共查询到20条相似文献,搜索用时 15 毫秒
1.
Edward P. Vicenzi Stephen Eggins Amelia Logan Richard Wysoczanski 《Journal of research of the National Institute of Standards and Technology》2002,107(6):719-727
An initial study of the minor element, trace element, and impurities in Corning archeological references glasses have been performed using three microbeam techniques: electron probe microanalysis (EPMA), laser ablation ICP-mass spectrometry (LA ICP-MS), and secondary ion mass spectrometry (SIMS). The EPMA results suggest a significant level of heterogeneity for a number of metals. Conversely, higher precision and a larger sampling volume analysis by LA ICP-MS indicates a high degree of chemical uniformity within all glasses, typically <2 % relative (1 σ). SIMS data reveal that small but measurable quantities of volatile impurities are present in the glasses, including H at roughly the 0.0001 mass fraction level. These glasses show promise for use as secondary standards for minor and trace element analyses of insulating materials such as synthetic ceramics, minerals, and silicate glasses. 相似文献
2.
Eric S. Windsor Robert A. Carlton Greg Gillen Scott A. Wight David S. Bright 《Journal of research of the National Institute of Standards and Technology》2002,107(6):663-679
Copper oxide has been detected in the copper containing alloys of NBS Standard Reference Material (SRM) 482. This occurrence is significant because it represents heterogeneity within a standard reference material that was certified to be homogeneous on a micrometer scale. Oxide occurs as elliptically to spherically shaped precipitates whose size differs with alloy composition. The largest precipitates occur in the Au20-Cu80 alloy and range in size from submicrometer up to 2 μm in diameter. Precipitates are observed using light microscopy, electron microscopy, and secondary ion mass spectrometry (SIMS). SIMS has demonstrated that the precipitates are present within all the SRM 482 wires that contain copper. Only the pure gold wire is precipitate free. Initial results from the analysis of the Au20-Cu80 alloy indicate that the percentage of precipitates is less than 1 % by area. Electron probe microanalysis (EPMA) of large (2 μm) precipitates in this same alloy indicates that precipitates are detectable by EPMA and that their composition differs significantly from the certified alloy composition. The small size and low percentage of these oxide precipitates minimizes the impact that they have upon the intended use of this standard for electron probe microanalysis. Heterogeneity caused by these oxide precipitates may however preclude the use of this standard for automated EPMA analyses and other microanalysis techniques. 相似文献
3.
Jianglei Fan Liubo Liang Zhanyun Liu Yuwen Li Ying Li Hongxia Gao 《Materials Science & Technology》2019,35(8):891-899
Intermetallic TiAl alloys are new generation high-temperature material. However, extensive application of TiAl alloys is hindered by some disadvantages, especially the high processing cost. Currently, precision casting is an effective method to manufacture TiAl components with complex shape. However, the interfacial reaction between the TiAl alloy melt and mould affects the quality of the castings and hinders extensive applications of casting TiAl components. In this paper, the research status of mould materials for the casting of TiAl alloys is reviewed. Performances of present used mould materials are compared in details. Reaction mechanisms between mould materials and the melts of TiAl alloys are also summarised. Finally, the future development tendency and prospect are pointed out. 相似文献
4.
We herein report the fabrication of highly porous titanium (Ti) scaffolds with unusually high compressive strength by freezing a titanium hydride (TiH2)/camphene slurries at 42 °C. As the freezing time was increased from 1 to 7 days, the pore size obtained was increased significantly from 143 to 271 μm due to the continual overgrowth of camphene dendrites. However, interestingly, the formation of the micro-pores inside the Ti walls was suppressed at longer freezing time. This resulted in a significant increase in compressive strength up to 110 ± 17 MPa with a porosity of 64%. It is believed that this unusually high compressive strength with large interconnected pores makes this material suitable for applications as load-bearing parts. 相似文献
5.
Fabrication of titanium scaffolds with porosity and pore size gradients by sequential freeze casting
This paper reports a novel method for producing porous Ti scaffolds with a gradient in porosity and pore size using the freeze casting method, in which TiH2/camphene slurries with various TiH2 contents (40, 25, and 10 vol.%) were cast sequentially into a mold, followed by freeze drying and heat-treatment in a vacuum at 1300 °C for 3 h. This simple sequential freeze casting method produced good bonding between the layers with different porosities of 35, 53, and 75 vol.% obtained using the TiH2 contents of 40, 25 and 10 vol.%, respectively. In addition, the pore size could be increased significantly by increasing the freezing time. The pore sizes obtained in the regions produced using 40, 25, and 10 vol.% TiH2 after freezing for 7 days were 96, 166, and 270 μm, respectively. 相似文献
6.
