The nature of the passivating oxide layer on iron powder

1978 ◽  
Vol 15 (2) ◽  
pp. 163-166 ◽  
Author(s):  
A. M. van Diepen ◽  
H. J. Vledder ◽  
C. Langereis
Keyword(s):  
Oxide Layer ◽  
Iron Powder ◽  
Passivating Oxide Layer ◽  
Passivating Oxide

An XPS Study of the Passivating Oxide Layer Produced on GaAs (001) Substrate by Heating in Air above 200°C

1988 ◽  
Vol 27 (Part 2, No. 2) ◽  
pp. L167-L169 ◽  
Author(s):  
J. P. Contour ◽  
J. Massies ◽  
H. Fronius ◽  
K. Ploog
Keyword(s):  
Oxide Layer ◽  
Passivating Oxide Layer ◽  
Xps Study ◽  
Passivating Oxide

Titanium Bulk Micromachining for BioMEMS Applications: A DEP Device as a Demonstration

2004 ◽  
Author(s):  
Yanting Zhang ◽  
Emily R. Parker ◽  
Masa P. Rao ◽  
Marco F. Aimi ◽  
Igor Mezic ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Oxide Layer ◽  
High Aspect Ratio ◽  
Traveling Wave ◽  
Cardiovascular Surgery ◽  
Biomedical Material ◽  
Spontaneous Formation ◽  
Passivating Oxide Layer ◽  
Traveling Wave Dielectrophoresis ◽  
Passivating Oxide

Titanium has been widely used as a biomedical material in orthopedics, dentistry, cardiology, and cardiovascular surgery due to the excellent biostability and biocompatibility that results from its spontaneous formation of a highly passivating oxide layer in air and blood. However, little research has been done on the development of titanium for bioMEMS applications. This is likely due to the immaturity of titanium bulk micromachining technology to date. Here we report the application of new high-aspect-ratio bulk titanium micromachining techniques recently developed within our group towards the fabrication of a titanium-based multi-frequency traveling wave dielectrophoresis (DEP) device targeted for the separation of bioparticles. The device serves to illustrate the potential of these techniques for enabling the realization of novel bioMEMS devices with enhanced functionality and capability.

scholarly journals Single magnetic domain Terfenol-D microstructures with passivating oxide layer

2021 ◽  
Vol 528 ◽  
pp. 167798
Author(s):  
Mohanchandra K. Panduranga ◽  
Zhuyun Xiao ◽  
Joseph D. Schneider ◽  
Taehwan Lee ◽  
Christoph Klewe ◽  
...  
Keyword(s):  
Oxide Layer ◽  
Magnetic Domain ◽  
Passivating Oxide Layer ◽  
Passivating Oxide

A study of the passivating oxide layer on fine nickel particles

1994 ◽  
Vol 4 (2) ◽  
pp. 199-206 ◽  
Author(s):  
T. Uchikoshi ◽  
Y. Sakka ◽  
M. Yoshitake ◽  
K. Yoshihara
Keyword(s):  
Oxide Layer ◽  
Nickel Particles ◽  
Passivating Oxide Layer ◽  
Passivating Oxide ◽  
Fine Nickel

scholarly journals Carbon Co-Deposition During Gas Reduction of Water-Atomized Fe-Cr-Mo Powder

2017 ◽  
Vol 62 (2) ◽  
pp. 1119-1124
Author(s):  
B. Ali ◽  
S.H. Choi ◽  
S.J. Seo ◽  
D.Y. Maeng ◽  
C.G. Lee ◽  
...  
Keyword(s):  
Carbon Content ◽  
Oxide Layer ◽  
Iron Powder ◽  
Flow Rate ◽  
Gas Flow ◽  
Gas Flow Rate ◽  
High Quality ◽  
Exponential Relationship ◽  
Water Atomization ◽  
Ar Gas

