原位镁基复合材料的研究进展

重点介绍了原位颗粒增强镁基复合材料的制备技术、原位增强体的形成机制、增强机理和原位镁基复合材料的力学性能等研究热点问题并展望了原位颗粒增强镁基复合材料的发展趋势。     

颗粒增强镁基复合材料的研究现状及发展趋势

综述了颗粒增强镁基复合材料的研究概况,着重介绍了颗粒增强镁基复合材料的制备技术,界面行为和制备热力学与动力学三大研究热点,另外,对颗粒增强镁基复合材料的增强机理及常温力学性能作了简单介绍,最后,对颗粒增强镁基复合材料的研究方向进行了一些看法和展望,指出原位颗粒增强镁基复合材料的制备技术交城为制备镁基复合材料的发展趋势,镁基复合材料由于具有高的比强度,比模量和良好的耐磨性、耐高温性能和减震性能,在航空航天,特别是汽车工业具有在的应用前景和广阔的市场。     

高阻尼镁基复合材料研究现状

简述了镁基复合材料阻尼性能的研究现状,介绍了高阻尼镁基复合材料的位错型和界面型阻尼微观机制,分别阐述了基体成分、增强相类型和含量、基体和增强体界面、应变振幅、温度、频率和处理工艺对镁基复合材料阻尼性能的影响。简要分析了镁基复合材料阻尼设计思想,并对其发展方向进行了展望。     

C/Al复合材料热膨胀与内应力研究

测试了碳纤维正交对称排布(0/90)增强铝基复合材料(x—y)面内热膨胀曲线和热膨胀系数,发现热处理状态对复合材料(x—y)面内热膨胀有影响。本文通过碳纤维正交对称排布增强复合材料内应力的分析,证实了导致热膨胀差异的主要原因是复合材料内部存在残余应力。     

增强体含量对Sip/LD11复合材料热物理性能影响

为研究增强体含量对电子封装用Si颗粒增强铝基复合材料热物理性能的影响,采用挤压铸造法制备了以高纯Si粉为增强体,LD11铝合金为基体,体积分数分别为55%、60%和65%的3种复合材料.利用金相显微镜、热膨胀分析仪、热导率测试仪等多种手段对复合材料的微观组织及热物理性能进行了研究,并对试验结果进行数值模拟.显微组织观察表明,复合材料的铸态组织均匀、致密.通过改变复合材料增强体的含量,复合材料的热膨胀系数介于(8.1～12)×10-6/℃之间可调,热导率大于87.7 W/m·℃,满足电子封装用材料的要求.Sip/LD11复合材料的热膨胀系数介于Rom模型和Turner模型之间,Kerner模型能够更好地预测Sip/LD11复合材料的热膨胀系数.热导率计算结果均大于测试值.     

颗粒增强镁基复合材料的研究现状

综述了颗粒增强镁基复合材料常用的基体合金,常用的增强相及其镁基复合材料的制备技术、组织和性能等,并对颗粒增强镁基复合材料的发展进行了展望.     

镁基复合材料的制备技术进展

镁基复合材料具有低的密度、优异的力学性能和物理性能,在汽车、航空航天等领域的应用需求日益增加,成为近年来新材料领域的研究热点。介绍了镁基复合材料基体的分类和不同的增强体类型,论述了镁基复合材料的制备方法及应用现状,并对镁基复合材料的发展进行了展望。     

大塑性变形制备铝、镁基颗粒增强复合材料的研究进展

综述了目前大塑性变形(SPD)制备铝、镁基颗粒增强复合材料工艺的研究进展;总结了在SPD过程中复合材料增强颗粒的细化、再分布及基体合金晶粒的超细化等组织演变特点;分析了经SPD加工后铝、镁基颗粒增强复合材料的强韧化机制以及其力学性能的提升空间。最后指出了SPD制备颗粒增强复合材料尚存在的问题及可能的发展方向。     

