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.
