Sökning: "surface oxides"

Visar resultat 1 - 5 av 305 avhandlingar innehållade orden surface oxides.

1. 1. ROLE OF SURFACE OXIDES IN SINTERING OF CHROMIUM-ALLOYED STEEL POWDER

   Författare :Henrik Karlsson; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; water atomisation; surface analysis; sintering; chromium-alloyed steel.; Powder metallurgy; surface reactions; surface; surface oxide; SEM; XRD; AES; XPS;

   Sammanfattning : During water-atomisation and handling of steel powder the surface inevitably oxidises. The surface bound oxide is an important factor in the processing of powder metallurgical (PM) steels, especially in case the powder contains elements forming stable oxides, such as Cr, Mn, and Si. LÄS MER

3. 2. Surface Chemical Characteristics of Chromium-alloyed Steel Powder and the Role of Process Parameters during Sintering

   Författare :Dimitris Chasoglou; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; carbothermal reaction; sintering atmosphere; depth profiling; XPS AES; HR SEM EDX; water atomized powder; surface coverage; reduction oxidation; PM steels; sintering; Cr-Mn-spinel oxides; surface oxides;

   Sammanfattning : Powder Metallurgy (PM) is a cost efficient method suitable for sustainable production of structural parts that have strict dimensional tolerances and complex geometries. It has been a common practice to utilize Ni and Cu as alloying elements in PM steels, but the high and fluctuating prices of Ni and the concerns around it associated with health hazards as well as the difficulty in recycling Cu lead the PM industry to search for effective alternatives such as Cr and Mn. LÄS MER

4. 3. The effect of surface steps and oxides on the catalytic activity on model Pd and Rh catalysts

   Författare :Chu Zhang; Synkrotronljusfysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Surface X-ray diffraction SXRD ; X-ray photonelectron spectroscopy; Catalytic activity; Oxide; Single Crystal surface; surface structure; vicinal surface; CO oxidation; stepped surface; Fysicumarkivet A:2018:Zhang;

   Sammanfattning : A catalyst is a substance that can speed up the rate of a chemical reaction without itself being consumed. Catalysts are crucial for chemical production industries, where about 90% of all chemicals are produced using catalysts. LÄS MER

5. 4. Surface Reactivity and Electronic Structure of Metal Oxides

   Författare :Anneli Önsten; Ulf Karlsson; Anne Borg; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; oxides; surfaces; defects; cuprous oxide; zinc oxide; magnetite; water; OH; sulfur dioxide; photoelectron spectroscopy; scanning tunneling microscopy; Material physics with surface physics; Materialfysik med ytfysik;

   Sammanfattning : The foci of this thesis are the metal oxides Cu2O, ZnO and Fe3O4 and their interaction with water and sulfur dioxide (SO2). The intention is to study SO2-induced atmospheric corrosion on a molecular level. All studies are based on photoelectron spectroscopy (PES) and scanning tunneling microscopy (STM) measurements. LÄS MER

7. 5. Reactions of aqueous radiolysis products with oxide surfaces : An experimental and DFT study

   Författare :Cláudio Miguel Lousada Patrício; Mats Jonsson; Jean-Philippe Renault; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; hydrogen peroxide; hydrogen production; metal; oxides; lanthanide; catalysis; density functional theory; surface; reactions; chemistry; SRA - Energy; SRA - Energi; SRA - Production; SRA - Produktion;

   Sammanfattning : The reactions between aqueous radiolysis products and oxide surfaces are important in nuclear technology in many ways. In solid-liquid systems, they affect (and at the same time are dependent on) both the solution chemistry and the stability of materials under the influence of ionizing radiation. LÄS MER