Compact-specimen burning with fresh metal surface production

Influence of Oxygen Dissociation on the Oxidation of Iron

“…Due to this, the rates of iron oxidation by molecular and atomic oxygen are similar. These results are in excellent agreement with previous works 4,5,8 . In particular, the parabolic rate constant at 925 K was determined in the present work as equal to 7.63 × 10 −8 g 2 cm −4 min −1 ; this value is very close to 9.66 × 10 −8 g 2 cm −4 min −1 reported in literature 4 .…”

Mechanism of metal ignition due to fracture

“…2, which also shows the dependence p * mix (T 0 ) from [7] for the Armko iron in an oxygen-containing mixture (p * mix is the minimum partial pressure of oxygen in the mixture with the composition used, at which metal fracture leads to metal ignition). The values of p * are seen to decrease with increasing T 0 for all materials.…”

“…(The assumption made in [5,7] that the primary initiators of ignition are massive conical parts of the halves of the fractured sample was not validated experimentally.) Ignition of the microfragments mentioned above in both mechanisms of metal fracture occurs when they are located in the fracture crack filled by oxygen at an operating pressure.…”

“…The assumption put forward in [5] implies that the limiting stage of oxygen-titanium interaction during fracture is dissociative chemical adsorption of O 2 molecules on the juvenile metal surface, which determines the form of the reaction rate as a function of the medium pressure [∂m/(∂t) ∼ p 0.5 ], and the critical conditions of ignition of fragments formed due to fracture are described by the criterial equation of the theory of the thermal explosion for a heterogeneous reaction [6]. Based on experimental data and results of [7], the mechanism described in [1,5] is extended in the present work to other metallic materials; results of studying the nature and conditions of heat transfer between ignition initiators are given; kinetic parameters of the reaction between oxygen and the juvenile surface of metals are calculated.…”

“…Points 1-4 refer fracture of tubes by oxygen pressure: 1) iron; 2) 12Kh18N10T steel; 3) EP202 alloy; 4) EI698 alloy; points 5 (see inset) refer to the fracture of iron cylindrical samples under uniaxial extension in the medium 0.3O2-0.66N2-0.04(N2O4 + NO2) [vol. %] from[7].…”