Research On Interfacial Properties Of Thermoelectric Materials/Copper Electrode Based On Soldering Nano-silver Paste

Thermoelectric power generation technology,which can recycle vehicle exhaust could save the engine resources and avoid pollution utmost has attracted worldwide attention.In this paper the interface of functionally gradient thermoelectric power generation devices based on nano-silver paste was investigated.W-Ti was deposited on the copper electrode by DC magnetron sputtering as diffusion barrier and nano-silver paste was considered as soldering paste.After thermal aging test,it is found that the diffusion barrier can work normally uder 350?,however for the case of aging 120 h at 350?,the trace of Cu element was discovered in the nano-silver paste even about 2~3 ?m far away from the diffusion barrier,moreover the same phenomenon occurred when aging 24 h at 400?.The results of shear strength test showed that with the increasing aging temperature and aging time,the junction of diffusion barrier and the nano-silver paste fracture would transform from the nano-silver paste to the junction of diffusion barrier and the nano-silver paste.The change of microstructure and diffusion of different elements in the interface of medium-high temperature thermoelectric materials/diffusion barrier/nano-silver paste was analyzed after thermal cycling test from 250? to 350?,and it showed that the component element of the medium temperature thermoelectric materials would redistribute as self-diffusion,which resulted in the reduce of shear strengh.The shear strengh of AgSbTe2.01/316/nano-silver paste interface decreased immediately when it reached to 300 cycles,however,even after 500 cycles,it was about 10 MPa,which met the requirement of reliability.While the shear strengh of Ag0.8Pb22.5SbTe20/316/ nano-silver paste interface decreased immediately when it reached to 100 cycles,and then declined slowly,it was over 10 MPa when the cycles was 300.Different phenomenon appeared on high temperature thermoelectric materials,whose shear strengh was over 15 MPa and remained stable during themal cycling.After using finite element analogy,thermal management system between 680 K~800 K was designed,whose thermoelectric conversion efficiency and output power can reach 1%,7.76×10-3 W,respectively.