MICROSTRUCTURE AND MECHANICAL PROPERTIES OF SiC W/BAS (BaAl 2Si 2O 8) GLASS CERAMIC COMPOSITE

１．ＩｎｔｒｏｄｕｃｔｉｏｎＢＡＳ（ＢａＯＡｌ２Ｏ３ＳｉＯ２）ｇｌａｓｓｃｅｒａｍｉｃｓｗｉｔｈｃｅｌｓｉａｎａｓｍａｉｎｃｒｙｓｔａｌｌｉｎｅｐｈａｓｅａｒｅｐｏｔｅｎｔｉａｌｍａｔｒｉｃｅｓｏｆｒｅｆｒａｃｔｏｒｙｆｉｂｅｒｏｒｗｈｉｓｋｅｒｒｅｉｎｆｏｒｃｅｄｃｏｍｐｏｓｉｔｅｓｄｕｅｔｏｔｈｅｈｉｇｈｍｅｌｔｉｎｇｐｏｉｎｔ（１７６０℃）ａｎｄｇｏｏｄｏｘｉｄａｔｉｏｎｒｅｓｉｓｔａｎｃｅｏｆｃｅｌｓｉａｎ．Ｃｅｌｓｉａｎｗｉｔｈｍｏｎｏｃｌｉｎｉｃｓｔｒｕｃｔｕｒｅｉｓｓｔａｂ…     

Interface and microstructure characteristics of SiC_p/2024 aluminium alloy composite

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｉｍｐｏｒｔａｎｃｅｏｆｐａｒｔｉｃｕｌａｔｅｒｅｉｎｆｏｒｃｅｄｍｅｔａｌｍａｔｒｉｘｃｏｍｐｏｓｉｔｅｓ(ＰＭＭＣｓ)ｄｕｅｔｏｈｉｇｈｓｐｅｃｉｆｉｃｓｔｒｅｎｇｔｈ ,ｈｉｇｈｓｐｅｃｉｆｉｃｍｏｄｕｌｕｓ ,ｂｅｔｔｅｒｒｅｓｉｓｔａｎｃｅｔｏｗｅａｒａｎｄｔｈｅｒｍａｌｓｔｅａｄｉｎｅｓｓｈａｓａｔｔｒａｃｔｅｄｍｕｃｈｉｎｔｅｒｅｓｔｉｎｔｈｅｄｅｖｅｌｏｐｍｅｎｔｏｆｔｈｅｍａｎｕｆａｃｔｕｒｉｎｇｐｒｏｃｅｓｓｆｏｒｓｕｃｈｃｏｍｐｏｓｉｔｅｓ .Ｔｈ…     

EFFECT OF PARTICULATE SIZE AND CONTENT ON STRENGTH OF SiC_p／2024Al COMPOSITE AND ITS RELATIONSHIP WITH T6－TREATMENT

ＥＦＦＥＣＴＯＦＰＡＲＴＩＣＵＬＡＴＥＳＩＺＥＡＮＤＣＯＮＴＥＮＴＯＮＳＴＲＥＮＧＴＨＯＦＳｉＣ_ｐ／２０２４ＡｌＣＯＭＰＯＳＩＴＥＡＮＤＩＴＳＲＥＬＡＴＩＯＮＳＨＩＰＷＩＴＨＴ６－ＴＲＥＡＴＭＥＮＴ￥Ｍａ，Ｚｏｎｇｙｉ；Ｌｉａｎｇ，Ｙａｎａｎ；Ｌｕ?..     

SiC／C层状陶瓷的断裂行为研究

利用流延法成膜和热压烧结工艺制备出了SiC层和石墨层交替排列、层厚均匀、界面清晰的SiC／C层状陶瓷。力学性能与单相SiC陶瓷相比，SiC／C层状陶瓷的抗弯强度略有降低，但断裂韧性却得到了大幅度的提高。层状陶瓷的载荷-位移曲线不同于单相陶瓷的1次性断裂曲线，而是呈锯齿状；同理论计算所得载荷-位移曲线相似。层状陶瓷的断裂路径呈台阶状，裂纹遇到弱界面时发生分叉产生并行扩展裂纹、晶须状微裂纹以及裂纹遇到弱界面时被吸收。认为裂纹偏转、裂纹分叉、裂纹并行扩展、裂纹遇弱界面被吸收等是SiC／C层状陶瓷的几种主要增韧机制。     

无压浸渗法制备SiC-Al复合材料的断口分析

采用SEM、EDX等分析技术对无压浸渗法制备SiC／Al复合材料的断口形貌进行了分析。结果表明，该类材料的断裂包括基体韧断、界面脱开和增强体颗粒断裂三种方式，该类复合材料的强化效果取决于基体与界面结合的关系；对该复合材料的断裂机理进行了分析讨论，SiC颗粒断裂和SiC颗粒相互搭接处与基体界面脱粘是微裂纹萌生的主要原因。     

