Slag Penetration Research Articles

Relation between Corrosion Rate of Magnesia Refractories by Molten Slag and Penetration Rate of Slag into Refractories

Corrosion tests on magnesia refractories in molten CaO-SiO2-CaF2-Al2O3 slags have been conducted at 1873K in a high frequency induction furnace. By combining the corrosion rate with the microstructures of tested specimens and the theoretical analysis of the slag penetration, a penetration resistance coefficient of refractory, Rp was introduced as an index for evaluating the corrosion behavior of the refractory. Using this index the penetration behavior of the slag into the refractory was evaluated and the penetration rate of slag into the refractory was related to the corrosion rate, which suggests the possibility of developing a refractory resistant to both spalling and corrosion.

Effect of Cr2O3 on Slag Resistance of Al2O3–SiO2 Refractories

Refractory bodies of 65 wt% Al2O3 were prepared from a mixture of calcined alumina and raw kaolin with the addition of Cr2O3 up to 15 wt%. The Cr2O3 addition effectively enhances slag resistance and reduces mullite formation. Petrographic analysis of the refractories after the slag test suggests that Cr2O3 increases the viscosity of both the glassy phase in the refractory as well as the slag, thereby retarding slag penetration and reaction at elevated temperature.

Strength degradation in SiC and Si3N4 ceramics by exposure to coal slags at high temperatures

Several commercial SiC and Si3N4 ceramics were exposed to the slag-like combustion products of coal—oil mixtures at approximately 1200° C to assess the effects of the ceramics composition on its corrosion behaviour and related changes in flexure strength including its temperature dependence. In the case of exposure to a slag from combustion of a basic coal—oil mixture, very accelerated corrosive attack occurs in both the SiC and Si3N4 ceramics such that the general rate of surface recession compared with localized corrosive attack limits the long-term load bearing capacity of the materials. Both the high-temperature corrosion for two different acidic slags and the resultant flexure strengths are dominated by either local enhanced surface corrosion (i.e. pitting) or slag penetration into the various materials which are strongly influenced by processing defects, impurities and/or second phases initially present in the ceramics. The SiC ceramics generally exhibited greater resistance to corrosive attack than did the Si3N4 ceramics.

溶銑予備処理用 Al<SUB>2</SUB>O<SUB>3</SUB>-SiC-C 質れんがの開発

In the past about five years, superduty fireclay or high alumina brick has been applied for torpedo car. Recently, in accordance with the progress of desulphurization and desiliconization of pig iron in torpedo car, its lining material comes into a problem awaiting the solution. Several kinds of brick were developed for this purpose, and tested in laboratory and practically. As a result of these tests, unburned Al2O3-SiC-C brick was excellent in resistance to corrosion, spalling, slag penetration and oxidation. The properties and application for torpedo car of this brick are reported in this paper.

MgO焼結体の溶融Fe<SUB>t</SUB>O-CaO-SiO<SUB>2</SUB>系スラグへの溶解速度

The sintered MgO (porosity 29.9% and 13.0%) was immersed into molten FetO-CaO-SiO2 slags at temperatures from 1 350 to 1 425°C and the dissolution rate of MgO was determined with the rotating cylinder method by measuring the decrease of the cylinder radius. Also, the section of the MgO cylinder after immersion was examined by EPMA to know the penetration of slag and the dissolution mechanism.The results obtained are as follows :(1) The dissolution rate of MgO was increased with the rotating speed of cylinder and with temperature, and was found to be controlled by mass transport in the boundary layer of molten slag.(2) The change of mass transfer coefficient at 1 400°C with slag composition was correlated well to the change of kinematic viscosity of slag. Utilizing the nondimensional correlation found in literature, the values of diffusion coefficient of MgO into molten slags were estimated to be 1.0×10-53.0×10-5cm2/s at 1 400°C.(3) The dissolution of MgO proceeded through the formation of (Fe, Mg)O solid solution layer at the interface and its dissolution. The penetration of slag was retarded by this dense (Fe, Mg)O layer and the depth of penetration after 560 min was only 13 mm in high porosity MgO and <1 mm in low porosity MgO.

The Effect of Addition of (CrO&lt;sub&gt;3&lt;/sub&gt;+MgO) aqua on Making of Zircon Brick

Some concentrated (CrO3+MgO) aqua were added into zircon powder in order to improve corrosive resistance of zircon brick by both promoting the sintering of zircon and by strengthening the structure after firing at 1500°C and 1600°C in air or reduction atmosphere. Their effects on sintering and dissociation of zircon, and corrosive resistance of specimens after firing were investigated.The results were as follows.Concentrated (CrO3+MgO) aqua promoted sintering of zircon without dissociation in air atmosphere, and it promoted remarkably with slight dissociation in reduction atmosphere.And, it improved more the corrosive resistance of zircon brick, especially on slag penetration, than Cr2O3.

A Study on Slagging Resistance of Basic Refractories through Slagging-under-Load Test

A new type of slagging test menthod for basic refractories, Slagging-under-Load Test, was proposed.The test is a kind of hot creep test with slagging. The procedure of this test is as follows.A columnar crucible made of specimen with the size of 50mm in diameter and 50mm in height and with the hole size of 20mm in diameter and 30mm in depth, is filled with slag powder.The slag-filled specimen is heated at a uniform rate up to a test temperature, at which the specimen is maintained and a compressive load is applied. The rate of subsidence of specimen is measured in the similar manner to refractoriness-under-load test.This test is based on the fact that the slagging resistance of basic refractories must be determined both by the tendency of slag penetration and by the change in refractoriness with slag absorption. Some examples of the test applied to the evaluation of basic bricks for oxygen converter and mixer lining were given.