Table 1.

Estimated heats of reactions involving Si with oxides and fluorides of Co and Bi for stoichiometric and fuel-rich (50/50 wt.%) composites reacting in inert and oxidizing environments.

Composite Type			Heat of Reaction
			kJ/g	kJ/cm3
Si with Bi2O3 and BiF3	Stoichiometric	3Si + 2Bi2O3 → 3SiO2 + 4Bi	−1.56	−11.25
		3Si + 4BiF3 → 3SiF4 + 4Bi	−1.05	−5.12
	50/50 wt.% (fuel rich) *	Si + Bi2O3 → Si + SiO2 + Bi	−0.85	−3.14
		Si + BiF3 → Si + SiF4 + Bi	−0.57	−1.84
		Added ambient oxidizer Si + Bi2O3 + O2 → SiO2 + Bi2O3	−15.6	−57.6
		Added ambient oxidizer Si + BiF3 + O2 → SiF4 + SiO2 + Bi2O3	−15.5	−50.22
Si with CoO and CoF2	Stoichiometric	Si + 2CoO → SiO2 + 2Co	−2.45	−12.32
		Si + 2CoF2 → SiF4 + 2Co	−1.28	−5.11
	50/50 wt.% (fuel-rich) *	Si + CoO → Si + SiO2 + Co	−1.45	−4.97
		Si + CoF2 → Si + SiF4 + Co	−0.60	−1.82
		Added ambient oxidizer Si + CoO + O2 → SiO2 + CoO	−14.63	−50.05
		Added ambient oxidizer Si + CoF2 + O2 → SiF4 + SiO2 + CoO	−14.46	−44.26

* For clarity of the concept, reactions are written without balancing reactants and products.