Production Rate of SiO Gas from Industrial Quartz and Silicon
Caroline Sindland, Merete Tangstad
Abstract
Abstract The production rate of SiO gas from industrial quartz and silicon has been investigated by isothermal heat treatment experiments. Mixtures of silicon and different quartz samples have been heated to temperatures ranging from 1650 °C to 1950 °C and held for 30 to 120 minutes before cooling. The weight loss of each sample has been correlated to degree of reaction and a model for the reaction rate of Si + SiO 2 has been developed based on these values. Five different types of industrial quartz were used in the experiments. No significant difference was found in their reaction rate, even though there are large variations in impurity content, melting rate, decrepitation, and phase transformation rate of each sample. Further on, it is shown that the reaction rate of silicon mixed with various types of quartz can be described by an Arrhenius equation: $${{\rm {d}}\alpha /{\rm {d}}t = k_0 \, A \, {\rm {exp}} (- Q / RT)}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>d</mml:mi> <mml:mi>α</mml:mi> <mml:mo>/</mml:mo> <mml:mi>d</mml:mi> <mml:mi>t</mml:mi> <mml:mo>=</mml:mo> <mml:msub> <mml:mi>k</mml:mi> <mml:mn>0</mml:mn> </mml:msub> <mml:mspace/> <mml:mi>A</mml:mi> <mml:mspace/> <mml:mi>exp</mml:mi> <mml:mrow> <mml:mo>(</mml:mo> <mml:mo>-</mml:mo> <mml:mi>Q</mml:mi> <mml:mo>/</mml:mo> <mml:mi>R</mml:mi> <mml:mi>T</mml:mi> <mml:mo>)</mml:mo> </mml:mrow> </mml:mrow> </mml:math> . A reaction constant ( k 0 ) equal to $${6.25 \, 10^8 {\rm {g}}\, {\rm {s}}^{-1}\, {\rm{m^{-2}}}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>6.25</mml:mn> <mml:mspace/> <mml:msup> <mml:mn>10</mml:mn> <mml:mn>8</mml:mn> </mml:msup> <mml:mi>g</mml:mi> <mml:mspace/> <mml:msup> <mml:mrow> <mml:mi>s</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> <mml:mspace/> <mml:msup> <mml:mi>m</mml:mi> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>2</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> and an activation energy ( Q ) equal to $${557\, {\rm {kJ \, mol^{-1}}}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>557</mml:mn> <mml:mspace/> <mml:mrow> <mml:mi>kJ</mml:mi> <mml:mspace/> <mml:msup> <mml:mi>mol</mml:mi> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:mrow> </mml:math> were obtained by linear regression. The degree of reaction ( $${\alpha }$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>α</mml:mi> </mml:math> ) is shown to be increasing with available reaction area, temperature, and time.