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Structure, Properties, and Oxidation Resistance of Prospective HfB 2 –SiC Based Ceramics
Russian Journal of Non-Ferrous Metals ( IF 0.8 ) Pub Date : 2020-12-28 , DOI: 10.3103/s1067821220060164
Yu. S. Pogozhev , A. Yu. Potanin , S. I. Rupasov , E. A. Levashov , V. A. Volkova , V. P. Tashev , A. N. Timofeev

Abstract

This work is devoted to the fabrication of heterophase powdered and sintered ceramics based on the hafnium diboride and silicon carbide by means of self-propagating high-temperature synthesis (SHS) and hot pressing (HP). The structure of SHS-powders consists of hafnium diboride grains and agglomerated polyhedral 2–6 μm silicon carbide grains. The produced composite powders are characterized by an average size of ~10 μm and maximum size of 30 μm. The phase composition of the synthesized powders and sintered ceramics are identical. The sintered ceramic is characterized by a high degree of structural and chemical uniformity, a residual porosity of 3.8%, a hardness of 19.8 ± 0.4 GPa, strength of 597 ± 59 MPa, and fracture toughness of 8.8 ± 0.4 MPa m1/2. Plasma torch tests (PTTs) are carried out to determine oxidation resistance under the influence of high-enthalpy gas flow. The phase composition and microstructure of the surface of the sample after testing are investigated. HP ceramics demonstrated outstanding resistance towards oxidation in a high-enthalpy plasma torch at 2150°С and heat flow of 5.6 MW/m2 for 300 s. During plasma torch testing, a dense protective oxide layer 30–40 μm thick is formed on the surface of HfB2–SiC ceramic. The layer consists of an HfO2 hull filled with amorphous borosilicate glass SiO2–B2O3. From the composite HfB2–SiC SHS powder, by hot pressing, experimental samples of model bushings of the combustion chamber of a low thrust liquid rocket engine are designed to conduct PTTs in realistic operating conditions.



中文翻译:

预期的HfB 2 -SiC基陶瓷的结构,性能和抗氧化性

摘要

这项工作致力于通过自蔓延高温合成(SHS)和热压(HP)的方法,制造基于二硼化and和碳化硅的异相粉末和烧结陶瓷。SHS粉末的结构由二硼化ha晶粒和2-6 µm的聚结多面体碳化硅晶粒组成。所生产的复合粉末的特征是平均粒径约为10微米,最大粒径为30微米。合成粉末和烧结陶瓷的相组成相同。该烧结陶瓷的特征在于高度的结构和化学均匀性,3.8%的残余孔隙率,19.8±0.4GPa的硬度,597±59MPa的强度和8.8±0.4MPa·m 1/2的断裂韧性。。进行等离子炬测试(PTT),以确定在高焓气流的影响下的抗氧化性。研究了测试后样品表面的相组成和微观结构。HP陶瓷在2150°С的高焓等离子炬和300 s的5.6 MW / m 2的热流下显示出出色的抗氧化性能。在等离子炬测试过程中,HfB 2 -SiC陶瓷表面形成了30-40μm厚的致密保护氧化层。该层由填充有无定形硼硅玻璃SiO 2 -B 2 O 3的HfO 2船体组成。从复合HfB 2–通过热压SiC SHS粉末,设计了低推力液体火箭发动机燃烧室模型衬套的实验样品,以在实际操作条件下进行PTT。

更新日期:2020-12-28
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