Determination of Solidification Parameters Used for the Prediction of the Thixoformability of Several Steel Alloys

2006 ◽  
Vol 116-117 ◽  
pp. 54-57 ◽  
Author(s):  
Jacqueline Lecomte-Beckers ◽  
Ahmed Rassili ◽  
Marc Robelet ◽  
Claude Poncin ◽  
R. Koeune
Keyword(s):  
Differential Scanning Calorimetry ◽  
Heating Rate ◽  
Liquid Fraction ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Steel Alloys ◽  
Fraction Versus ◽  
Solidification Parameters ◽  
Industrial Heating

This paper focuses on the liquid fraction curves of several steels and the correlation between liquid fraction, temperature and heating rate. The work has been performed along two main axes. First, the solid fraction versus temperature has been obtained experimentally by differential scanning calorimetry (DSC), limited to low heating rates. Then, a shift of the liquid fraction curves has been noticed at high industrial heating rates. The quantification of this effect could not be carried out by DSC and required the elaboration of another experimental device.

scholarly journals Alloy Characterization to Adapt Steels to Thixoforming: Study of a High Chromium High Carbon Steel

2008 ◽  
Vol 141-143 ◽  
pp. 523-527 ◽  
Author(s):  
Celine Fraipont ◽  
Jacqueline Lecomte-Beckers
Keyword(s):  
Differential Scanning Calorimetry ◽  
Chemical Composition ◽  
Liquid Fraction ◽  
High Carbon Steel ◽  
Alloying Elements ◽  
High Carbon ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
High Chromium ◽  
Fraction Versus

This paper deals with the examination of the influence of alloying elements on the thixoformability of a Cr steel. It focuses on the liquid fraction curves of different Cr steels with modifications of composition. The effect of composition modifications was observed. The solid fraction versus temperature has been obtained by a thermodynamics software (MTData) and by Differential Scanning Calorimetry (DSC), limited to low heating rates. MTData permits to obtain information on the influence of alloying elements, with the advantage of the possibility to change the chemical composition very easily. The DSC tests determine the influence of the heating rate on these curves.

Effect of Molecular Weight on Glass Transition by Differential Scanning Calorimetry

1974 ◽  
Vol 52 (18) ◽  
pp. 3170-3175 ◽  
Author(s):  
Louis-Philippe Blanchard ◽  
Jean Hesse ◽  
Shadi Lal Malhotra
Keyword(s):  
Molecular Weight ◽  
Differential Scanning Calorimetry ◽  
Heat Capacity ◽  
Glass Transition ◽  
Heating Rate ◽  
Low Molecular Weight ◽  
Glass Transitions ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Polystyrene Sample

The influence of molecular weight (900 to 1.8 × 106) on the glass transition temperature of low polydispersity polystyrene (anionically prepared) has been studied by differential scanning calorimetry at heating rates of 5 to 80 °C min−1. Over the range of molecular_weight studied, and at an extrapolated heating rate of 1 °C min−1,[Formula: see text] A thermally prepared polystyrene sample ([Formula: see text]and Pd = 3.2) showed a Tge value of 93 °C, some 10° below the value predicted by the above equation. Low molecular weight species in the highly polydisperse sample are believed to be responsible for the discrepancy. The changes in heat capacity brought about by the glass transitions are accompanied in all cases on heating by an endothermic peak and this regardless of the heating rate (even extrapolated to 1 °C min−1) or the molecular weight of the sample, suggesting that the glass transition phenomenon encountered with polystyrene is a process involving a positive heat effect.

scholarly journals Analysis of DSC (differential scanning calorimetry) thermograms of milk fat

2021 ◽  
Vol 5 (3(61)) ◽  
pp. 36-39
Author(s):  
Maltam Shamilova ◽  
Sevinj Hajiyeva
Keyword(s):  
Fatty Acids ◽  
Differential Scanning Calorimetry ◽  
Melting Point ◽  
Heat Flow ◽  
Heating Rate ◽  
Milk Fat ◽  
Oxidation Time ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Melting Properties

The object of current research is the oxidation and melting properties of milk fat samples in different heating rates. One of the most problematic issues is the evaluation dependence of temperature and oxidation time regarding to heat flow, and the estimation of attitude of enthalpy values to heating rates. In order to gain a comprehensive assessment of oxidation and melting properties of milk fat samples on differential scanning calorimeter in various heating rates, it is necessary to conduct experimental studies. The analysis was performed using the dynamic option of the differential scanning calorimetry (DSC) with the following sample heating rates: 2.5, 4, 5, 7.5, 10, 12.5, 15 °C⋅min–1. Analyses were performed on 14 samples of milk fat, thus, for each heating rate were intended to two milk fat samples. As a result of the analysis, in the proper heating rates increased, it was found, that the oxidation properties of milk fat depend on the heating rates on DSC examination. In the thermal DSC analysis, the start temperature (Ts) (inlet), the onset temperature (Ton), and the maximum heat flow-peak temperatures (Tp) of oxidation were rising gradually. All the value of oxidation increased gradually with increasing heating rate, only in the Tend values were chainable among all heating rates. However, the oxidation time of milk fat is inversely proportional to the various heating rates in DSC. The oxidation enthalpy was calculated according to the heating rates too. The masses of the samples differ from each other, albeit slightly, which the individuality in the value of enthalpy could be explained through this ratio and duration of exothermic. The melting point considers the important indicator to explain the purity of samples. Melting curves of extracted milk fat samples on DSC were characterized by endothermic behavior and observed with the mild peaks, the first and the second distinct peaks due to the low-melting triacylglycerols (with high unsaturated fatty acids content) and high-melting fats, which present in milk fat. In concluded results, the characteristics of DSC oxidation curves are melting point due to the chemical structure of the fatty acids which milk fat samples contain.

