The performance of periclase-carbon refractories cemented with a phenolic bond that are intended for use in the lining of the cone section of the oxygen converter vessel has been studied by x-ray diffraction and petrography techniques. The results obtained provide a basis for further improvement of the oxygen converter technology and refractory fabrication.In this paper, we report on the results of a study of the wear of periclase-carbon refractories used for the lining of the mouth of a converter vessel. Our interest in this subject stems from the observation that excessive wear of this part of the refractory lining has been the major reason for the decommissioning of oxygen converters at the DMW JSC. Specimens for inspection were sampled from the refractory lining of the mouth of a converter vessel with a service life of 1600 heats. The specimens were analyzed for phase composition on a DRON-2 x-ray diffractometer (MoK a -radiation); diffraction patterns were measured in the range of 2q = 5 -70°. Macro and microtextures of the specimens were inspected using a Neophot-21 light microscope in the bright and dark field in polarized light. Photographic pictures were taken using a Nicon COOI PIX 5700 digital camera.The specimens were inspected by using a layer-by-layer surface removal technique to a depth of 100 mm. A comparison of the textures of used and intact refractory materials (Fig. 1) allowed easy identification of the changes that the refractory had undergone during service.The slag crust in post-service specimens displayed a mosaic-like crack pattern; most cracks (named the "old" cracks by convention) were impregnated with secondary periclase (Fig. 2) that formed owing to oxidized magnesium vapors extended from the bulk to the surface. New cracks could also be identified that required some time to become filled with secondary periclase. Acicular periclase crystals were observed to occur in the pores (Fig. 3a ). The pores were formed because of the evolution of magnesium vapors and

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Based on data of petrographic and x-ray spectral microprobe analyses of periclase-carbon specimens sampled from the refractory lining of a decommissioned oxygen converter, a mechanism for the corrosive attack of slag on the refractory material is proposed and its kinetic parameters discussed.The goal of our study was to inspect the performance of a periclase-carbon refractory in the slag zone of an oxygen converter. Refractory specimens for testing were sampled from an area located close to the trunion of the converter that was temporarily removed from service after a campaign of 2000 heats. The area in question was the most affected by wear, and it was not protected by a scull from attack by the low-basicity slag.The test specimens were analyzed petrographically at 500 magnification in reflected light under an Epignost 21 microscope; the refractory hot zone (operating zone) and the least affected zone were inspected. The specimens were analyzed for quantitative and qualitative composition by the x-ray spectral method on a Cameca MS-46 microprobe using KAP and PET crystal analyzers. The component concentrations at specified points were determined using a personal computer and a "PAP, Cameca" program; relevant data are given in Fig. 1.The concentration profiles in Fig. 1 traced as the microprobe and microscope were moved in the direction hot zone (HZ) ® least affected zone (LAZ) indicate that periclase grains are surrounded by liquid low-basicity slag and iron oxides as the slag and iron oxides find their way along the grain boundaries.Considering that the FeO concentration in the LAZ decreases from 50% to 0 over a distance of 0.2 mm, iron oxides should regarded as the most consumable component of the slag infiltrated in close vicinity of the LAZ. At the HZ/LAZ boundary, minute reguluses make their appearance. This indicates the early stage of wear of the periclase-carbon refractory schematized by the reaction C + FeO = Fe solid + CO.(1) Refractory Slag Reguluses Pore formationEven a microscopic pore may serve as the site for nucleation and growth of a CO gas bubble; therefore to inhibit the nucleation of CO bubbles and to retard reaction (1), the porosity of the refractory should be reduced to a minimum. A necessary condition is also the absence of through pores which provides conditions for closing the channels with gas

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