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预制体结构对SiC_(f)/SiC复合材料力学和热性能的影响

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Journal of Central South University 2024年第1期31卷 101-113页

作者：王徐辉吴宗绪陈招科伍艳熊翔 science and technology on high strength structural materials laboratory Central South UniversityChangsha 410083China State key laboratory of Powder Metallurgy Central South UniversityChangsha 410083China

本文采用化学气相渗透法制备了具有二维多层、三维角联锁机织和多轴三维编织三种预制体结构的SiC_(f)/SiC复合材料。在综合分析纤维排列、SiC基体和孔隙分布的基础上,详细讨论了预制体结构对SiC_(f)/SiC复合材料力学性能和热性能的影响... 详细信息

本文采用化学气相渗透法制备了具有二维多层、三维角联锁机织和多轴三维编织三种预制体结构的SiC_(f)/SiC复合材料。在综合分析纤维排列、SiC基体和孔隙分布的基础上,详细讨论了预制体结构对SiC_(f)/SiC复合材料力学性能和热性能的影响。结果表明,复合材料的力学性能和热导率受纤维排列方式和复合材料密度的综合影响,而热膨胀系数主要受纤维排列方式的影响。此外,二维多层复合材料、三维角联锁机织复合材料和多轴三维编织复合材料的热导率可以分别用串联模型和平行模型来解释。多轴三维编织复合材料由于内部具有连续的可以作为热流快速通道的三维网状SiC基体层,因此具有较高的室温热导率。而随着温度的升高,SiC声子间的散射逐渐增强,SiC基体层在多轴三维编织复合材料中作为声子传播快速通道的作用逐渐减弱,热导率随温度降低的趋势更明显。

关键词：预制体结构抗弯强度热导率热膨胀系数 SiC_(f)/SiC复合材料

Controlling the Si/C ratio in SiC matrix based on the modified polymethysilane for C/C-SiC composites with enhanced mechanical properties

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Journal of Advanced Ceramics 2024年第2期13卷 220-236页

作者： Mingdong Liao Xiebo Hu Chenghao Zhong Ping Xu Xiaodong Wang Ze Zhang Peng Zhou Mingyu Zhang Zhean Su Qizhong Huang National Key Laboratory of Science and Technology on High-Strength Structural Materials Central South UniversityChangsha 410083China

Fabricating SiC matrix with controllable Si/C ratio for C/C-SiC composites via precursor infiltration and pyrolysis is difficult to realize due to the absence of suitable precursors.Here,SiC precursors with Si-rich(Si/C=1.23),nearstoichiometric(Si/C=1.01),and C-rich(Si/C=0.88)pyrolyzed ceramics at 1200℃ were successfully synthesized by the novel modification of polymethysilane.The structure and ceramization of synthesized SiC precursors were studied,and C/C-SiC composites with similar Si/C ratio in SiC matrix were also fabricated.The results revealed that the defects and Young’s modulus of SiC matrix and the thermal residual stress on pyrolytic carbon coated carbon fiber were determined by the Si/C ratio.As a result,the Si/C ratio exerted significant effects on the crack deflection behavior and the mechanical properties of the composites.The composites with near-stoichiometric SiC matrix showed excellent mechanical properties because of the effective crack deflection and the moderate Young’s modulus of their SiC matrix.The flexural strength,flexural modulus,and compressive strength were 423±27 MPa,33.41±4.52 GPa,and 393±8 MPa,respectively.Meanwhile,after a heat treatment at 1600℃,the role of carbon fiber toughening was improved and accompanied by a decrease in mechanical properties for all composites,which was attributed to the increased defects in SiC matrix and the damaged interfaces by the thermal residual stress.

