Fabrication of NiAl Intermetallic from Dense Elemental Powder Blends VIA Solid State Reactions

1996 ◽  
Vol 460 ◽  
Author(s):  
L. Farber ◽  
I. Gotman ◽  
E. Y. Gutmanas
Keyword(s):  
Solid State ◽  
Solid State Reactions ◽  
Full Density ◽  
Reaction Products ◽  
Liquid Phases ◽  
High Temperature Synthesis ◽  
Heat Treated ◽  
Micron Size ◽  
Different Temperatures ◽  
Two Stages

ABSTRACTDense NiAl intermetallic was synthesized from very fine elemental powders via solid state reactions. Homogeneous blends of micron size Ni and Al powders were consolidated to full density and heat treated in a 425–800°C temperature range. During heat treatment, formation of various intermediate intermetallics phases: NiAl3, Ni2A13, Ni3Al and NiAl was observed. The sequence and kinetics of these phase formations at different temperatures were studied employing X-ray diffraction analysis (XRD). A model for a description of synthesis reaction kinetics in Ni-Al blends was developed. Based on the obtained results, the synthesis of NiAl was performed in two stages : reactions in 425–550°C range with consumption of Al, followed by a reaction at up to 800°C. It allowed uncontrolled SHS (self propagating high temperature synthesis, resulting in the occurrence of liquid phases and in formation of reaction products in a very fast /explosive manner) to be avoid. The synthesis temperatures are considerably lower than those used currently in processing of NiAl.

Co Anomalous Growth Kinetics of the CoSi Reaction Layer in a Si/System

2008 ◽  
Vol 273-276 ◽  
pp. 99-104
Author(s):  
Csaba Cserháti ◽  
Györgyi Glodán ◽  
A. Csik ◽  
G.A. Langer ◽  
Z. Erdélyi ◽  
...  
Keyword(s):  
Solid State ◽  
Electrical Resistance ◽  
Interface Reaction ◽  
Solid State Reactions ◽  
Heat Treated ◽  
Different Temperatures ◽  
Amorphous Si ◽  
Kinetics Of ◽  
Interface Reaction Control ◽  
Anomalous Growth

Solid state reactions between amorphous Si and crystalline Co have been investigated by 4W electrical resistance and TEM. Multilayered (with 10 periods of 5nm a-Si/5nm Co and 10 nma- Si/10nm Co layers) as well as tri-layered samples (20nm a-Si/3nmCoSi/6nm Co) were produced by magnetron sputtering and isothermally heat treated at different temperatures between 473 and 523K. From the time evolution of the normalized resistance the kinetics of the process were determined by fitting a power law, tk, and k was between 0.8 and 1. Possibility of the interface reaction control and/or the effect of the diffusion asymmetry (which was recently published for the non-parabolic interface shifts on the nanoscale) will be discussed.

Crosslinking Reaction of Rubber with Aldehydes

1970 ◽  
Vol 43 (2) ◽  
pp. 188-209
Author(s):  
Y. Minoura ◽  
M. Tsukasa
Keyword(s):  
Solid State ◽  
Organic Acids ◽  
Physical Properties ◽  
Lewis Acids ◽  
Solid State Reactions ◽  
Crosslinking Reaction ◽  
Reaction Products ◽  
Toluenesulfonic Acid ◽  
Ionic Reaction ◽  
Acidic Catalysts

Abstract The reactions of rubber with aldehydes have previously been studied in latex or in solutions and the reaction products formed by cyclization, condensation, or addition, have been reported. In the present study, solid-state reactions of rubber with aldehydes were carried out. It was found that crosslinked rubbers may be obtained by press curing in the presence of aldehydes with acidic catalysts. Poly-chloroprene and Hypalon especially undergo these reactions without a catalyst or with a small amount of catalyst. In the experiments using various aldehydes, some improvements in the properties of the crosslinked rubber were observed when aldehydes such as paraformaldehyde or α-polyoxymethylene were used. Some Lewis acids such as SnCl2·2H2O were found to be more effective catalysts than the above, and it was found that organic acids such as p-toluenesulfonic acid could also be used. The curing seemed to be an ionic reaction. The physical properties of the crosslinked rubber are similar to those of sulfur-cured rubbers.

