scholarly journals Exfoliation Resistance, Microstructure, and Oxide Formation Mechanisms of the White Oxide Layer on CP Ti and Ti–Nb–Ta–Zr Alloys

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6599
Author(s):  
Eri Miura-Fujiwara ◽  
Soichiro Yamada ◽  
Keisuke Mizushima ◽  
Masahiko Nishijima ◽  
Yoshimi Watanabe ◽  
...  
Keyword(s):  
Oxide Layer ◽  
Fine Particles ◽  
Interfacial Microstructure ◽  
Formation Mechanisms ◽  
Oxide Formation ◽  
Electron Microscopic ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Frictional Coefficients ◽  
Cp Ti

We found that specific biomedical Ti and its alloys, such as CP Ti, Ti–29Nb–13Ta–4.6Zr, and Ti–36Nb–2Ta–3Zr–0.3O, form a bright white oxide layer after a particular oxidation heat treatment. In this paper, the interfacial microstructure of the oxide layer on Ti–29Nb–13Ta–4.6Zr and the exfoliation resistance of commercially pure (CP) Ti, Ti–29Nb–13Ta–4.6Zr, and Ti–36Nb–2Ta–3Zr–0.3O were investigated. The alloys investigated were oxidized at 1273 or 1323 K for 0.3–3.6 ks in an air furnace. The exfoliation stress of the oxide layer was high in Ti–29Nb–13Ta–4.6Zr and Ti–36Nb–2Ta–3Zr–0.3O, and the maximum exfoliation stress was as high as 70 MPa, which is almost the same as the stress exhibited by epoxy adhesives, whereas the exfoliation stress of the oxide layer on CP Ti was less than 7 MPa, regardless of duration time. The nanoindentation hardness and frictional coefficients of the oxide layer on Ti–29Nb–13Ta–4.6Zr suggested that the oxide layer was hard and robust enough for artificial tooth coating. The cross-sectional transmission electron microscopic observations of the microstructure of oxidized Ti–29Nb–13Ta–4.6Zr revealed that a continuous oxide layer formed on the surface of the alloys. The Au marker method revealed that both in- and out-diffusion occur during oxidation in Ti–29Nb–13Ta–4.6Zr and Ti–36Nb–2Ta–3Zr–0.3O, whereas only out-diffusion governs oxidation in CP Ti. The obtained results indicate that the high exfoliation resistance of the oxide layer on Ti–29Nb–13Ta–4.6Zr and Ti-36Nb-2Ta-3Zr-0.3O are attributed to their dense microstructures composing of fine particles, and a composition-graded interfacial microstructure. On the basis of the results of our microstructural observations, the oxide formation mechanism of the Ti–Nb–Ta–Zr alloy is discussed.

scholarly journals Effect of Nb addition on high-temperature oxidation behavior, oxide layer structure, and its exfoliation resistance of Ti-Nb Alloys

2020 ◽  
Vol 321 ◽  
pp. 05018
Author(s):  
Eri Miura-Fujiwara ◽  
Yuya Ogawa ◽  
Mitsuo Niinomi ◽  
Tohru Yamasaki
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Temperature ◽  
Oxide Layer ◽  
High Temperature Oxidation ◽  
Interfacial Microstructure ◽  
Temperature Oxidation ◽  
Transmission Electron ◽  
Cp Ti ◽  
Nb Addition

The authors proposed an oxide coating on Ti alloys for the dental abutment tooth, and they had reported that Ti–29Nb–13Ta–4.6Zr (TNTZ) alloy forms a dense oxide layer by high-temperature oxidation. On the other hand, CP Ti forms a multilayered oxide consisted of rutile monolayers and the void layer. This morphological change by alloying is supposed to be mainly caused by Nb addition in Ti since the dense oxide layer of TNTZ mainly consists of rutile TiO2 and TiNb2O7. Therefore, in this study, oxidation behaviors of various range of Nb content of Ti-xNb alloys (x = 1 ~ 32 mol%) were investigated, and exfoliation resistance was evaluated. And in this paper, the oxide/metal interfacial microstructure of oxidized CP Ti, TNTZ alloy, and Ti-Nb alloy was studied by a transmission electron microscopy (TEM) and by a scanning transmission electron microscopy with an electron dispersive spectroscopy (STEM-EDS). The cross-sectional observations suggested that the substrate was gradually oxidized during heat treatment, and nucleation and grain growth of TiO2 and TiNb2O7 proceed at the metal/oxide interface. Consequently, the gradual oxidation process in TNTZ and Ti-Nb alloys could lead to its continuous interfacial microstructure and dense oxide structure, which can achieve high exfoliation resistance.

