【作者】 张扬；

【导师】 于万里；

【作者基本信息】 燕山大学 ， 材料物理与化学， 2022， 硕士

【摘要】 高熵陶瓷源自于高熵合金,随后又扩展出多种类型,高熵氧化物陶瓷则是其中的一种。高熵氧化物陶瓷又称为熵稳定的氧化物,是一种新型的功能材料,自提出以来就引起了广泛的关注。最初的（Mg Co Ni Cu Zn）O系高熵氧化物陶瓷是单相岩盐结构,随后出现了萤石结构、钙钛矿结构和尖晶石结构的高熵氧化物陶瓷。不同的结构会给这类高熵氧化物陶瓷材料带来不同的性能,从而拓宽关于它的研究思路和应用前景。本文选择MgO、CoO、NiO、ZnO和Li₂CO₃的组合制备高熵氧化物陶瓷,利用刚玉球磨罐与氧化锆磨球的组合,按照1:1:1:1:0.35的摩尔比对原料粉末进行细化混合。随后将原料粉末预压成型,采用放电等离子烧结技术制备（CoNiMgZn）_xLi_1-xO高熵氧化物陶瓷,研究了不同制备工艺（细化混合时间、烧结温度、保温时间）对其显微结构的影响。并根据理论计算了高熵氧化物陶瓷的构型熵,得到了关于碳酸锂的添加范围（0.15-0.35 mol）,随后采用优化之后的烧结参数均制备出了单相岩盐结构的高熵氧化物陶瓷。随后运用XRD、SEM、EDS能谱仪以及拉曼光谱对其进行表征分析。通过对（CoNiMgZn）_xLi_1-xO高熵氧化物陶瓷的物相和微观结构的分析,发现（CoNiMgZn）_xLi_1-xO高熵氧化物陶瓷的形成是一个自扩散和互扩散的过程。其中,具有岩盐结构的金属氧化物率先相互扩散形成单相,随后其他结构的金属氧化物扩散并进入上述结构,并最终形成单相的岩盐结构。另外,断面的微观结构展示出了高熵氧化物陶瓷的主要断裂形式是沿晶断裂为主,有少部分出现穿晶断裂。根据对（CoNiMgZn）_xLi_1-xO高熵氧化物陶瓷的性能测试,发现细化混合20 h的高熵氧化物陶瓷粉末在烧结压力为40 MPa、1100℃的烧结温度下保温10 min,所得的样品的致密度为96.8%,其显微硬度达到了最大值594±5 HV。同时利用电化学工作站还发现（CoNiMgZn）_xLi_1-xO高熵氧化物陶瓷具有一定的电化学性能,为之后的研究提供了基础。更多还原

【Abstract】 High-entropy ceramics originated from high-entropy alloys,then extended into various types,and high-entropy oxide ceramics are one of them.High-entropy oxide ceramics,also known as entropy-stabilized oxides,are a new functional material that has attracted widespread attention since they are proposed.The original（Mg Co Ni Cu Zn）O-based high-entropy oxide ceramics were single-phase rock-salt structures,followed by fluorite-structured,perovskite-structured,and spinel-structured high-entropy oxide ceramics.Different structures brought different properties to these high-entropy oxide ceramic materials and broadened their research ideas and application prospects.In this paper,MgO,CoO,NiO,ZnO,and Li₂CO₃ were selected to prepare high-entropy oxide ceramics.The raw material powder with the molar ratio of 1:1:1:1:0.35 was mixed by a corundum ball mill and zirconia balls.Then the composite powder was pre-pressed and sintered rapidly to prepare the（CoNiMgZn）_xLi_1-xO high-entropy oxide ceramics by spark plasma sintering technology.The effect of different sintering parameters（refinement mixing time,sintering temperature,holding time）on the microstructure of the high-entropy oxide ceramics was investigated.The conformational entropy of the high-entropy oxide ceramics was calculated according to the theory,and the content range of lithium carbonate（0.15-0.35 mol）was obtained.Moreover,then these high-entropy oxide ceramics with single-phase rock salt structures were prepared using the optimized sintering parameters.High-entropy ceramics were studied using XRD,SEM,EDS and Raman spectroscopy,then their properties were tested and analyzed.By analyzing the phase composition and microstructure of the prepared（CoNiMgZn）_xLi_1-xO high-entropy oxide ceramics,it was found that the formation of（CoNiMgZn）_xLi_1-xO high-entropy oxide ceramics was a process of self-diffusion and interdiffusion.Metal oxides with the rock salt structure mutually diffused into each other to form a single-phase structure,and then metal oxides with other structures diffused into the single-phase structure.Eventually,a single-phase rock salt structure was formed.In addition,the fracture morphology indicates that the main fracture form of the high-entropy oxide ceramics was an inter-granular fracture,with a small number of trans-granular fractures.According to the performance test of（CoNiMgZn）_xLi_1-xO high-entropy oxide ceramics,it was found that the high-entropy oxide ceramic which was mixed for 20 h and was sintered at 1100℃for 10 min with 40 MPa,obtained the highest relative density of 96.8%and its micro-hardness reached the maximum 594±5 HV.At the same time,the（CoNiMgZn）_xLi_1-xO high-entropy oxide ceramics were found to have certain electrochemical properties,which provids the basis for the subsequent studies.更多还原