硅酸盐学报

ZnO多孔陶瓷的近净尺寸制备及机理

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夏尊 ¹ , 戎烨东 ² , 李昊 ² , 董晔 ² , 于洪波 ¹ , 王修慧 ¹ , 杨金龙 ¹^,²

硅酸盐学报 | 研究论文 2024,52(9): 2950-2958

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硅酸盐学报 |研究论文 2024 , 52 (9) : 2950 -2958

ZnO多孔陶瓷的近净尺寸制备及机理

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夏尊¹, 戎烨东², 李昊², 董晔², 于洪波¹, 王修慧¹, 杨金龙¹^,²

作者信息

^1．大连交通大学材料科学与工程学院，辽宁省教育厅无机超细粉体制备及应用重点实验室，辽宁大连 116028

^2．清华大学材料学院，新型陶瓷与精细工艺国家重点实验室，北京 100084

通讯作者:

于洪波（1977-），女，博士，副教授；

杨金龙（1966-），男，博士，教授。

作者简介:

夏尊（1996-），男，博士研究生。

Preparation and Mechanism of Near Net Size ZnO Porous Ceramics

Zun XIA¹, Yedong RONG², Hao LI², Ye DONG², Hongbo YU¹, Xiuhui WANG¹, Jinlong YANG¹^,²

Affiliations

^1.Key Lab of Preparation and Application of Inorganic Ultrafine Powder, Liaoning Provincial Department of Education, School of Materials Science and Engineering, Dalian Jiaotong University, Dalian 116028, Liaoning, China

^2.State Key Lab of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China

Corresponding Author:

YU Hongbo (1977-), female, Ph.D., Associate Professor. E-mail: yhb961@163.com;

YANG Jinlong (1966-), male, Ph.D., Professor. jlyang@mail.tsinghua.edu.cn

XIA Zun (1996-), male, Doctoral candidate. E-mail: zmj86644621@126.com

出版时间: 2024-09-20 doi: 10.14062/j.issn.0454-5648.20230975

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摘要

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多孔陶瓷在烧结过程中会伴随着显著的收缩，导致变形或开裂，实现多孔陶瓷的近净尺寸制备是该领域新的发展方向。本研究以氧化锌与球形锌粉为原料采用干压成型工艺制备氧化锌多孔陶瓷，该过程不使用任何有机造孔剂，材料内部的气孔来自锌与氧之间的Kirkendall效应。由于锌、氧原子扩散速率的差异，锌颗粒氧化空心化产生的膨胀有效地抵消了整个烧结过程中产生的收缩，得到了近净尺寸的氧化锌多孔陶瓷。研究了金属锌粉的添加量以及颗粒尺寸对材料性能以及微观结构的影响。结果表明：多孔陶瓷的烧结线收缩率强烈依赖于金属锌粉的颗粒尺寸，当金属锌粉［50%（体积分数）］的颗粒尺寸为10 μm时，多孔陶瓷的烧结线收缩率仅为-0.36%。

关键词

多孔陶瓷 / 氧化锌 / Kirkendall效应 / 氧化空心化 / 收缩率

Abstract

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Introduction

During the sintering process, porous ceramics undergo significant shrinkage with volume changes even half. Such volumetric alterations may lead to materials cracking or deformation, severely affecting the yield of the prepared products. Researchers have proposed several methods such as adjusting the sintering temperature, utilizing reactions and expansion phases during the sintering process to address these issues. The most commonly method was to utilize the expansion characteristics of the materials themselves to solve the shrinkage problem. However, this method requires complex raw materials and lacks universality. Recently, our group proposed an in-situ hollow sphere method with the addition of spherical metal powders, successfully preparing porous ceramics without sintering shrinkage. The main theoretical support for this process is the Kirkendall effect that occurs during two-phase diffusion. When metal spherical particles are oxidized, the difference in diffusion rates forms a hollow structure, effectively offsetting the shrinkage caused by sintering. In this work, hollow zinc oxide particles were successfully prepared using the direct oxidation of metallic zinc powders and applied in the preparation of zinc oxide porous ceramics. During the oxidation process of metallic zinc powder, its addition amount, particle size, and their effects on the properties and microstructure of porous ceramics were investigated. The relationship between the pore size of porous ceramics and the particle size of metallic zinc particles was analyzed. This study could broad the application scenarios of this process and hollow zinc oxide particles.

Methods

Firstly, zinc oxide powder and metallic zinc powder with different particle size were thoroughly ground and mixed in a grinding bowl according to a certain ratio (the volume percentage of metallic zinc powder to zinc oxide powder). Subsequently, a 5% PVA aqueous solution (50 g/L) was added to the total mass of powder as a binder, then stired further until the raw powders and binder were uniformly mixed. Secondly, the mixture was poured into molds for dry pressing at a pressure of 5 MPa for 2 min. Finally, the samples were demolded and subjected to oxidation and sintering with a rate of 1 ℃·min^-1 and a holding time of 2 h. The linear shrinkage were calculated by measuring the changes in diameter of samples before and after sintering. The volume density and apparent porosity of samples were determined using the Archimedes' displacement method, and relative density calculated as the measured volume density divided by the theoretical density of zinc oxide (5.6 g·cm^-3). Weight changes, as well as endothermic and exothermic effects during heating were measured using a thermal analyzer. The morphology of the samples was observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). X-ray diffraction (XRD) was employed to analyze the phase composition of the samples. The three-point bending strength of the samples was tested using an electronic universal testing machine, with a span of 30 mm, a crosshead speed of 0.5 mm·min^-1, and sample dimensions of 3 mm × 4 mm, ensuring the length exceeded the span.

