Study On The Preparation And Process Of Nanoprous Platinum Based Metallic Materials By Dealloying

Nanoporous metallic materials have nanoscale pores and ligaments,both of the characteristics and excellent properties of both nanoscale and metal materials,which are several orders of magnitude higher than those of other materials.Therefore,it has considerable application value in optics,chemistry,physics and so on,and has been widely used in the fields of sensing,catalysis,excitation and so on,and has achieved considerable achievements.Then the preparation of nano porous metal materials is also very important.Dealloying has been paid more and more attention by researchers in the long period of preparation process development.In this work,we successfully prepared precursor sheets by melting,suction casting and rolling with a thickness of millimeter level.Cu99.99Pt0.01,CU99.9Pt0.1,Cu99Pt1,Cu98Pt2,Ni99Pt1(at.%)precursors were prepared.Then the precursor alloy were placed in dilute nitric acid for Pt-based nanoporous materials by dealloying.The macrostructure of the corrosion products is basically consistent with the precursor alloy,in other words,the basic flake shape can be maintained.The precursors and dealloying products were characterized by X ray diffraction,scanning electron microscope and energy dispersive spectrometer.The effects of precursor alloy composition,solution concentration and thickness of the precursor sheets on the dealloying process and nanoporous structure were systematically investigated.The result show that the Cu-Pt series precursor alloy sheets consist of pure copper phase,and Pt exists in Cu lattice in the form of solid solution.Ni-Pt precursor alloy sheets consist of pure nickel phase,and Pt also exists in Ni lattice as solid solution.Other Cu-Pt precursor(except Cu9.99Pt0.01)can be dealloyed completely in acidic solution of low concentration to make PtCu nanoporous materials.The ability of corrosion products to maintain macrostructure is becoming better with the increase of Pt content in Cu-Pt precursor alloys.The size of ligaments of nanoporous PtCu materials is gradually narrowing,and the nanoporous materials with different microstructure are obtained.It is obvious that the composition and phase composition of the precursor alloys have a significant effect on the dealloying process and nanoporous structure.For Ni99Pt1 precursor,it was found that the precursor alloy sheet shape was more and more difficult to maintain after dealloying when the concentration of the solution increased.The microstructure of the samples also has great differences.The nanoporous PtNi metallic materials with ligament size refinement and no obvious micro cracks can be obtained by choosing suitable solution.When we adjusted the thickness of Ni99Pt1 precursor alloy sheet,we could get the corrosion products with little difference in macrostructure before and after dealloying,but the microstructure and ligament size changed with the thickness of the precursor alloy sheet,which indicates that the thickness of the precursor alloy sheet has a significant influence on the dealloying process.To investigate the dealloying process of Zr99Pt,(at.%)alloy and compare with Cu-Pt,Ni-Pt dealloys,we found that the microstructure of Zr99Pt1 corrosion production is characterized by a typical double continuous pattern,consisting of three dimensional islands/channel structure Our present findings show that the composition and proportion of precursor alloys,the acid solution concentration and the thickness of the precursor alloy sheet are the important factors affecting dealloying.The nanoporous macrostructure and microstructure are regulated by these factors,The morphology and size are maintained before and after dealloying on a macro level,and the ligament/channel structure is refined.Finally the nanoporous materials without micro cracks can be fabricated.