Crystallisation kinetics of amorphous Si–C–N ceramics: Dependence on nitrogen partial pressure

The properties of various CrxNy films grown by direct current (DC) reactive sputtering process with different values of nitrogen partial pressures (0, 2?10-4, 3.5?10-4 and 5?10-4 mbar) were studied. The structural analysis of the samples was performed by using X-ray diffraction and transmission electron microscopy (TEM), while an elemental analysis was realized by means of Rutherford backscattering spectrometry. By varying nitrogen partial pressure the pure Cr layer, mixture of Cr, Cr2N and CrN phases, or single-phase CrN was produced. TEM analysis showed that at pN2 = 2?10-4 mbar the layer has dense microstructure. On the other hand, the layer deposited at the highest nitrogen partial pressure exhibits pronounced columnar structure. The optical properties of CrxNy films were evaluated from spectroscopic ellipsometry data by the Drude or combined Drude and Tauc-Lorentz model. It was found that both refractive index and extinction coefficient are strongly dependent on the dominant phase formation (Cr, Cr2N, CrN) during the deposition process. Finally, the electrical studies indicated the metallic character of Cr2N phase and semiconducting behaviour of CrN.

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The dissolution kinetics of feldspars at 25°C and 1 atm CO2 partial pressure

Geochimica et Cosmochimica Acta ◽

10.1016/0016-7037(76)90192-7 ◽

1976 ◽

Vol 40 (1) ◽

pp. 41-49 ◽

Cited By ~ 250

Author(s):

Eurybiades Busenberg ◽

Charles V Clemency

Keyword(s):

Partial Pressure ◽

Dissolution Kinetics ◽

Co2 Partial Pressure ◽

Kinetics Of

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Non-Isothermal Crystallisation Kinetics of Polypropylene at High Cooling Rates and Comparison to the Continuous Two-Domain pvT Model

Polymers ◽

10.3390/polym12071515 ◽

2020 ◽

Vol 12 (7) ◽

pp. 1515

Author(s):

Jonathan Alms ◽

Christian Hopmann ◽

Jian Wang ◽

Tobias Hohlweck

Keyword(s):

Injection Moulding ◽

Polymer Processing ◽

Nucleation And Growth ◽

Growth Theory ◽

Crystallisation Kinetics ◽

Cooling Rates ◽

Dsc Measurements ◽

Wide Range ◽

High Cooling Rates ◽

Kinetics Of

The modelling of the correlation between pressure, specific volume and temperature (pvT) of polymers is highly important for applications in the polymer processing of semi-crystalline thermoplastics, especially in injection moulding. In injection moulding, the polymer experiences a wide range of cooling rates, for example, 60 °C/min near the centre of the part and up to 3000 °C/min near the mould walls. The cooling rate has a high influence on the pvT behaviour, as was shown in the continuous two-domain pvT model (CTD). This work examined the Hoffman–Lauritzen nucleation and growth theory used in the modified Hammami model for extremely high cooling rates (up to 300,000 °C/min) by means of Flash differential scanning calorimeter (DSC) measurements. The results were compared to those of the empirical continuous two-domain pvT model. It is shown that the Hammami model is not suitable to predict the crystallisation kinetics of polypropylene at cooling rates above 600 °C/min, but that the continuous two-domain pvT model is well able to predict crystallisation temperatures at high cooling rates.

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