热压反应烧结制备ZrB2-SiC复合材料的工艺及性能研究

以二硼化锆、正硅酸乙酯、蔗糖为原料,采用溶胶-凝胶法制备ZrB2-SiC前躯体,然后利用热压反应烧结方法,在1800℃,30MPa压力,流动的Ar气氛条件下,制备出高致密的ZrB2-SiC复合材料。其最大相对密度达到99.6%。ZrB2-SiC复合材料的抗弯强度和断裂韧性都随着SiC含量的增加先增加后降低。当SiC含量为20%时,ZrB2-SiC复合材料断裂韧性最大达到5.1MPa·m1/2。ZrB2-SiC复合材料的最大弯曲强度为272MPa,比报道出的值要低,这可能与过大的ZrB2晶粒有关。但当SiC含量为30%时,由于出现大量气孔而使材料不致密,从而导致其力学性能下降。     

Effects of dip-coated BN interphase on mechanical properties of SiCf/SiC composites prepared by CVI process

BN interphase was successfully synthesized on SiC fiber fabrics by dip-coating process using boric acid and urea as precursors under N₂ atmosphere. The morphology of BN interphase was observed by SEM, and the structure was characterized by XRD and FT-IR spectra. The SiC_f/SiC composites with dip-coated BN interphase were fabricated by chemical vapor infiltration (CVI) process, and the effects of BN interphase on the mechanical properties of composites were investigated. The results show that the SiC fibers are fully covered by BN interphase with smooth surface and turbostratic structure (t-BN), and the thickness is about 0.4 μm. The flexural strengths of SiC_f/SiC composites with and without BN interphase are about 180 and 95 MPa, respectively. Compared with the as-received SiC_f/SiC composites, the composites with BN interphase exhibit an obvious toughened fracture behavior. From the microstructural analysis, it can be confirmed that the BN interphase plays a key part in protecting the fibers from chemical attack during matrix infiltration and weakening interfacial bonding, which can improve the mechanical properties of SiC_f/SiC composites remarkably.     

SiC_p/Al合金基复合材料的室温拉伸性能

通过对采用半固态搅拌液态模锻工艺制备的ＳｉＣｐ／Ａｌ 合金基复合材料室温拉伸性能的研究, 分析了这种复合材料屈服强度和极限强度提高的原因, 对颗粒增强复合材料的强化机理进行了探讨; 同时, 采用扫描电子显微镜对材料的拉伸断口进行了观察, 发现复合材料及未增强基体合金的断裂虽均属于塑性断裂与脆性断裂的混合型模式, 但随着ＳｉＣ 颗粒在复合材料中的体积分数的增加, 脆性断裂特征变得更为显著。     

改善颗粒增强金属基复合材料塑性和韧性的途径与机制

评述了影响颗粒增强金属基复合材料塑性和韧性的各种因素,在此基础上深入研究了颗粒形状对ＳｉＣｐ／ＬＤ２复合材料塑性和断裂韧性的影响规律。采用有限单元法分析不同形状的ＳｉＣ颗粒增强的ＬＤ２复合材料的微区力学环境和整体力学行为,结果表明颗粒的尖锐化导致基体内应变集中和颗粒尖端断裂的可能性加剧,因而降低材料的塑性;而在外加载荷的作用下,由于复合材料基体整体均处于较高的加工硬化状态,因此颗粒形状对材料断裂韧     

弥散质点和SiC颗粒复合强化Al基复合材料 Ⅱ．性能和断裂特征

对机械合金化制备的Ａｌ_４Ｃ_３、Ａｌ_２Ｏ_３弥散质点和ＳｉＣ颗粒复合强化Ａｌ基复合材料进行了拉伸试验和断口分析，并测定了弹性模量和热膨胀系数．研究表明，在ＳｉＣ_ｐ／Ａｌ复合材料中引入弥散的Ａｌ_４Ｃ_３和Ａｌ_２Ｏ_３质点可以明显提高复合材料的室温和高温强度，随加入Ｃ含量的增加或Ａｌ粉氧化时间的加长，复合材料的强度提高．在Ａｌ_４Ｃ_３／Ａｌ复合材料的基础上加入ＳｉＣ颗粒可以提高复合材料的弹性模量并进一步降低其热膨胀系数．复合材料断口为大韧窝加细小韧窝的混合断口，随复合材料基体强度的增加，拉伸断口上断裂的ＳｉＣ颗粒数量增多．     

