Fig 1.
A ceramic combustion boat filled with ~ 3.0 g PGA particulate of size 2.0–6.0 mm.
Fig 2.
A schematic of the thermal treatment apparatus used.
Fig 3.
An energy level diagram of the oxidation of graphite to CO2.
ΔH is given in kJ/mol.
Fig 4.
The various kinetic regimes thought to be involved in graphite oxidation.
Artwork inspired by Clark et al [38]. The temperature ranges shown are an approximation and can vary depending on many factors.
Fig 5.
The effect of temperature on graphite oxidation rate in air (top) and 60% O2 (bottom).
Fig 6.
The effect of temperature on the CO/CO2 production ratio in air (top) and 60% O2 (bottom).
Fig 7.
Comparison of weight loss against temperature in air and 60% O2.
Table 1.
Measured weight loss after 1 hour oxidation at various temperatures for an initial graphite mass of ~ 3.0 g (± 0.01 g).
The flow rate was fixed at 100 ml/min.
Fig 8.
The effect of increasing temperature on the graphite oxidation rate for both air and 60% O2.
Fig 9.
Arrhenius plot showing the temperature dependence of graphite oxidation rates from 500–1200°C.
Data from T < 500°C is omitted due to negligible oxidation rates.
Table 2.
The data derived from fitting a linear line of best-fit over the various temperature regimes in the Arrhenius plot.
Values of Ea are in kJ/mol.
Table 3.
The effect of O2 concentration and flow rate on the maximum graphite oxidation rate.
The figures assume that that 1 mole of O2 produces one mole of CO2, as described by Eq 7.
Fig 10.
The effect of increasing oxidant flow rate on the graphite oxidation rate.
Experiments carried out at 1000°C and in air (top) and 60% O2 (bottom).
Fig 11.
The effect of flow rate on oxidation induced weight loss at 1000°C in both air and 60% O2.