Results and discussion

From TG-DTA analysis, it can be observed that the oxidation process of metallic zinc powder can be divided into three stages: a low-speed oxidation stage before 400 ℃, a high-speed oxidation stage from 400 ℃ to 900 ℃, and a complete oxidation stage after 900 ℃. However, when varied the particle size of metallic zinc powders, XRD results revealed that some unoxidized metallic zinc remained in the samples containing 1μm metallic zinc powder, being due to the relationship between the particle size of metallic zinc and zinc oxide; Regarding the shrinkage rate, when amount of added metallic zinc powder increased and the particle size enlarged, the reduction in the linear shrinkage of the porous ceramic during sintering process became notably apparent, suggesting that the shrinkage rate of samples were mainly dependent on the size of the metallic particles. When size of particle was 10 μm and addition amount equaled to 50%, the linear shrinkage rate of the sample was only -0.36%, with a porosity of 25%, achieving the near net-size preparation of the sample. As for the microscopic structure, it can be observed that distinct pore structures existed inside the material, and the pores size of was closely related to the particle size of the added metallic zinc powder. In TEM analysis, it can be clearly seen that particle size of metallic zinc affected the temperature at which metal zinc begins to hollow, and the radius of Kirkendall pores formed inside the material after the oxidation of metallic zinc was 0.54 to 0.99 times the initial radius of metallic zinc.

Conclusions

The in-situ hollow sphere method allowed for the preparation of near-net-size zinc oxide porous ceramics, offering a simple and efficient process without the addition for any organic pore-forming agents. When temperatures exceeded it's melting point, metallic zinc powder undergone vigorous oxidation, typically concluding around 900 ℃. The linear shrinkage of the sintered zinc oxide porous ceramics was closely related to the amount and particle size of added metallic zinc; higher amounts and larger particle sizes of added metallic zinc powders resulted in a lower linear shrinkage rate, potentially leading to negative shrinkage (expansion). After computational analysis, it was determined that the pores formed in the porous ceramics were smaller than the particle size of metallic zinc powder, consistent with the Kirkendall effect. The pore diameter was approximately 0.54 to 0.99 times the initial spherical metallic zinc particle size.

Key words

porous ceramics / zinc oxide / Kirkendall effect / oxidation hollowing / shrinkage rate

引用本文

夏尊, 戎烨东, 李昊, 董晔, 于洪波, 王修慧, 杨金龙. ZnO多孔陶瓷的近净尺寸制备及机理. 硅酸盐学报, 2024 , 52 (9) : 2950 -2958 . DOI: 10.14062/j.issn.0454-5648.20230975

Zun XIA, Yedong RONG, Hao LI, Ye DONG, Hongbo YU, Xiuhui WANG, Jinlong YANG. Preparation and Mechanism of Near Net Size ZnO Porous Ceramics[J]. Journal of the Chinese Ceramic Society, 2024 , 52 (9) : 2950 -2958 . DOI: 10.14062/j.issn.0454-5648.20230975

基金

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国家自然科学基金(52072202)

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2024年第52卷第9期

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文章信息

doi: 10.14062/j.issn.0454-5648.20230975

接收时间：2023-12-09
首发时间：2026-10-22
出版时间：2024-09-20

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收稿日期：2023-12-09
修回日期：2024-01-10

基金

国家自然科学基金(52072202)

作者信息

^1．大连交通大学材料科学与工程学院，辽宁省教育厅无机超细粉体制备及应用重点实验室，辽宁大连 116028

^2．清华大学材料学院，新型陶瓷与精细工艺国家重点实验室，北京 100084

通讯作者:

于洪波（1977-），女，博士，副教授；

杨金龙（1966-），男，博士，教授。

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https://castjournals.cast.org.cn/joweb/gsyxb/CN/10.14062/j.issn.0454-5648.20230975

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2种不同金属材料的力学参数

科 Family	属数 Number of genus	种数 Number of species	占总种数比例 Percentage of total species (%)	属 Genus	种数 Number of species	占总种数比例 Percentage of total species (%)
鹅膏菌科Amanitaceae	2	11	5.26	鹅膏菌属 Amanita	10	4.78
小菇科 Mycenaceae	2	12	5.74	丝盖伞属 Inocybe	5	2.39
多孔菌科 Polyporaceae	8	14	6.70	蜡蘑属 Laccaria	5	2.39
红菇科 Russulaceae	3	23	11.00	小皮伞属 Marasmius	6	2.87
				小菇属 Mycena	11	5.26
				光柄菇属 Pluteus	5	2.39
				红菇属 Russula	17	8.13
				栓菌属 Trametes	5	2.39

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