, 王俊翔, 侯思焓, 李曙
, WANG Junxiang, HOU Sihan, LI Shu
制备不同添加量碳化硅、不同规格泡沫镍增强的环氧树脂双连续复合材料, 对其拉伸性能进行了评价。结果表明, 泡沫镍的孔径较小、体密度较大时复合材料的拉伸强度高, 碳化硅添加量对力学性能的影响较小。根据对拉伸断口和拉伸曲线的观察和分析, 探讨了泡沫镍/环氧树脂/碳化硅双连续复合材料拉伸破坏过程和机制。
Co-continuous composites of nickel foam/epoxy/silicon carbide with different SiC content and different specification of nickel foam were prepared and then their tensile property was investigated. The results show that the tensile strength of the composite is high when made of nickel foam with small pore diameter and high relative density, while the SiC content have small influence on the tensile property. The damage process of the co-continuous composite and the relevant mechanism was revealed by observing the morphologies of the tensile fracture and analyzing the tensile curves.
力学性能是材料研究和使用的基本参数, 在一定程度上决定着材料的应用领域。双连续复合材料泡沫镍/环氧树脂/碳化硅的结构与传统复合材料显著不同, 因此, 研究其力学性能具有重要的意义。目前, 人们对双连续复合材料力学行为的研究不多[8-12]。双连续复合材料的两相在三维空间中均匀连续, 使应力均匀向各个方向传递, 阻碍裂纹向某个方向扩展, 使材料具有更高的损伤容限。复合材料的力学性能主要决定于组成相的性质、复合结构以及制备方法。在双连续复合材料泡沫镍/环氧树脂/碳化硅的结构和制备方法确定后, 其力学性能决定于树脂相中陶瓷颗粒的添加量、金属相泡沫镍的结构参数。针对腐蚀介质冲蚀工况, 作者设计了泡沫镍/环氧树脂/碳化硅复合材料, 以泡沫镍为骨架起支撑和传递应力的作用; 环氧树脂作为充填粘结相将陶瓷颗粒与金属骨架粘结在一起, 具有优异的耐腐蚀性能; 碳化硅陶瓷颗粒作为硬质增强相, 提高了材料的强度和硬度。本文用真空灌注方法制备不同碳化硅添加量、不同规格泡沫镍的双连续复合材料, 研究关键因素对其拉伸性能的影响。
制备复合材料所用环氧树脂为双酚A型环氧树脂E-44, 环氧值(eq/100g)0.41-0.47, 固化剂为聚酰胺固化剂651, 胺值400±20(mgKOH/g)。碳化硅颗粒的尺寸分别为纳米、亚微米和微米, 具体规格列于
表1 碳化硅颗粒的规格
Table 1 Specifications of the silicon carbide particles
复合材料的制备工艺为: 将硅烷偶联剂KH550:水:乙醇=1:2:10的质量比在室温混合水解1 h, 用水解液分别浸没泡沫镍、SiC颗粒并超声振动10 min, 进行表面有机改性, 烘干后待用。在每100 g的环氧树脂中加入SiC颗粒、20 g稀释剂C12-14烷基缩水甘油醚(AGE), 用高速剪切均质分散机高速剪切搅拌10 min使SiC颗粒分布均匀, 再加入50 g固化剂聚酰胺651, 搅拌均匀, 静置除气泡。最后将混有SiC颗粒的树脂真空灌注到泡沫镍的孔隙中, 移入相应的模具中进行室温自然固化, 得到拉伸试样。
为了研究双连续复合材料的力学性能, 先测试组成它的树脂相和泡沫金属相的力学性能。