AbstractThe water atomization of iron powder with a composition of Fe-3Cr-0.5Mo (wt.%) at 1600°C and 150 bar creates an oxide layer, which in this study was reduced using a mixture of methane (CH4) and argon (Ar) gas. The lowest oxygen content was achieved with a 100 cc/min flow rate of CH4, but this also resulted in a co-deposition of carbon due to the cracking of CH4. This carbon can be used directly to create high-quality, sinter hardenable steel, thereby eliminating the need for an additional mixing step prior to sintering. An exponential relationship was found to exist between the CH4gas flow rate and carbon content of the powder, meaning that its composition can be easily controlled to suit a variety of different applications.

scholarly journals Low-Temperature Carburization of AL-6XN Enabled by Provisional Passivation

Metals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 997 ◽  
Author(s):  
Zhen Li ◽  
Cyprian Illing ◽  
Arthur Heuer ◽  
Frank Ernst
Keyword(s):  
Hydrochloric Acid ◽  
Low Temperature ◽  
Underlying Mechanism ◽  
New Method ◽  
Surface Activation ◽  
Industrial Manufacturing ◽  
The Reformation ◽  
Technological Impact ◽  
Passivating Oxide Layer ◽  
Passivating Oxide

Employing AISI-AL-6XN as example, we introduce a new method of surface activation for low-temperature carburization. This method consists of two steps: (i) removing the passivating surface oxide and a potentially existing severely plastically deformed surface layer (Beilby layer) by aqueous (liquid) hydrochloric acid, and (ii) immersion in ethanol and subsequent drying in nitrogen. Upon carburization with a gas mixture of acetylene, hydrogen, and nitrogen, this new method of surface activation enables the formation of a fully developed “case”, a uniform solid solution of interstitial carbon in austenite with carbon fractions up to 0.20 near the alloy surface. The underlying mechanism of surface activation is shown to involve the formation of a provisional passivating layer. It consists of chlorides or ethoxides that are insoluble in ethanol. It prevents the reformation of the regular Cr-rich passivating oxide layer and is readily removed upon heating and exposure to the carburizing gas. As the new activation method is quicker, more effective, and less destructive to furnace hardware than activation with hot gaseous hydrochloric acid that is currently applied in industrial manufacturing, it may have considerable technological impact.

Nucleation and Pattern Formation of Coherent Islands During Epitaxial Growth of Ge on Si(110) Surfaces

1996 ◽  
Vol 440 ◽  
Author(s):  
J. D. Weil ◽  
Bi-Ke Yang ◽  
C. G. Slough ◽  
M. Krishnamurthy
Keyword(s):  
Epitaxial Growth ◽  
Buffer Layer ◽  
Heterogeneous Nucleation ◽  
Buffer Layers ◽  
Dipole Orientation ◽  
Nucleation Behavior ◽  
Molecular Beam Epitaxial ◽  
Passivating Oxide Layer ◽  
Molecular Beam Epitaxial Growth ◽  
Passivating Oxide

AbstractMolecular beam epitaxial growth of Ge on Si(110) surfaces reveals interesting aspects of the heterogeneous nucleation of coherent Ge islands. Cleaning of the Si substrate by desorption of a passivating oxide layer at high temperature creates surface pits. Two sets of experiments, including deposition of Ge on as-cleaned substrates, and surfaces with a thin Si buffer layer are compared to illustrate the nucleation behavior of Ge. Typical Ge deposition temperatures range from 600°C to 725°C.For Ge deposition on as-cleaned surfaces, the faceted edges of pits serve as preferential sites for the heterogeneous nucleation of coherent Ge islands. Experiments were also performed on surfaces with thin (˜20nm) Si buffer layers grown on the as-cleaned surface. Though the faceted pits have not been completely covered by the Si buffer layer, they have decreased in lateral size. In addition, the Si(110) surface shows ledges that are formed along specific crystallographic directions. Ge deposited on the Si buffer nucleates first at the corners of the pits, in an interesting dipole orientation, as well as along the ledges on the surface.

scholarly journals Oxide reduction and oxygen removal in water-atomized iron powder: a kinetic study

