Preparation of quasi-isotropic thermal conductive composites by interconnecting spherical alumina and 2D boron nitride flakes

Achieving thermal management composite material with isotropic thermal dissipation property by using an environmentally friendly and efficient method is one of the most challenging techniques as a traditional approach tending to form a horizontally arranged network within the polymer matrix or the preparation steps which are unduly cumbersome.What presented here is a closestack thermally conductive three-dimensional(3D) hybrid network structure prepared by a simple and green strategy that interc...     

Effect of aging treatment on mechanical properties of （SiCw＋SiCp）/2024Al hybrid nanocomposites

1 Introduction Metal matrix composites(MMCs) have received much attention because of their improved specific strength, good wear resistance and higher thermal conductivity [1?3]. Up to now, most investigators have studied the fabrication process and mecha…     

Liquid-liquid phase separation in highly undercooled Ni-Pb hypermonotectic alloys

1 Introduction Hypermonotectic alloys with homogeneous structure have good physical and chemical properties and can be used as self-lubricating materials, electrical contact materials and superconducting materials, and so on [1,2]. However, it is very dif…     

Al_(80)Ni_6Y_8Co_4Cu_2 GLASS ALLOYS CONTAINING NANOSCALE PARTICLES BY ISOTHERMAL ANNEALING OR QUENCHING

1. IntroductionPartial nanocrystalline Al-rich glajssy alloys have attracted great attention as a newmaterial because their specific strength are much higher than that of the fully amorphousAl-rich alloys and the conventional crystalline Al-based alloy[1,2]. Kim et al.I2] and Chenet al.13] reported that the values of fracture strength are above 1000MPa for Al-rich alloyswith mixed structure of nanoscale or-Al particles embedded on the amorphous matrix afterpartial crystallization. However,…     

Fabrication of AlN-TiC/Al composites by gas injection processing

1. Introduction Al-based metal matrix composites (MMCs) with ceramics like SiC, Al2O3, TiC, AlN, TiN, and TiB2 as the reinforcement phase have been widely studied by some researchers. It has been reported that TiC and AlN are particularly attractive because of good wettability and high stability with molten aluminum, high hardness, and elastic modulus [1-4]. To fabricate MMCs, various techniques have been developed. Among these, the in situ technolo- gies are particularly attractive b…     

STUDY ON THE SiC_p./Al-ALLOY COMPOSITE AUTOMOTIVE BRAKE ROTORS

1. IntroductionThe SiC particulate reinforced aluminum matrix composites (AMC) have sucll characteristics as high specific stiffness and strength, high wear resistance, high thermal condllctivity, and lightweight etc. Using such lightweight material, as aluminum matrix compositein brake systems is one of the ways to reduce unsprung weight of motor vehicles. Thetribological and wear behavior of the aluminum matrix composite have been reported bydifferent ...ea.chers[1--4], and AMC brake roto…     

Review on preparation techniques of particle reinforced metal matrix composites

The need for new engineering materials with theadvancement of modern technology in the areas ofaerospace, automotive and numerous other industries haslead to a rapid development of metal matrix composites(MMCs) [1]. They can be tailored to have outstandingmechanical and physical properties such as high specificstrength and stiffness, good wear resistance, enhancedhigh-temperature performance, and better thermal andmechanical fatigue and creep-resistance than that ofmonolithic materials. Among…     

Preparation technique of SiCp reinforced Al matrix composite

The advancement of modern technology in the areas of aerospace and automotive industries has generated demand for new engineering materials, leading to a rapid development of metal matrix composites (MMCs) [1]. These composites can be tailored to have outstanding mechanical and physical properties such as high specific strength and stiffness, increased wear resistance, enhanced high-temperature performance and better thermal, mechanical fatigue and creep resistance than those of monolithic mat…     

Synthesis and properties of bulk nanocrystalline Mg2Si through ball-milling and reactive hot-pressing

1 Introduction The intermetallic compound Mg2Si is useful as strengthening phase in the metal matrix composites (MMC) due to its low density (1.99 g/cm3) and high strength-to-mass ratio[1?5]. It is also promising as a basic material for thermoelectric ene…     

Designing electrolytes for lithium metal batteries with rational interface stability