scholarly journals Thermal Decomposition and Thermal Reaction Process of PTFE/Al/MnO2 Fluorinated Thermite

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2451 ◽  
Author(s):  
Jun Zhang ◽  
Junyi Huang ◽  
Xiang Fang ◽  
Yuchun Li ◽  
Zhongshen Yu ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Control Systems ◽  
Thermal Reaction ◽  
Reaction Process ◽  
Reaction Products ◽  
Subsequent Reaction ◽  
Comparison Results ◽  
Different Temperatures ◽  
Xrd Phase Analysis ◽  
Two Stages

To better understand the thermal decomposition and reaction process of a fluorine-containing powdery thermite, PTFE/Al/MnO2, reactions at different temperatures were investigated by the TG/DSC-MS technique. The corresponding reaction products were characterized with XRD phase analysis. Another three thermite materials, i.e., PTFE/Al, Al/MnO2, and PTFE/MnO2, were also prepared for comparison. Results showed that PTFE behaved as both oxidizer and reducer in PTFE/Al/MnO2 fluorinated thermite. The thermal decomposition and reaction process of as-fabricated ternary thermite could be divided into two stages—the mutual reaction between each of PTFE, Al, and MnO2 and the subsequent reaction produced between Al and Mn2O3/Mn3O4/MnF2. Compared with the three control systems, the specially designed ternary system possessed a shorter reaction time, a faster energy release rate, and a better heat release performance.

An Investigation on Solid State Reactions in Heat Treated Au/Pd Thin Films for Electrodes Applications

2010 ◽  
Vol 10 (4) ◽  
pp. 2635-2640 ◽  
Author(s):  
Soroush Nazarpour ◽  
Albert Cirera ◽  
Cèsar Ferrater ◽  
Jofre Ventura ◽  
Eric Langenberg ◽  
...  
Keyword(s):  
Thin Films ◽  
Solid State ◽  
Solid State Reactions ◽  
Heat Treated

Correlation between energy transfers and solid state reactions induced by mechanical alloying on the Mo33Si66 system

1997 ◽  
Vol 12 (9) ◽  
pp. 2281-2287 ◽  
Author(s):  
L. Liu ◽  
M. Magini
Keyword(s):  
Energy Transfer ◽  
Solid State ◽  
Metastable Phase ◽  
Solid State Reactions ◽  
Stable Phase ◽  
X Ray Diffraction ◽  
High Temperature Synthesis ◽  
Transmission Electron ◽  
Energy Transfers ◽  
Milling Tools

Phase transformations of the Mo33Si66 powder mixture under different milling conditions have been systematically investigated by x-ray diffraction, and scanning and transmission electron microscopy. The effect of the milling conditions on the Mo/Si solid state reactions (SSR) has been examined in detail. The energy transfer from the milling tools to the powder under processing has been quantified by an already assessed collision model. It has been found that the higher energetic input favors the formation of the room temperature stable phase αMoSi2, while the lower energetic input promotes the formation of the metastable phase βMoSi2. In addition, if the energy transfer is high enough, the Mo/Si reaction proceeds in a form of self-propagating high temperature synthesis (SHS). Thermodynamics and kinetics aspects related to the different SSR's are discussed.

scholarly journals Ni-Doped Protonated Layered Titanate/TiO2 Composite with Efficient Photocatalytic Activity for NO x Decomposition Reactions

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Kanji Saito ◽  
Shota Orikasa ◽  
Yusuke Asakura ◽  
Yusuke Ide ◽  
Yoshiyuki Sugahara ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Solid State ◽  
Room Temperature ◽  
High Photocatalytic Activity ◽  
Solid State Reactions ◽  
Decomposition Reactions ◽  
Ni Content ◽  
Layered Titanate ◽  
Different Temperatures ◽  
Lower Temperature

