作者：Zongqi Guo;
作者單位：
刊名：The Refractories Engineer
ISSN：1362-4547
出版年：2002-01-05
卷：0
期：september
起頁：10
止頁：13
分類號：TQ175
語種：英文
關鍵詞：
內容簡介Phase-equilibrium relations in silicate systems containing chromium oxide lend support to the observation that phases containing chromium oxide would have high resistance to corrosion by typical coal-ash slags, the solubility of Cr_2O_3, in such slags is quite low under the conditions of temperature and atmosphere commonly encountered in slagging coal gasifiers. At unusual combinations of high temperature and extremely reducing conditions, a substantial proportion of the chromium may be present in silicate liquids in the divalent state (Cr~(2+)). This may cause a drastic lowering of liquidus and solidus temperatures and thus cause much more severe slag attack on a chromium-oxide-bearing refractory lining than would be the case if all the chromium were present in the trivalent state. High-density Cr_2O_3 and MgCr_2O_4 grains can be obtained in industrial production. A suitable Al_2O_3 addition could enhance the strength of ZrO_2-containing chromia materials due to formation of annular (Cr, Al)_2O_3 crystals and cold crushing strength of more than 100MPa could be reached. Slag penetration dissolved ZrO_2 near the slag/refractory interface, but 6 percent ZrO_2 additive most improves thermal shock resistance. The trade-offs between corrosion resistance, thermal shock resistance and mechanical properties could be made by 4-8 percent Al_2O_3 and 6 percent ZrO_2 additives. Annular (Cr, Al)_2O3 grains and well-distributed fine ZrO_2 grains bonding large granular Cr_2O_3 grains optimised the microstructure of high chrome refractories. The active powder of picrochromite, a light-burned mixture of MgO and Cr_3O_3 improved cold and hot strength of the fused picrochromite bricks, which had the well-distributed matrix with larger crystals and less porosity.
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