Preparation And Properties Of Zn/Si/（Zn,Sn,Mn）NMn₃ Composites With Low Thermal Expansion

In the family of negative thermal expansion materials,antiperovskite manganese-based nitride(chemical formula is ANMn3,where A is partial transition metal or main group element)has attracted extensive attention due to its adjustable isotropic negative thermal expansion effect,appropriate electrical conductivity,thermal conductivity and mechanical properties.Metal/ANMn3 composites exhibit excellent thermal properties,such as low thermal expansion and high thermal conductivity,and show great potential for applications in electronic packaging,mechanical systems and structural design.However,the research progress of metal/ANMn3 composites is relatively slow.ANMn3 were mainly used to reduce the expansion coefficient of common metals(such as Cu,Al and Ti)in the existing research.However,due to the melting point of these metals is close to or even higher than the phase formation temperature of ANMn3,it is difficult to obtain a better composite interface,which greatly limits the practical application of these composites.Therefore,it is still a challenge to prepare metal/ANMn3 composites with good comprehensive properties and interfaces.In this paper,low-melting and high thermal conductivity metal Zn was used as adhesive,ANMn3-type compound(Zn,Sn,Mn)NMn3 with cheap raw materials was used as positive expansion inhibitor,and the following works were done about Zn-based(Zn,Sn,Mn)NMn3-type composites by using the low-melting metal bonding method:1.Zn/Zn0.75Sn0.2Mn0.05NMn3 composites with different volume ratios were prepared.The experimental results showed that the low-melting bonding method controlled the interfacial reaction effectively,and the Zn0.75Sn0.2Mn0.0sNMn3 effectively repressed the positive expansion of zinc.When the concentration of Zn0.75Sn0.2Mn0.05NMn3 is 40 vol%,the composite showed near zero expansion effect(linear expansion coefficient αL=1.8 ppm/K,253-304 K),high thermal conductivity(46 W/K m)and high compressive strength(241 MPa)at room temperature.However,this kind of composites still possessed the large coefficient of thermal expansion at high and low temperatures,which was not conducive to its practical application.2.On the basis of the works about two-phase compositing,Si with low expansion and high thermal conductivity was added as the third phase.In order to obtain low expansion above the room temperature,Zn0.65Sn0.3Mn0.05NMn3,whose negative expansion temperature was above room temperature,was selected to prepare three-phase composites Zn/Si/Zn0.65Sn0.3Mn0.05NMn3 with different volume ratios.The experimental results showed that the addition of Si successfully reduced the thermal expansion.When the volume ratio of Zn,Si and Zn0.65Sn0.3Mn0.05NMn3 was 0.28:0.55:0.17,the composite showed low thermal expansion(αL=6.1 ppm/K,165-360 K),high thermal conductivity(52 W/K m)and compressive strength(225 MPa)at room temperature.At the same time,these composites showed potential application value in the field of medium and low power consumption electronic thermal management.