Preparation Of Zr₂P₂WO₁₂/Cu Composite Material

Effect of thermal phenomena in scientific research and daily life can not beignored, especially the precision and service life of materials.To solve this problemwe take composite materials into consideration. We can adjust the expansioncoefficient in the guarantee of basic properties of materials, which will effectivelyreduce the influence of the thermal properties on the material properties and servicelife.Negative thermal expansion material Zr2P2WO12has many excellent properties:its negative thermal expansion coefficient（CTE）is relative large; compared withother materials it does not absorb water; in the negative expansion zone there does notexist a transformation. Although its structure is orthorhombic, but it acts as ananisotropic material in powder sintering ceramic, which is similar to a polycrystallinematerial.This paper mainly studies the preparation of Zr2P2WO12/Cu composite material.To get the best result, different methods and conditions were chosen. We useco-precipitation method and sol gel method to make a mixture of the NTE materialprecursor and the salt of Cu.In the preparation of sol-gel method, the components are complicatedly hybrid.There are too many kinds of chemical reaction between the elements, and differenttemperature intervals will have the corresponding chemical reactions process, whichmakes it difficult to understand the specific reaction in the sintering process. We useTG-DSC method to analysis the gel samples, and the XRD method to analysis thesintered products, which will show the reaction process corresponding to eachtemperature. We could divide the process into seven periods: gel softening, moistureand volatile matter overflow, the destruction of gel network, the oxidation of carbon,metal salt reduction, the formation of mesophase, and the formation of Zr2P2WO12.In the co-precipitation method, alcohol was used as the solvent instead of water,and citric acid or tartaric acid was used as the reducing agent. The samples of thismixture were sintering in protective gas environment. In this sintering experiment, thereaction of Zr2P2WO12precursor and the reduction of Cu occurred at the same time. In the wet-chemical period, sedimentation was found better dispersion. And the purityof sample is higher after sintering. Compared with the traditional composite method,the sintered bulk composite materials are more uniform and better compactness.