High-resolution transmission electron microscopic study of highly oxygen doped silicon layer

1989 ◽  
Vol 47 ◽  
pp. 692-693
Author(s):  
H. Takaoka ◽  
M. Tomita ◽  
T. Hayashi
Keyword(s):  
High Resolution ◽  
Oxygen Concentration ◽  
Silicon Layer ◽  
Detailed Structure ◽  
Electron Microscopic ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Doped Silicon ◽  
Argon Ion

High resolution transmission electron microscopy (HRTEM) is the effective technique for characterization of detailed structure of semiconductor materials. Oxygen is one of the important impurities in semiconductors. Detailed structure of highly oxygen doped silicon has not clearly investigated yet. This report describes detailed structure of highly oxygen doped silicon observed by HRTEM. Both samples prepared by Molecular beam epitaxy (MBE) and ion implantation were observed to investigate effects of oxygen concentration and doping methods to the crystal structure.The observed oxygen doped samples were prepared by MBE method in oxygen environment on (111) substrates. Oxygen concentration was about 1021 atoms/cm3. Another sample was silicon of (100) orientation implanted with oxygen ions at an energy of 180 keV. Oxygen concentration of this sample was about 1020 atoms/cm3 Cross-sectional specimens of (011) orientation were prepared by argon ion thinning and were observed by TEM at an accelerating voltage of 400 kV.

Study of “Reverse Annealing” of Boron Under Low Temperature Lamp Anneals

1985 ◽  
Vol 52 ◽  
Author(s):  
J. Huang ◽  
R. J. Jaccodine
Keyword(s):  
Annealing Temperature ◽  
Halogen Lamp ◽  
Electron Microscopic ◽  
Cross Sectional ◽  
Temperature Range ◽  
Silicon Crystals ◽  
Float Zone ◽  
Transmission Electron ◽  
Effect Of Oxygen ◽  
Tungsten Halogen Lamp

ABSTRACTThe reverse annealing of ion implanted boron, namely, the decrease in the concentration of electrically active boron as the isochronal annealing temperature increases, occurs in the temperature range from 550 to 650°C during conventional furnace heating. In this study, silicon crystals were boron implanted at 50 Kev to a dose of 1×1015 cm-2 followed by both furnace and tungsten-halogen lamp annealing in the reverse annealing temperature range. Cross-sectional Transmission electron microscopic (TEM) technique was used to examine the microstructural changes during annealing as a function of depth. Sheet resistance measurements gave a quick check of the electrical properties, while spreading resistance profiling with shallow angle lapping and Hall measurements reveals the mobility and carrier concentration as a function of depth. Czochralski and Float Zone crystals were studied to examine the effect of oxygen. Tungsten-halogen lamp thermal processing was found to have a more pronounced effect on the annealing of secondary defects than did furnace annealing. The reverse annealing of boron was eliminated completely for lamp annealing time as short as 60 seconds.

scholarly journals Development of a Chemical-free Floatation Technology for the Purification of Vein Graphite and Characterization of the Products

2021 ◽  
Author(s):  
Gamaralalage R. A. Kumara ◽  
Herath Mudiyanselage G. T. A. Pitawala ◽  
Buddika Karunarathne ◽  
Mantilaka Mudiyanselage M. G. P. G. Mantilaka ◽  
Rajapakse Mudiyanselage G. Rajapakse ◽  
...  
Keyword(s):  
Fine Particles ◽  
Xrd Analysis ◽  
Electron Microscopic ◽  
Tem Analysis ◽  
Environmental Friendliness ◽  
X Ray ◽  
Transmission Electron ◽  
Edge Defects ◽  
Crystallite Sizes ◽  
Notable Increase

Abstract A novel and simple flotation technique has been developed to prepare high-purity graphite from impure graphite. In this method, a suspension of powdered graphite (PG) is dispersed and stirred in water without adding froth formers or supportive chemicals. This makes fine particles of graphite to move upwards and float on water. X-ray diffraction (XRD) analysis reveals that the floated graphite (FG) has a lower c-axis parameter, indicating the removal of interlayer impurities. A notable increase in the intensity ratio of the D band to G band in the Raman spectra indicates that the FG has more edge defects due to their smaller crystallite sizes. Transmission electron microscopic (TEM) analysis shows the number of layers in FG has been reduced to 16 from 68 in PG. The absence of C = O vibration of Fourier Transformed Infrared (FT-IR) spectroscopy in treated and untreated samples suggests that layers of them are not significantly oxidized. However, X-ray photoelectron spectroscopic (XPS) analysis shows the presence of C-O-C ether functionalities, possibly on edge planes. Further, the product has higher purity with increased carbon content. Therefore, the technique is useful in the value enhancement of graphite, the reduction of the chemical cost of the conventional techniques, environmental friendliness, and improvement of its applications.

