Study on the Mechanism of Carbon Steel Sparks

Abstract

Spark testing is an effective and convenient method that can be used be identify general classification of the steel material by observing the sparks projected by the grinding wheel. In order to more accurately identify the type of spark, the spark streams of carbon steels are described and illustrated by a high-speed camera. The appearance and phase analysis of the residues collected from the spark streams are studied separately by scanning electron microscope and X-ray diffractometer. Results show that the spark streams are the trajectory of the movement of carbon steel wear debris. The luminescence of the debris is provided by the heat released by the iron oxidation reaction. The carbon burst is caused by the explosion of carbon monoxide (CO) on the surface of carbon steel wear debris, and CO is produced by the reduction reaction of carbon and iron oxides. The main shape of the residues is flaky and spherical. There are some holes caused by carbon burst on the surface of the spherical residues. For the qualitative phase analysis of the residues, the main phase is composed of iron, ferrous oxide (FeO), ferric oxide (Fe2O3), and ferroferric oxide (Fe3O4). As the increase of the carbon content of steel, the quantity of iron phase is greatly reduced, and the quantity of Fe2O3 and Fe3O4 phase is gradually increased. Moreover, the amount and density of carbon burst is increased, and the number of the holes in the spherical residues are also increased.