كليدواژه :
هيدرايد تيتانيم , تجزيه حرارتي , اكسيداسيون تيتانيم , اتمسفر محيط , فوم هاي فلزي , مهندسي متالورژي ومواد , سرعت حرارت دهي , رفتار تجزيه حرارتي , آناليز حرارتي
چكيده لاتين :
Understanding the thermal decomposition mechanism of titanium hydride, especially determining of the best conditions of the primary heat-treatment of this material, would be an important step on the process of production of Al foams. In this research, the ST A diagram of titanium hydride powder with the heating rate of 10°C/min in the presence of Argon gas with %99.99 purity and, also, ST A diagrams of this powder with the heating rates 5, 10, 20, 25, 30°C/min at air were determined. In addition, the DSC diagram with the heating rate of 10°C/min at 500°C was studied and determined. Results showed that titanium hydride powder (TiH1.924) decomposes in two stages TiH1.924—>d-TiHx---Ti, at 534°C and 624°C, respectively. The thermal decomposition mechanism of TiH2 complexes, in conventional atmosphere, is quite complex and different in comparison with the similar condition in the Argon gas. In the presence of air, hydrogen comes out from titanium hydride during eight stages. In the DTG diagram a minimum was noticed, at the temperature of 835°C, which can be the sign of reducing of the rate of oxidation and weight gaining of the powder. The thermal decomposition mechanism of TiH2 powder seems to be under control of both internal diffusion (diffusion of hydrogen and oxygen atoms within the. layers of a solid solution, titanium oxide and titanium hydride) and the chemical reaction (titanium oxidation). The temperature of hydrogen excretion from TiH2, in the presence of air, increased relative to its excretion, in the presence of the argon gas at the first stage from 534°C to 550°C and at the second stage from 642°C to 660°C. Based on the results of this work it seems that the most appropriate temperature, for the primary heat treatment of TiH2 powder, is between 300-500°C.