颗粒增强镁基复合材料专利技术综述

颗粒增强镁基复合材料凭借其优良的比强度、比刚度、耐磨性、耐高温、减震性能以及优异的阻尼性能和电磁屏蔽性能等,作为功能材料被广泛地应用在电子、航空、航天特别是汽车工业等行业中。本文主要对颗粒增强镁基复合材料专利申请中专利申请的国内外的年度变化趋势、申请人类型进行分析,并总结了颗粒增强镁基复合材料专利申请中增强颗粒类型以及其专利技术改进方向。     

聚合物的热膨胀

热膨胀既是聚合物的基本属性,同时也与聚合物结构与性能密切相关。本文在提出聚合物热膨胀产生机制的基础上,介绍了测量聚合物热膨胀的方法,讨论了热膨胀在聚合物基础研究中的应用,着重评述了热膨胀在PTC材料为代表的聚合物基复合材料设计中的重要价值。     

滑石粉粒径对PVC/滑石粉复合材料力学性能和热膨胀系数的影响

使用钛酸酯偶联剂对不同粒径的滑石粉改性,并通过熔融共混方法制备了PVC/滑石粉复合材料。通过力学性能测试、线性膨胀测试等方法研究了滑石粉粒径对复合物的形态结构、力学性能和线性膨胀系数的影响。实验结果表明,在实验范围内随着滑石粉含量的增加,400 mesh滑石粉会使复合体系拉伸强度降低较多,冲击强度基本不变;800 mesh及1250 mesh滑石粉则使复合体系拉伸强度降低明显减少,同时增加体系的冲击强度,1250 mesh滑石粉体系冲击强度在滑石粉含量为20份时有极大值。线性膨胀系数结果显示,滑石粉的引入能明显降低PVC体系的线性膨胀系数,滑石粉粒径尺寸为800 mesh和1250 mesh时降低幅度比400 mesh时明显。     

Thermal expansion of graphite fiber-reinforced metals

The presence of graphite fibers in metal matrices greatly influences the properties of the composites. Graphite fibers have been used in conjunction with aluminum, magnesium, and copper matrices. The type of graphite fiber, layup of the fiber, and volume percentage of the fibers are all important parameters in controlling the properties of the composites. The present status, particularly in the case of graphite/copper, can be considered to be the original developmental stage and is definitely far-removed from a matured technology. The present paper focuses on thermal expansion behavior of several graphite-metal matrix composites from –60 to +200°C.Paper presented at the Tenth International Thermal Expansion Symposium, June 6–7, 1989, Boulder, Colorado, U.S.A.     

高温处理对3D C/SiC复合材料热膨胀性能的影响

研究了不同高温处理前后3D C/SiC复合材料热膨胀系数(CTE)的变化规律,从材料内部热应力变化及结构改变的角度定性地分析了其变化机理。研究发现,3D C/SiC复合材料的热膨胀系数受界面热应力的影响,其变化规律是纤维和基体相互限制、相互竞争的结果;高温处理可提高材料的热稳定性,并通过改变界面热应力及材料内部结构,来影响材料热膨胀系数的变化规律;通过增加基体裂纹来降低复合材料的低温热膨胀,但不影响其变化规律;通过改变材料内部结构,使热应力发生变化并重新分布,对复合材料的高温热膨胀产生显著影响。但高温处理没有改变3D C/SiC复合材料的基体裂纹愈合温度(900℃)。      

碳纤维网络增强环氧树脂基复合材料的制备与表征

为提高碳纤维/环氧树脂复合材料的刚性和热尺寸稳定性,首先利用短切碳纤维制备了碳纤维网络增强体(CFNR),并将其与环氧树脂复合制备了CFNR/环氧树脂新型复合材料。然后,分别利用扫描电镜和热机械分析仪对CFNR/环氧树脂复合材料的微观结构和热力学性能进行了表征。结果表明:CFNR/环氧树脂复合材料中有明显的网络节点,即碳质粘结点;CFNR/环氧树脂复合材料具有较好的导电性、较高的刚性和较低的热膨胀性,其弹性模量分别为常规短切碳纤维/环氧树脂复合材料及纯环氧树脂的3倍和6倍,平均热膨胀系数(60~200℃)分别为常规短切碳纤维/环氧树脂复合材料的1/15及纯环氧树脂的1/40;随着温度升高,CFNR/环氧树脂复合材料、常规短切碳纤维/环氧树脂复合材料及纯环氧树脂的弹性模量均因环氧树脂变软而降低,当温度高于80℃时,CFNR/环氧树脂复合材料的弹性模量分别约为常规短切碳纤维/环氧树脂复合材料的7倍和纯环氧树脂的近70倍。研究结论可以为开发高刚性、低膨胀聚合物基复合材料提供实验依据和理论指导。     