决定泡沫镍拉伸强度的因素, 主要是密度, 其次使孔径。Gibson与Ashby[13]的研究表明, 孔隙率比较高的泡沫金属的拉伸强度与相对密度的1.5次方成正比。在实验研究范围内, 前三种泡沫镍试验数据基本与之相符。4#泡沫镍(50PPI、2.2460 g/cm3)的孔隙率为74.76%, 其拉伸强度最大, 但是小于根据密度计算所得值; 而5#泡沫镍(25PPI、2.843 g/cm3)的孔隙率为68.06%, 其密度虽然最大, 但是力学性能相比4#却反而降低。其原因可能是, 用电沉积工艺制备泡沫镍时, 随着镀层厚度的增加镀层内部缺陷和残余应力增加。
图3 环氧树脂/碳化硅复合材料的拉伸强度
Fig.3 Tensile strength of epoxy resin composites with different SiC content
由
添加陶瓷颗粒增强树脂, 是一种很成熟的树脂材料改性的方法。当陶瓷添加量较少时颗粒比较均匀的分散在环氧树脂中, 传递应力, 阻碍裂纹的扩展, 起增强作用; 但是过多的陶瓷颗粒难以在树脂中完全分散, 自身容易发生一定的团聚, 反而增加了内部缺陷, 使复合材料的力学性能降低。
表2 不同的复合材料的拉伸强度
Table 2 Tensile strength of various composites
从
对拉伸断面的形貌观察表明, 材料断裂后其表面凹凸不平, 有大量球状凹坑或凸起, 如
复合材料由损伤到断裂有两种模式[14], 一种是固有缺陷较小, 随着载荷的增大引发更多的缺陷和扩大损伤区范围, 导致整体破坏, 称为整体损伤模式; 另一种是缺陷裂纹尺寸较大, 应力集中造成裂纹扩展, 这种裂纹扩展导致破坏, 称为裂纹扩展模式。在材料的破坏过程中往往先出现总体损伤模式, 当最大裂纹尺寸达到某临界值时出现裂纹扩展模式的破坏。泡沫镍/环氧树脂/碳化硅双连续复合材料中的泡沫镍具有正十二面体结构[15], 可推测其破坏过程为: 先在缺陷处萌生许多微裂纹, 然后裂纹在树脂相两相的界面扩展。由于两相的界面结合较弱, 裂纹在界面上扩展较快, 到达泡沫镍两孔洞连接处时应力集中使树脂相断裂, 随后金属棱断裂, 树脂相从金属网格中脱出, 金属棱与树脂分离。因此, 泡沫镍/环氧树脂/碳化硅双连续复合材料的拉伸破坏过程, 包括金属棱与树脂相的界面开裂、树脂相的断裂及金属棱的断裂, 其破坏以裂纹扩展模式为主, 如
载荷-位移曲线是应力-应变曲线的宏观表现, 反映出相同的物理性质与规律。对五种规格泡沫镍、双连续复合材料(每百克树脂碳化硅添加量为20 g)以及树脂相的拉伸载荷-位移数据作曲线, 如
从
图6 不同泡沫镍和不同双连续复合材料的载荷-位移曲线
Fig.6 Load-displacement curves of different nickel foam (a) and different co-continuous composites (b)
从
将双连续复合材料的载荷-位移曲线与其对应的泡沫镍、环氧树脂的载荷-位移曲线对比, 以C2#(碳化硅添加量为20 g)和与其对应的两相为例, 如
本文的实验所有拉伸试样的横截面积相同, 均为10 mm×10 mm。因此, 载荷-位移曲线的斜率反应材料的弹性模量大小。对比可见, 在受力的初始阶段, 当载荷小于双连续复合材料能承受的最大载荷时双连续复合材料的弹性模量, 相比树脂相有一定程度的增加, 并远大于金属相。这说明, 互穿的双连续结构对复合材料性能有一定的增强作用。
但是, 树脂相与金属相的载荷-位移曲线的斜率相差一个数量级以上, 二者对载荷的响应相差过大。同时, 由于两相界面结合较弱导致界面脱粘, 相比完整的树脂相其力学性能反而有所降低。
1. 碳化硅陶瓷颗粒的添加量对树脂相和双连续复合材料的力学性能影响不大。双连续复合材料的拉伸强度主要由对应的泡沫金属的孔径决定, 孔径小、密度大的复合材料拉伸强度高; 碳化硅含量对复合材料的拉伸强度的影响较小; 双连续复合材料的拉伸强度比泡沫金属都有很大的提高。
2. 在拉伸载荷作用下双连续复合材料的断裂过程与环氧树脂接近, 表现出脆性材料的特征; 载荷较小时双连续结构对复合材料的拉伸性能有一定的协同增强作用, 载荷较大时复合材料的破坏以裂纹扩展模式为主, 使其拉伸强度比树脂/碳化硅复合材料的低。
The authors have declared that no competing interests exist.