Y. Zou 《Thin solid films》2007,515(13):5524-5527
C-TiC films with a content of 75% TiC were prepared with magnetron sputtering deposition followed by Ar+ ion bombardment. Effect of heating on the behaviors of hydrogen in C-TiC films before and after heating was studied with Auger Electron Spectroscopy and Secondary Ion Mass Spectroscopy (SIMS) analyses. SIMS depth profiles of hydrogen after H+ ion implantation and thermal treatment show different hydrogen concentrations in C-TiC coatings and stainless steel. SIMS measurements show the existence of TiH, TiH2, CH3, CH4, C2H2 bonds in the films after H+ ion irradiation and the changes in the Ti LMM, Ti LMV and C KLL Auger line shape reveal that they have a good hydrogen retention ability after heating up to the temperature 393 K. All the results show that C-TiC coatings can be used as a hydrogen retainer or hydrogen permeable barrier on stainless steel to protect it from hydrogen brittleness. 相似文献
7.
《Materials at High Temperatures》2013,30(3-4):505-519
AbstractSecondary ion mass spectrometry (SIMS) is widely used to investigate the oxidation mechanism of alumina formers, being various MeCrAl (Me=Fe, Ni, Co) alloys and β-NiAl intermetallic compound. Frequently, it is combined with dedicated oxidation exposures, mostly in atmospheres containing different amounts of oxygen tracer (18O2) in order to investigate the scale growth mechanism. However, there are several practical aspects which have to be taken into account during planning the oxidation experiments as well as during interpretation of their results in order to avoid misleading conclusions. In particular, the effects related to the formation of non-uniform scales as well as to the relationship between the exposure conditions and the scale microstructure and morphology at various stages of its growth should be dealt with.This paper discusses the implications of sputtering process with respect to elemental in-depth distribution profiling and the results of the oxidation mechanism investigation of various alumina formers by means of SIMS. It is shown that the obtained shapes of the SIMS profiles and images strongly depend on the choice of the exposure conditions and on the analysis parameters, including the spatial resolution. The exposure conditions are related to the scale microstructure and morphology, the evolution of which occurs during the oxidation process. Formation of duplex alumina scale is reported which comprises an inner more compact sub-layer and an outer ridged and less-compact sub-layer. 相似文献
8.
The aim of this work is to understand the characteristics of the pozzolanic reactivity of nanoSiO2 from studies of its pozzolanic reaction kinetics, morphology and structure of the hydrates and the influences of these features on the properties of cement-based materials, so as to explore a more targeted way of using nanoSiO2 in cement or concrete. It revealed that the pozzolanic reaction of nanoSiO2 is of the first-order and the apparent reaction rate constant of nanoSiO2-4 nm is about one order of magnitude bigger than that of silica fume, but the specific reaction rate constant is about one half to that of silica fume. A compacter gel structure and poorer crystallinity of the hydrates of nanoSiO2 to those of silica fume are found, as well. The rate of hydration of cement at very early ages is enhanced by nanoSiO2, but the rate slows down with aging due to the compact gel structure. To make the use of the high pozzolanic reactivity and ultrafine particle size of nanoSiO2, as well as its resulting compact gel structure, colloidal nanoSiO2 was applied onto the hardened cement mortar by brushing technique and a less permeable surface was resulted, which shows the potential of using nanoSiO2 as a surface treatment material for cement-based materials. 相似文献
9.
10.
B.R. Chakraborty S.K. HalderK.K. Maurya A.K. SrivastavaV.K. Toutam M.K. DalaiG. Sehgal S. Singh 《Thin solid films》2012,520(20):6409-6414
A multilayer thin film structure of ten alternate Ta and Si layers with approximately 18 nm thickness for the combined (Ta + Si) layer, was evaluated to explore the individual layer thickness and the interface mixing behavior using different surface characterization techniques like Time-of-Flight Secondary Ion Mass Spectrometry (TOFSIMS), X-ray Reflectometry (XRR) and Kelvin Probe Force Microscopy (KPFM). These results were compared with measurements performed earlier using cross section Transmission Electron Microscopy (TEM). The TOFSIMS depth profile results indicate the individual thickness of Si and Ta layers to be 8.1 nm and 5.9 nm respectively which are less than the corresponding actual thickness measured by cross section TEM as 10.5 nm and 7.5 nm. The difference in thickness measurement has been explained in the light of ion bombardment induced atomic mixing in the interface during sputter depth profiling. A scanning electron micrograph shows the actual crater and its edges created due to the sputtering including the multilayer for real view of the structure. The XRR observations however reveal better agreement with the cross section TEM data, both being non-destructive in nature. Attempts were made to characterize the multilayer using KPFM technique which clearly elucidated the grating type cross section of the structure. 相似文献
11.