正Lithium (Li)-ion batteries (LIBs) have promoted the development of portable electronics and electric vehicles [1,2].However,with the rapid increase in energy demand,it is increasingly urgent to develop batteries with high energy density [3].Li metal batteries (LMBs) are considered as the"Holy Grail" which have attracted much attention due to the high theoretical capacity (3860 mAh·g~(-1)) and low redox potential (-3.040 V vs.the standard hydrogen electrode)[4,5].However,before the practical application of LMBs,     

The abrasive wear properties of Al-Mg-Si3N4 metal matrix composites

One kind of three-dimensional network structure, reinforced aluminum magnesium matrix composites, has been prepared by pressure-assisted and vacuum-driven infiltration technology. The composites interpenetrated with ceramic have higher wear resistance than the metal matrix owing to their special topology structure. The reinforcement volume fraction has a large effect on abrasive wear. The wear rate decreases with the increase of the volume fraction of reinforcement and increases with the increase of sliding time and applied load. The wear mechanism of the composites (abrasive wear) differs greatly from the matrix alloy (adhesive wear).     

PCD刀具车削钛基复合材料的刀具磨损研究

采用PCD刀具在不同切削速度下对增强相钛基复合材料进行切削，研究高速切削时的刀具磨损情况。结果表明:增强相体积分数对PCD刀具耐用度有显著影响，体积分数越高，刀具磨损越严重，刀具耐用度越低；增强相种类对刀具的耐用度也有明显影响，增强相TiB_w对刀具耐用度的影响要大于增强相TiC_p的。PCD刀具在切削不同钛基复合材料时的刀具磨损形态相似，主要为前刀面和后刀面的磨损，且伴有崩刃及微裂纹现象发生；其主要磨损机理是磨粒磨损以及黏结磨损，且增强相的体积分数越高，刀具黏结磨损越显著。      

Equation for the density of particle-reinforced metal matrix composites: A new approach

This paper presents a novel equation for the density of ceramic particle reinforced metal matrix composites. An overall density change occurs in composites due to the thermal mismatch between the metal matrix and the reinforcement. The thermal mismatch occurs because the coefficient of thermal expansion and the elastic properties are different for the matrix and the reinforcement. The values obtained using the proposed equation for density were compared with both the rule of mixtures for density and the experimental values obtained for aluminium and zinc alloy composites. The composite specimens were fabricated using compocasting technique (one of the types of liquid metallurgy route). The proposed mathematical model is found have better agreement with the experimental results at lower volume fractions of the reinforcement; however, some deviations were observed at higher volume fractions of the reinforcement. The proposed equation yields agreeable results for aluminium composites and fairly agreeable results for zinc alloy composites.     

Wear resistance of WCp/Duplex Stainless Steel metal matrix composite layers prepared by laser melt injection

Laser Melt Injection (LMI) was used to prepare metal matrix composite layers with a thickness of about 0.7 mm and approximately 10% volume fraction of WC particles in three kinds of Cast Duplex Stainless Steels (CDSSs). WC particles were injected into the molten surface layer using Nd:YAG high power laser beam. As a result the microstructure characterized by hard ceramic particles distributed in a metal matrix with the strong bonding to substrate is formed in the surface layer of the treated metal.Dry sliding wear properties of these metal matrix composites layers were measured and compared with the wear properties of the substrate and with surfaces simply remelted by the laser beam. The observed wear mechanisms are summarized and related to detailed microstructural observations. The layers have been found to show excellent interfacial bonding, coupled with substantially improved tribological properties expressed through the wear resistance increase of 8 times. The amount of WC particles was sufficient to reinforce the matrix and the particles have shown a good bonding to the matrix to support the contact stress in the layer.     

The effect of primary and secondary processing on the abrasive wear properties of compocast aluminum 6061 alloy matrix composites

In this present work, the compocasting method was used to produce Aluminum 6061 alloy matrix composites reinforced SiC particles with a variety of particle average sizes of 1, 5, 20 and 50 μm. The influences of particle volume fraction of metal matrix composites on the dry sliding wear behaviour have been investigated. The acceptable quality of the fabricated composites calls for a proper selection of process parameter such as pouring temperature, stirring speed, stirring time, preheat temperature of reinforcement, minimum level of the porosity and prevention of the chemical reaction between reinforcement and matrix. Experimental test was carried out on the porosity and hardness of the composites. A pin-on-disc wear test was used to assess the effect of SiC content, SiC size and secondary mechanical processing with different rolling reductions on wear characteristics of Al matrix composites. It is noted that the particle distribution in the cold rolled composites is much more uniform than the as-cast one.     

