On the Stability of Hetastable and Amorphous Pvd-Compound Films

1989 ◽  
Vol 157 ◽  
Author(s):  
Otto Knotelc ◽  
Frank Jungblut ◽  
Arman Barimani
Keyword(s):  
Thermal Stability ◽  
Low Temperature ◽  
Amorphous Materials ◽  
Vapour Deposition ◽  
Physical Vapour Deposition ◽  
Thin Coatings ◽  
Wear And Corrosion ◽  
Amorphous Structures ◽  
The Stability ◽  
Equilibrium Phases

ABSTRACTIn using low temperature physical vapour deposition (PVD) techniques new metastable and amorphous materials can be deposited. Structural order in a coating is produced largely by the mobility of the adatoms. Low mobility does not allow the formation of equilibrium phases and metastable and/or amorphous structures are observed. These coatings have sufficient thermal stability for tools, and for both wear- and corrosion-protection. Examples are given within the systems Al-O-N, Ti-Al-N and Cr-Al-N and the properties, crystalline and thermodynamic state of the coatings are characterized. An example of decomposition phenomena is given in metastable thin coatings by the Ti-Zr-N system.

Interface Stabilization of W-N Coatings by Chromium Alloying

1991 ◽  
Vol 237 ◽  
Author(s):  
O. Knotek ◽  
F. Löftier ◽  
A. Barimani
Keyword(s):  
Thin Films ◽  
Low Temperature ◽  
Vapour Deposition ◽  
Reactive Sputtering ◽  
Interface Layer ◽  
Stable Configuration ◽  
Tungsten Nitride ◽  
Physical Vapour Deposition ◽  
Metastable Structures ◽  
Equilibrium Phases

ABSTRACTNew metastable materials can be deposited using low temperature physical vapour deposition (PVD) techniques. During reactive sputtering, the atoms condensing in an intermixed state attempt to achieve a stable configuration. Due to low mobility of the adatoms, equilibrium phases cannot form and metastable structures are observed. Reactive sputtering can be used to deposit films with different stoichiometries and structures in the W-N system. The metastable phases α-W. β-W. W2N and WN1−x are obtained. All coatings are, however, thermally unstable. At temperatures above 570 °C. all phases are transformed into the a-W modification. By alloying chromium to the coatings in the W-N system, it is possible to stabilize all tungsten and tungsten nitride modifications as well as the interface layer between the substrate and the thin films.

Nano-ceramic support materials for low temperature fuel cell catalysts

Nanoscale ◽  
2014 ◽  
Vol 6 (10) ◽  
pp. 5063-5074 ◽  
Author(s):  
Haifeng Lv ◽  
Shichun Mu
Keyword(s):  
Thermal Stability ◽  
Fuel Cell ◽  
Low Temperature ◽  
Acid Corrosion ◽  
Ceramic Materials ◽  
Excellent Thermal Stability ◽  
Support Materials ◽  
Ceramic Support ◽  
Fuel Cell Catalysts ◽  
The Stability

Nano-ceramic materials have attracted much attention for increasing the stability of low temperature fuel cell catalysts due to their outstanding oxidation and acid corrosion resistance, and excellent thermal stability.

TEM studies of amorphization processes and amorphous structures

1988 ◽  
Vol 46 ◽  
pp. 448-449
Author(s):  
T. E. Mitchell ◽  
R. B. Schwarz
Keyword(s):  
Amorphous Materials ◽  
Fission Products ◽  
Rapid Quenching ◽  
Surface Films ◽  
List Type ◽  
Oxide Glasses ◽  
Crystalline Materials ◽  
Amorphous Structures ◽  
Amorphous Surface ◽  
Interfacial Films

Traditional oxide glasses occur naturally as obsidian and can be made easily by suitable cooling histories. In the past 30 years, a variety of techniques have been discovered which amorphize normally crystalline materials such as metals. These include [1-3]:Rapid quenching from the vapor phase.Rapid quenching from the liquid phase.Electrodeposition of certain alloys, e.g. Fe-P.Oxidation of crystals to produce amorphous surface oxide layers.Interdiffusion of two pure crystalline metals.Hydrogen-induced vitrification of an intermetal1ic.Mechanical alloying and ball-milling of intermetal lie compounds.Irradiation processes of all kinds using ions, electrons, neutrons, and fission products.We offer here some general comments on the use of TEM to study these materials and give some particular examples of such studies.Thin specimens can be prepared from bulk homogeneous materials in the usual way. Most often, however, amorphous materials are in the form of surface films or interfacial films with different chemistry from the substrates.

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