In Situ Fabrication and Characterization of (NiCr)Al-Al2O3 Nanocomposite by Mechanical Alloying

2012 ◽  
Vol 16 ◽  
pp. 21-27 ◽  
Author(s):  
Amir Reza Shirani-Bidabadi ◽  
Ali Shokuhfar ◽  
Mohammad Hossein Enayati ◽  
Mazda Biglari
Keyword(s):  
Electron Microscopy ◽  
Mechanical Alloying ◽  
Structural Changes ◽  
Formation Mechanisms ◽  
Cross Sectional ◽  
Molar Ratios ◽  
Transmission Electron ◽  
Powder Particles

In this research, the formation mechanisms of a (NiCr)Al-Al2O3 nanocomposite were investigated. The structural changes of powder particles during mechanical alloying were studied by X-ray difractometry (XRD) and the morphology and cross sectional microstructure of powder particles were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The methodology involved mechanical alloying of NiO, Cr, and Al with molar ratios of 3:3:8. During mechanical alloying, NiO was first quickly reduced by aluminum atoms to produce NiAl nanocrystalline and Al2O3. Subsequently, and when a longer milling time was applied, chromium atoms diffused into the NiAl lattice. The heat treatment of this structure led to the formation of the (NiCr)Al intermetallic compound as well as Al2O3 with crystalline sizes of 23 nm and 58 nm, respectively.

XTEM Observation of 4H-SiC (0001) Surfaces Processed by Plasma Assisted Polishing

2012 ◽  
Vol 497 ◽  
pp. 156-159
Author(s):  
Hui Deng ◽  
Kazuya Yamamura
Keyword(s):  
Water Vapor ◽  
Oxide Layer ◽  
Atmospheric Pressure ◽  
Oxidation Potential ◽  
Cross Sectional ◽  
Plasma Irradiation ◽  
Transmission Electron ◽  
Surface Damages ◽  
Pressure Water ◽  
20 Nm

We proposed a novel polishing technique named plasma assisted polishing (PAP) which combined atmospheric pressure water vapor plasma irradiation and soft abrasive polishing. Plasma irradiation oxidized the surface of workpiece and made it easier to be polished. PAP was applied to 4H-SiC, and an automatic flat surface without any scratches was obtained. In this study, we observed the processed surfaces using cross-sectional transmission electron microscopy (XTEM). The XTEM images showed us that an oxide layer with a thickness of about 20 nm was generated after plasma irradiation for 1 h, which proved the strong oxidation potential of OH radical in water vapor plasma. The surfaces processed by PAP were next observed, oxide layer was completely removed and no surface damages were introduced as the crystal structure of 4H-SiC was clearly observed and well ordered.

Microstructural study of MBE-grown ZnO film on GaN/sapphire (0001) substrate

Open Physics ◽  
2008 ◽  
Vol 6 (3) ◽  
Author(s):  
Hua Li ◽  
Jianping Sang ◽  
Chang Liu ◽  
Hongbing Lu ◽  
Juncheng Cao
Keyword(s):  
Interface Layer ◽  
Interfacial Microstructure ◽  
X Ray Diffraction ◽  
Zno Film ◽  
Epitaxial Relationship ◽  
Cross Sectional ◽  
X Ray ◽  
Transmission Electron ◽  
Diffraction Patterns ◽  
Gan Heterostructure

AbstractSingle crystalline ZnO film is grown on GaN/sapphire (0001) substrate by molecular beam epitaxy. Ga2O3 is introduced into the ZnO/GaN heterostructure intentionally by oxygen-plasma pre-exposure on the GaN surface prior to ZnO growth. The crystalline orientation and interfacial microstructure are characterized by X-ray diffraction and transmission electron microscopy. X-ray diffraction analysis shows strong c-axis preferred orientation of the ZnO film. Cross-sectional transmission electron microscope images reveal that an additional phase is formed at the interface of ZnO/GaN. Through a comparison of diffraction patterns, we confirm that the interface layer is monoclinic Ga2O3 and the main epitaxial relationship should be $$ (0001)_{ZnO} \parallel (001)_{Ga_2 O_3 } \parallel (0001)_{GaN} $$ and $$ [2 - 1 - 10]_{ZnO} \parallel [010]_{Ga_2 O_3 } \parallel [2 - 1 - 10]_{GaN} $$.

A microstructural and electrical investigation of Pd/Ge/Ti/Au ohmic contact to n-type GaAs

1996 ◽  
Vol 427 ◽  
Author(s):  
J. S. Kwak ◽  
H. K. Baik ◽  
H. Kim ◽  
J. -L. Lee ◽  
D. W. Shin ◽  
...  
Keyword(s):  
Ohmic Contact ◽  
Gaas Substrate ◽  
Isothermal Annealing ◽  
Interfacial Microstructure ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
X Ray ◽  
Electrical Investigation ◽  
Transmission Electron ◽  
Elemental Diffusion

AbstractInterfacial microstructure and elemental diffusion of Pd/Ge/Ti/Au ohmic contact to n-type GaAs have been investigated using x-ray diffraction(XRD), Auger electron spectroscopy(AES), and cross-sectional transmission electron microscopy(XTEM), and their results are used to interpret the electrical properties. The lowest contact resistance of 0.43 Ωmm is obtained after annealing at 380°C. The contact is thermally stable even after isothermal annealing for 5h at 400°C. The good Pd/Ge/Ti/Au ohmic contact is due to the formation of both AuGa and TiO compounds. The AuGa compound enhances the creation of more Ga vacancies, followed by incorporation of Ge into Ga vacancies and TiO compound suppresses As outdiffusion from GaAs substrate, respectively.

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