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- Yousfi, Mohamed Amine, 1986, et al.
(författare)
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Creep of un-doped and Cr-doped WC-Co at high temperature and high load
- 2023
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Ingår i: International Journal of Refractory Metals and Hard Materials. - 0263-4368 .- 2213-3917. ; 117
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Tidskriftsartikel (refereegranskat)abstract
- Un-doped and Cr-doped WC-10 vol% Co cemented carbides with a WC grain size of 1.4 μm have been investigated before and after hot compressive creep tests under an applied load of 900 MPa at 1000 °C and 300 MPa at 1100 °C. The Cr-doped material showed a much higher creep resistance at 1000 °C and a somewhat higher creep resistance at 1100 °C than the un-doped material. Quantitative microscopy showed that WC grain growth occurred in the plane perpendicular to the load axis during creep deformation and that the growth process was slower in the Cr-doped material. In addition, binder phase redistributed and a number of WC grain boundaries were infiltrated with binder phase. This suggests that accommodated WC grain boundary sliding occurred during creep deformation. The formation of intergranular cavities implies that also unaccommodated grain boundary sliding occurred, especially at 1000 °C. It is suggested that WC grain growth perpendicular to the load axis is rate limiting in the creep deformation process, and that Cr segregation to WC/binder phase boundaries hinders grain growth. The weak effect of Cr on creep resistance at 1100 °C at 300 MPa is explained by Cr giving a larger volume fraction of binder phase and therefore a larger number of infiltrated grain boundaries, facilitating grain growth.
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| 3. |
- Kryzhanivskyy, V., et al.
(författare)
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Experimental study and modeling of the heat flux acting on the tool flank when machining
- 2021
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Ingår i: 18th CIRP Conference on Modeling of Machining Operations (CMMO), Ljubljana, Slovenia, June 15-17, 2021. - : Elsevier BV. - 2212-8271. ; 102, s. 97-102
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Konferensbidrag (refereegranskat)abstract
- Adequate setting of the boundary conditions for the heat equation when modeling the temperature distribution in the cutting tool is one of the key points. The boundary conditions on the tool surfaces can be divided into two groups: conditions that describe heat losses (heat exchange with the environment) and conditions that characterize the heat source that heats up the tool (heat flux from the cutting zone). Additional complexity in modeling is provided by the fact that during cutting the surface on which the heat source acts changes, for example, due to wear on the flank surface. In this paper, a method is proposed for measuring the power of a heat source acting on the flank surface. The hardware of the method includes a sensor equipped tool and specially manufactured inserts that imitate the geometry of worn flank surface. In turn, the software is based on the method of solving the inverse heat conduction problem in metal cutting, which allows restoring the heat flux flowing into the tool by measuring temperature with sensors installed in the toolholder. The experimental plan included inserts with negative and positive rake, different cutting speeds (190, 235, 280 m/min), and feeds (0.15, 0.3, 0.45 mm/rev).
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| 4. |
- Loberg, Bengt, et al.
(författare)
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Role of alloy composition on the stability of nitrides in Ti-microalloyed steels during weld thermal cycles
- 1984
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Ingår i: Metallurgical Transactions. A, Physical Metallurgy and Materials Science. - 0360-2133. ; 15:1, s. 33-41
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Tidskriftsartikel (refereegranskat)abstract
- The effect of cycling on titanium nitride stability in a range of normalized steels containing additions of V, Al, and N has been investigated. Nitride dispersions and chemical analysis of individual particles are studied using transmission electron microscopy and a quantitative 200 kV STEM-EDX-EELS microanalysis system. Whereas normalized material contains nitrides of mixed compositions, only nitrides based on TiN survive high energy simulated weld cycles. Grain growth is dependent on stability, and this depends on the original composition of the nitrides. The presence of aluminum is particularly detrimental. The best gain growth control and highest toughness are found in steels based on optimum ratios of Ti/V/N and on low Al levels
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| 5. |
- Schiessling, Joachim, et al.
(författare)
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The Role of Charge-Charge Correlations and Covalent Bonding in the Electronic Structure of Adsorbed C-60 : C-60/A1
- 2010
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 114:43, s. 18686-18692
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Tidskriftsartikel (refereegranskat)abstract
- Aromatic molecules are central components of model systems for molecular electronics, with C-60 one of the most studied. Upon adsorption on (metallic) substrates a splitting of the frontier orbitals is commonly observed, with a strong dependence on substrate material, but little dependence on substrate structure. We report the detailed photoelectron angle dependence of C-60/A1(110) over a wide range of energy, finding a strong remnant molecular character. In particular, certain HOMO-derived suborbitals couple strongly, and others weakly, with the metal, which results in final state charging for those weakly coupled. C Is data correlate well with the assignments made on this basis, as does the comparison of ground state partial densities-of-states (PDOS) to photoelectron spectra. Detailed analysis of the PDOS supports a rough division into surface-near and surface-far components, in agreement with the molecular picture. The component spectral widths are attributed to intramolecular vibrational coupling, which is suggested to aid in the electronic decoupling of certain suborbitals from the substrate, facilitating the observed final state charging.
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