| 1 |
[本文引用:1]
近年来，三维连续网络结构陶瓷/金属复合材料的研究引起了国内外 材料科研工作者的重视，并得到了较快发展。其主要原因是：与颗粒增强、纤维增强和晶须增强等常规的陶瓷/金属复合材料相比，三维连续网络结构陶瓷/金属复 合材料的每一种组成相的特性都能够得到保留，并且各相同性，可充分发挥陶瓷相、金属相各自的优势，以获得最佳的综合性能。这种复合材料可获得良好的耐磨性 和减振性等性能，有着广阔的应用前景。对这种复合材料的高效率低成本制备方法的探索已成为目前复合材料学界新的研究热点之一。 本文首先通过对国内外相关文献的分析，对三维连续网...
|
| 2 |
[本文引用:1]
介绍了三维网络陶瓷增强复合材料的内部结构特点、主要制备方法以及摩擦磨损性能和抗冲击性能等研究进展。三维网络陶瓷/金属复合材料可以抑制基体合金的塑性变形和高温软化以及严重的三体磨损,使得复合材料的抗磨性能提高;这种结构有利于将集中在点或面上的应力迅速在空间体范围内分散和传递,提高复合材料的抗冲击能力;同时,这种三维双连续的结构还可能引起结构互锁的效应,使得材料具有更高的损伤容限,材料失效的危险性降低。
|
| 3 |
A new image-plate reader which can read image plates (IPs) having various sizes and shapes has been developed. The machine consists of a rotating laser head to induce luminescence photons from IPs and a porous cylindrical holder made of a composite of cast iron and porous ceramic – so-called `breathnite'. Image plates can be fixed onto the inner surface of the cylindrical holder by evacuating the outer surface through a vacuum chamber with a mechanical pump. Image plates having various shapes and sizes up to 40002× 40061mm can be fixed without covering the open surface on the cylinder. In spite of such flexibility to various applications, the reader produces competitive performances compared with other commercial readers.
|
| 4 |
In this paper an assessment of the processing and properties of interpenetrating phase composites is presented. Such materials, defined as multiphase composites in which each phase is topologically interconnected throughout the microstructure, were the subject of a DOE Basic Energy Sciences sponsored workshop on research needs and opportunities held in July 1989 in Snowmass, Colorado. In place of a report representing the proceedings of the workshop, this paper provides a review of the field in its present, nascent state and identifies some of the critical scientific and technological issues posed by development of this class of material. The emphasis is on processing approaches and properties of interpenetrating phase composites. A list of the participants contributing to the workshop is given.
|
| 5 |
The dry friction and wear behaviors of co-continuous composites SiC/Fe-40Cr against SiC/Al 2618 alloy were investigated on a ring-on-ring friction and wear tester at sliding speed of 30-105 m/s under the load of 1.0-2.5 MPa. The experimental result reveals that the characteristic of two body abrasive wear and oxidation wear mechanisms are present for SiCn/2618 Al composite under higher load and sliding speed. SiC ceramic continuous network as the reinforcement can avoid composite from the third body wear that usually occurs in traditional particle reinforced composite. The mechanically mixed layer (MML) controls greatly the wear rate and friction coefficient of the composites. The composites tested at higher sliding speed exhibit higher value of friction coefficient and fluctuation, which is associated with the intermittent formation and removal of the MML. The wear and stress-strain behaviors of SiCn/Fe-40Cr against SiCn/Al 2168 at 30-105 m/s under 1.0-2.5 MPa were analyzed by finite element method with the software Solidwork2012 Simulation, respectively. The wear and stress-strain behavior of the composite predicted by the FEM correlated well with the experimental results.
