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Humidity controlled thermal analysis

The effect of humidity on thermal decomposition of zinc acetylacetonate monohydrate

Journal of Thermal Analysis and Calorimetry
Authors:
T Arii
and
A Kishi

Abstract  

The low temperature formation of crystalline zinc oxide via thermal decomposition of zinc acetylacetonate monohydrate C10H14O4ZnH2O was studied by humidity controlled thermal analysis. The thermal decomposition was investigated by sample-controlled thermogravimetry (SCTG), thermogravimety combined with evolved gas analysis by mass spectrometry (TG-MS) and simultaneous differential scanning calorimetry and X-ray diffractometry (XRD-DSC). Decomposition of C10H14O4ZnH2O in dry gas by linear heating began with dehydration around 60C, followed by sublimation and decomposition above 100C. SCTG was useful because the high-temperature parallel decompositions were inhibited. The decomposition changed with water vapor in the atmosphere. Formation of ZnO was promoted by increasing water vapor and could be synthesized at temperatures below 100C. XRD-DSC equipped with a humidity generator revealed that C10H14O4ZnH2O decomposed directly to the crystalline ZnO by reacting with water vapor.

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Abstract  

The paper deals with results of thermal analysis of low-alloyed chromium-molybdenum steel. The methods of analysis were dilatometry, differential thermal analysis (DTA) and differential scanning calorimetry (DSC). The Ac1 and Ac3 temperatures of the steel samples measured by dilatometry and DTA during the heating period were in good agreement. Generated by cooling a martensitic structure first became apparent at 503 K. Tempering of the as-quenched samples showed the presence of the second tempering stage in the region between 473 and 573 K. At that stage heat capacity decreased from 0.48 to 0.32 J g-1 K-1, as a result of conversion of transition carbide due to heat consumption. After normalization of the as-quenched samples the heat capacity values were restored to between 0.42 and 0.47 J g-1 K-1 in the temperature range from 373 to 673 K.

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References 1 Kambe , H. Garn , D. D. 1974 Thermal Analysis John Wiley and Sons

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Controlled-rate thermal analysis

Study of the process of super hard material debinding

Journal of Thermal Analysis and Calorimetry
Authors:
Tadashi Arii
,
Kiyoshi Terayama
, and
Nobuyuki Fujii

Binder burnout has been carried out by a controlled heating programme which depends on the composition of the binder system used. The present paper gives the principle of constant decomposition rate thermogravimetry, which falls within controlled-rate thermal analysis, and the advantage of this technique when evolved gas analysis is used in discriminating the process of super hard material burnout by comparison with the conventional linear heating method is described. In this technique, the sample temperature is varied to maintain a constant rate of mass loss by control of the heating of the infrared image furnace. Since the constant decomposition rate control (CDRC) allows a much better control of the sample environment, which generally depends on the rate of gas evolution, it is possible for uniform conditions to exist throughout the sample, and the total burnout time can be reduced considerably without crack formation. The efficiency of this CDRC was proved by the obtained temperaturevs. time curve and SEM observations of the heat-treated sample after the debinding process.

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References 1 Wendlandt , WWM et al. 1986 Thermal Analysis Jonh Wiley and Sons New York . 2 Schwenker , RF

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Journal of Thermal Analysis and Calorimetry
Authors:
S. Cebulak
,
B. Smieja-Król
,
S. Duber
,
M. Misz
, and
A. Morawski

Abstract  

The paper presents the applicability of Oxyreactive Thermal Analysis (OTA) for the investigation of different kinds of carbon matter. For comparative reasons and more precise interpretation, along with OTA some physico-chemical properties of analyzed materials were used as the methods commonly applied for the investigations. The carbon materials of both natural (anthracites, graphite and diamonds) and synthetic origin (active carbon, glass carbon, expanded graphite, soot and synthetic diamonds) were investigated. It was stated that there is close relationship between structure parameters and physico-chemical properties and the thermal reactivity within the investigated groups of carbon matters. The results show that OTA can be accepted as a good investigative way for such materials.

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Abstract  

This review traces the development of thermal analysis over the last 50 years as it was experienced and contributed to by the author. The article touches upon the beginning of calorimetry and thermal analysis of polymers, the development of differential scanning calorimetry (DSC), single-run DSC, and other special instrumentations, up to the recent addition of modulation to calorimetry and superfast calorimetry. Many new words and phrases have been introduced to the field by the author and his students, leaving a trail of the varied interests over 50 years. It began with cold crystallization and more recently the terms oriented, intermediate phase, glass transitions of crystals, and decoupled chain segments were coined. In-between the following phenomena were named and studied: extended-chain crystals, irreversible thermodynamics of melting of polymer crystals, zero-entropy-production melting, dynamic differential thermal analysis (DDTA), the rule of constant increase of C p per mobile bead within a molecule at the glass transition temperature, superheating of polymer crystals, melting kinetics, crystallization during polymerization, chin-folding principle, molecular nucleation, rigid amorphous phase, system of classifying molecules, macroconformations, amorphous defects, rules for the entropy of fusion based on molecular shape and flexibility, single-molecule single-crystals, systems for classifying phases and mesophases including condis phases, and the globally metastable semicrystalline polymers with reversible, local subsystems.

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experience, thermal analysis (TA) is a very useful tool in the study of biomaterials behavior under the influence of thermal treatment [ 4 , 5 ]. Another technique extensively used in calcium phosphate investigations is fourier-transformed infrared

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Abstract  

Results of a literature search on thermal analysis reference materials are listed

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References 1 Brown , M. E. 1988 Introduction to Thermal Analysis Chapman and Hall London

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