Hydrogen plasma arc melting (HPAM) of commercial Ti sponges (> 99.7%) was examined. Ti sponges had main impurities such as Fe, Al, Cl and Mn. These main impurities could be reduced more efficiently by HPAM than by Ar PAM. Other small amount of impurities also had a tendency of reduction by HPAM. In addition, it was found that each removal degree is attributable to a differential refining effect caused by the difference of initial impurity concentration. For the unique refining effect of HPAM, dissociated and activated hydrogen atoms involved in the high temperature plasma arc are considered to play an important role in the melting process. 相似文献
12.
Atom Probe Tomography (APT) was applied to analyze the silicidation reaction between a titanium metal film, capped by a TiN layer, and a boron-implanted silicon substrate. The concentration depth profile observed by APT, depicts low concentrations of B in titanium silicide itself and the B accumulation at the interface between the TiSi2 and the TiN capping layer. Moreover the three dimensional atomic reconstruction from APT revealed a laterally inhomogeneous B distribution along the interface as well as B precipitation. APT enables the stoichiometric identification of TiB2 precipitates smaller than 7 nm in diameter. 相似文献
13.
AbstractOsseointegration, the direct bonding of titanium implant materials with bone, is critical for implant success where nanostructured surface features contribute to nano-osseointegration. However, we also know that features and processes on the microscale influence the biocompatibility of implant materials. We highlight the advantages of using mutlilength scale analyses, focusing on three-dimensional techniques, ranging from X-ray microcomputed tomography, to focused ion beam, to high resolution electron tomography to identify markers of osseointegration. A titanium implant with modified biomimetic coating studied in vitro and in vivo at various time points is used to exemplify the complementary information gained from three-dimensional analyses from the micro- to nanoscale. 相似文献
14.
固体氧化物燃料电池阳极材料的流延制备和电池性能研究 总被引:1,自引:0,他引:1
利用流延法制备NiO-YSZ阳极,采用磁控溅射、多层流延法制备YSZ电解质薄膜,丝网印刷制备BSCF-YSZ阴极,制备出Ni-YSZ/YSZ/BSCF-YSZ单电池。阳极制备中探索了浆料配比对生坯性能的影响;研究了不同造孔剂得到的流延阳极的微结构形貌差异。考察了双层流延、磁控溅射制备YSZ薄膜的微观结构,并测试评价了电池性能。 相似文献
15.
Titanium carbide (TiC) coatings for tribological applications were deposited on high speed steel. Several coatings with different titanium to carbon ratio were deposited by means of physical vapour deposition in which titanium was evaporated and carbon was sputtered. The coatings were characterised using analytical electron microscopy. It was observed that the change in titanium to carbon ratio significantly changed the microstructure of the coatings. The low carbon containing coatings consisted of columnar grains exhibiting a preferred crystallographic orientation whereas the coating with highest carbon content consisted of randomly ordered TiC grains in an amorphous carbon matrix. Energy filtered transmission electron microscopy revealed a change in Ti/C ratio as the distance from the substrate increased. The titanium to carbon ratio was observed to increase with distance from the substrate until a stable level was reached. This is due to a variation in the titanium evaporation during the early stages of film growth. This change of the titanium to carbon ratio affected the columnar growth in the initial stage of coating growth for the coatings with low carbon content. 相似文献
16.
The growth of thin Ti-oxide films (12 nm) on alumina substrate films formed by reactive evaporation of Ti in an oxygen atmosphere was studied by in situ internal stress measurements under ultra high vacuum conditions and transmission electron microscopy. Oxygen pressure and substrate temperatures were the varied parameters of the reactive evaporation. These Ti-oxide-films with different oxygen content (O2/Ti-films) were then used as substrate films for the deposition of a clean titanium film. The growth stress of the titanium film on the as-deposited O2/Ti-substrate films is comparable with that previously found for H2O/Ti-substrates and indicates island growth and the formation of polycrystalline titanium films. Annealing (400°C, 20 min) of the as-deposited – amorphous – O2/Ti-films gives rise to the formation of crystalline TiO2. The amount of TiO2 formed during annealing is strongly dependent on the oxygen content of the O2/Ti-film. The oxygen content, in return, is dependent on oxygen partial pressure and substrate temperature during O2/Ti-film deposition. The corresponding changes in the substrate film properties (oxygen content, crystallinity, etc.) are reflected in significant changes in the growth stress of the titanium film. The stress vs. thickness curve of these titanium films appears to indicate a superposition of the growth stress of two different growth modes, i.e. growth of a polycrystalline film with island growth on the as-deposited, amorphous oxide substrate and epitaxial growth of a quasi single crystalline film on the crystalline TiO2-substrate. 相似文献
17.