关键词： SiC precursor Si/C ratio polymethysilane C/C–SiC composites mechanical properties

湿磨与SPS烧结制备Al添加ODS钢的显微组织结构与力学性能研究

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Journal of Central South University 2021年第4期28卷 1219-1232页

作者：孙煜舟吝楠章伍军张永森李忠涛韩现奇吴正刚王祖勇马超 College of materials science and Engineering Hunan UniversityChangsha 410082China National Key Laboratory of Science and Technology on High-Strength Structural Materials Central South UniversityChangsha 410083China

本文利用湿磨和放电等离子烧结技术制备了Al含量分别为0,1 wt%,2 wt%和3 wt%的15Cr-ODS钢。通过XRD、SEM、TEM、EBSD和拉伸测试等对ODS钢的显微组织结构与力学性能进行了研究。研究结果表明,Al元素的添加能够显著细化Fe-Cr相基体中的析... 详细信息

本文利用湿磨和放电等离子烧结技术制备了Al含量分别为0,1 wt%,2 wt%和3 wt%的15Cr-ODS钢。通过XRD、SEM、TEM、EBSD和拉伸测试等对ODS钢的显微组织结构与力学性能进行了研究。研究结果表明,Al元素的添加能够显著细化Fe-Cr相基体中的析出相颗粒,减小基体晶粒尺寸并改善材料的力学性能。Al添加ODS钢基体中尺寸为5~300 nm的弥散颗粒可以被标定为Al_(2)O_(3)与Y_(2)Ti_(2)O_(7)纳米粒子,这些弥散颗粒的尺寸分布较为不均匀。随着Al元素添加量的增加,材料的伸长率降低,但其抗拉强度显著的提升。当Al元素添加量为3 wt%时,15Cr3Al-ODS钢抗拉强度与伸长率分别为775.3 MPa和15.1%。Al元素的添加还可增强材料的耐腐蚀性能,Al含量为2 wt%ODS钢的腐蚀电位(Ecorr)与钝化电流密度(ipass)分别为0.39 V和2.61×10^(−3)A/cm^(2)(1.37 V)。因此,本文使用湿磨和放电等离子烧结方法制备的Al添加ODS钢在核能系统结构部件中能够具有良好的应用前景。

关键词： ODS钢氧化物纳米粒子微观结构拉伸强度弥散强化

Dislocation ordering and texture strengthening of naturally aged Al-Cu-Mg alloy

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Journal of materials science & technology 2022年第23期118卷 1-14页

作者： F.Liu Z.Y.Liu G.Y.He L.N.Ou School of materials science and Engineering Central South UniversityChangsha 410083China key laboratory of Nonferrous Metal materials science and Engineering Ministry of EducationCentral South UniversityChangsha 410083China National Key Laboratory of Science and Technology on High-Strength Structural Materials Central South UniversityChangsha 410083China

Stability of grain structure,dislocation ordering and strengthening mechanisms of the naturally aged AlCu-Mg alloy after solution treatment are investigated by using optical microscope(OM),scanning electron microscope(SEM),electron back-scattered diffraction(EBSD),X-ray diffraction(XRD) and transmission electron microscope(TEM).Results show that {100},{100},{110} and {110}slip systems can be activated after solution treatment,which can promote the formation of {110}Goss texture.The combination effect of T-Al_(20)Cu_(2) Mn_(3) phase and Goss-oriented grains with large Taylor factor makes the solution-treated alloys display excellent stability of grain structure.The enhanced yield strength of the alloy is ascribed to grain-refine strengthening,dispersed particles strengthening,dislocation strengthening and texture strengthening.The coarsening of the second phase is responsible for softening of the alloy after annealing at 400 ℃+solution treatment at 475 ℃.

关键词： Al-Cu-Mg alloy Dislocation ordering Goss texture Grain structure stability Texture strengthening

Microstructures and mechanical behaviors of CVI-based C/C composites containing h-BN powdered additives

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Journal of materials science & technology 2019年第12期35卷 2824-2831页

作者： Peng Xiao Zhichao Li Zeyan Liu Zhuan Li Bengu Zhang Jinwei Li Yang Li national key laboratory of science and technology for national Defence on high-strength structural materials Central South UniversityChangsha 410083China State key laboratory of Powder Metallurgy Central South UniversityChangsha410083China

