Browsing by Subject "crystallization"

Now showing 1 - 6 of 6

Access status: Open Access ,
Considering semi-crystallinity in molecular simulations of mechanical polymer properties - using nanoindentation of polyethylene as an example
(Wydawnictwa AGH, 2021) Fritz, Susanne
Molecular dynamic (MD) simulations have been used to investigate the response of semi-crystalline polymers in nanoindentation tests, using polyethylene (PE) as an example. To that purpose, semi-crystalline simulation boxes of linear PE with various chain lengths up to C2000 were created by homogeneous nucleation during the non-isothermal cooling of melts. The final crystallinity depended on the chain length and the cooling rate used and could be estimated using various parameters like density, fraction of bonds in trans conformation, and energy terms. The simulation boxes were transferred into surface models and subjected to nanoindentation tests using non equilibrium MD. This allowed the deformation behaviour of the material to be analysed directly. Strong dependencies on the crystallinity of the PE were found, which underlines the importance of considering crystallinity when investigating the mechanical properties of semi-crystalline polymers by means of simulations.
Access status: Open Access ,
Ewaporaty. Nowe dane mineralogiczno-petrograficzne
(Wydawnictwa AGH, 2009) Pawlikowski, Maciej
Research on evaporates is conducted very intensively, which is both due to the fact that they are of utmost value to many branches of economy, and also (and this seems to be the main reason) that often deposits of oil and gas are found close to evaporites. Hence the comprehension of phenomena may contribute, in a fundamental way, to correct decisions related to the exploration of both fuels. The publication deals with various theories concerning functioning of evaporate basins and various way of salty water condensation. Moreover various types of evaporate crystals representing differentiated way of evaporate formation and crystallization are presented. Additionally examples of karstic forms crystallizing at salt main are described and the way of their crystallization is explained.
Access status: Open Access ,
Model of dendrite growth in metallic alloys
(2010) Żak, Paweł; Lelito, Janusz; Krajewski, Witold; Suchy, Józef Szczepan; Gracz, Beata; Szucki, Michał
The aim of this study was to develop a model of dendrite growth. The model should emphasis on solute depletion around dendrite tip and its influence on dendrite growth rate. Prepared model can be used to predict dendrite growth rate in metallic alloy. It was assumed that dendrite while growing occupy a spherical envelope with radius R that consists of solid dendrite and interdendritic melt enclosed by dendrite arms. Set of differential equations that built the model can be solved with numerical methods. The solution allows determination of dendrite growth rate and alloy component distribution in the liquid adjected to the dendrite and inside the solid dendrite.
Access status: Open Access ,
Numerical model for dendrite growth - an application of the Rank Controlled Differential Quadrature method
(2012) Żak, Paweł; Suchy, Józef Szczepan
Rank Controlled Differential Quadrature (RCDQ) is an innovative method for numerical approximation of problems described by Partial Differential Equations (PDEs). In this paper the authors apply the RCDQ for the numerical simulation of a simplified model for dendrite growth during Al-Ti alloy crystallization. The authors put most concern on building an accurate numerical model for this phenomenon. In the simplified model the symmetry and flux on boundary condition appears. Additionally, dendrite tip growth into adjacent liquid change the computation domain size, what indicates a need for node coordinate recalculation during each new time step. The authors analyze the results of numerical modelling of alloying element concentration and dendrite growth rate. The modelling results shows that the RCDQ method can be used for modelling problems with moving grid and that the method approximation proposed by the authors is proper.
Access status: Open Access ,
Odporność piaskowca szydłowieckiego na krystalizację soli w aspekcie wzmacniania strukturalnego
(Wydawnictwa AGH, 2011) Kłopotowska, Agnieszka Katarzyna
This article presents the results of tests on the crystallization of salt on the example of treatment of szydłowiecki sandstone, which underwent treatment of structural strengthening. During the study two types of sandstone were analyzed: A - from a building in Warsaw and B - with a similar lithological formation, but from the quarry in Śmiłów. The progress of degradation was monitored by measurements of ultrasound tests. Final results were observed in a scanning electron microscope. It was shown that the impregnation of sandstone did not materially affect the improvement of its resistance to salt crystallization, but the additional hydrophobisation largely limited the progress of degradation.
Access status: Restricted ,
Wpływ szybkości krystalizacji na mikrostrukturę stopów Zn-Zr
(Data obrony: 2018-01-23) Lechowska, Jagoda
Wydział Inżynierii Metali i Informatyki Przemysłowej