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Visar resultat 1 - 5 av 65 avhandlingar som matchar ovanstående sökkriterier.

1. 1. Tailored process gases for laser powder bed fusion

   Författare :Camille Nicole Géraldine Pauzon; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Helium; Laser powder bed fusion; AM process productivity; Spatter particles; Residual oxygen; 316L stainless steel; Argon; Nitrogen; Additive manufacturing; Process atmosphere; Process stability; Residual stresses.; Ti-6Al-4V; Alloy 718;

   Sammanfattning : Metal laser powder bed fusion (L-PBF) allows for production of complex components using the energy from a laser to locally melt micron-sized powder following a layer-wise approach. Considerable scientific efforts are focused on addressing the influence of the process parameters on the melting stability and the control of material properties, while developing necessary monitoring and characterization tools. LÄS MER

3. 2. Some aspects on TCF-bleachability of softwood alkaline pulps

   Författare :Karin Sjöström; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Bleachability; chlorine-free bleaching; softwoods; kraft pulps; alkaline sulfite pulps; oxygen; hydrogen peroxide; ozone; hydrogen sulfide ion; hydroxide ion; temperature; sodium ion.; Cellulose and paper engineering; Cellulosa- och pappersteknik;

   Sammanfattning : The bleachability of softwood oxygen delignified pulps has been studied, i.e. the ease (requirement of bleaching chemicals) with which the pulps can be brightened to a target brightness in totally chlorine free (TCF) bleaching stages, including hydrogen peroxide, ozone and chelating agent stages. LÄS MER

4. 3. Powder degradation during powder bed fusion processing

   Författare :Ahmad Raza; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Laser-based powder bed fusion; Alloy 718; Powder degradation; Oxidation; Electron beam powder bed fusion; Additive manufacturing; AlSi10Mg; Residual oxygen; Spatter particles; Sublimation.;

   Sammanfattning : Powder bed fusion (PBF) techniques, including laser-based powder bed fusion (LB-PBF) and electron beam powder bed fusion (EB-PBF), are two rapidly growing additive manufacturing (AM) processes due to their ability to produce complex geometries in near-net shapes. To attain reproducibility and repeatability in PBF processes, a consistent set of powder properties is vital. LÄS MER

5. 4. Powder degradation during powder bed fusion processing: impact of processing conditions and alloy composition

   Författare :Ahmad Raza; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; residual oxygen; powder bed fusion – electron beam; powder degradation; oxidation; Alloy 718; AlSi10Mg; powder bed fusion - laser beam; TiAl6V4; Hastelloy X.; sublimation; spatter particles; Keywords: additive manufacturing;

   Sammanfattning : In the recent decade, powder bed fusion (PBF) metal additive manufacturing (AM) has attracted huge attention both from the industry and the research community. This effort has helped mature PBF technology as a potential alternative to conventional manufacturing processes as casting, machining, forging, etc. LÄS MER

7. 5. The effects of oxygen on the degradation of lignin model compounds and residual lignin

   Författare :Eva Johansson; KTH; []
   Nyckelord :;

   Sammanfattning : The aim of this work was to achieve a further understandingof the reactivity of lignin structures and residual ligninduring oxygen bleaching. The kinetics of lignin model compoundssuch as diguaiacyl stilbene, propylguaiacol,dipropylbiguaiacol, enol ether and β-aryl ether structuresunder oxygen bleaching conditions have been studied. LÄS MER