Hexagonal boron nitride(h-BN) powders were introduced into carbon fiber preform by powder addition and subsequent combined with chemical vapor infiltration(CVI) for densification to prepare carbon fiber reinforced/carbon and boron nitride dual matrix composites(C/C-BN). Microstructures and mechanical properties of C/C composites with three different volume contents of h-BN powders were investigated in comparison to pure C/C composites. Results indicated that the introduction of h-BN powders into C/C composites significantly reduced the size of Py C and the anisotropy of thermal contraction in matrix,leading to a gradual disappearance of ring defects as the h-BN content increased. In addition, an enhanced interfacial bonding between fiber and matrix obtained due to higher-textured Py C and rougher fiber surface. Thereby, the flexural strengths and modulus of as-prepared composites decreased firstly and then increased, while the impact toughness presented a decreasing tendency as the content of BN powders increased. Furthermore, with the increasing of h-BN content, anisotropies of compressive properties were weakened, and the compressive strength of C/C-BN composites were always higher than that of pure C/C composit. However, when C/C composites modified by 13.5 vol% content of h-BN, excessive loose BN aggregates appeared in C/C-BN composites, leading to a relatively slight reduction of compressive strength.

关键词： C/C composites h-BN Pyrolytic carbon Interfacial bonding Mechanical properties

Interface Design Strategy for GNS/AZ91 Composites with Semi-Coherent Structure

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Acta Metallurgica Sinica(English Letters) 2024年第3期37卷 467-483页

作者： Jing-Peng Xiong Yi-Qi Zeng Jin-Long Liu Wei-Cheng Wang Lan Luo Yong Liu key laboratory of Lightweight and high strength structural materials of Jiangxi Province School of Advanced ManufacturingNanchang UniversityNanchang 330031China School of Physics and materials science Nanchang UniversityNanchang 330031China

The interfacial structure plays an important role in the mechanical properties of magnesium matrix composite(MMCs)reinforced with graphene nanosheet(GNS)due to their poor wettability with the Mg matrix.An interface design strategy was proposed to form the semi-coherent interfacial structure with superior bonding strength.The lattice mismatch and interfacial bonding strength between Mg/rare earth oxide/carbon were utilized as key characteristics to evaluate the interfacial structure.Lanthanum oxide(La2O3)was selected as the intermediate candidate due to its low lattice mismatch and high interfacial bonding strength.To identify the interfacial structure of Mg/La2O3/graphene,first-principles calculations were conducted to calculate the ideal work of separation and electronic structure of the interfaces.Results demonstrated the presence of strong ionic and covalent interactions at the interface,which theoretically verified the strong interfacial bonding strength among Mg/La2O3/graphene interfaces.To experimentally validate the interface strength,MMCs with the interface structure of Mg/La2O3/GNS were developed.The formation of in-situ La2O3 led to the successful attainment of semi-coherent structures between Mg/La2O3 and La2O3/GNS,resulting in high strength and good ductility of the composite.Overall,this work proposes a new approach to interface design in MMCs with an enhancement of mechanical properties.

关键词： Interface design strategy Magnesium matrix composite Graphene nanosheets Semi-coherent interface Mechanical properties

MoS_(2)表面镀铜对青铜-石墨-MoS_(2)自润滑摩擦性能的影响

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Journal of Central South University 2022年第11期29卷 3608-3619页

作者：王慧灵姜锋童蒙蒙吴明锦蒋靖宇 School of materials science and Engineering Central South UniversityChangsha 410083China Light Alloy Research Institute Central South UniversityChangsha 410083China The national key laboratory of science and technology for national Defence on high-strength Lightweight structural materials Central South UniversityChangsha 410083China

采用粉末冶金法制备了含镀铜MoS_(2)和不镀铜MoS_(2)两种青铜-石墨-MoS_(2)自润滑材料,并在4 N和10 N载荷下分别进行摩擦磨损实验,研究MoS_(2)表面镀铜对材料摩擦性能的影响。研究结果表明,在MoS_(2)表面镀铜可以增强MoS_(2)与基体的结... 详细信息

采用粉末冶金法制备了含镀铜MoS_(2)和不镀铜MoS_(2)两种青铜-石墨-MoS_(2)自润滑材料,并在4 N和10 N载荷下分别进行摩擦磨损实验,研究MoS_(2)表面镀铜对材料摩擦性能的影响。研究结果表明,在MoS_(2)表面镀铜可以增强MoS_(2)与基体的结合性,同时抑制材料中硬质相MoO_(2)的形成。此外,两种材料在摩擦过程中均在表面形成了一层MoS_(2)润滑膜,但是在MoS_(2)表面镀铜后形成的润滑膜更厚,并且具有凹凸不平的形貌,更有利于改善材料的摩擦性能。与常规材料相比,在4 N和10 N载荷下进行滑动摩擦时,镀铜材料的磨损率均降低了一个数量级,摩擦因数也分别降低了22.44%和22.53%,表明在MoS_(2)表面镀铜可以进一步改善青铜-石墨-MoS_(2)自润滑材料的摩擦性能。

