INFLUENCE OF ION IMPLANTATION ON OXIDATION BEHAVIOR OF TiAl

2006 ◽  
Vol 20 (25n27) ◽  
pp. 4667-4672 ◽  
Author(s):  
MICHIKO YOSHIHARA ◽  
SHIGEJI TANIGUCHI
Keyword(s):  
Ion Implantation ◽  
Selective Oxidation ◽  
Oxidation Behavior ◽  
Complex Oxide ◽  
The Other ◽  
Alloying Elements ◽  
Implantation Technique ◽  
Other Hand ◽  
Initial Stage ◽  
Cu And Zn

The influence of alloying elements on oxidation behavior of TiAl has been investigated using an ion-implantation technique and the mechanisms were discussed. The influence can be classified into several groups according to their effects. The implantation of β-forming elements, halogens, Cu and Zn results in a significant improvement of the oxidation behavior through formation of Al 2 O 3 layer in the initial stage of oxidation. The improvement by Zn is attributed to the formation of complex oxide of Zn and selective oxidation of Al beneath the layer. The implantation of Al , Si or P is also effective. On the other hand, implantation of Ag , Se and other several elements enhance the oxidation. The deterioration by Ag or Se is explained in terms of Al depletion in the implanted layer.

Influence of Ion Implantation of Several Elements on Oxidation Behavior of TiAl

2006 ◽  
Vol 522-523 ◽  
pp. 633-640 ◽  
Author(s):  
Michiko Yoshihara ◽  
Shigeji Taniguchi ◽  
D. Furumaki ◽  
M. Aono
Keyword(s):  
Ion Implantation ◽  
Atmospheric Pressure ◽  
Oxidation Behavior ◽  
Alumina Scale ◽  
Complex Oxide ◽  
Oxidation Products ◽  
X Ray ◽  
Cyclic Oxidation Test ◽  
Initial Stage ◽  
Acceleration Voltage

TiAl-based alloys have attractive properties as light weight heat-resisting material. In the present work, the influence of Cu, Zn, Ag and Se on the oxidation behavior of TiAl was investigated by ion implantation at acceleration voltage of 50 kV and ion doses of 1019 to 2x1021 ions/m2. The oxidation behavior was assessed by a cyclic oxidation test at 1200 K in a flow of purified oxygen under atmospheric pressure. The oxidation products were analyzed by conventional methods including X-ray diffractometry, SEM and EPMA. The implantation of Zn and Cu improves the oxidation resistance significantly by forming virtually Al2O3 scales, while Ag and Se enhance the oxidation. The improvement by Zn is attributable to the formation of complex oxide of Zn in the initial stage of oxidation. The oxygen partial pressure under the layer seems to be very low, resulting in the formation of alumina scale due to a selective oxidation of Al. The influence of Cu is not certain. The influence of Ag and Se is explained in terms of Al depletion in the implanted layer.

scholarly journals Thermo-Mechanical Fatigue of Grey Cast Iron for Cylinder Heads - Effect of Niobium, Molybdenum and Solidification Time

2018 ◽  
Vol 925 ◽  
pp. 377-384 ◽  
Author(s):  
Peter Skoglund ◽  
Jessica Elfsberg ◽  
Nulifer Ipek ◽  
Lucian Vasile Diaconu ◽  
Mari Larsson ◽  
...  
Keyword(s):  
Mechanical Performance ◽  
Cyclic Stress ◽  
The Other ◽  
Solidification Time ◽  
Alloying Elements ◽  
Static Properties ◽  
Mechanical Fatigue ◽  
Other Hand ◽  
The Matrix ◽  
Grey Cast

