Search results for "Surfaces"
showing 10 items of 2837 documents
Preparation by radio-frequency magnetron co-sputtering and characterization of thin films of lanthanum–strontium ferromanganites
2005
Abstract (La 0.8 Sr 0.2 )(Mn 1 − y Fe y )O 3 ± δ films with y = 0, 0.2, 0.5, 0.8 and 1, a few hundred nanometers thick, were deposited onto polycrystalline yttria-stabilized zirconia YSZ by a magnetron co-sputtering technique using individual targets of La 0.8 Sr 0.2 MnO 3 and La 0.8 Sr 0.2 FeO 3 . The deposition parameters, substrate temperature and gas pressure, were studied by scanning electron microscopy, energy dispersive X-ray spectrometry, X-ray diffraction and interferential microscopy for their effects on the morphological, chemical, topographic and crystallographic properties of films and YSZ-film interfaces. (La 0.8 Sr 0.2 )(Mn 1 − y Fe y )O 3 ± δ thin films were found to be …
Effect of the surface stoichiometry on the interaction of Mo with TiO2 (110)
2000
Abstract Molydenum has been deposited at room temperature on (110) TiO2 surfaces with different stoichiometries, roughnesses and crystallinities. Whatever the substrate preparation is, in-situ Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) studies as well as ex-situ atomic force microscopy (AFM) and reflexion high-energy electron diffraction (RHEED) studies reveal a Stranski–Krastanov growth mode: the completion of three monolayers followed by islands growth is observed in every case. The three monolayers are always composed of amorphous molybdenum oxide with an oxidation state of molybdenum less than IV. The oxidation of the molybdenum layers generates Ti3+ an…
Initial chemical transport of reducing elements and chemical reactions in oxide cathode base metal
2002
Abstract In the present work, the formation of compounds associated to the diffusion of reducing elements (Mg and Al) to the nickel surface of a one-piece oxide cathode has been studied. Those compounds have been evidenced after the annealing steps at high temperature performed on cathode base metal prior to the emitting coating deposition. Therefore, they form the “initial” interface between the nickel and the coating, in other words, the interface existing at the beginning of cathode life. Extensive analysis to characterize the nickel base prior to coating deposition has been performed by means of scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX), …
Aurophilicity as a cofactor in crystal engineering. Dicyanoaurate(I) anion as a building block in a novel Co(II)–Au(I) bimetallic assembly
2002
A 2D grid-shaped cyanide-bridged Co(II)–Au(I) bimetallic coordination polymer, [Co(DMF)2{Au(CN)2}2], has been prepared from the [Au(CN)2]2 building block; sheets associate pair-wise by aurophilic interactions and the compound exhibits zeolite-like properties. Lloret Pastor, Francisco, Francisco.Lloret@uv.es
An integrated approach to evaluating the tribo-contact for coated cutting inserts
2000
Abstract The orthogonal machining process when end turning medium carbon and austenitic stainless steels with cemented WC-Co tools coated with single-layer (TiC), two-layer (TiC/TiN), and three-layer (TiC/Al2O3/TiN) hard thin films was investigated. Extensive experimental investigations including the thermal, mechanical and tribological responses of the tribo-contact between the coating–substrate system and the chip, under different cutting conditions, were carried out. The study sheds light on the cutting forces, the interface temperatures and the tribo-contact conditions, including the friction energy dissipated at the tool–chip interface, the frictional heat flux conducting into either t…
The influence of thin hard coatings on frictional behaviour in the orthogonal cutting process
2000
New knowledge about the tribological response deriving from the interaction of the substrate/coating-chip system, with special attention to the orthogonal cutting process when chatter-free end turning using natural contact tools, is developed. In order to evaluate the frictional behaviour of this process under modified contact conditions, experimental investigations including the contact temperature, the contact loads, friction and the frictional heat flux per unit area were carried out. In contrast to the most obvious approach, the coefficient of sliding friction versus the cutting speed, the contact temperature, the normal pressure and the interface control factor is considered. A number …
Microstructural evolution of wear-resistant FeCrB and FeCrNiCoB coating alloys during high-energy mechanical attrition
2008
Mechanical milling/attrition provides a convenient scope of simulating the microstructural changes encountered by wear-resistant coating alloys subjected to deformation under high frequency and high-intensity impact loading or accelerated wear condition. In the present study, the microstructural evolution of two commercial coating materials, FeCrB (Armacor M) and FeCrNiCoB (Armacor C), in the course of low- and high-intensity mechanical attrition, was monitored by X-ray diffraction and high-resolution transmission electron microscopy. While low-intensity milling leads to marginal grain refinement but no change in phase-aggregate in FeCrB, similar mechanical attrition causes boride precipita…
Influence of friction on the local mechanical and electrochemical behaviour of duplex stainless steels.
2006
International audience; The electrochemical behaviour of ferritic and austenitic phases in duplex stainless steel (UNS S32304) and the modifications induced by straining during sliding were studied by potentiodynamic polarisation curves determined at the microscale in a 1MNaCl (pH 3) solution, using an electrochemical microcell. The mechanical properties and stress state of each phase were determined by microhardness and X-ray microdiffraction measurements, before and after straining. The results show that sliding generates elastic straining of the ferrite and plastic deformation of the austenite. The electrochemical behaviour of these phases is dramatically altered, inducing a reduction of…
Inhibitoren der Korrosion 21 (1) - Autoxidationsstudien an Fe2+-Salzen der Tetramethylen-1,4-bis-phosphonsäure, der Hexamethylen-1,6-bis-phosphonsäur…
1978
Die Wirksamkeit der organischen Bisphosphonsauren als Inhibitoren der Korrosion von Eisen ist dadurch bedingt, das die aus der Eisenoberflache auftretenden Fe2+-Ionen direkt am Austrittsort mit den Sauren reagieren und an Ort und Stelle dreidimensional vernetzte Deckschichten aufbauen. Je dichter die Struktur dieser Schichten, je bestandiger das Netzwerk gegen Sauerstoff und je hydrolysebestandiger die FeOP-Bindungen, desto besser ist die Schutzwirkung: Dadurch wird sowohl dem Sauerstoff als auch dem Chloridion der Zugang zur Metalloberflache verwehrt. Die Modellversuche ermoglichen aufgrund der Verteilung des Phosphors in den Niederschlagen Ruckschlusse auf den Vernetzungsgrad. Corrosion I…
Inhibitoren der Korrosion 19 (1). Autoxidationsstudien an Fe2+-Trimethylen-1,3-bis-phosphonat als Modell einer die Korrosion inhibierenden Deckschicht
1976
Die Autoxidationsgeschwindigkeit der Fe2+. Salze ist stark abhangig vom pH und ist bei pH 2 praktisch gleich Null, bei pH 5–7 sehr hoch. Durch Zusatz von Trimethylen-1,3-bis-phosphonsaure wird die Autoxidation etwas verlangsamt und der Sauerstoffverbrauch starker erhoht als es der Stochiometrie der Fe2+-Oxidation entspricht. Dieser Umstand erklart sich durch den oxidativen Abbau der Trimethylen-1,3-bis-phosphonsaure zu Phosphorsaure, wobei Salze des dreiwertigen Eisens als Niederschlag ausfallen. Diese Fe3+-bis-phosphonate sind dreidimensional vernetzt; das Fe:P-Verhaltnis liegt zwischen 0.5 und 0.9 und wird mit abnehmendem pH-Wert geringer. Inhibitors of corrosion 19 (1). Autoxidation stud…