A unique structural transformation of a lepidocrocite-type layered titanate, K0.8Ti1.73Li0.27O4, into a rutile-type TiO2 has recently been realized via dilute HCl treatment and subsequent drying at room temperature for producing rutile-nanoparticle-decorated protonated layered titanate exhibiting highly efficient photocatalytic activity. Herein, the authors report synthesis of a lepidocrocite-type layered cesium titanate with nominal compositions of C s 0.7 T i 1.825 ‐ x / 2 N i x □ 0.175 ‐ x / 2 O 4 ( x = 0 , 0.05, 0.1, and 0.35) through solid-state reactions of Cs2CO3, TiO2, and Ni(CH3COO)2·4H2O at different temperatures (600 or 800°C), followed by treatment with dilute HCl and subsequent drying to produce a Ni-doped protonated layered titanate/TiO2 composite. C s 0.7 T i 1.825 ‐ x / 2 N i x □ 0.175 ‐ x / 2 O 4 with an optimized Ni content obtained at a lower temperature was converted into a Ni-doped protonated layered titanate/TiO2 composite to exhibit high photocatalytic activity for NO x decomposition reactions.

Microstructure of SiC / TiAl Interface Formed by Solid-State Diffusion Bonding

2005 ◽  
Vol 502 ◽  
pp. 461-466
Author(s):  
Masakatsu Maeda ◽  
Kazuyuki Tenyama ◽  
Toshiya Shibayanagi ◽  
Masaaki Naka
Keyword(s):  
Solid State ◽  
Diffusion Bonding ◽  
Titanium Aluminide ◽  
Chemical Potential ◽  
Interfacial Microstructure ◽  
Solid State Diffusion ◽  
Reaction Products ◽  
Phase Sequence ◽  
Heat Treated ◽  
State Diffusion

The microstructure of the solid-state diffusion bonded interfaces of silicon carbide (SiC) and titanium aluminide (TiAl) were investigated. A 100-µm-thick Ti-48at%Al foil was inserted between two SiC specimens and then heat-treated in vacuum. The interfacial microstructure has been analyzed by scanning electron microscopy, electron probe microanalysis and X-ray diffractometry. Four layers of reaction products are formed at the interface by diffusion bonding: a layer of TiC adjacent to SiC followed by a diphase layer of TiC+Ti2AlC, a layer of Ti5Si3CX containing Ti2AlC particles and a layer of TiAl2. However, the TiAl2 layer is formed during cooling. The actual phase sequence at the bonding temperatures of 1573 K and 1673 K are described as SiC/TiC/(TiC+ Ti2AlC)/(Ti5Si3CX+Ti2AlC)/Ti1-XAl1+X/TiAl and SiC/TiC/(TiC+Ti2AlC)/(Ti5Si3CX+Ti2AlC)/Ti5Al11 /Ti1-XAl1+X/TiAl, respectively. The phase sequences are successfully expressed on the basis of the Ti-Al-Si-C quaternary chemical potential diagram.

Anomalous Kinetics and Regimes of Growth of Intermetallic Phases during Solid State Reactions in Nanosystems

2014 ◽  
Vol 2 ◽  
pp. 107-139 ◽  
Author(s):  
D.L. Beke ◽  
Zoltán Erdélyi ◽  
G.L. Katona
Keyword(s):  
Solid State ◽  
Grain Boundary ◽  
Limit Of Detection ◽  
Normal Growth ◽  
Intermetallic Phases ◽  
Solid State Reactions ◽  
Parabolic Growth ◽  
Linear Kinetics ◽  
Two Stages ◽  
New Phase

