Preparation of Zirconia Powder by Hydrogenation
Abstract
Zirconia powder is a kind of important functional related materials and has been widely used in fields such as ceramics and catalysts. With the development of technology, hydrogenation has been included in the research to prepare zirconia powder. As a clean method, hydrogenation reaction has certain advantages in the preparation of zirconia powder, small reaction period and simple operation. This paper provides a review of the current research and development of the preparation of zirconia powder by hydrogenation and its application prospects,which provides reference for the research and development of zirconia powder.
Key words：Zirconia powder；Hydrogenation、Preparation
1 Introduction
Zirconia powder is a kind of important functional related materials which has the characteristics of chemically stability,high temperature resistant,low thermal expansion coefficient and good electrical insulation,etc.It is widely used in petrochemical industry,medical and metalsurgical fields,such as nuclear industry[4],protective coatings[5], catalyst support layers[6], internal combustion engine components[7], automotive catalytic converters[8], medical implants[9] and so on.At present,there are many kinds of technology to prepare zirconia powder,like sol-gel method, precipitation methods and sol-gel combined with other methods.Hydrogenation is also a common method to prepare zirconia powder[10]. With the development of technology, hydrogenation has been included in the research to prepare zirconia powder.
2 Preparation ofZirconia Powder by Hydrogenation
2.1 General Process
Hydrogenation is a chemical reaction in which a compound combines with hydrogen. In the case of zirconia powder, it is the reaction between zirconia and hydrogen. The general process of zirconia powder hydrogenation preparation is shown in Fig1.
Fig.1 General process of Zirconia powder preparation by Hydrogenation
2.2 Referential Factors
2.2.1 Hydrogenation Conditions
The hydrogenation conditions are one important factor to determine the preparativeresultof zirconia powder by hydrogenation. Because hydrogen is a kind of highly reactive gas,the hydrogenation reaction is greatly influenced by the hydrogenation temperature, hydrogen pressure, reaction time, catalysts, solvents and so on[11]. Generally, the hydrogen pressure should in a certain range, not more than 5 MPa, in order to make sure the reaction is completed. The suitable reaction temperature is between 300 and 400°C. And if a catalyst is added, zirconia can start to reaction below 300°C. The reaction time should also be set in a proper time range. If the reaction time is too long, the product will become agglomeration and will be difficult to be separated from the reaction system.
2.2.2 Solvents
At present, the solvents commonly used in the preparation of zirconia powder by hydrogenation are water and alcohols (methanol, ethanol)[12].Different solvents can affect the morphology of the final product, if hydrogenation is conducted in water as solvent, then the morphology of powder is more uniform [13].
2.2.3 Catalysts
The addition of an appropriate catalyst can improve the reaction rate and can also reduce the reaction temperature. The commonly used catalyst is NH4Cl and NH4F,it can speed up the reaction rate and reduce the reaction time[14].
3 Application Prospect
With environmental protection becoming the highest point in energy research and development, the extensive use of hydrogenation has led to zirconia powderhas become a spotlight in the field of preparation. Due to its excellent properties and wide application prospects, zirconia powder prepared by hydrogenation will become a new research direction in the future, and will have a broad application prospect.
4 Conclusion
Hydrogenation is an important method for the preparation of zirconia powder. With the development of technology, hydrogenation has been included in the research to prepare zirconia powder. With superior properties, hydrogenation can reduce reaction temperature and shorten reaction time compared with traditional methods. It has a broad application prospectin the preparation of zirconia powder. However, further research should consider the mechanism of hydrogenation reaction, the influence of catalysts, solvents, hydrogen pressure, reaction temperature and other factors on the reaction system to improve the method of hydrogenation.
