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| 2. |
- Ekroth, M., et al.
(författare)
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Gradient zones in WC-Ti(C,N)-Co-based cemented carbides : Experimental study and computer simulations
- 2000
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Ingår i: Acta Materialia. - 1359-6454 .- 1873-2453. ; 48:9, s. 2177-2185
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Tidskriftsartikel (refereegranskat)abstract
- The formation of surface zones with a composition gradient during sintering of WC-Ti(C,N)-Co cemented carbides has been studied experimentally and by computer simulations. The microstructure has been investigated with SEM and EPMA. The simulations are based on a solution of the multicomponent diffusion equations, coupled with thermodynamic calculations using thermodynamic descriptions of the individual phases. The results from the simulations are in good agreement with the experimental results, indicating that diffusion and the thermodynamic properties are the two major factors that control the gradient structure formation.
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| 3. |
- Frisk, K., et al.
(författare)
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Development of a database for cemented carbides : Thermodynamic modeling and experiments
- 2001
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Ingår i: Journal of phase equilibria (Print). - 1054-9714 .- 1544-1032. ; 22:6, s. 645-655
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Tidskriftsartikel (refereegranskat)abstract
- A new database, for thermodynamic information for cemented carbides has been developed. A full description of the alloy system C-Co-N-Nb-Ta-Ti-W is presented. The work has involved both thermodynamic evaluations of lower order systems and experimental investigations. Full new assessments of the quaternary Ti-W-C-N, Ta-W-C-N, and Nb-W-C-N systems have been performed, including tests of the influence of model parameters on miscibility gaps in higher order systems. A new improved description of the Co-W-C system based on new experiments is used in the present work. The main results of the experimental work are measurements of the composition of the cubic carbide in selected equilibria; measurements of the temperatures of the liq + fcc + WC + gr. and liq + fcc + WC + M6C equilibria in the Co-W-C and Co-W-X-C (X = Ti, Ta, Nb) systems; and measurements of the solubility of Ti, Ta, and Nb in liquid in multicomponent alloys. The results of the assessments have been implemented into a new database. The database has successfully been used in a parallel project to simulate the formation of gamma -phase free zones in cemented carbides. A few other applications of industrial relevance are presented.
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| 4. |
- Frykholm, R., et al.
(författare)
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A new labyrinth factor for modelling the effect of binder volume fraction on gradient sintering of cemented carbides
- 2003
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Ingår i: Acta Materialia. - : Elsevier BV. - 1359-6454 .- 1873-2453. ; 51:4, s. 1115-1121
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Tidskriftsartikel (refereegranskat)abstract
- To increase the cutting performance of WC-MC-Co cemented carbide tools, it is common to use a high temperature CVD process to coat them with thin wear resistant layers. During the process cracks are unavoidably introduced in the coating. To prevent crack propagation it is of interest to create a tough surface zone in the substrate, enriched in WC and binder phase. A way to create such a zone is to sinter a nitrogen-containing cemented carbide in a nitrogen free atmosphere. This formation of gradient structures has been extensively studied using microscopy and simulations, and it has been shown that the process is driven by diffusion in the binder phase. However, the diffusion paths are partly blocked by the dispersed particles. This effect can be formally handled by considering effective diffusivities by introducing a so-called labyrinth factor, lambda. In prior work it has been assumed that lambda =f(2) where f is the volume fraction of the binder. The validity of this assumption has been studied by simulations and experimental analysis of gradient sintered WC-Ti(C,N)-Co cemented carbides containing 5.0, 6.7, 10.0 and 20.0 vol% binder phase. It was found that by using the labyrinth factor lambda = f(2) instead of a better correspondence between experiments and simulations can be achieved.
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| 5. |
- Frykholm, R., et al.
(författare)
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Effect of cubic phase composition on gradient zone formation in cemented carbides
- 2001
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Ingår i: International journal of refractory metals & hard materials. - 0263-4368. ; 19:06-apr, s. 527-538
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Tidskriftsartikel (refereegranskat)abstract
- Cemented carbide cutting tool inserts with a surface zone depleted of hard cubic carbides and enriched in ductile binder phase have been studied experimentally using scanning electron microscopy (SEM), electron probe micro analysis (EPMA) and transmission electron microscopy (TEM). The results are compared with simulations based on a solution of the multicomponent diffusion equations, coupled with calculations using thermodynamic descriptions of the individual phases. The materials in the study are based on WC-Ti(C,N)-Co, WC-Ti(C,N)-NbC-Co and WC-Ti(C,N)-TaC-Co. The surface zone is formed by creating a gradient in nitrogen activity in the material, leading to an outward diffusion of N. Due to thermodynamical coupling between N and Ti, the outward diffusion of N will lead to an inward diffusion of Ti, and a surface zone depleted in cubic carbides is formed. Additions of elements like Ta or Nb will affect the width of the surface zone. A material with a Ta-containing cubic phase will have a narrower surface zone than a material with a Nb-containing cubic phase. Ta or Nb additions also affect the distribution of the different phases in and adjacent to the surface zone.
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| 6. |
- Lindblom, Anna, 1959-
(författare)
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Take a Walk on the Wild Side : The Behaviour, Attitude and Identity of Women Approached by Satyrs on Attic Red-Figure Vases from 530 to 400 BC
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This study examines the behaviour, attitude and identity of women approached by satyrs on Attic red-figure vases from 530 to 400 BC and in particular how modern conceptions have influenced earlier interpretations of these women. In order to illustrate the diversity of the interactions between women and satyrs, five motifs have been chosen for study – Movement, Rest, Reclining, Body care and Sex. The aim is to establish the women’s behaviour as a way to define their attitude towards the satyrs, and subsequently to reconsider the women’s identity since scholars’ view of the women’s behaviour and attitude has influenced how they have identified the women. The work is divided in three parts. The first part is an analysis of the behaviour and attitude of the women. Contrary to the prevalent theory that the women were negative toward the approaches of the satyrs, and that the satyrs were believed to be incapable of having sex with women, it is demonstrated that the women approved of the satyrs’ advances and that the satyrs were effective lovers. In the second part, the appearance of the women and the settings where the female-satyr interaction takes place are examined in order to show that it is impossible to divide the women into distinct categories on iconographical grounds. Scholars’ designations of these women as hetairai, maenads or nymphs are thus questionable. The third part discusses chronological considerations and it is found that certain features of the images can be attributed to their time period, rather than being generally important for how the behaviour, attitude and identity of the women are to be interpreted. It is suggested that the women should be understood as images of female behaviour with no stipulated identity besides existing in the world of images. Their appearance and actions reflect the fact that the figure they interact with is a satyr, and have nothing to do with a negative attitude towards the satyr or the women’s identity or status.
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