| Preparation of high quality ZrO2 powder is the basis of application. Although there are a lot of methods for the preparation of ZrO2 nanocrystalline powder, it is difficult to obtain ZrO2 nanocrystalline powder with controlled surface morphology and particle size as well as a concentrated size distribution. Low temperature combustion synthesis is a method using the heat released from the redox reaction between fuel (reducing agent) and oxidants to promote the combustion reaction with the advantage of simplifying the technique, shortening the experiment cycle, and obtaining a product with concentrated particle size distribution, high purity and activity. In this paper, low temperature combustion synthesis was used to prepare ZrO2 nanocrystalline powder, while XRD, TG-DTA,TEM and other analytical tools were used for the characterization of the powder. The main conclusions obtained were as follows:Well dispersed nanocrystalline powder was obtained when the molar ratio between zirconium nitrate and urea was 1:1.5 during the preparation of ZrO2 nanocrystalline powder and complex ZrO2 nanocrystalline powder with an additive of 3mol% Y2O3(YSZ). The variety of burning agents had a significant influence on the particle size of the obtained ZrO2 nanocrystalline powder. While, by using citric acid as oxidation agent for the combustion, the obtained powder showed a better uniformity in particle size which was within 10nm. The author believes that ZrO2 crystal transformed from a tetragonal phase (t phase) to a monoclinic phase (m phase) at room temperature with a critical size of 10nm. As the particle size of ZrO2 grew up, the volume fraction of m-ZrO2 in the synthesized powder gradually increased. The addition of Y2O3 could stabilize ZrO2's phase which was tetragonal at room temperature. ZrO2 powder prepared by low temperature combustion synthesis with 3mol% Y2O3 (particle size were less than 30nm) had stabilized tetragonal phase which would not change into monoclinic phase when heated at 1300℃.MgO nanocrystalline powder and ZrO2-MgO nanocrystalline composite powder were synthesized using magnesium nitrate and citric acid. When the molar ratio between nitrate and citric acid was 9:4, and the solution pH was 4, the synthesized MgO nanocrystalline powder had a high purity and concentrated distribution with a particle size of 9-25nm. The low-temperature combustion synthesis of composite ZrO2-MgO powder by addition of 8mol% MgO to ZrO2 obtained tetragonal phase composite powder. When the heating temperature increased,the particle size grew up and the stability of ZrO2-MgO nanocrystalline composite powder's phase structure decreased while a t→m phase transformation occurred.Al2O3 nanocrystalline powder and ZrO2-Al2O3 nanocrystalline composite powder were synthesized by aluminum nitrate and citric acid. With a molar ratio of 1:2.5 between nitrate and urea, a pH of 3 in the solution, and an ignition temperature above 300℃, we obtainedα-Al2O3 nanocrystlline powder with a particle size ranging from 30 to 40 nm. For the preparation of ZrO2-Al2O3 nanocrystalline composite powder, the particle size of the powders and the proportion of the m-ZrO2 phase regularly changed along with the increase of the content of A12O3. The inhibition of ZrO2's t→m phase transformation was intensified when the content of Al2O3 increased and there was no longer occurrence of it below 1300℃.
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