A new calcium aluminate cement CA-670 was studied in the system of tabular alumina, white fused alumina （WFA）, and bauxite based low cement castables. The flow ability, strength development, and hot strength （ HMOR...A new calcium aluminate cement CA-670 was studied in the system of tabular alumina, white fused alumina （WFA）, and bauxite based low cement castables. The flow ability, strength development, and hot strength （ HMOR ） were investigated. Different types of additives were used for the CA-670 bonded castables. The results show CA-670 provides a good workability for each type of＂ castables. CA-670 displays a good compatibility with different types of additives. Testing on different batches of CA-670 shows good reproducible properties in each castable, which manifests good consistency and reliability of CA-670.展开更多
This work explored the way to improve hot modulus q/＇ rupture （HMOR） and refractoriness under load （RUL） by adding mild-calcined coal gangue （MCG） in Al2O3 -SiO2 ultra low cement （ULC） castables, making use o...This work explored the way to improve hot modulus q/＇ rupture （HMOR） and refractoriness under load （RUL） by adding mild-calcined coal gangue （MCG） in Al2O3 -SiO2 ultra low cement （ULC） castables, making use of the in-situ effect of the MCG during heating-up. The influence of respective additions of 5%, 10% and 1.5% of the MCG powders calcined at 700℃ was investigated on HMOR at 1400 ℃ and RUL of the castables. With increased addition of the MCG, HMOR and RUL become significantly enhanced. At 10% of the MCG addition, HMOR reaches 3 MPa, as compared to 0. 3 MPa in the case of no MCG addition. RUL of the specimens dried at 110 ℃for 24 h can be increased by some 270 ℃ with 10% of the MCG addition. RUL 0.11 the specimens preheated at 1 500℃ for 3 h maintains the growth trend with the MCG addition increasing. The microstructure of the heated castable samples was investigated by means of SEM. The in-situ formed needle-like and interlaced mullite in the matrix is contributive to the tmprovement.展开更多
Water addition has direct impact on castables and needs to be under control placement and properties, In this work, two rheological properties, flow resistance and torque viscosity, have been measured against time, wi...Water addition has direct impact on castables and needs to be under control placement and properties, In this work, two rheological properties, flow resistance and torque viscosity, have been measured against time, with different water addition in the same bauxile-based LC Castable mix. The flow resistance indicates the mobility, whereas the torque viscosity dictates the stability of a castable during installation. It has been observed that with 6.0wt% water addition, such a mix possesses good vibration castable characteristics; with 6.5 wt%, it shows good self-flow castable characteristics; and with 7.0 wt%, it can be a good pumpable castable, in every case with comparable mechanical properties. While with 7.5 wt% water addition, the properties of such castable are definitively impaired.展开更多
Advanced high alumina refractory castables of ultra-low and to cement types, are well-known because of their ability on developing similar and/or superior thermal and mechanical properties. Following the recent trend ...Advanced high alumina refractory castables of ultra-low and to cement types, are well-known because of their ability on developing similar and/or superior thermal and mechanical properties. Following the recent trend of including nanoparticles in refractory castables, in this work, it is presented a novel way to obtain the benefit effects on the thermal and mechanical properties, promoted by the development in situ, of alumina’s nanoparticles in the matrix of castable (85 wt% Al2O3). The alumina nanoparticles were originated in situ after firing, due to the pyrolysis and oxidation of an aqueous resin, produced by the Pechini process. The resin played a double role, one as mixing liquid vehicle and the other as the aluminum oxide nanoparticles precursor. The results indicate a strong increase in flexural strength and elastic modulus as well as leading to a higher residual strength after thermal shock.展开更多
文摘A new calcium aluminate cement CA-670 was studied in the system of tabular alumina, white fused alumina （WFA）, and bauxite based low cement castables. The flow ability, strength development, and hot strength （ HMOR ） were investigated. Different types of additives were used for the CA-670 bonded castables. The results show CA-670 provides a good workability for each type of＂ castables. CA-670 displays a good compatibility with different types of additives. Testing on different batches of CA-670 shows good reproducible properties in each castable, which manifests good consistency and reliability of CA-670.
文摘This work explored the way to improve hot modulus q/＇ rupture （HMOR） and refractoriness under load （RUL） by adding mild-calcined coal gangue （MCG） in Al2O3 -SiO2 ultra low cement （ULC） castables, making use of the in-situ effect of the MCG during heating-up. The influence of respective additions of 5%, 10% and 1.5% of the MCG powders calcined at 700℃ was investigated on HMOR at 1400 ℃ and RUL of the castables. With increased addition of the MCG, HMOR and RUL become significantly enhanced. At 10% of the MCG addition, HMOR reaches 3 MPa, as compared to 0. 3 MPa in the case of no MCG addition. RUL of the specimens dried at 110 ℃for 24 h can be increased by some 270 ℃ with 10% of the MCG addition. RUL 0.11 the specimens preheated at 1 500℃ for 3 h maintains the growth trend with the MCG addition increasing. The microstructure of the heated castable samples was investigated by means of SEM. The in-situ formed needle-like and interlaced mullite in the matrix is contributive to the tmprovement.
文摘Water addition has direct impact on castables and needs to be under control placement and properties, In this work, two rheological properties, flow resistance and torque viscosity, have been measured against time, with different water addition in the same bauxile-based LC Castable mix. The flow resistance indicates the mobility, whereas the torque viscosity dictates the stability of a castable during installation. It has been observed that with 6.0wt% water addition, such a mix possesses good vibration castable characteristics; with 6.5 wt%, it shows good self-flow castable characteristics; and with 7.0 wt%, it can be a good pumpable castable, in every case with comparable mechanical properties. While with 7.5 wt% water addition, the properties of such castable are definitively impaired.
基金The authors thank the support of the Sao Paulo State Research Funding FAPESP through CDMF/CEPID programto Capes for the scholarship to Jose Antonio Alves Jr.
文摘Advanced high alumina refractory castables of ultra-low and to cement types, are well-known because of their ability on developing similar and/or superior thermal and mechanical properties. Following the recent trend of including nanoparticles in refractory castables, in this work, it is presented a novel way to obtain the benefit effects on the thermal and mechanical properties, promoted by the development in situ, of alumina’s nanoparticles in the matrix of castable (85 wt% Al2O3). The alumina nanoparticles were originated in situ after firing, due to the pyrolysis and oxidation of an aqueous resin, produced by the Pechini process. The resin played a double role, one as mixing liquid vehicle and the other as the aluminum oxide nanoparticles precursor. The results indicate a strong increase in flexural strength and elastic modulus as well as leading to a higher residual strength after thermal shock.