Reaction kinetics in the combustion synthesis of Al–Ir–Ni intermetallic compounds

2008 ◽  
Vol 23 (7) ◽  
pp. 1953-1960
Author(s):  
Kai Cai ◽  
Machiko Ode ◽  
Hideyuki Murakami
Keyword(s):  
Differential Scanning Calorimetry ◽  
Combustion Synthesis ◽  
Heating Rate ◽  
Ignition Temperature ◽  
Effective Control ◽  
Vacuum Furnace ◽  
Heating Rates ◽  
Product Density ◽  
Scanning Calorimetry ◽  
Reactant Powder

The combustion synthesis of Al50Ir48Ni2 (at.%) was conducted at different heating rates in both a differential scanning calorimetry (DSC) chamber and a vacuum furnace. It was found that a higher heating rate, a sufficient amount of reactant powder, and effective control of the heat loss facilitated the complete reaction and resulted in combusted single IrAl phase products. Otherwise, multiphase products containing IrAl, unreacted Ir, and Al3Ir were synthesized. The reactions involved in different processes were discussed in terms of the thermal competition between heat generation and loss during the reaction. All ignition temperatures were below 773 K, indicating that the combustion reaction occurs at the solid–solid state. With increasing heating rate, the ignition temperature increased while the product density decreased.

Comparison between Prediction of Liquid Fraction versus Temperature and Experimental Results from DSC and SPSC

2014 ◽  
Vol 217-218 ◽  
pp. 442-449
Author(s):  
Du Yao Zhang ◽  
Helen V. Atkinson ◽  
Hong Biao Dong ◽  
Qiang Zhu
Keyword(s):  
Sample Size ◽  
Liquid Fraction ◽  
Experimental Results ◽  
Large Sample Size ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Fraction Liquid ◽  
Fraction Versus ◽  
Order Of Magnitude ◽  
Semi Solid

The processing window is important for the semisolid processability of alloys. This study focusses on the kinetics of diffusion. It compares prediction of fraction liquid versus temperature taking into account both thermodynamic and kinetics, with experimental results from Differential Scanning Calorimetry (DSC) and Single Pan Scanning Calorimetry (SPSC). SPSC is a novel technique with an order of magnitude higher accuracy than DSC. A range of Al-Si binary alloys has been investigated. The studies reveal that the simulation results predicted by DICTRA (DIffusion-Controlled TRAnsformations) show the same pattern with experimental results in the relationship of fraction liquid-temperature. However, the SPSC results are closer to the prediction results than DSC curves even with the relatively large sample size associated with SPSC. This is potentially a significant result as conventionally one of the difficulties is predicting the liquid fraction versus temperature for the heating of a billet for semi-solid processing. DSC results are known to be unrepresentative because the heating rates which can be achieved in DSC are much lower than those in induction heating. In addition, the DSC results are dependent on sample size and heating rate. The long term aim is to gain confidence in prediction with software packages which will reduce trial and error.

scholarly journals Comprehensive Thermal Characteristics of Different Cultivars of Flaxseed Oil (Linum usittatissimum L.)

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 1958
Author(s):  
Jolanta Tomaszewska-Gras ◽  
Mahbuba Islam ◽  
Liliana Grzeca ◽  
Anna Kaczmarek ◽  
Emilia Fornal
Keyword(s):  
Differential Scanning Calorimetry ◽  
Heating Rate ◽  
Fatty Acid Content ◽  
Thermal Characteristics ◽  
Principal Component ◽  
Flaxseed Oil ◽  
Scanning Calorimetry ◽  
Total Oxidation ◽  
Increasing Temperature ◽  
Linear Correlations

The aim of this study was to describe the thermal properties of selected cultivars of flaxseed oil by the use of the differential scanning calorimetry (DSC) technique. The crystallization and melting profiles were analyzed depending on different scanning rates (1, 2, 5 °C/min) as well as oxidative induction time (OIT) isothermally at 120 °C and 140 °C, and oxidation onset temperatures (Ton) at 2 and 5 °C/min were measured. The crystallization was manifested as a single peak, differing for a cooling rate of 1 and 2 °C/min. The melting curves were more complex with differences among the cultivars for a heating rate of 1 and 2 °C/min, while for 5 °C/min, the profiles did not differ, which could be utilized in analytics for profiling in order to assess the authenticity of the flaxseed oil. Moreover, it was observed that flaxseed oil was highly susceptible to thermal oxidation, and its stability decreased with increasing temperature and decreasing heating rate. Significant negative linear correlations were found between unsaturated fatty acid content (C18:2, C18:3 n-3) and DSC parameters (OIT, Ton). Principal component analysis (PCA) also established a strong correlation between total oxidation value (TOTOX), peroxide value (PV) and all DSC parameters of thermo-oxidative stability.

Sign in / Sign up

Export Citation Format

Share Document