease additive can effectively enhance the friction-reduction and antiwear ability of lithium grease. Tribochemical reactions were involved for steel–steel frictional pair lubricated with the lithium grease containing amorphous Ni–P alloy nanoparticles, with the formation of a boundary lubricating and protecting film composed of additives of lithium grease and tribochemical reaction products (iron phosphate, iron oxides, nickel oxide, nickel, etc.) of the lubricants. This contributes to improve the tribological properties of the lithium grease.     

Quasicrystalline Materials

SIMS matrix effects (mass interferences, sputter yield variations and practical ion yield variations) were evaluated in freeze-fractured, freeze-dried cultured cells at the ～0.5 μm spatial resolution of the Cameca IMS-3f ion microscope. Cell lines studied include normal rat kidney (NRK), 3T3 mouse fibroblast, L6 rat myoblast, chinese hamster ovary (CHO) and rat kangaroo kidney (PtK2) cells. High mass resolution studies indicated that the secondary ion signals of H^—, C^—, O^—, Na⁺, Mg⁺, CN^—, P^—, S^—, Cl^—, K⁺ and Ca⁺ were free from major mass interferences. However, a large mass interference was observed for nitrogen at mass 14. No significant sputtering yield difference between the nuclear and cytoplasmic compartments of the cells studied was observed. The subcellular distributions of the major (H, C, N and O) and minor (P, S, K, Cl, Na, Mg and Ca) matrix elements were found to be largely homogeneous with the exception of Ca, which was observed mainly in the cell cytoplasm. Practical ion yield variations were compared by three different approaches: (i) by the use of cells doped with known electrolyte concentrations, (ii) by quantitative ion implantation, and (iii) by analysis of the same cell with both electron probe and ion microscope. Each approach indicated an absence of significant practical ion yield differences between the nuclear and cytoplasmic regions of these specimens. These observations indicate that secondary ion signals in this type of sample are not significantly affected by local matrix effect variations. Hence, qualitative imaging of such specimens provides a true representation of subcellular elemental distribtions. These observations should allow the development of quantitative ion imaging methodologies and enhance the applicability of ion microscopy to biomedical problems.     

Investigation on the tribology of Zr ion implanted tool steel

AISI D3 tool steel was ion implanted with zirconium and the improvement in surface tribological properties investigated. The Zr ion implantation was done using a metal vapor vacuum arc (Mevva) broad-beam ion source, with a mean ion energy of 130 keV and at doses of 3.6×10¹⁶, 5×10¹⁶ and 1×10¹⁷ ions/cm². Wear, friction and hardness of the implanted samples were measured and compared to the performance of unimplanted steel. The wear resistance was increased by about a factor of two, the friction remained about the same or was possibly increased by a small amount and the near-surface hardness was improved by a factor of five or more by the ion implantation. We also investigated the effect on the Zr implantation profile of the multi-component energy distribution of the ion beam.     

Improvement of surface electrical conductivity in poly carbonate composite by nitrogen ion implantation

This study is to investigate the nitrogen ion implantation process in PC (Polycarbonate) composite for improving surface electrical conductivity. The suggested process is applied for the thin wall shape polymer which is composed of low carbon black and carbon fiber in order to increase electric conductivity. The acceleration voltage which is relatively low 3∼50 keV in ion implantation process is used to obtain the thin conductive surface layer around 2 micrometer. The surface electrical conductivity of PC composite is realized up to below 10⁶ Ω/cm² by controlling ion dose without degrading mechanical properties. This technology can be adopted to make conductive plastic product which is applicable for static electricity prevention and electromagnetic wave masking. In order to evaluate the effect of surface modification of PC by nitrogen ion implantation, its surface resistance, tensile strength, tensile elongation, and half-life have been measured. The properties of PC/CF and PC/CB increased surface resistance and tensile strength. Also, the properties of PC/CF and PC/CB significantly decreased tensile elongation and half-life.     

