Chin-Wang Huang

Thermal behaviour and firing characteristics of Zr/KClO4 primer mixture containing different particle sizes of zirconium

Abstract The effect of the particle size of zirconium on the thermal behaviour and firing characteristics of Zr/KClO4 primer mixtures was studied by thermoanalytical techniques. A pilot-scale process was developed for preparing pressure cartridges whose primer mixtures had different particle sizes of zirconium. The firing characteristics were evaluated by Brucetons method and its related calculation. It was found that the Zr/KClO4 primer mixture with average particle size of 3 or 5 μm is a suitable primer mixture for 1 A 1 W−1, 5 min, No-Fire pressure cartridges.

Kinetic study of Y, Ba, Cu oxalates and coprecipitated Y-Ba-Cu oxalate

The kinetics of the decomposition of Y, Ba and Cu oxalates and coprecipitanted Y-Ba-Cu oxalate was investigated under a nitrogen atmosphere on the basis of dynamic thermogravimetric data, the average activation energies of the decomposition of Y, Ba and Cu oxalates were obtained from the slopes of the T. Ozawa plot.The average activation energies for the dehydration of these oxalate and coprecipitated Y-Ba-Cu oxalate were also evaluated from the thermogravimetric curves.

Kinetic studies on crystallization of CaO · P2O5 glass by differential thermal analysis

Abstract The crystallization mechanism of CaO·P 2 O 5 glasses was studied using non-isothermal differential thermal analysis (DTA) by comparing the kinetic parameters of the fine and coarse glass powders. The effect of a small amount of TiO 2 on the nucleation and growth kinetics was also investigated. The kinetic parameters were evaluated from DTA curves by using the variation of heating rate method. Experimental results suggest that the devitrification behaviour has a tendency to promote a change from surface nucleation to bulk nucleation when the particle size of the glass and/or the TiO 2 content is increased.

The Thermal Properties and Firing Characteristics of Zr/KClO4 Priming Compositions Containing Graphite, Fe2O3 and Al2O3 additives

Thermal decomposition of Zr/KClO4 priming compositions containing different concentration of additives, such as graphite, Fe2O3 and Al2O3 have been studied by DSC/TG techniques. The firing characteristics of these primer mixtures have also been examined by Bruceton test and by adiabatic calorimeter. The results of these experiments suggest that strong interaction has been occurred between KClO4 and Fe2O3 in the solid state.

Devitrification Behavior of Calcium Phosphate Glasses Containing Al2O3 and SiO2 Additives

The effects of Al2O3 and SiO2 additives on the crystallization of calcium phosphate glasses were studied. When the Al2O3 content was higher than 7 mol%, surface devitrification occurred in the glasses. However, for glasses with Al2O3 contents higher than 10 mol%, bulk devitrification predominanted. For the glasses with SiO2, a surface devitrification mechanism predominanted. Non-isothermal DTA techniques were applied in order to establish the devitrification mechanism, and the kinetic parameters of crystal growth were obtained. The parameter m depends on the mechanism and morphology of devitrification of calcium phosphate, glass containing SiO2 as additive, the values of m being lower than 1.2. These results indicate that the devitrification is controlled by the reaction at the glass-crystal interface, or occurs from surface nuclei.

Thermal behaviour and firing characteristics of Zr/KClO4 primer mixture containing CuO

The effect of CuO on the thermal behaviour of Zr/KClO4 primer mixtures was studied by thermoanalytical techniques, and the Bruceton method and its related calculation. It was found that the CuO catalytically promoted the decomposition of Zr/KClO4 primer mixtures and shifted the exothermic peak of DSC curves to lower temperatures. In addition, the Zr/KClO4 primer mixture containing CuO had a significant effect on the firing characteristics of electro-explosive devices.ZusammenfassungMittels thermoanalytischen Verfahren, der Bruceton-Methode und der damit verbundenen Berechnungen wurde der Einfluß von CuO auf das thermische Verhalten von Zr/KClO4 Primärgemischen untersucht. Es wurde gezeigt, daß ein Zusatz von CuO die Zersetzung von Zr/KClO4 Primärgemischen katalytisch begünstigt und den exothermen Peak der DTA-Kurve in Richtung niedriger Temperaturen verschiebt. Außerdem haben Zr/KClO4 Primärgemische mit einem Gehalt an CuO einen eindeutigen Einfluß auf die Brenncharakteristik von Elektroexplosi vapparaturen.

Devitrification studies of the PbO-ZnO-B2O3 glass system with added SiO2, BaTiO3 and NiO2

Abstract The devitrification mechanism of the glass system PbO-B 2 O 3 -ZnO was studied using non-isothermal techniques. Experimental results show that the devitrification mechanism of the glass system PbO-B 2 O 3 -ZnO with added SiO 2 is virtually bulk nucleation controlled, but that surface nucleation occurs when NiO 2 or BaTiO 3 is added to PbO-B 2 O 3 -ZnO glass.

A Study on the Thermal Behaviour of Solder Glass

Vitreous solder glasses, such as Mansol #40 and FEG-2002, are commercialized solder glasses, which are compression sealing glasses that can be used to solder materials with expansions between 55-68⊙10-7°C-1, such as Al2O3.In order to understand and tailor the thermal behaviour of solder glasses, cylindrical-like glasses were first carefully ground with a stainless steel mortar and pestle. Initially, no exothermic or endothermic data were obtained from the DTA/DSC curves except those relating to melting. However, exothermic peaks appeared after the glass samples were re-melted. In this work, kinetic parameters such as the activation energy, and the morphology of the devitrification mechanisms for two kinds of solder glasses were also investigated, using non-isothermal DTA techniques. The activation energies ranged from 220 to 235 kJ mol-1 and the devitrification mechanism parameters were close to 1. This indicates that the devitrification mechanisms of the two kinds of solder glasses involve surface nuclei.

Physical Properties of Calcium Phosphates Glasses with Various Cao/P2O5 Mole Ratios

Abstract The physical properties of calcium phosphate glasses with various CaO/P2O5 mole ratios, Vickers surface hardness, weight loss percentage after dipping Ringers solution were investigated in this study. The best surface hardness of crystallized glass has an average hardness of 670Kg/mm2 and the minmum weight loss percentage of crystallized glass were lower than 1%. The major crystalline phase that developed after heat treatment of these glasses was β-Ca(PO3)2 which characterized by X-ray powder diffraction method, and we found that the rod-like (3-5 μmD x 60 μmL) β-Ca(PO3)2 crystals from the photograph of SEM, the oxides composition of crystal was examined by EDS analysis also.

Directional Solidification of CaO-P205 Bioglass-Ceramics

Abstract Calcium phosphate glass-ceramics were prepared by reheating the glass rods between 675° and 750°C under a temperature gradient of ∼100°C/cm. Floating zone method and silicon carbide furnace was made use to crystallizing the glass. The crystalline phases occurred as long fibers aligned parallel to the growth direction of the specimen. The spacings between the fibrous phases were smaller than 1 μm and very uniform. Microstructure of the crystallized phases was examined by scanning electron microscope. Crystalline phases and crystallography were checked by X-ray diffraction.