Endre søk
RefereraExporteraLink to record
Permanent link

Direct link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Aqueous Processing of WC-Co Powders
KTH, Tidigare Institutioner (före 2005), Kemi.
2004 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

The object of this work is to obtain a fundamentalunderstanding of the principal issues concerning the handlingof an aqueous WC-Co powder suspension.

The WO3 surface layer on the oxidised tungsten carbidepowder dissolves at pH>3 with the tungsten concentrationincreasing linearly with time. Adding cobalt powder to thetungsten carbide suspension resulted in a significant reductionof the dissolution rate at pH<10. Electrokinetic studiesindicated that the reduced dissolution rate may be related tothe formation of surface complexes; the experiments showed thatCo species in solution adsorb on the oxidised tungsten carbidepowder.

The surface forces of oxidised tungsten and cobalt surfaceswere investigated using the atomic force microscope (AFM)colloidal probe technique. The interactions at various ionicstrengths and pH values are well described by DLVO theory. Theadsorption of cobalt ions to tungsten oxide surfaces resultedin an additional non-DLVO force and a reduced absolute value ofthe surface potential. It was shown that the adsorption ofpoly(ethylene imine) (PEI) to the WO3 surfaces induces anelectrosteric repulsion.

The properties of spray-dried WC-Co granules were related tothe WC primary particle size, and the poly(ethylene glycol)(PEG) binder and PEI dispersant content in aqueous WC-Cosuspensions. The granule characterisation includes a new methodfor measuring the density of single granules. The increase inthe fracture strength of granules produced from suspensionsthat were stabilised with PEI was related to a more densepacking of the WC-Co particles.

The AFM was used to study the friction and adhesion ofsingle spray-dried WC-Co granules containing various amounts ofPEG binder. The adhesion and friction force between two singlegranules (intergranular friction) and between a granule and ahard metal substrate (die-wall friction) have been determinedas a function of relative humidity. The granule-wall frictionincreases with binder content and relative humidity, whereasthe granule-granule friction is essentially independent of therelative humidity and substantially lower than the granule-wallfriction at all PEG contents.

Key words:Hard Metal, Cemented Carbide, WC-Co, TungstenCarbide, Cobalt, Oxidation, Dissolution, Surface Complexation,XPS, AFM, Colloidal Probe, Hamaker Constant, Cauchy, WO3,CoOOH, ESCA, Zeta-Potential, Surface Potential, Poly(ethyleneimine), PEI, Suspension, van der Waals, Steric, Spray-Dried,Poly(ethylene glycol), Strength, Density, Friction, Adhesion,Granule, PEG, Pressing, FFM.

sted, utgiver, år, opplag, sider
Stockholm: Kemi , 2004. , s. x, 64
Serie
TRITA-YTK, ISSN 1650-0490 ; 0401
Emneord [en]
Hard Metal, Cemented Carbide, WC-Co, Tungsten Carbide, Cobalt, Oxidation, Dissolution, Surface Complexation, XPS, AFM, Colloidal Probe, Hamaker Constant, Cauchy, WO3, CoOOH, ESCA, Zeta-Potential, Surface Potential, Poly(ethylene imine), PEI, Suspensi
HSV kategori
Identifikatorer
URN: urn:nbn:se:kth:diva-3725ISBN: 91-7283-714-4 (tryckt)OAI: oai:DiVA.org:kth-3725DiVA, id: diva2:9566
Disputas
2004-04-16, 00:00
Merknad

QC 20161027

Tilgjengelig fra: 2004-05-06 Laget: 2004-05-06 Sist oppdatert: 2022-06-22

Open Access i DiVA

fulltekst(1902 kB)5431 nedlastinger
Filinformasjon
Fil FULLTEXT01.pdfFilstørrelse 1902 kBChecksum MD5
23757cc0e7f2723aff9dc8ad146995dd33a9596849709fe3103e2b4e4eb99c9c90539bf5
Type fulltextMimetype application/pdf

Søk i DiVA

Av forfatter/redaktør
Andersson, Karin M.
Av organisasjonen

Søk utenfor DiVA

GoogleGoogle Scholar
Totalt: 5466 nedlastinger
Antall nedlastinger er summen av alle nedlastinger av alle fulltekster. Det kan for eksempel være tidligere versjoner som er ikke lenger tilgjengelige

isbn
urn-nbn

Altmetric

isbn
urn-nbn
Totalt: 7793 treff
RefereraExporteraLink to record
Permanent link

Direct link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf