无压两步烧结法制备超细晶(Ce_(0.2)Nd_(0.2)Sm_(0.2)Gd_(0.2)Y_(0.2))_(2)Zr_(2)O_(7)高熵陶瓷  

Preparation of Ultrafine-Grained(Ce_(0.2)Nd_(0.2)Sm_(0.2)Gd_(0.2)Y_(0.2))_(2)Zr_(2)O_(7)High-Entropy Ceramics via Pressureless Two-Step Sintering

作　　者：耿畅 李玉 李琳琳 张帅 娄程广 李汶金 苏兴华[1] GENG Chang;LI Yu;LI Linlin;ZHANG Shuai;LOU Chengguang;LI Wenjing;SU Xinghua(School of Materials Science and Engineering,Chang’an University,Xi’an 710061,China)

机构地区：[1]长安大学材料科学与工程学院,西安710061

出　　处：《硅酸盐学报》2024年第9期2915-2924,共10页Journal of The Chinese Ceramic Society

基　　金：陕西省重点研发项目(2021GY-250);长安大学研究生科研创新实践项目(300103723016)。

摘　　要：超细晶高熵陶瓷具有优异的机械及物理化学性能。然而,由于烧结后期晶粒的快速长大,使得超细晶高熵陶瓷的常规无压烧结制备非常困难。采用两步烧结法,克服了无压烧结致密化过程中晶粒的快速长大,成功制备了理论密度为99.0%、晶粒尺寸为162 nm的(Ce_(0.2)Nd_(0.2)Sm_(0.2)Gd_(0.2)Y_(0.2))_(2)Zr_(2)O_(7)高熵陶瓷。与常规无压烧结方法相比,两步烧结所制备的样品不仅具有更细小的晶粒尺寸,还具有更均匀的微观结构,这使其具有优良的力学性能,其硬度达到12.5 GPa,断裂韧性达到2.4 MPa·m^(1/2)。无压两步烧结法解决了传统无压烧结方法难以制备超细晶高熵陶瓷的困难,将有助于探索超细晶高熵陶瓷的物理化学性能,并有助于推动超细晶高熵陶瓷的广泛应用。Introduction High-entropy zirconate ceramics(HEZCs)have been studied extensively in recent years for the potential applications in thermal barrier coatings and high-level nuclear waste immobilization.While these HEZCs have the issue of poor toughness,which impedes their applications.The toughness of HEZCs can be improved by decreasing its grain size.While preparation of ultrafine-grained or nanocrystalline HEZCs is a challenge because the rapid grain growth inevitably occurred at high temperature densification process(typically above 1500℃).In this work,the challenge of preparing dense ultrafine-grained high-entropy ceramics through conventional pressureless sintering process was addressed via a simple two-step sintering method.Ultrafine-grained(Ce_(0.2)Nd_(0.2)Sm_(0.2)Gd_(0.2)Y_(0.2))_(2)Zr_(2)O_(7)high-entropy zirconate with 99.0%theoretical density and 162 nm grain size was fabricated.Compared to the conventional method,two-step sintering provided the high-entropy zirconate with finer grain size and better microstructural uniformity,and excellent comprehensive mechanical properties including high hardness of 12.5 GPa and high fracture toughness of 2.4 MPa·m^(1/2).This work could help to understand the sintering kinetics of HEZCs,and also supplied a guidance to prepare the ultrafine-grained or nanocrystalline HEZCs by pressureless sintering method.Methods The starting high-entropy(Ce_(0.2)Nd_(0.2)Sm_(0.2)Gd_(0.2)Y_(0.2))_(2)Zr_(2)O_(7)ceramic powders were prepared via a polyacrylamide gel method.Analytical grade rare earth nitrate hexahydrates RE(NO_(3))_(3)⋅6H_(2)O(RE=Ce,Nd,Sm,Gd,Y)with a purity of 99.9%,zirconium oxychloride(ZrOCl_(2)⋅8H_(2)O,99.0%purity),acrylamide(AM,C_(3)H_(5)NO,99.0%purity),N-N’-methylene-bis-acrylamide(MBAM,C_(7)H_(10)N_(2)O_(2),99.0%purity)and ammonium persulfate((NH_(4))_(2)S_(2)O_(8),99.0%purity)were used as starting materials,which were purchased from Macklin Chemical(Shanghai,China).First,RE(NO_(3))_(3)⋅6H_(2)O and ZrOCl_(2)⋅8H_(2)O were mixed in distilled water accordi

关 键 词：高熵陶瓷 锆酸盐 超细晶 两步烧结 力学性能 

分 类 号：TB32[一般工业技术—材料科学与工程]