Hydrothermal Synthesis of Copper Zirconium Phosphate Hydrate [Cu(OH)(2)Zr(HPO4)(2)center dot 2H(2)O] and an Investigation of its Lubrication Properties in Grease

Abstract

Copper zirconium phosphate hydrate (Cu(OH)(2)Zr(HPO4)2 center dot 2H(2)O, hereafter referred to as Cu-alpha-ZrP) with high crystallinity was directly synthesized in a NaF-CuO-ZrO-P2O5-H2O system under hydrothermal conditions. The copper ion was confirmed to be an exchangeable cation in the Cu-alpha-ZrP through elemental analysis and a proton ion exchange process. The crystal structure of the Cu-alpha-ZrP was determined ab initio by using X-ray powder diffraction data. In the structure, the CuO6 octahedron would be located in an exchangeable atom position. Moreover, Cu-alpha-ZrP was evaluated as an additive in grease in a four ball test. The maximum nonseizure load (P-B, representing the load-carrying capacity) of the base grease containing Cu-alpha-ZrP was increased from 353 to 1235 N. The excellent load-carrying capacity may be explained by the easier adherence of the material to the worn surface forming a tight protective film.