DISPERSOID AND SiC PARTICULATE STRENGTHENED Al COMPOSITES Ⅱ. PROPERTIES AND FRACTURE BEHAVIOUR

对机械合金化制备的Ａｌ_４Ｃ_３、Ａｌ_２Ｏ_３弥散质点和ＳｉＣ颗粒复合强化Ａｌ基复合材料进行了拉伸试验和断口分析，并测定了弹性模量和热膨胀系数．研究表明，在ＳｉＣ_ｐ／Ａｌ复合材料中引入弥散的Ａｌ_４Ｃ_３和Ａｌ_２Ｏ_３质点可以明显提高复合材料的室温和高温强度，随加入Ｃ含量的增加或Ａｌ粉氧化时间的加长，复合材料的强度提高．在Ａｌ_４Ｃ_３／Ａｌ复合材料的基础上加入ＳｉＣ颗粒可以提高复合材料的弹性模量并进一步降低其热膨胀系数．复合材料断口为大韧窝加细小韧窝的混合断口，随复合材料基体强度的增加，拉伸断口上断裂的ＳｉＣ颗粒数量增多．     

Deformation of SiC/Al Composites

This article reviews some aspects of plastic deformation of Al/SiC composites with an emphasis on strengthening mechanisms, the role of coefficient of thermal expansion (CTE), the role of particle-matrix interfaces (PMI), and the fracture process. There is a tremendous potential for structural applications of SiC/Al composites. However, a complete understanding of the mechanisms of strengthening and fracture have not yet been obtained. Therefore, continued detailed fundamental investigations are required.     

多孔SiC陶瓷/Zr基非晶合金复合材料动态压缩性能研究

通过压力-浸渗法制备多孔SiC陶瓷/Zr基非晶合金复合材料。利用分离式霍普金森压杆装置(SHPB)、S-4800场发射扫描电镜等测试分析手段,探究复合材料制备保温时间和多孔碳化硅性能对多孔SiC陶瓷/Zr基非晶合金复合材料动态压缩性能的影响,并揭示了其变形机制。结果表明:保温时间和多孔碳化硅性能对多孔SiC陶瓷/Zr基非晶合金复合材料的动态抗压强度都有较大影响,当多孔碳化硅孔隙率为23.77%,平均孔径尺寸为26.72μm时,在复合材料制备浸渗温度为860℃,浸渗后保温6.0 min时,复合材料具有最高的动态抗压强度,为1757 MPa。多孔SiC陶瓷/Zr基非晶合金复合材料动态压缩断裂为脆性断裂,断口微观形貌特征包括SiC陶瓷相上形成具有不同特征的解理台阶,Zr基非晶合金相形成不同形态的脉状花样,非晶相保持相对完整。Zr基非晶合金相能有效阻碍裂纹的扩展,导致非晶相周围的碳化硅碎裂并挤压非晶相整体运动,从而提高了多孔SiC陶瓷/Zr基非晶合金复合材料动态抗压强度。     

Fabrication and mechanical properties of SiCw/MoSi2–SiC composites by liquid Si infiltration of pyrolyzed rice husk preforms with Mo additions

Dense SiC ceramic matrix composites containing SiC whiskers (SiC_w) and MoSi₂ phase (SiC_w/MoSi₂–SiC) are fabricated by a liquid Si infiltration (LSI) method. Pyrolyzed rice husks (RHs) containing SiC whiskers, particles and amorphous carbon are mixed with different amounts of Mo powder to form preforms for the infiltration. Microstructure and mechanical properties of the composites are studied. Fracture mode of the composites is discussed. Results show that the SiC whiskers and fine particles in the pyrolyzed RHs were preserved in the composites after the LSI process. The amorphous carbon and Mo powder in the preforms reacted with molten Si, forming SiC and MoSi₂ in the composites. The presence of MoSi₂ in the composite increases the elastic modulus but lowers the flexure strength. Content of MoSi₂ of ca. 20 wt.% provides an enhanced fracture toughness of 4.1 MPa m^1/2 for the composite. But too large amount of MoSi₂ caused crack formation in the composite. The compressive residual stress introduced by the formation of MoSi₂ and SiC, and the de-bonding of the fine SiC particles and SiC whiskers from the residual Si phase are considered to favor the fracture toughness of the composites.     

Mechanical properties and fractograph of SiC foam-SiC particles-Al composites

A new type of hybrid SiC foam-SiC particles-Al composites used as an electronic packaging substrate material were fabricated by squeeze casting technique. The mechanical properties and the fracture mechanism of the hybrid composites were investigated. The influence of SiC particles and foam hybrid reinforcement on the behavior of the composites was studied. The results show that the interface bonding in the hybrid composites is good for the composites with the unique double interpenetrating structure. The compressive strength of the hybrid composite reinforced by the SiC with the volume fraction of 59.9% is 680 MPa, which is higher than that of any other composites with the same volume fraction of SiC particles reinforcement.     

