Study On Sintering Process Of Foamed Silver And Its Microstructure And Properties

Silver is a conventional industry catalyst in petrochemical, chemical,pharmaceuticals industry. Foamed silver is a kind of new functional material that has a lot of characteristic such as high porosity, large specific area, good currency and so on.So foamed silver catalyst is a kind of perfect material instead of existing silver catalyst due to its high catalytic activity, good stability and good catalyst selectivity.The orthogonal tests was used to optimize the sintering process of foamed silver according to the influence of sintering temperature and time on tensile strength ,temper, porosity and apparent density. The results show that the appropriate sintering process is that foamed silver is sintering at 770℃for 30 minutes.According to the influence of sintering process on surface morphologies, properties of foamed silver, it is found that crystalline grain grow with the rise of sintering temperature or the extension of sintering time, the rise of sintering temperature is benefit to the straightness of crystal boundary, the extension of sintering time is benefit to smoothing of the surface crystalline grain,the influence of sintering process on porosity and apparent density is insignificant,the temper is increased with the extension of sintering time,the tensile strength and temper increase till the temperature reaches to 770℃,then with the rise of temperature ,the tensile strength is decreaseed a little,while the pemper hold the line.The microstructure and surface morphologies of foamed silver was studied by means of scanning electron microscope(SEM) and optical microscope(OM).The results shows that the foamed silver has the microstructure of triaxialp reticulation,which is dodecahedron with pentagon casement outspreading toward space, the cross section of skeleton has the microstructure of hollow curve-triangle the entire skeleton is made up of triangular tube,there are a lot of dispersal bulges on the surface of the skeleton.The X-ray diffraction(XRD) results show that the foamed silver is face-centered cubic crystal structure. The special surface areas of foamed silver is 0.6~0.8 m2·g-1 from BET method.