The prediction of oxidation rates of carbonaceous materials from plasma arc tests

Abstract

A theory is presented for the mass loss of carbonaceous materials exposed to a hot air stream. This theory includes both oxidation and spalling effects, and it applies to the regimes wherein oxidation rate is controlled by chemical reaction rate, by oxygen diffusion rate, and by a combination of these mechanisms. The theory was applied to the analysis of plasma arc tests on carbonaceous materials, including the computation of chemical and physical constants for the prediction of mass loss rate. Three series of plasma arc tests were conducted. These included side and stagnation heating conditions and three materials. Results fell into all three oxidation regimes and, above 4000°F, reflected mass loss by spalling. One material exhibited marked oxidation resistance. It is concluded that sufficient information can be obtained from plasma tests to compute the oxidation and spalling rates of a carbonaceous material on a re-entry vehicle.