Grey iron alloyed with molybdenum and niobium in seven different compositions has been casted using three, in industrial components viable, solidification times which resulted in 21 different samples. The samples have been investigated with respect to microstructure, static properties and thermo-mechanical fatigue performance. It was found that the solidification time is very important for both the static and thermo-mechanical performance. If the solidification time is long the properties are controlled entirely by the large graphite flakes and there is no influence of the alloying elements. On the other hand if the solidification time can be kept short the need for alloying elements may be removed. For the shorter solidification times an influence from the matrix and thus the alloying elements can be seen. It was found that molybdenum enhances TMF-life while no such effect was found for niobium. Niobium, on the other hand, has a larger effect on static strength than molybdenum and also on the cyclic stress in the thermo-mechanical fatigue experiments.

scholarly journals VIABILITY OF THE CREATION OF A UNIVERSITY INCUBATOR WITH A VIEW TO BENEFIT THE RURAL AND INDIGENOUS POPULATION OF THE STATE OF QUERÉTARO

2021 ◽  
Vol 9 (7) ◽  
pp. 199-211
Author(s):  
Jorge Arturo Velázquez Hernández ◽  
Jorge Adán Romero Zepeda ◽  
Rosalía Alonso Chombo ◽  
Epigmenio Muñoz Guevara
Keyword(s):  
Participatory Research ◽  
Indigenous Population ◽  
Indigenous Communities ◽  
The State ◽  
The Other ◽  
Other Hand ◽  
Initial Stage ◽  
Incubation Periods ◽  
The One ◽  
Economic Nature

The objective of this work is to analyze the feasibility of creating a university incubator (INCUERUAQ) aimed at benefiting the rural and indigenous population of the state of Querétaro. On the one hand, INCUERUAQ would represent the propitious scenario so that current students and those who are graduating, have the necessary spaces in order to face and solve problems of a technical and economic nature that may exist in their communities, always counting on the guidance of its professors and, on the other hand, the Autonomous University of Querétaro (UAQ) would establish a permanent link with rural and indigenous communities, providing them with continuous advice in areas such as legal, administrative, marketing, etc., providing for this, the necessary infrastructure that allows them to carry out their ventures successfully, facilitating, among other things, training to access the various sources of financing, when required. The methodology with which it is intended to work is participatory research, whose initiation will be marked by a diagnosis that helps to visualize how feasible this project would be, it would also allow to devise the best incubator model to implement, in such a way that they can be carried out in practice the pre-incubation, incubation and post-incubation periods. This article aims to reflect an advance of the initial stage of the link, the diagnosis.

scholarly journals On the Problem of the Mechanism of the Origin of Stars in Stellar Associations

1958 ◽  
Vol 8 ◽  
pp. 944-948
Author(s):  
V. A. Ambartsumian
Keyword(s):  
Observational Data ◽  
Point Of View ◽  
The Other ◽  
Stellar Systems ◽  
Other Hand ◽  
T Tauri ◽  
Initial Stage ◽  
Stellar Associations

Almost ten years have passed since the idea of stellar associations as nonstable stellar systems was formulated. The complex of observational data obtained during this time indicates that stars contained in the associations are young objects of some million years of age. We would like to stress here that this concerns both the O and T associations. It is also known that those O associations which could be sufficiently investigated in this respect, contain, as a rule, T Tauri type stars and are consequently T associations as well. There are, on the other hand, T associations which do not contain hot giants. But apparently the mechanisms of stellar formations must be similar in O and T associations. This means that any theory of stellar origin for a given type of association must permit variations, which will provide an explanation of the origin of stars in associations of other type.Two hypotheses on the origin of stellar associations have been thus far discussed. One of them, suggested by the author at the initial stage of the idea about associations, supposes that each association has originated as a result of an expansion from a body or a system, the volume of which was initially very small. The dimensions of the latter was in any case less than one parsec. According to this point of view, these initial bodies (protostars) have either not been observed up to the present, or have not yet been identified with any known object. This point of view does not give any indication about a concrete mechanism of stellar origin, postponing its explanation to the time, when the earliest stages of the expansion of the association may be studied in detail.