混合铝基复合材料的力学性能和耐磨性

混合金属基复合材料是重要的工程材料,因为他们比纯铝具有更低的密度、更高的比强度和更好的物理力学性能而广泛应用于汽车、航空航天等方面。研究了混合铝金属基复合材料的力学性能和磨损性能。通过搅拌铸造将云母和SiC颗粒加入到Al 356合金中。采用扫描电子显微镜(SEM)研究样品的显微组织,用能谱分析(EDX)其化学成分。结果表明,所制备的Al/10SiC?3云母复合材料具有较好的强度和硬度。增加复合材料中云母含量能提高复合材料的耐磨性。     

High-Speed Tribological and Mechanical Properties of Layered Fe/SiC Composites

In this work, we studied the high-speed tribological and mechanical properties of layered SiC particulate reinforced iron matrix composites. The layered composites consisted of a surface layer with high volume fraction of the reinforcement particles and a layer with low volume fraction in the bulk. The layered composites are a form of functionally graded materials with high wear resistance near the surface and high thermal conductivity in the bulk. The composites were prepared by standard powder metallurgy techniques. The tribological behavior of the composites was evaluated at 25 to 35 m/s sliding speeds using a sub-scale dynamometer disk brake testing system. The properties of the layered composites were compared to those of uniform composites. The results showed that the layered composites have better wear resistance and braking effectiveness in the range of braking speeds considered. The layered composites also showed higher bending strength than the monolayer composites due to the presence of the interfaces between the layers.     

碳纤维含量对Al2O3+C/ZL109混杂复合材料摩擦磨损性能的影响

利用挤压铸造法制备了A1203 C／ZLl09短纤维混杂金属基复合材料，并探讨了A1203纤维体积分数为12％时，C纤维含量对该混杂复合材料摩擦磨损性能的影响。结果表明：随着C纤维体积分数的增加，复合材料的摩擦因数和磨损率逐渐降低。12％A1203和4％C短纤维的协同作用使复合材料从轻微磨损到急剧磨损的临界转变载荷比基体合金提高了1倍。当载荷低于临界载荷时，复合材料的主要磨损机制为犁沟磨损和层离，C纤维的加入有利于磨损表面裂纹尺寸的减小。但随着载荷的逐渐增加并发生严重磨损时，基体和复合材料的磨损机制均为严重的粘着磨损甚至局部熔化磨损。     

Microstructural and abrasive wear properties of SiC reinforced aluminum-based composite produced by compocasting

The effect of SiC particles reinforcement with average size of 1, 5, 20 and 50 μm and volume fraction of 5%, 10% and 15% on the microstructure and tribological properties of Al-based composite was investigated. Composites were produced by applying compocasting process. Tribological properties of the unreinforced alloy and composites were studied using pin-on-disc wear tester, under dry sliding conditions at different specific loads. The influence of secondary mechanical processing with different rolling reductions on the dry sliding wear characteristics of Al matrix composites was also assessed. Hardness measurement and scanning electron microscopy were used for microstructural characterization and investigation of worn surfaces and wear debris. The proper selection of process parameter such as pouring temperature, stirring speed, stirring time, pre-heated temperature of reinforcement can all influence the quality of the fabricated composites. The porosity level of composite should be minimized and the chemical reaction between the reinforcement and matrix should be avoided.     

Preparation and Characterization of Binder Less Mg/Mg Alloy Infiltrated SiC<Subscript>p</Subscript> Reinforced Composites

SiC_p-reinforced commercial pure magnesium and AZ91 alloy MMCs’ were prepared through infiltration route without the use of any special atmospheres. The preform was prepared using a mixture of reinforcement particles and the matrix metal particles. The composites were prepared with various volume percentage of the reinforcement and their properties with the variation of SiC_p were analyzed. The interfacial properties of the composites were analyzed using microstructure, microhardness, and wear studies. Calculation of thermal conditions during infiltration was done to study the effect of adding matrix metal particles on the infiltration behavior and its effect on the uniformity distribution of the reinforcements.