| Popis: |
A least-squares linear-Taylor differential-correction technique has been used for the rapid evaluation of thermogravimetric curves obtained during the decomposition of magnesium hydride, iron—titanium hydride and lanthanum—nickel hydride. For magnesium hydride and iron—titanium hydride the Avrami—Erofe'ev equation fits the experimental data, thus indicating that nucleation is the rate-determining step under thermogravimetric conditions. For lanthanum—nickel hydride a combination of the Avrami—Erofe'ev equation and the phase boundary movement equation fits the data up to a fractional decomposition of 0.8. For magnesium hydride decomposition the activation energy E and the pre-exponential factor Z are dependent on the hydrogen pressure ( E = 101.2 kJ mole −1 and Z = 8.96 × 10 7 at 0.30 MPa, while E = 66.3 kJ mole −1 and Z = 4.77 × 10 7 at 0.11 MPa). For iron—titanium hydride ( E = 28.4 kJ mole −1 ) and lanthanum—nickel hydride ( E = 13.4 kJ mole −1 ) the values are independent of pressure. |