2020 ◽  
Vol 142 (1) ◽  
pp. 309-320 ◽  
Author(s):  
Johan Wendel ◽  
Swathi K. Manchili ◽  
Eduard Hryha ◽  
Lars Nyborg
Keyword(s):  
High Temperature ◽  
Mass Loss ◽  
Oxide Layer ◽  
Iron Powder ◽  
Oxygen Removal ◽  
Surface Oxide ◽  
Surface Oxide Layer ◽  
Pure Hydrogen ◽  
Oxide Reduction ◽  
Reference Samples

Abstract Reduction of oxides during sintering is a prerequisite for the manufacturing of powder metallurgy steels. Inadequate control of the sintering atmosphere may impede sinter neck formation and cause entrapment and growth of oxides in sinter necks, ultimately deteriorating the mechanical properties of sintered components. In this study, the oxide reduction and oxygen removal in water-atomized iron powder was investigated by means of thermogravimetric analysis in pure hydrogen. Two principal mass loss events were recorded, corresponding to the removal of the surface oxide layer at around 400 °C and reduction of internal and stable oxides in the range 600–1350 °C. The apparent activation energies of these mass loss processes were determined by means of kinetic analyses, giving values around 100 kJ mol−1 and 200–400 kJ mol−1, respectively. The validity of the results was asserted using hematite reference samples which displayed good correlation with the reduction of the surface oxide layer, thereby showing that the powder surfaces are covered by an Fe2O3 oxide. The high-temperature mass loss, with no analogy in the reference samples, is believed to originate from a combination of oxygen removal from internal oxides and stable oxide particulates on the surface. Analysis of the oxide reduction in iron powder compacts show a slightly lower activation energy for the oxide layer reduction, indicating an influence of the compaction step on the initial state of the powder and oxide layer. At the same time, the high-temperature mass loss event was shifted to higher temperatures, which is believed to be caused by the increasingly restricted mass transport of reduction products along the pores in the sintered compact.

PtSi Contact Metallurgy by Different Formation Processes

1985 ◽  
Vol 54 ◽  
Author(s):  
Chin-An Change ◽  
H. -C. Huang ◽  
A. Segmüller ◽  
F. E. Turene ◽  
B. Cunningham ◽  
...  
Keyword(s):  
Oxide Layer ◽  
Surface Oxide ◽  
Surface Oxide Layer ◽  
Formation Processes ◽  
High Quality ◽  
Aqua Regia ◽  
Oxide Layers ◽  
Single Temperature ◽  
Passivating Oxide

ABSTRACTPtSi films have been formed using sputtered Pt and different annealing sequences and ambients. A clear dependence on the annealing sequence and ambient is observed for both the PtSi films and the passivating oxide layers formed. The single-temperature process at 550°C using forming gas (N2-H2 9:1), nitrogen and oxygen shows incomplete reactions between Pt and Si, with a surface oxide layer of poor resistance against etching in aqua regia. A three-temperature process using forming gas is shown to provide complete reactions between Pt and Si, with a surface oxide layer of excellent resistance against aqua regia. The three-temperature process using nitrogen or oxygen, however, fails to provide films of high quality, and the results are similar to those obtained by the single-temperature process in various gases.

Structural changes in silicon-on-insulator material during post-implantation annealing

1986 ◽  
Vol 44 ◽  
pp. 736-737
Author(s):  
C. O. Jung ◽  
S. J. Krause ◽  
S.R. Wilson
Keyword(s):  
Integrated Circuits ◽  
Oxide Layer ◽  
High Speed ◽  
Structural Changes ◽  
Device Fabrication ◽  
Silicon On Insulator ◽  
High Quality ◽  
Radiation Hardened ◽  
Post Implantation ◽  
Very High

Silicon-on-insulator (SOI) structures have excellent potential for future use in radiation hardened and high speed integrated circuits. For device fabrication in SOI material a high quality superficial Si layer above a buried oxide layer is required. Recently, Celler et al. reported that post-implantation annealing of oxygen implanted SOI at very high temperatures would eliminate virtually all defects and precipiates in the superficial Si layer. In this work we are reporting on the effect of three different post implantation annealing cycles on the structure of oxygen implanted SOI samples which were implanted under the same conditions.

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