Slip casting porous silicon nitride for high-temperature radar frequency radomes

IF 2.3 4区材料科学 Q2 MATERIALS SCIENCE, CERAMICS

International Journal of Applied Ceramic Technology Pub Date : 2025-07-21 DOI:10.1111/ijac.70016

Averyonna R Kimery, Matthew A Thompson, Carlos J Martinez, Rodney W Trice

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Abstract

Silicon nitride (Si₃N₄) is a promising candidate for ceramic radar frequency (RF) radomes. In this study, suspensions have been developed to slip cast Si₃N₄ for RF windows utilizing 6 wt.% yttrium oxide (Y₂O₃)-2 wt.% aluminum oxide (Al₂O₃) and 5–15 wt.% ytterbium oxide sintering aids. Suspensions were evaluated via rheology, zeta potential, and casting rate to determine the optimal ball milling time, concentration of polyethylenimine dispersant, and suspension pH for a low viscosity, high stability slip. Choice of sintering aids tailored porosity from 7% to 38% in slip-cast Si₃N₄ components after sintering at 1850°C, where the Y₂O₃–Al₂O₃ system had higher relative density compared with the Yb₂O₃ systems. Extending this work, layered structures of alternating Si₃N₄ compositions and hollow, curved Si₃N₄ radome shapes were also fabricated through slip casting. The layered structures had a graded microstructure and smooth interfaces between Si₃N₄ regions. The radomes were able to be cast and sintered crack-free. Overall, slip casting was demonstrated as a processing pathway to produce porous Si₃N₄ components desirable for RF and high-temperature applications.

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高温雷达频率天线罩用滑移铸造多孔氮化硅

氮化硅（Si3N4）是陶瓷雷达频率（RF）天线罩的有前途的候选者。在这项研究中，利用6 wt.%的氧化钇(Y2O3)-2 wt.%的氧化铝（Al2O3）和5-15 wt.%的氧化钇烧结助剂，开发了用于射频窗口的滑动铸造Si3N4悬浮液。通过对悬浮液的流变性、zeta电位和浇注速率进行评估，以确定最佳的球磨时间、聚乙烯亚胺分散剂的浓度和悬浮液的pH值，以获得低粘度、高稳定性的滑移。在1850°C烧结后，烧结材料的孔隙率从7%降至38%，其中Y2O3-Al2O3体系比Yb2O3体系具有更高的相对密度。在此基础上，通过滑移铸造还制备了交替的Si3N4成分层状结构和中空弯曲的Si3N4天线罩形状。层状结构具有渐变的微观结构和Si3N4区域之间光滑的界面。天线罩可以通过铸造和烧结无裂纹。总体而言，滑移铸造被证明是一种生产射频和高温应用所需的多孔Si3N4组件的工艺途径。

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来源期刊

International Journal of Applied Ceramic Technology 工程技术-材料科学：硅酸盐

CiteScore

3.90

自引率

9.50%

发文量

280

审稿时长

4.5 months

期刊介绍： The International Journal of Applied Ceramic Technology publishes cutting edge applied research and development work focused on commercialization of engineered ceramics, products and processes. The publication also explores the barriers to commercialization, design and testing, environmental health issues, international standardization activities, databases, and cost models. Designed to get high quality information to end-users quickly, the peer process is led by an editorial board of experts from industry, government, and universities. Each issue focuses on a high-interest, high-impact topic plus includes a range of papers detailing applications of ceramics. Papers on all aspects of applied ceramics are welcome including those in the following areas: Nanotechnology applications; Ceramic Armor; Ceramic and Technology for Energy Applications (e.g., Fuel Cells, Batteries, Solar, Thermoelectric, and HT Superconductors); Ceramic Matrix Composites; Functional Materials; Thermal and Environmental Barrier Coatings; Bioceramic Applications; Green Manufacturing; Ceramic Processing; Glass Technology; Fiber optics; Ceramics in Environmental Applications; Ceramics in Electronic, Photonic and Magnetic Applications;