Investigations on oxidation and microstructure evolution of pure Cu in simulated air–kerosene combustion atmospheres

Abstract

Summary Copper is among the most frequently found metallic residues in fire scene environment. Investigations on the thermal patterns produced on copper after fire scene exposure can provide important physical evidence for fire cause/origin determination. In this paper, the high temperature oxidation behaviors and the accompanying micro‐structural changes of pure copper have been studied in air and laboratory simulated kerosene‐combustion atmospheres at 600–800 °C. The oxidation kinetics, morphologies and microstructures of the oxide scales‐substrate were characterized by thermogravimetric analysis, scanning electron microscopy, energy‐dispersive spectroscopy and X‐ray diffractions. The results reveal that the increasing temperature can significantly affect the oxide properties and modify the substrate metallurgical microstructure. Especially, the presence of kerosene in the environmental atmosphere has caused accelerated oxidation and produced oxide scales different from those formed in air alone. These feature evolutions in surface oxides and substrate are expected to offer complementary insight on determining the fire characteristics, such as the exposure temperature, time period and whether liquid accelerant is involved. Copyright © 2016 John Wiley & Sons, Ltd.

Influence of liquid accelerant on scaling behavior of stainless steel in fire: An experimental study

“…On the other hand, oxide scale formed on metallic materials during a fire might reveal information about fire temperature and the composition of atmosphere. The growth and morphology of surface oxide scale and the metallurgical microstructure of alloy can be useful in determining the maximum temperatures reached, similar to the tests already performed on copper, carbon steel and aluminum alloy . Therefore, combination of the oxide scale and metallurgical microstructure technique could be helpful to reconstruct fire scenes.…”

“…As for the effect of accelerant, the combustion products of kerosene, such as CO 2 , H 2 O, and SO 2 , are more aggressive than O 2, which might be deleterious to the chemo‐stability of protective scale. The detailed mechanism has been discussed in our previous work . It is worth noting that the influence of temperature and accelerant on scaling behavior for stainless steel is different to that for aluminum alloy and copper in some extent.…”

“…A horizontal three zones electric furnace equipped with quartz tube is used as reaction furnace for heating the samples at maintained temperatures. To simulate kerosene combustion conditions, a separate combustion chamber was established in an adjacent furnace, and the two furnaces were connected in series, as shown in previous work . The kerosene fuel was injected through a nozzle at a pumping rate of 1.5 SCCM (standard‐state cubic centimeter per minute), mixed with air that was introduced at a flowing rate of 20 SCCM, and ignited in the combustion furnace.…”

“…To simulate kerosene combustion conditions, a separate combustion chamber was established in an adjacent furnace, and the two furnaces were connected in series, as shown in previous work. [5][6][7] The kerosene fuel was injected through a nozzle at a pumping rate of 1.5 SCCM (standard-state cubic centimeter per minute), mixed with air that was introduced at a flowing rate of 20 SCCM, and ignited in the combustion furnace. The kerosene-air combustion atmosphere flowed into the reaction furnace through the quartz tube.…”

“…The detailed mechanism has been discussed in our previous work. [5][6][7] It is worth noting that the influence of temperature and accelerant on scaling behavior for stainless steel is different to that for aluminum alloy and copper in some extent. The car- Finally, the microstructures of stainless steel after hightemperature exposure are illustrated in Figure 8.…”