| With excelle nt therma l and electric ity behaviorm, high strength and hardness,W-Cu composites ha ve been used wide ly in the fie lds of electrical materials, electron,ordnance ind ustry a nd spaceflight. Alo ng with the further progress on the electronicindustria l, the need of high performance W-Cu composite is more and more urge ntly.However, because of the mutua l inso lub ility between W and Cu, it is difficult to getdens ified W-Cu composites by traditio nal methods. In this dissertation, Solge l andspray drying are used to prepare ultra fine W-Cu composite powders. And thenproduce the W/Cu compos ite materia l by C ompression Mo ld ing and Powder InjectionMolding sintering method．The powder and the sintered composite ha ve been stud iedby means of SEM、 EDX、Che mica l compositio n and Lsser instrume nt for therma lconductio n, and discuss io n of parameters,which can affect the proprieties andmicrostruct ure of W/Cu composites, the fo llowing ma in results can be obtained:Firstly, the series of W/Cu ultra fine composite powders were synthes ized bysol-spray drying, calc inatio n and subsequent hydroge n reductio n process withreactio n of a mmonium paratungstate and copper nitrate. Through comparativeanalys is, a better craft is: copper nitrate5.44g, ammonium paratungstate18.38g, citricac id3.50g, deio nized water30ml, and then mix the m under90℃in a beaker until itchange to gel, and then dry it by spray drying tower, the collected precursor powerwere calc ined under600℃with a furnace in the a ir, and reduction it under800℃atlast. The morpho logy of the powder on the scanning e lectron microscope, found thatthe powder has the following characteristics: its shape present spherica l; the partic ledia meter were under1um; the W and Cu phase distributes ho mogeneous ly.Secondly, the series powder were mo lded to gree n parts by micro-isostatic press,and the n sintered under different temperature. The dens ity of the sintered compactswas measured using the Archimedes method. The microstructure of sintered body wasobserved by scanning electron microscope(SEM). The phys ical and electrica lproperties of the obtained W-Cu co mposites were also tested. It was found that: thepowders’ Maximum pressure mo lding is350MPa; the best sintering temperature:W-10Cu is1350℃, W-15Cu is1350℃, W-20Cu is1200℃, W-25Cu is1200℃,W-30Cu is1150℃, W-60Cu is1120℃, the relative dens ity reach almost99%, and theW partic les and Cu phase distributes homo geneous ly in the parts; The electrica l conductivity of thes intered bodies increased with the copper content and the relativeincrease of the dens ity, but the Rockwell hardness of the sintered bodies reduced withthe copper content.Third ly, For develop ing W-Cu therma l mana geme nt co mponents in comp lexshapes, MIM process has been tested by using the W-10Cu ultra fine compositepowder. The poor flowability o f the powder leads to a low critica l solid loading as47vol.%with21N·m of Torque for MIM feedstock. However, experime nts based on thefeedstock with solid load ing of45vol.%have been successfully carried out and nodefects are fo und in injectio n and debind ing stages,and the best sintered temperatureis1400℃, The re lative density of s intered parts reaches99%and no Cu is extruded tothe surface of the parts during s intering.Lastly, the thermal properties、 conductivity、 Rockwell hardness and themicrostructure of the mold pressing parts、MIM parts and the Cu infiltration partswere studied. It found that: the re lative density of the MIM parts(99.3%) is a littermore than the mo ld pressing parts(98.9%).M icrostructures of the MIM parts us ingW-10Cu ultra fine composite powder are more homoge neous than those of the moldpressing parts and Cu infiltrated parts. Due to more ho mogeneous microstructure andfiner grain size, therma l、 mecha nical and electrical properties of the W-10Cu MIMparts are close or better than those made by Cu infiltration. |
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