Filling Sintering Method To Prepare Porous Copper Alloy And Its Performance Research

The Porous metal has some properties which are not available for dense metals due to its special pore structure.So it has gradually become a widely concerned structural and functional material,and has been widely applied in many areas.At present,the preparation and characterization of porous metals have made great progress over the past 70 years.However,there are still few attention has been paid to the preparation of porous alloys metals by filling sintering method.Therefore,the high energy ball milling(MA)and the lost carbonate sintering method(LCS)were combined to prepare the porous Cu-Sn and Cu-Cr alloys in this article.The preparation of porous copper was studied firstly before the preparation of porous copper alloy in order to determined the reasonable process parameters.Then,the composite powder was treated by ball milling in order to get better performance.In addition,the powder particle size distribution test,performance test,morphology observation,XRD analysis were carried out to research the change of powder at different milling time and selected the appropriate composite powder for sintering.The porous copper alloy with different alloy contents was prepared according to the appropriate parameters which adjusted from the initial process parameters.Then the characterization of the porous copper alloy was carried out to study the effect of alloy content on the preparation of porous copper alloy.The results are as follows:(1)The decomposition temperature of K2CO3 is about 880℃.The appropriate sintering temperature is between 900℃ and 975℃ when use the K2CO3 as a space holder.And high temperature will make the body melt collapse.The reasonable pressure is between 50MPa and 100MPa,the K2CO3 powder will break when the pressure reach 200MPa and cracks on the surface of the samples were produced when the pressure is 150MPa.The heat preservation time between 1 and 3h has little effect on the porosity of the sample.It shows that after sintering 1h,the powder has basically completed the stage of bond and growth.(2)When the milling time is 20min,the Cu-Sn powder have good fluidity,the bulk density is the highest,the average particle size is minimized and no obviously agglomerated particles.Besides,some Sn powders are covered by Cu realize a simple composite and the powder just contain Cu phase and Sn phase.However,when the milling time is 30～40min,the particle size increases and Cu6Sn5 phase appears.Through the analysis of Cu-Cr powder after milling test.We can find that when the milling time is 6h,the powder has good flowability and apparent density.Moreover,the large Cr powder particles have been obviously broken,the average particle size of the powder is small.Some Cr are found to be dissolved in Cu by XRD analysis.(3)The porous Cu-Sn alloy was successfully prepared by LCS and the final sintering temperature 900℃,the hole forming is better and the distribution is uniform.The Sn element is evenly distributed in the matrix,and no apparent segregation is found.With the increase of Sn addition,the porosity of porous copper alloy decreases,but the difference is not very large.The porous copper alloy contains Cu phase,Cu3Sn phase,Cu6Sn5 phase and Cu31Sn8 phase.The addition of Sn makes the compression curve move up compared with pure copper,and its compressive property becomes stronger.At the same time,with the increase of Sn content,the greater the slope of the elastic phase,the stronger the ability of its anti plastic deformation.However,the addition of Sn does not have much effect on the strain range distribution in each phase of the curve,indicating that its ductility have no much changed.The porous Cu-Cr alloy with Cr content of 0.2%～0.8%was successfully prepared at 975 ℃.It has good appearance and uniform distribution and no collapse.It can be found that the content of Cr has little effect on porosity and the size of pore size.The matrix only contains the Cu phase and the Cr phase,and the alloy phase is not formed.In addition,the Cr phase is evenly distributed in the matrix.Some of them are undissolved in Cu and others are precipitated from Cu during cooling.The porous Cu-Cr alloy with Cr content of 0.2%～0.8%was successfully prepared at 975℃.It has good appearance and uniform distribution and no collapse.It can be found that the content of Cr has little effect on porosity and the size of pore size.The matrix only contains the Cu phase and the Cr phase,and the alloy phase is not formed.In addition,the Cr phase is evenly distributed in the matrix.Some of them are undissolved in Cu and others are precipitated from Cu during cooling.When the content of Cr is between 0.4%～0.8%can improve the compression performance of the porous copper,but reduced its ductility.The compression ability is lower than that of the porous pure copper when the content is 0.2%.