| 1. |
- Lissel, Linda, et al.
(författare)
-
Prediction of the microstructural evolution during hot strip rolling of Nb microalloyed steels
- 2007
-
Ingår i: Materials Science Forum. - 0255-5476 .- 1662-9752. ; 558-559:2, s. 1127-1132
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A physically based model is used to describe the microstructural evolution of Nb microalloyed steels during hot rolling. The model is based on a physical description of dislocation density evolution, where the generation and recovery of dislocations determines the flow stress and also the driving force for recrystallization. In the model, abnormally growing subgrains are assumed to be the nuclei of recrystallized grains and recrystallization starts when the subgrains reach a critical size and configuration. The model is used to predict the flow stress during rolling in SSAB Tunnplat's hot strip mill. The predicted flow stress in each stand was compared to the stresses calculated by a friction-hill roll-force model. Good fit is obtained between the predicted values by the microstructure model and the measured mill data, with an agreement generally within the interval +/-15%.
|
|
| 2. |
- Ahmed, Naeem, et al.
(författare)
-
The Hydrophilization and Subsequent Hydrophobic Recovery Mechanism of Cold Plasma (CP) Treated Bambara Groundnuts
- 2022
-
Ingår i: Materials Science Forum. - : Trans Tech Publications. - 0255-5476 .- 1662-9752. ; 1055, s. 161-169
-
Tidskriftsartikel (refereegranskat)abstract
- Plasma hydrophilization and subsequent hydrophobic recovery in Bambara groundnuts are studied for the first time. Bambara groundnut seeds were treated with cold plasma (CP) for 10 seconds at 10 watts using water as a monomer. The contact angle, as well as physical and chemical changes, were used to determine the kinetics of hydrophobic recovery. The hydrophilic state of Bambara groundnut seeds had decreased after 60 days, but not to original hydrophobicity, and also the recovery rate is slower than those observed on synthetic polymer. However, this slower hydrophobic recovery makes CP treatment as an effective method for long-term seed storage.
|
|
| 3. |
- Allerstam, Fredrik, 1978, et al.
(författare)
-
A study of deep energy-level traps at the 4H-SiC/SiO2 interface and their passivation by hydrogen
- 2009
-
Ingår i: Materials Science Forum. - 1662-9752 .- 0255-5476. ; 600-603, s. 755-758
-
Konferensbidrag (refereegranskat)abstract
- This study is focused on characterization of deep energy-level interface traps formed during sodium enhanced oxidation of n-type Si face 4H-SiC. The traps are located 0.9 eV below the SiC conduction band edge as revealed by deep level transient spectroscopy. Furthermore these traps are passivated using post-metallization anneal at 400°C in forming gas ambient. © (2009) Trans Tech Publications, Switzerland.
|
|
| 4. |
- Allerstam, Fredrik, 1978, et al.
(författare)
-
Effect of high temperature oxidation of 4H-SiC on the near-interface traps measured by TDRC
- 2009
-
Ingår i: Materials Science Forum. - 1662-9752 .- 0255-5476. - 9780878493340 ; 615 617, s. 537-540
-
Konferensbidrag (refereegranskat)abstract
- In this work the effect of oxidation temperature of 4H-SiC on the density of nearinterface traps is studied. It is seen that the portion of traps with slower emission times decreases with increasing oxidation temperature. Despite this reduction, high temperature oxidation alone is not useful to achieve low density of interface traps at the SiO2/4H-SiC interface.
|
|
| 5. |
- Allerstam, Fredrik, 1978, et al.
(författare)
-
Formation of deep traps at the 4H-SiC/SiO2 interface when utilizing sodium enhanced oxidation
- 2007
-
Ingår i: Materials Science Forum. - 1662-9752 .- 0255-5476. ; 556-557, s. 517-520
-
Konferensbidrag (refereegranskat)abstract
- This paper reports studies of deep acceptor-type interface traps at the 4H-SiC/SiO2 interface. These traps are created during sodium enhanced oxidation of Si-terminated 4H-SiC. The trap concentration is above 3×1012 cm-2 and their activation energy is larger than 0.8 eV.
|
|
| 6. |
- Andersson, Petter, 1970, et al.
