| 1. |
- Kim, Karl, et al.
(författare)
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Modeling the causes and consequences of collisions with utility poles
- 1998
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Ingår i: Proceedings of Traffic safety on two continents. Conference in Lisbon, Portugal, September 22-24, 1997. - Linköping : Statens väg- och transportforskningsinstitut. ; , s. 153-167
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 2. |
- Li, W.B., et al.
(författare)
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A kinetic model for reaction bonding process of silicon powder compact
- 1997
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Ingår i: Journal of the European Ceramic Society. - 0955-2219 .- 1873-619X. ; 17:9, s. 1119-1129
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Tidskriftsartikel (refereegranskat)abstract
- In order to obtain detailed information about the kinetics and the reaction nature of a complex reaction process like reaction bonding of silicon nitride, mathematical modelling of the process is necessary. The previous quantitative models for this process have been based only on the mechanism that the nitrogen diffuses through the solid silicon nitride without taking into account the multiple reaction mechanisms. In the present study, a comprehensive kinetic model, which is based on analysis of the multiple mechanisms in a silicon powder compact reacting with nitrogen gas and forming silicon nitride, is constructed for a solid-gas reaction bonding process with specific application to the reaction-bonding of silicon nitride. The model will incorporate the rate equation for each mechanism into a constitutive equation from which more complete information of process kinetics can be predicted. The results predicted by the present model have been compared with previous experimental results and satisfactory agreement obtained
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| 3. |
- Li, Wen Bin, et al.
(författare)
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Stresses developed in reaction-bonded ceramics
- 1995
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Ingår i: Ceramic materials and components for engines. - : World Scientific Publishing Co Pte Ltd. - 9810219059 ; , s. 465-468
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Konferensbidrag (refereegranskat)abstract
- For a number of reaction-bonded ceramics, the reaction starts from the surface of the particles, forming a shell of products surrounding a reactant core. The reaction is continued by inward growth of the shell by means of diffusion of the reactant elements from the particle surface to the interface between the shell and core and vice versa. Since there exists a volumetric change due to the reaction, the products forming at the shell/core interface will be severely constrained. Strain and stress fields are then built up within the particles. A physical and mathematic model to calculate the strain and stress during and after the reaction bonding process is constructed. The preliminary results of estimation of stresses within the particles and their possible effect on reaction kinetics are presented and briefly discussed
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| 4. |
- Li, Wen Bin, et al.
(författare)
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Stresses developed in reaction-bonded ceramics
- 1999
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Ingår i: Journal of the European Ceramic Society. - 0955-2219 .- 1873-619X. ; 19:3, s. 277-283
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Tidskriftsartikel (refereegranskat)abstract
- A physical model is presented that predicts the stress distribution created in a particle during its reaction with a surrounding reactant to form a uniform layer of reaction product on its surface, when the reaction involves a volume change. The results of the model are applied specifically to the case of silicon reacting with nitrogen to form Si3N4. The model predicts the generation of a high, tensile hydrostatic stress in the Si core as well as high tensile radial stress and compressive tangential stress in the nitride layer. Although the model is restricted to elastic deformation only and therefore predicts unrealistically high stresses in some cases, the results are anyway of relevance in the consideration of possible non-elastic processes such as creep and fracture and also in assessing the possible effect of stress on the reaction equilibrium. It is predicted that the nitride reaction layer would fracture during the nitridation process. A second model is also presented predicting the residual stresses arising during cooling of a partially reacted particle as a result of the difference in thermal expansion of the reactant core and the reaction product layer. In the case of the reaction of silicon to silicon nitride these thermal expansion mismatch stresses are significant but small compared to the stresses due to the chemical reaction.
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| 5. |
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