To solve the problem of poor high-temperature service performance caused by low carbonization of MgO–C refractories, low-carbon MgO–C refractories with excellent thermal shock, oxidation and corrosion resistances were successfully designed by using SiC whiskers as reinforcing phases and introducing micro-Al 2 O 3 powders as additives. The results indicated that the addition of micro-Al 2 O 3 powders optimized the internal structure of the material, like the columnar β-Si 3 N 4 with a stepped distribution and the mosaic structure formed between granular and flaky Mg 2 SiO 4 , which synergistically strengthened and toughened the material and gave the material excellent mechanical properties and thermal shock resistance. Specifically, the cold modulus of rupture and cold crushing strength after thermal shock were increased by 4.1 and 20.3 MPa, respectively. Moreover, the addition of micro-Al 2 O 3 powders promoted the formation of fine particles of Mg 2 SiO 4 , MgAl 2 O 4 and MgO, as well as a dense protective layer of Mg 2 SiO 4 in the material under high-temperature environment. Furthermore, spinel and high-temperature solid solution were formed in the corrosion environment. The oxidation and corrosion resistances were greatly improved by 41% and 15%, respectively.
Yang Chen,Chengji Deng,Xing Wang,Jun Ding,Chao Yu,Hongxi Zhu
Si 3 N 4 -MgO-C refractories were prepared using fused magnesia, flake graphite, and Si powder-supported Fe(NO 3 ) 3 ·9H 2 O as the raw materials and phenolic resin as the binder under the flow of N 2 . The effect of different nitriding temperatures on the morphology and production of Si 3 N 4 in the uncatalyzed refractories was investigated. The effect of the morphology of β-Si 3 N 4 on the properties of the refractories with different catalyst contents was investigated. The oxidation resistance of the refractories was also investigated. The results showed that the increase in the nitriding temperature was beneficial for the formation of β-Si 3 N 4 in the refractories. However, very high nitriding temperatures generated a large number of pores in the refractories and deteriorated their properties. The refractory with 1 wt% catalyst exhibited good mechanical properties and oxidation resistance. However, the addition of excessive catalyst inhibited the formation of β-Si 3 N 4 and deteriorated the performance of the refractories.
Jing Zhou,Xingang Li,Jinze Du,Lin He,Chengyang Wang,Hong Sui
A new resourcezation way has been proposed to address the treatment challenges of the light phenolic distillation residue (LPDR) from the coal-based phenolic distillation residue. Herein, the LPDR, which was collected at 20 kPa and 220 °C from the phenolic distillation residue, has been further used to synthesize the phenolic resin (named as RPF) for MgO-C refractories. It is found that the conversion efficiency of crude phenol mixture to RPF is 71.3%, which is lower than that of pure phenol. To increase the conversion efficiency and improve the properties of RPF, the crude phenolic mixture was blended with pure phenol for the synthesis. The optimal addition mass ratio of phenol in the crude phenol mixture (phenol/total phenolic compounds) is determined to be 0.8, where the obtained RPF could satisfy or even better than the national standard. Further addition of 10 wt% of urotropine (HMTA) as curing agent and 9 wt% of ferrocene (Fc) as modifier (named as MRPF) are found to significantly improve the graphitization of RPF. Under these conditions, the DTG at temperature of maximum mass lose rate (T max ) of MRPF was lower than that of commercial resin. The graphitization level was as high as 61.6% with the residual carbon rate up to 41.4%, which are higher than those of national standard. These findings provide insights for the resourcezation of the phenolic distillation residue.
危险品化学品经营许可证（带存储）