(författare)
-
Scale growth on austenitic alloys under KCl deposits at 500 deg C
- 2008
-
Ingår i: Materials Science Forum. - 1662-9752 .- 0255-5476. ; 595-598:I, s. 333-342
-
Tidskriftsartikel (refereegranskat)abstract
- The scale growth on two austenitic alloys, Alloy 310 and Sanicro 28, under KCl deposits was examined. This is relevant to the long term corrosion of superheater tubes in biofuel combustion. Coupons were encapsulated in tablets so that 1 mm of KCl with a relative density of 91% covered the metal. Samples were tested at 500 deg C in 5%O2-10%H2O-N2 for 24, 168 and 672 h. After exposure the salt was broken off and the scale was characterised by using SEM-EDX and AES. After 24 h a 50 nm thick oxide surrounded 500 nm thick chromates on the surface. No oxide layer was detected under the chromates and no Cl was found under either layer. The chromate growth requires lateral transportation of Cr along the surface. This reduces the protectiveness of the oxide and accelerates the formation of less protective Fe rich oxides. The formation of chromates also releases HCl inside the KCl tablet. The chromates did not grow significantly between 24 and 168 h, but the oxide grew equally thick beneath and between them and Cl was enriched around the metal oxide interface. After 672 h the oxides were about 5 mum thick and only few chromates were seen. Crystals of KCl formed in areas with thick porous and Fe rich oxides on both alloys.
|
|
| 7. |
- Anghel, Clara, et al.
(författare)
-
Gas-tight oxides – Reality or just a Hope
- 2006
-
Ingår i: Materials Science Forum. - 0255-5476 .- 1662-9752. ; 522-523, s. 93-101
-
Tidskriftsartikel (refereegranskat)abstract
- A better understanding of the transport properties of gases in oxides is certainly very important in many applications. In the case of metals, a general protection measure against corrosion implies formation of a dense metal oxide scale. The scale should act as a barrier against gas transport and consequently it needs to be gas-tight. This is often assumed but rarely, if ever, confirmed. Hence there is a need for characterization of micro- and/or meso- pores formed especially during the early oxidation stage of metallic materials. This paper presents a novel and relatively straightforward method for characterization of gas release from an oxide previously equilibrated in a controlled atmosphere. The geometry of the sample is approximated to be a plate. The plate can be self-supporting or constitute a scale on a substrate. A mathematical model for calculation of diffusivity and gas content is given for this geometry. A desorption experiment, involving a mass spectrometer placed in ultra high vacuum, can be used to determine diffusivity and amount of gas released with aid of the mathematical model. The method is validated in measurements of diffusivity and solubility of He in quartz and applied in characterization of two Zr-oxides and one Fe oxide. From the outgassed amounts of water and nitrogen the H2O/N-2 molar ratio can be used to estimate an effective pore size in oxides.
|
|
| 8. |
- Azizov, Talyat, et al.
(författare)
-
Consideration of the Torsional Stiffness in Hollow-Core Slabs’ Design
- 2019
-
Ingår i: Materials Science Forum. - 0255-5476 .- 1662-9752. ; 968, s. 330-341
-
Tidskriftsartikel (refereegranskat)abstract
- The paper discusses the principles of precast concrete hollow-core slabs taking into account their spatial work. It is shown that consideration of spatial work makes it possible to determine the forces in individual floor slabs significantly more precise. The fact that strain redistribution between precast floor slabs depends on slabs’ bending and torsional stiffness is shown. The research has been mostly devoted to the determination of the bending stiffness with regard to the formation of cracks and the change in torsional stiffness, especially considering the presence of normal cracks, which is still unstudied. This paper presents the technique for determining the torsional stiffness of hollow-core slabs with normal cracks. In order to determine the components included in the resolving system of equations, it is proposed to use an approximation method based on the processing of numerical data using spatial finite elements.
|
|
| 9. |
- Badger, J., et al.
(författare)
-
Grinding of cermets with cup-wheels
- 2016
-
Ingår i: Materials Science Forum. - 1662-9752 .- 0255-5476. - 9783035710342 ; 874, s. 115-123
-
Konferensbidrag (refereegranskat)abstract
- Cup-wheels are frequently used to grind cermets, a difficult-to-grind material. An investigation was made into the transient geometry of the cup-wheel rim, grit dulling, wheel loading, and wheel self-sharpening with chip thickness. Tests were performed on a saw-tip grinding machine and specific energies, G-ratios and rim geometries were measured. Results showed that, like grinding of tungsten-carbide, loading is prevalent. However, unlike grinding of tungstencarbide, grit dulling is also prevalent and wheel conditioning is of limited use. Much better results, particularly with respect to surface finish, can be obtained if the wheel is trued to a predetermined geometry. In addition, grinding parameters must be chosen to induce wheel self-sharpening. Practical recommendations are given.
|
|
| 10. |
|
|
