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It is found that heterogeneous nucleation can promote the formation of coloring phases, significantly decrease↓ the volatilization, and improve the uniformity of coloring elements by reducing the mass transferring distance during sintering. It is believed that the method of heterogeneous nucleation could be a facile and cost saving route to facilitate solidstate reaction and guarantee the uniform distribution of new phases within the matrix for the fabrication of colored ceramics.
② precursor solution
metal nitrates in aqueous solution:
0.1 mol/L Co(NO3)2 and 0.2 mol/L Al(NO3)3
pH= 3.0
③ tailor the pH value of the suspension
0.01 mol/L aqueous NH3
pH= 9.1-9.5
RESULT
BEI (backscattered electron images)
1400 °C
CONCLUSION
It is found that heterogeneous nucleation can promote the formation of CoAl2O4,significantly decrease the volatilization, and improve the uniformity of coloring phases within ceramics by reducing the mass transferring distance during sintering. It is believed that heterogeneous nucleation could be a facile and cost saving route to facilitate solid-state reaction and guarantee the uniform distribution of new phases within the matrix for the fabrication of colored ceramics.
X X X Advised by Prof. X X X
[1] Wei Wang, Zhipeng Xie, Guanwei Liu, Crystal Growth & Design,2009,vol.9,4373-4377
ABSTRACT
We have demonstrated, for the first time, the fabrication of uniformly bluewk.baidu.comcolored CoAl2O4ZrO2 ceramics via a heterogeneous nucleation method. Polyethylene glycol (PEG2000) was used as the dispersant for the ZrO2 powders followed by Al and Co hydrates introduced to the suspension for preparation of coated powders. Then NH3 was added into the suspension to tailor the pH values to favor the heterogeneous nucleation of CoAl2O4 spinels.
EXPERIMENTAL METHOD
① coated powders were prepared first
Y-TZP powder (ZrO2-3 mol%Y2O3, YSZ-DM-3.0) with a purity of 99.4% was used as the starting powders, mixed with dispersants of polyethylene glycol (PEG2000), dispersed in a bath under ultrasound
heterogeneous nucleation method form at preferential sites (such as phase boundaries or impurities) the effective surface energy is lower diminishing the free energy barrier and facilitating nucleation requires less energy
INTRODUCTION
Colored Zirconia Ceramics Advantage
unique properties of beautiful colors, metallic lusters, lack of hypersusceptibility<过敏反应> excellent mechanical properties high wear resistance