Effect of nitrogen ion implantation on impact wear

The effect of nitrogen ion implantation on the impact wear of several metals and alloys with different hardnesses was studied. An impact testing machine was built for this study. In this machine, bullet-shaped projectiles are bounced against a metal surface which is either stationary or rotating. Wear was determined by weight loss measurements. Scanning electron microscopy pictures were taken to study the surface damage. It was found that nitrogen ion implantation improved the impact wear of most of the materials studied. With sliding motion added during the impact, nitrogen ion implantation has little effect.     

Ion implantation and surface modification in tribology

Ion implantation is a vacuum process by which virtually any element can be injected into the surface regions of a solid target. Current interest in materials technology and recent developments in ion implantation machines have resulted in ion-induced surface property changes in a variety of different fields including tribology. Large changes in friction coefficient (up to ± 60%) have been recorded on steel surfaces implanted with such ions as Pb⁺ and Sn⁺. Implantation of boron, nitrogen and molybdenum reduces wear by more than a factor of 10, from measurements with a pin-and-disc machine. An outline is given of the scope and application of ion implantation and the results evaluated in the context of the testing methods used. Examples are given of some present and future applications of ion implantation to tribology.     

离子束金属材料表面改性技术

本文综述了国内外离子束金属材料表面改性技术的研究概况,叙述了离子镀、离子注入、离子束混合、离子束增强沉积和等离子体浸没离子注入等表面技术的特点和应用.     

离子色谱-三重四极杆质谱联用法测定奶粉中氟乙酸钠

采用离子色谱-三重四极杆质谱联用技术测定奶粉中氟乙酸钠。奶粉样品经3%高氯酸超声提取,除去蛋白和脂肪等杂质,在pH 0.5~1.0条件下提取液中氟乙酸钠被叔丁基甲醚萃取,萃取液氮吹浓缩后溶于0.1%(V/V)氨水,以IonPac AS 19型阴离子色谱柱（2 mm×250 mm×7.5 μm）作为分离柱,以自动在线产生的氢氧化钾为淋洗液进行梯度分离,色谱柱流出液经阴离子抑制器抑制后进入质谱系统,电喷雾电离负离子多反应监测模式（MRM）检测,稳定同位素内标法定量分析。结果表明：奶粉中氟乙酸钠的平均加标回收率为89.7%~104%,相对标准偏差在0.50%~11%之间(n=6),方法的检出限（S/N≥3）为0.2 μg/kg,定量限（S/N≥10）为0.6 μg/kg。本法操作简单、灵敏度高、准确性好,可用于奶粉中氟乙酸钠的检测。     

油溶性CuO纳米颗粒的抗磨性能研究

利用四球摩擦磨损实验机考察了油酸铜修饰CuO纳米颗粒作为润滑油添加剂的抗磨性能,并用扫描电子显微镜（SEM）和X-射线光电子能谱（XPS）等对钢球磨损表面进行了分析。摩擦磨损试验结果表明,当添加质量分数仅为0.025%时,油酸铜修饰CuO纳米颗粒作为润滑油添加剂即能够明显提高基础油的抗磨能力。SEM及XPS分析结果表明,油酸铜修饰CuO纳米颗粒作为润滑油添加剂在摩擦过程中形成了一层富含Cu2O和Fe2O3的化学反应膜,正是这层膜的存在使得其表现出良好的抗磨性能。     

甘草酸钾盐和甘草酸钠盐的电喷雾离子阱质谱研究

用(+)电喷雾离子阱质谱对三元有机弱酸甘草酸的钾盐和钠盐进行了研究。结果显示,甘草酸的一级、二级和三级钾盐或钠盐均可产生很强的质子化分子离子峰;在甘草酸各级钾盐和钠盐的质子化分子离子的二级质谱中,可产生丢失一个葡萄糖醛酸单元的子离子,同时出现双葡萄糖醛酸单元加合相应金属离子的子离子,并且以上子离子均包含与母离子相同数目的相应金属离子。因此,(+)ESI离子阱质谱是区别甘草酸各级钾盐和钠盐的一种有效手段。另外,在甘草酸二钾和甘草酸二钠的(+)ESI-MS一级质谱中,可清楚地观察到一级盐和三级盐的质子化离子,表明甘草酸二盐在水溶液中存在分子间的离子交换