热挤压工艺对Bi_(2)Te_(2.7)Se_(0.3)材料热电性能和力学性能的影响  

Effect of Hot Extrusion Processes on the Thermoelectric and Mechanical Properties of Bi_(2)Te_(2.7)Se_(0.3) Materials

作　　者：李泉 邢通 李小亚[2] 仇鹏飞[2] 史迅[2] LI Quan;XING Tong;LI Xiaoya;QIU Pengfei;SHI Xun(School of Materials and Chemistry,University of Shanghai for Science and Technology,Shanghai 200093,China;State Key Laboratory of High Performance Ceramics and Superfine Microstructure,Shanghai Institute of Ceramics,Chinese Academy of Sciences,Shanghai 200050,China)

机构地区：[1]上海理工大学材料与化学学院,上海200093 [2]中国科学院上海硅酸盐研究所,高性能陶瓷和超微结构国家重点实验室,上海200050

出　　处：《硅酸盐学报》2024年第10期3243-3251,共9页Journal of The Chinese Ceramic Society

基　　金：国家重点研发计划(2023YFB3809400);国家自然科学基金(52202330)。

摘　　要：碲化铋(Bi_(2)Te_(3))基化合物作为室温附近性能最优异的热电材料,在热电制冷及发电技术中已获得广泛商业化应用。目前商业化生产的Bi_(2)Te_(3)基热电材料主要采用区熔法制备,虽然具有优异的热电性能,但材料容易解理,力学性能较差,无法满足微型热电器件的加工需求。本工作探索最佳热挤压工艺参数,采用热挤压技术在不同工艺条件下制备了n型Bi_(2)Te_(2.7)Se_(0.3)热电材料样品,并对样品进行物相分析、热电性能以及力学性能表征。结果表明,在确定的挤压比以及挤压速率下,提高挤压温度有利于减少样品裂纹,而过快的挤压速率则会导致样品断裂,最佳工艺参数为挤压温度400℃以及挤压速率0.05 mm/s。采用最佳工艺参数在不同工艺条件下制备的n型Bi_(2)Te_(2.7)Se_(0.3)样品中,通过放电等离子烧结结合热挤压所制备的样品热电性能最高,在400K时zT值可达到0.83,并且其力学性能显著提升,维氏硬度可达602.5 N/mm^(2),为区熔Bi_(2)Te_(2.7)Se_(0.3)材料的2倍。Bi_(2)Te_(2.7)Se_(0.3)材料的机械加工性能也随之提升,采用封装切割工艺可以加工出最小尺寸达到147μm的微型热电粒子,为后续Bi_(2)Te_(3)基微型热电器件的加工制备提供了材料基础。Introduction Bi_(2)Te_(3)-based alloys are the most well-known thermoelectric materials for room-temperature applications.The existing Bi_(2)Te_(3)-based thermoelectric materials produced commercially are prepared by a zone melting method,resulting in highly oriented materials with high thermoelectric properties.However,the ingots produced by the zone melting method are prone to disintegration due to the weak van der Waals forces between the layers of Te atoms,leading to the poor mechanical properties and the proclivity for fracture during processing and practical applications.It is thus important to improve the mechanical properties and machinability of Bi_(2)Te_(3)-based materials with the excellent thermoelectric properties.This work was to prepare a n-type Bi_(2)Te_(2.7)Se_(0.3) thermoelectric material via spark plasma sintering combined with hot extrusion(SPS+HE).The parameters affacting hot extrusion process and preparation of n-type Bi_(2)Te_(2.7)Se_(0.3) materials under different process conditions were optimized,and the thermoelectric performance and mechanical properties were investigated.In addition,the machinability of the extruded Bi_(2)Te_(2.7)Se_(0.3) material was also analyzed.Methods The commercial zone-melting crystal rods were pulverized and sintered via spark plasma sintering(SPS)at 350℃and 20 MPa for 5 min.The ingot was then put into a hot extrusion mold,and treated at 390-550℃,extrusion speed of 0.05-0.50 mm/s,extrusion ratio of 9:1,and extrusion angle of 30°.Under the determined hot extrusion parameters,n-type Bi_(2)Te_(2.7)Se_(0.3) materials were prepared by different processes,i.e.,the raw materials were ground for 1 h and then sintered by SPS and subsequent hot extrusion(HE);the raw materials were melted at 700℃for 5 h and then cold-pressed(MT),and sintered by subsequent hot extrusion(HE);the raw materials were melted and cold-pressed,followed by annealing and hot extrusion(MT+AN+HE);and the raw materials were ground for 1.5 h and cold-pressed,followed by hot extrusion(BM+HE).The

关 键 词：热电材料 碲化铋 热挤压 热电性能 力学性能 

分 类 号：TG132.24[一般工业技术—材料科学与工程] TN304.2[金属学及工艺—合金]