Evaluation of interface fracture toughness in SiC fiber reinforced titanium matrix composite

The finite element method based on the equivalent domain integral technique was developed to simulate the push out test and evaluate the interfacial fracture toughness of SiC reinforced titanium matrix composites. A special subroutine was introduced while modeling the push-out test to control interfacial failure process. In addition, the residual stresses, Poisson ratio and friction stresses were all considered in the finite element analysis and the interface debonding was described as a continuous process. The results show that the interfacial fracture toughness of SiC/Timetal-834 is about 50 Jim2. Moreover, the effects of various parameters on the interfacial fracture toughness and the variations of energy release rates at both ends of the specimen were analyzed in detail.     

Effect of Particle Size on Mechanical Properties and Fracture Behaviors of Age-Hardening SiC/Al-Zn-Mg-Cu Composites

15 vol.％ SiC/Al-6.5Zn-2.8 Mg-l.7Cu (wt％) composites with varying particle sizes (3.5,7.0,14 and 20 μm),i.e.,C-3.5,C-7.0,C-14,and C-20,respectively,were fabricated by powder metallurgy (PM) method and subjected to microstructural examination.The effect of particle size on mechanical properties and fracture behaviors of the T6-treated composites was revealed and analyzed in detail.Element distribution and precipitates variations in the composites with varying particle sizes were emphatically considered.Results indicated that both tensile strength and plasticity of the T6-treated composites increased first and then decreased with particle size decreasing.The C-7.0 composite simultaneously exhibited the highest ultimate tensile strength (UTS) of 686 MPa and best elongation (El.) of 3.1％.The smaller-sized SiC particle would intro-duce more oxide impurities,which would react with the alloying element in the matrix to cause Mg segregation and deple-tion.According to strengthening mechanism analysis,the weakening of precipitation strengthening in the T6-treated C-3.5 composite was the main cause of the lower tensile strength.Additionally,the larger SiC particle,the more likely to fracture,especially in the composites with high yield strength.For the T6-treated C-20 composites,more than 75％ SiC particles were broken up,resulting in the lowest plasticity.As decreasing particle size,the fracture behaviors of the T6-treated composites would change from particle fracture to matrix alloy fracture gradually.     

等温锻造对碳化硅颗粒增强铝基复合材料断裂韧性的影响

开展了粉末冶金法制备的20%SiC_p/2009Al复合材料坯锭的等温锻造实验,通过金相观察、扫描电镜(SEM)、拉伸和断裂韧性测试等方法研究了不同变形量对锻件微观组织和力学性能的影响。结果表明,随着等温锻造变形量的增大,SiC颗粒分布更加均匀,锻件的强度和塑性显著提高。通过SEM对材料断裂韧性裂纹扩展路径观察发现,主裂纹扩展发生在SiC颗粒偏聚区域的铝基体中。复合材料的断裂方式为以基体韧性断裂和增强体脆性断裂这2种方式为主。     

纳米SiC颗粒增强ADC12铝基复合材料的制备及性能

采用机械搅拌和超声分散相结合的方法制备出了纳米SiC颗粒增强ADC12铝合金基复合材料,并对制备出的复合材料进行微观结构分析和力学性能测试.结果表明,与基体合金相比,当纳米SiC颗粒的含量为2.0%时,所制得的复合材料的抗拉强度、弹性模量、断面收缩率及硬度分别提高23%、43%、160%和7.4%.用扫描电镜对试样拉伸断口的形貌和SiC颗粒的分散情况进行观察,发现纳米SiC颗粒在基体内呈均匀的弥散分布,没有发现大的团聚.同时,纳米SiC颗粒的均匀分布起到了阻碍或者阻止裂纹产生和扩展的作用.     

Study on fracture behavior of SiCp/A356 composites

The fracture behavior of SiCp/A356 composite at room and high temperatures was studied.Under tensile stress condition at room temperature, the fracture is mostly a combination of the brittle fracture of SiC particles and ductile fracture of A356 matrix.As the tensile temperature increases, the composite changes the main fracture behavior to the separation fracture of the bonding surface between SiC particles and A356 matrix.When the tensile temperature reaches 573 K, the fracture behavior of the composites is almost the whole separation fracture of the bonding surface, which is the main strengthening mechanism at high temperature.Under the cycle stress condition at room and high temperatures, the main fracture behavior of the composites is always a combination of the brittle fracture of SiC particles and ductile fracture of A356 matrix.However, under the cycle stress at high temperature, cycle behavior of the composites changes from cycle hardening at room temperature to the cycle softening at high temperature.