Anatolii Babutskyi Andreas Chrysanthou Marija Smelina Gennadii Stepanov Maciej Ziętara 《Materials Science & Technology》2017,33(12):1461-1472
ABSTRACTResults of corrosion tests of titanium in the initial state and after treatment using pulsed magnetic field are presented. It is shown that samples after treatment have better corrosion resistance due to the formation of denser and finer corrosion products with better adhesion to the substrate. Samples after treatment have more homogeneous microstructure due to a substantial increase of dislocations which are uniformly distributed. Mechanisms of dislocation multiplication and a model explaining the effect of the treatment on the corrosion are discussed.This paper is part of a themed issue on Materials in External Fields. 相似文献
18.
Evaluation of solid-liquid interface profile during continuous casting by a spline based formalism 总被引:1,自引:0,他引:1
S. K. Das 《Bulletin of Materials Science》2001,24(4):373-378
A numerical framework has been applied which comprises of a cubic spline based collocation method to determine the solid-liquid
interface profile (solidification front) during continuous casting process. The basis function chosen for the collocation
algorithm to be employed in this formalism, is a cubic spline interpolation function. An iterative solution methodology has
been developed to track the interface profile for copper strand of rectangular transverse section for different casting speeds.
It is based on enthalpy conservation criteria at the solidification interface and the trend is found to be in good agreement
with the available information in the literature although a point to point mapping of the profile is not practically realizable.
The spline based collocation algorithm is found to be a reasonably efficient tool for solidification front tracking process,
as a good spatial derivative approximation can be achieved incorporating simple modelling philosophy which is numerically
robust and computationally cost effective. 相似文献
19.
Motomichi Koyama Michael Rohwerder Cemal Cem Tasan Asif Bashir Eiji Akiyama Kenichi Takai 《Materials Science & Technology》2017,33(13):1481-1496
ABSTRACTThis paper gives an overview of recent progress in microstructure-specific hydrogen mapping techniques. The challenging nature of mapping hydrogen with high spatial resolution, i.e. at the scale of finest microstructural features, led to the development of various methodologies: thermal desorption spectrometry, silver decoration, the hydrogen microprint technique, secondary ion mass spectroscopy, atom probe tomography, neutron radiography, and the scanning Kelvin probe. These techniques have different characteristics regarding spatial and temporal resolution associated with microstructure-sensitive hydrogen detection. Employing these techniques in a site-specific manner together with other microstructure probing methods enables multi-scale, quantitative, three-dimensional, high spatial, and kinetic resolution hydrogen mapping, depending on the specific multi-probe approaches used. Here, we present a brief overview of the specific characteristics of each method and the progress resulting from their combined application to the field of hydrogen embrittlement.This paper is part of a thematic issue on Hydrogen in Metallic Alloys 相似文献
20.
T. Vandevelde T. D. Wu C. Quaeyhaegens J. Vlekken M. DOlieslaeger L. Stals 《Thin solid films》1999,340(1-2):159-163
The mechanisms of nitrogen incorporation in diamond are still an unsolved riddle. This is mainly due to the complexity of the processes involved as they not only depend on empirical parameters (e.g. vessel pressure, substrate temperature, the gas phase composition, type and concentration of the nitrogen containing compound used), but also on the plasma chemistry and the surface chemical reactions. In this study, small quantities (ppm range) of diatomic nitrogen are added to a conventional hydrogen-methane feed gas mixture in order to investigate the effect of nitrogen incorporation in diamond films prepared by microwave plasma assisted chemical vapour deposition (CVD). Optical emission spectroscopy (OES) is used to survey the plasma composition during deposition. The intensities of the CN, CH and C2 emitting radicals and the Balmer atomic hydrogen emission lines are correlated to the Raman film quality and to the nitrogen content in the film measured by secondary ion mass spectrometry (SIMS). 相似文献