Thermal expansivities in fibrous composites incorporating hybrid interphase regions

The aim of this paper is the prediction of coefficients of thermal expansion in unidirectional fiber-reinforced composites. The representative volume element is a three phase composite structure subjected to a uniform temperature change. The advanced hybrid interphase concept is introduced, in which the interphase thickness depends on the property under consideration. This model involves also imperfect adhesion by immediate softening of material properties. Equations for the prediction of coefficients of thermal expansion are presented. Results are illustrated and discussed in terms of fiber volume fraction and adhesion coefficient. To validate the accuracy of these results finite element analysis has also been utilized. Predictions of coefficients of thermal expansion are in good agreement with experimental, finite element analysis and previous published results. The coefficients of thermal expansion of the considered polymer matrix composites are affected significantly by the parameters characterizing interphase.     

Thermal expansion and stress relaxation of metal-matrix composites

The coefficient of thermal expansion (CTE) of a series of Al-6%Si matrix samples, with reinforcements of carbon, SiC, Al₂O₃, or boron fibres, cloths, or ceramic particles was measured in the range 60°–220°C with a dilatometer. The anisotropy of the CTE was measured and found to be very large for specimens unidirectionally reinforced with carbon fibre. Relaxation of stresses due to the different thermal expansion of matrix and reinforcement was studied by using the bending of asymmetrically reinforced samples and the magnitude of the stresses evaluated using bending beam theory.     

Thermal expansion and mechanical properties of pure magnesium containing zirconium tungsten phosphate particles with negative thermal expansion

The magnesium composites containing Zr₂(WO₄)(PO₄)₂ (ZWP) particles with negative thermal expansion (NTE) were synthesized. Dense, unreacted Mg/ZWP composites were fabricated by extruding the two component powders. The coefficient of thermal expansion (CTE) and the mechanical properties of the composites were examined. The CTE of Mg/ZWP composites decreased with an increase in the amount of ZWP in the composites, though the effect was not significant probably because of the low bulk modulus of ZWP. Although there was a tension–compression asymmetry in the room temperature yield strength of Mg without ZWP, the difference reduced in the composites. The decreased asymmetry of yield behavior was suggested to be resulting from the tensile residual stress in the matrix produced during fabrication process because of the NTE of ZWP.     

Thermal expansion characteristics of cast Cu based metal matrix composites

Like any other metal/alloy, copper and its alloys also soften at elevated temperatures. Reinforcing with ceramic or carbon fibres is one of the suggested solutions to overcome this. Very limited literature is available on Cu based metal matrix composites (MMCs); none of these pertain to liquid phase fabrication. Hence, a systematic investigation was carried out on MMCs based on copper, with alumino-silicate fibres and carbon fibres as reinforcements. The MMCs thus produced exhibit a uniform distribution of reinforcement in the matrix. Coefficient of thermal expansion (CTE) values are lower than that of pure copper.     

PP/LCP复合材料的物性及力学特性

通过对容易再生的PP/LCP复合材料的微观结构、动态粘弹性特性、热膨胀特性以及力学特性进行讨论,明确了PP/LCP虽为不相溶的两相复合材料,但由于PP和LCP相的热膨胀系数不同,使两相具有比较好的界面结合强度。当LCP加入量低于40 ％时,形成以PP为基LCP为纤维状的强化相并沿流动方向分布。LCP的含量高于60 ％后,PP相的存在对复合材料的延性及强度均带来不利影响。