Persistent Electronic Conduction in 12CaO7Al2O3 Thin Films Produced by Ar Ion Implantation: Selective Kick-Out Effect Leads to Electride Thin Films

2004 ◽  
Vol 811 ◽  
Author(s):  
Masashi Miyakawa ◽  
Katsuro Hayashi ◽  
Yoshitake Toda ◽  
Toshio Kamiya ◽  
Masahiro Hirano ◽  
...  
Keyword(s):  
Thin Films ◽  
Ion Implantation ◽  
The Other ◽  
New Method ◽  
Electronic Conduction ◽  
High Concentration ◽  
Electronic Conductor ◽  
Other Hand

ABSTRACTA new method to convert 12CaO7Al2O3 (C12A7) thin films to electronic conductor by hot Ar+ ion implantation has been developed and its mechanism is discussed. It was found that hot Ar+ ion implantation extruded free O2- ions in C12A7 films by kick-out effects at fluences higher than 1×1017 cm−2, which left electrons in the cages embedded in C12A7 crystal and produced high concentration F+-like centers (∼1.4×1021 cm−3). The resulting films show coloration and persistent electronic conduction with conductivities up to ∼1 Scm−1. On the other hand, fluences less than 1×1017 cm−2 kept the films transparent and insulating.

Effects of alloying elements on thermoelectric properties of ReSi1.75

2003 ◽  
Vol 793 ◽  
Author(s):  
Min Wook Oh ◽  
Jia-Jun Gu ◽  
Kosuke Kuwabara ◽  
Haruyuki Inui
Keyword(s):  
Electrical Resistivity ◽  
Temperature Dependence ◽  
Thermoelectric Property ◽  
Thermoelectric Properties ◽  
Binary Alloy ◽  
Figure Of Merit ◽  
The Other ◽  
Alloying Elements ◽  
Dimensionless Figure Of Merit ◽  
Other Hand

ABSTRACTS:The thermoelectric properties as well as microstructure of binary and some ternary ReSi1.75 have been investigated. Binary ReSi1.75 exhibits a nice thermoelectric property as exemplified by the high value of dimensionless figure of merit (ZT) of 0.70 at 800 °C when measured along [001], although the ZT value along [100] is just moderately high. Mo substitution for Re in ReSi1.75 considerably increases the ZT value along [001] because of the decreased electrical resistivity, while the property improvement is not significant along [100]. On the other hand, Al and Ge substitutions for Si in ReSi1.75 considerably increase the ZT value along [100]. This is also because of the decreased electrical resistivity. When Al is added to ReSi1.75, the value of electrical resistivity is significantly reduced when compared to the binary counterpart and the temperature dependence of electrical resistivity changes from of semiconductor for the binary alloy to of metal for the Al-added alloys.

Study of Oxidation Behavior of Zn Nanoparticles

2011 ◽  
Vol 399-401 ◽  
pp. 565-568
Author(s):  
Min Wang
Keyword(s):  
Oxygen Atom ◽  
Oxygen Content ◽  
Oxidation Behavior ◽  
Oxidation Process ◽  
The Other ◽  
Effective Size ◽  
Other Hand ◽  
Atom Position ◽  
Zn Nanoparticles

Abstract. Zn nanoparticles prepared by the arc was used in the present study. The microsturcture, oxygen content and oxygen atom position in Zn nanoparticles were investigated. Furthermore, the variation of oxygen content with time in the Zn nanoparticles was also studied. The results showed that the effective size of oxidized Zn nanoparticles was about 100nm, and oxidation process was conducted on the surface. On the other hand, the oxygen content in oxidized Zn nanoparticles reduced by comparing with that laying in the air for the same time.