关键词：青铜-石墨-MoS2 自润滑材料摩擦磨损磨损机制

Corrosion behavior and failure mechanism of SiC whisker and c-AlPO_(4) particle-modified novel tri-layer Yb_(2)Si_(2)O_(7)/mullite/SiC coating in burner rig tests

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Journal of Advanced Ceramics 2022年第12期11卷 1901-1917页

作者： Pengju CHEN Peng XIAO Xian TANG Yang LI School of Nuclear science and technology University of South ChinaHengyang 421001China Powder Metallurgy Research Institute Central South UniversityChangsha 410083China National Key Laboratory of Science and Technology on High-Strength Structural Materials Central South UniversityChangsha 410083China

The corrosion behavior of environmental barrier coatings(EBCs)directly affects the service life and stability of ceramic matrix composite(CMC)structural parts in the aero-engines.The silicon carbide(SiC)whisker toughening phase and c-AlPO_(4) bonding phase are firstly used to improve the service life of novel tri-layer Yb_(2)Si_(2)O_(7)/mullite/SiC EBCs in the burner rig test.The formation of penetrating cracks in Yb_(2)Si_(2)O_(7)/mullite/SiC coating caused the failure of coating at 1673 K.The SiC whiskers in mullite middle coating significantly inhibited the formation of penetrating cracks in Yb_(2)Si_(2)O_(7)/mullite/SiC coating,and efficiently prevented the oxidation of carbon fiber reinforced silicon carbide(C_(f)/SiC)samples for 360-min thermal cycles(24 times)with a weight loss of 6.19×10^(−3) g·cm^(−2).Although c-AlPO_(4) particles further improved the service life of SiC_(w)-mullite(SM)coating,the overflow of PO_(x) gas aggravated the formation and expansion of cracks in the Yb_(2)Si_(2)O_(7) outer coating,and caused the service life of overall Yb_(2)Si_(2)O_(7)/c-AlPO_(4)-SiC_(w)-mullite(ASM)/SiC coating to be slightly lower than that of Yb_(2)Si_(2)O_(7)/SM/SiC coating.This study guides the design of modified tri-layer EBCs with long service life in high-temperature and high-speed gas environment.

关键词： Yb_(2)Si_(2)O_(7) mullite tri-layer sol-gel burner rig test

Morphological Evolution of Fe-Rich Phases in the AlSi_9Cu_3Mg_(0.19)(Fe)Alloy with the Addition of Minor Mn and Cr

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Acta Metallurgica Sinica(English Letters) 2018年第6期31卷 629-640页

作者： Zhi-Qiang Qiu Xiang-Chen Meng Qiu-Hong Yuan Xiao-Shu Zeng Xi-Xin Rao Yan Ding Lan Luo Yong Liu key laboratory of Lightweight and high strength structural materials of Jiangxi Province Nanchang University Physical science and technology College Yichun University School of materials science and Engineering Nanchang University

The morphological evolution of Fe-rich phases in the Alalloy has been investigated with various contents of Fe,Mn,and Cr.The results show that coarse Chinese script Fe-rich phases appear in the alloy with 0.6 wt%Fe combined with trace Mn,while the blocky Fe-rich phases appear combined with trace Cr.Under the coexistence of trace Mn and Cr,a large number of fine Chinese script Fe-rich phases could be visible in the low iron-bearing AlSi_9Cu_3-alloy（0.60 wt%）.At high Fe level（1.30 wt%）,numerous Fe-rich phases with hexagonal morphologies are observed with the trace Cr,while fish-bone and pentagonal morphologies of Fe-rich phases could be simultaneously observed with the addition of both Mn and Cr.The results reveal that the trace Mn and Cr promote the morphological evolution of Fe-rich phases.The morphology evolution mechanism of Fe-rich phases has been discussed by using the atom radius and electronegativity differences of Fe,Mn,and Cr.

关键词： AlSi_9Cu_3Mg_（0.19）（Fe） alloy Fe-rich phase Sludge factor Microalloying Electronegativity differences