Effect of Al(H2PO4)3/Zn/B4C doped resin on properties and microstructure of unfired Al2O3–C slide plate materials

Abstract The unfired Al2O3–C slide plates have the advantages of energy saving, environment friendly, efficiency and relatively low-cost. However, the decomposition and oxidation of the phenol-formaldehyde (PF) resin at elevated temperatures deteriorate the properties and decrease service life of the unfired slide plates. In order to improve the property of resin, the doped PF resin is prepared by incorporating Al(H2PO4)3, Zn and B4C powders. The effects of the doped resin on medium-high temperature properties and microstructure of the unfired slide plate materials have been investigated. The results show that Zn and B4C doped resin contributes to notable increasing the density and strength properties at medium temperature, because Zn and B4C easily oxide and thus protect resin from oxidation, leading to form a dense structure. Zn and B4C doped resin can significantly improve hot modulus of rupture of material at 1400 °C, which is due to Zn and B4C react with oxidative gases leading to increase in concentration of C(g), CO and N2, Al and Si would react with C(g), CO(g) and N2(g) to form AlN and SiC whiskers creating strengthening effect. Specimens with Zn and B4C doped resin addition had good oxidation resistance at 1500 °C, because Zn and B4C in the surface of the material react with O2 to form ZnAl2O4 or mullite containing dense glass film, which would retard O2 diffusion into the inner of the specimens.