Activity Comparison of MCM-41 and V-MCM-4 Catalysts for Ethanol Selective Oxidation and DRIFTS Analysis

2009 ◽  
Vol 7 (1) ◽  
Author(s):  
Yesim Gucbilmez ◽  
Timur Dogu ◽  
Suna Balci
Keyword(s):  
Hydrogen Atom ◽  
Gas Phase ◽  
Selective Oxidation ◽  
The Other ◽  
Lattice Oxygen ◽  
Molar Ratio ◽  
Surface Species ◽  
Other Hand ◽  
Activity Comparison ◽  
Mcm 41

The activity of a V-MCM-41 catalyst with a V/Si molar ratio of 0.04 was compared with the activity of a pure MCM-41 catalyst and some DRIFTS studies were performed in order to understand the mechanism of selective oxidation of ethanol. V-MCM-41 was found to be much more active than pure MCM-41, favouring the formation of high amounts of ethylene over 300°C. MCM-41, on the other hand, was found to favour the formation of acetaldehyde over ethylene at all studied temperatures. It was shown by reaction findings that over V-MCM-41, ethylene was produced mainly in the presence of gas phase oxygen whereas acetaldehyde was produced using the lattice oxygen even in the absence of gas phase oxygen. DRIFTS studies indicated the formation of acetaldehyde molecules from acetate-like surface species which were formed by the removal of a hydrogen atom from the ?-carbon of chemisorbed ethoxy species by the help of the lattice oxygen. On the other hand, removal of a hydrogen atom from the ?-carbon of the ethoxy species, in the presence of gas phase oxygen, resulted in the formation of vinyl-like surface species which then yielded ethylene molecules.

Effects of Alloying Elements on Physical and Mechanical Properties of Co-Al-W-Based L12/fcc Two-Phase Alloys

2014 ◽  
Vol 783-786 ◽  
pp. 1195-1200 ◽  
Author(s):  
Katsushi Tanaka ◽  
Haruyuki Inui
Keyword(s):  
Mechanical Properties ◽  
Volume Fraction ◽  
Lattice Mismatch ◽  
Physical And Mechanical Properties ◽  
The Other ◽  
Alloying Elements ◽  
Alloying Element ◽  
Two Phase ◽  
Solvus Temperature ◽  
Other Hand

The changes in the γ’ solvus temperature and the volume fraction of Co-Al-W based alloys with fcc / L12 two-phase microstructures upon alloying with quaternary elements have been investigated. All investigated quaternary elements, except for Fe and Re, increase the γ’ solvus temperatures of Co-Al-W based alloys with varying efficiencies depending on quaternary element. On the other hand, the variation of the γ’ volume fraction with alloying depends on the alloying element. Of the investigated quaternary elements, Ta is found to be the most effective in increasing the γ’ solvus temperature of Co-Al-W based alloys. The lattice mismatch significantly increase upon alloying with Ta of 4at.%, which destroys the coherent cuboidal structure.

A Review of BIM Adoption in Turkey

2018 ◽  
Vol 7 (4) ◽  
pp. 59-68
Author(s):  
Mustafa Nabi Kocakaya ◽  
Osman Hürol Türkakin ◽  
Ömer Giran
Keyword(s):  
Developing Countries ◽  
Lower Cost ◽  
The Other ◽  
Main Issue ◽  
Personnel Training ◽  
Other Hand ◽  
Software Licenses ◽  
Initial Stage ◽  
Interview Analysis ◽  
New System

BIM has been initiated in developing countries in recent years. It is a fact that adopting BIM has a large cost from the initiation of the implementation of the projects. This is the main reason that, in the company perspective, BIM methodology is not well-known at the beginning of a project, during the adaptation stage. Therefore, the transition to such a new system is quite costly, especially in terms of software licenses and personnel training. On the other hand, after some period of time, BIM starts to impact the progress of the projects in a positive way, such as the project becomes more transparent and more visible, as well as more manageable and controllable. So, the main outcome is the company starts to complete projects within a shorter duration and lower cost by using BIM. At the initial stage, BIM implementation investment is quite high, however in later stages these costs become more affordable. The main issue is quantifying effects and inserting to the evaluation of the investment. In this study, we proposed an interview analysis to conclude the keypoints of BIM adoption.

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