The microstructure and properties of phosphate bonded Cr2O3 - -Al2O3 - ZrO2 specimens fired in air or coke bed were investigated firstly. Then property change of the Cr2 O3 - Al2 O3 - ZrO2 bricks after secondary treat...The microstructure and properties of phosphate bonded Cr2O3 - -Al2O3 - ZrO2 specimens fired in air or coke bed were investigated firstly. Then property change of the Cr2 O3 - Al2 O3 - ZrO2 bricks after secondary treat- ment in simulation environment was studied. Finally, corrosion resistances of the Cr2 O3 - Al2 O3 - ZrO2 bricks in air and simulation environment were compared; and microstructure of on-site used Cr2O3 - Al2O3 - ZrO2 bricks in slagging gasifiers was analyzed. The results show that the atmosphere has significant effect on the mi- crostructure and properties of the phosphate bonded Cr2O3 -Al2O3 -ZrO2 bricks. As the specimens are fired in air, the phosphate forms a composite solid solution with Cr2 O3 and Al2 O3, therefore, strength of the speci- mens is enhanced. For specimens fired in coke bed, a certain amount of gases are generated owing to the re- duction of phosphate and part of Cr2 O3, which results in the increasing number and size of the pores, bad interfa- cial bonding between Cr2O3 aggregates and matrix as well as low strength of the specimens. During service process in reducing atmosphere, the phosphate binder and part of Cr2O3 in edge of the specimens are also re- duced, leading to significant increase of number and size of the pores in the edge of the specimens; as a result, inreducing atmosphere, the specimens show much worse corrosion resistance than in air.展开更多
A basic alumina -spinel low cement castables （ castables A） and another castables （ castables B） with 5% addition of sodium hexametaphosphate were prepared and heat treated at 110 ℃, 900℃ and 1 400 ℃. It is sho...A basic alumina -spinel low cement castables （ castables A） and another castables （ castables B） with 5% addition of sodium hexametaphosphate were prepared and heat treated at 110 ℃, 900℃ and 1 400 ℃. It is shown that after heat treating at 110 ℃ , cold crushing strength （CCS） of castables B is more than 3 times of castables A and apparent porosity （ AP ） is less than half of castables A. The presence of Mg2P207 and AIPO4 · 2H2O is the main difference. At 800- 1 000 ℃ that hydraulic bond reverses to dehydrate condition and castables A becomes weak with high porosity, castables B shows a CCS more than 4 times of castables A. Needles of magnesium phosphate are responsible for reinforcing microstructure of castables B at 900 ℃. After firing at 1 400 ℃, castables B shows extra ordinary CCS of more than 100 MPa. Reasons were discussed with X-ray diffraction and scanning electron microscopy.展开更多
文摘The microstructure and properties of phosphate bonded Cr2O3 - -Al2O3 - ZrO2 specimens fired in air or coke bed were investigated firstly. Then property change of the Cr2 O3 - Al2 O3 - ZrO2 bricks after secondary treat- ment in simulation environment was studied. Finally, corrosion resistances of the Cr2 O3 - Al2 O3 - ZrO2 bricks in air and simulation environment were compared; and microstructure of on-site used Cr2O3 - Al2O3 - ZrO2 bricks in slagging gasifiers was analyzed. The results show that the atmosphere has significant effect on the mi- crostructure and properties of the phosphate bonded Cr2O3 -Al2O3 -ZrO2 bricks. As the specimens are fired in air, the phosphate forms a composite solid solution with Cr2 O3 and Al2 O3, therefore, strength of the speci- mens is enhanced. For specimens fired in coke bed, a certain amount of gases are generated owing to the re- duction of phosphate and part of Cr2 O3, which results in the increasing number and size of the pores, bad interfa- cial bonding between Cr2O3 aggregates and matrix as well as low strength of the specimens. During service process in reducing atmosphere, the phosphate binder and part of Cr2O3 in edge of the specimens are also re- duced, leading to significant increase of number and size of the pores in the edge of the specimens; as a result, inreducing atmosphere, the specimens show much worse corrosion resistance than in air.
文摘A basic alumina -spinel low cement castables （ castables A） and another castables （ castables B） with 5% addition of sodium hexametaphosphate were prepared and heat treated at 110 ℃, 900℃ and 1 400 ℃. It is shown that after heat treating at 110 ℃ , cold crushing strength （CCS） of castables B is more than 3 times of castables A and apparent porosity （ AP ） is less than half of castables A. The presence of Mg2P207 and AIPO4 · 2H2O is the main difference. At 800- 1 000 ℃ that hydraulic bond reverses to dehydrate condition and castables A becomes weak with high porosity, castables B shows a CCS more than 4 times of castables A. Needles of magnesium phosphate are responsible for reinforcing microstructure of castables B at 900 ℃. After firing at 1 400 ℃, castables B shows extra ordinary CCS of more than 100 MPa. Reasons were discussed with X-ray diffraction and scanning electron microscopy.