Two interesting features of formation and growth of intermetallic phases in nanoscale solid state reactions will be discussed:Linear-parabolic “normal” growth: it will be summarized that at the very early stages of the growth of an already existing new phase (i.e. when nucleation problems can be neglected) the linear kinetics can be observed due to the so-called diffusion asymmetry. Indeed, it was shown that if the ratio of the diffusion coefficients differ by orders of magnitude in the parent materials (and so also in the new phase), during the growth of a phase bordered by parallel interfaces from the parent phases (normal growth geometry), the shift of the individual interfaces can be linear at the beginning and a transition to the parabolic regime can take place even after a shift of several tens of nanometres. In addition, an AB compound in contact with the pure A and B phases can be dissolved if the diffusion in B is much faster than in either A and AB. This means that the thickness of this phase should decrease, or even can be fully dissolved, at the beginning and only after some time—when the composition in B will be high enough allowing the re-nucleation of this AB phase—will the AB phase grow further.The common problem oftwo stages of solid state reactionswill be revisited: usually the growth can be divided into two stages: a) the formation (nucleation) and lateral growth of the new phases and b) the “normal” growth of the already continuous phase. It was concluded in different previous reviews that in stage b) in the majority of cases the parabolic growth was observed in accordance with the above i) point: the linear-parabolic transition length was typically below 1 μm, which was the lower limit of detection in many previous investigations. On the other hand recently the application of the linear-parabolic growth law for the analysis of experimental data obtained in nanoscale reactions became very popular, not making a clear distinction between a) and b) stages. It will be emphasized here that care should be taken in all cases when the experimental methods applied provide information only about the increase of the amount of the reaction product and there is no informationwhere and howthe new phase (s) grow. We have illustrated in a series of low temperature experiments - where the bulk diffusion processes are frozen - that even in this case a full homogeneous phase can be formed by cold homogenization called Grain Boundary Diffusion Induced Solid State Reaction (GBDIREAC). In this case first the reaction starts by grain-boundary (GB) diffusion and nucleation of the new phase at GBs or their triple junctions, then the growth of the new phase happens by the shift of the new interfaces perpendicular to the original GB. This is a process similar to the diffusion induced grain-boundary motion (DIGM) or diffusion induced recrystallization (DIR) phenomena and in this case the interface shift, at least in the first stage of the reaction until the parent phases have been consumed, can be considered constant. This means that the amount of the phase increases linearly with time, giving a plausible explanation for the linear kinetics frequently observed in stage a).

Solid Phase’s Transformations in Boron Carbide Based Composites during Heat Treatment

2008 ◽  
Vol 138 ◽  
pp. 175-180
Author(s):  
Lembit A. Kommel ◽  
Eduard Kimmari
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Boron Carbide ◽  
Environmental Conditions ◽  
Sliding Wear ◽  
Bending Strength ◽  
Reaction Products ◽  
Temperature Synthesis ◽  
High Temperature Synthesis ◽  
Different Temperatures

Lightweight B4C/Al composites were produced from powders of boron carbide and aluminum by self-propagating high-temperature synthesis (SHS). The effects of postdensification heat treatment at different temperatures and environmental conditions on phase transformations and properties evolution were studied. Heat treatment processing that followed the synthesis was applied using low heating rate in temperature range from 400°C up to 1500°C. An interconnected multiphase (B4C, Al3BC, and c-BN) microstructure was produced in composite as a result of heat treatment at temperatures below 1080°C. The formation of hard and brittle reaction products (AlN, AlB2, Al4C3, and Al8B4C7) at temperatures above 1150°C causes decrease in bending strength and increase in resistance to unlubricated sliding wear.

Solid State Interfacial Reactions Between Tic Thin Films and Ti3AI Substrates

1995 ◽  
Vol 398 ◽  
Author(s):  
Weimin Si ◽  
Michael Dudley ◽  
Pengxing Li ◽  
Renjie Wu
Keyword(s):  
Thin Films ◽  
Solid State ◽  
Ion Beam ◽  
Depth Profiling ◽  
Solid State Reactions ◽  
Reaction Products ◽  
Ion Beam Sputtering ◽  
Thermodynamical Equilibrium ◽  
Beam Sputtering ◽  
Kinetics Of

ABSTRACTThe products and kinetics of solid state reactions between TiC and Ti3Al have been investigated using X-ray diffractometry (XRD) and Auger electron spectroscopy (AES) with Ar ion beam sputtering. Diffusion couples were prepared by sputtering TiC thin films onto polished Ti3AI substrates, and then isothermally annealed in vacuum in the temperature range of 800 to 1000°C for 0.25 to 2.25 hours. The thickness of the interfacial reaction layer was obtained from AES elemental concentration depth profiling, while the reaction products were identified from XRD spectra. In the TiC/Ti3Al system, the reaction product was primarily P(Ti3AlC) phase. The growth-rate of the reaction product was fitted to a parabolic growth law (dZ/dt = k1/Z) and the activation energy of the rate constant was about 36.16 kcal/mole. The reaction mechanism will be discussed on the basis of thermodynamical equilibrium in Ti-Al-C ternary system.

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