|
| 6 |
[本文引用:0]
研究了T6热处理(固溶处理+时效)对复式连通双连续相SiC/A1复合材料的组织和压缩性能的影响.结果表明,经T6热处理后,复合材料基体中第二相共晶硅从粗大的针状变成了细小的粒状,增强了弥散强化效果,时效析出相Mg2Si强化了基体;界面附近的基体中残余应力增大,使复合材料的压缩强度显著提高,材料的弹性模量和塑性稍稍降低.随着固溶时间的延长,复合材料的压缩强度先升高后降低.其影响机制是,随着固溶时间的延长共晶硅扩散充分,球化完全,继而粗化长大,从而提高了弥散强化效果.随着时效时间的延长,材料中的残余应力减小,位错密度降低,时效强化相Mg2Si的强化能力减弱,使复合材料的压缩强度降低.
DOI:
Magsci
|
| 7 |
Abstract The experimental and numerical simulations of mechanical properties of co-continuous composites SiCn/Al produced by infiltration of SiC preforms with melted 2024 Al alloy using Solidwork2012 Simulation code were carried out. The results showed that ultimate tensile strengths of SiCn/Al up to 410 MPa at a failure strain of up to 0.7% without any heat treatment. The compression strength was up to 710 MPa with 2% strain to failure. The composites show an excellent resistance to high cycle fatigue. Fatigue life for specimen was 4.5脳105 cycles for 250 MPa while R=-1.0, and 4.9脳105 cycles for 164 MPa while R=-0.05. Simulated data shows there is different mechanical behavior between SiC structs and Al matrix, difference of elasticity modulus of two constituents occasion difference of generated deflection, Al has taken place large deformation; Due to structural characteristic of SiC, the force on each rib affects other adjacent rib, Al and SiC restrict each other to prevent from producing the strain.
|
| 8 |
[本文引用:1]
在火电厂脱硫方法中，石灰石-石膏湿法烟气脱硫技术在世界上占主导地位，是目前最成熟、应用最广的脱硫技术。然而由于此方法中石灰石、石膏浆液浓度大，且浆液具有腐蚀性，脱硫管道和循环泵面临着严重的腐蚀破坏和浆液冲蚀的问题。通过材料复合技术，将耐腐蚀、耐冲蚀以及高强度的不同材料高效有机的结合为一体是解决传统单一材料耐腐蚀和耐冲蚀性能不能兼顾的问题的有效手段。 本论文以环氧树脂为基体材料，SiC泡沫陶瓷为增强体，采用真空吸注、模压固化的工艺成功制备了SiC泡沫陶瓷/树脂(SiCfoam/EP)双连续相复合材料。在SiC泡沫筋表面制成多孔过渡层...
|
| 9 |
****
|
| 10 |
[本文引用:0]
选用具有连通气孔的多孔有机物作为骨架,利用浸渗工艺,将多孔骨 架浸入一定配比的TiAl浆料中,制备出具有一定孔隙率及高通孔率的TiAl坯体,经低温和高温两个阶段烧结获得性能良好的多孔网状骨架.当烧结温度在1 380 ℃时,网状金属间化合物具有最佳的烧结效果,既能保持很高的通孔率,又保证了材料具有较高的抗压强度.研究了以TiAl网状结构为增强体的Al基复合材料 的摩擦磨损行为和压缩性能.结果表明,TiAl网状结构增强效果明显,复合材料的抗磨损性能和抗压缩性能明显优于基体铝,其磨损行为主要为牯着磨损.
|
| 11 |
The co-continuous AlN composites with different Al contents were fabricated through the squeeze casting of porous AlN preform with varied porosities obtained by carbothermal reduction. The effects of volume fraction of Al phase and the heat treatment temperature on the mechanical properties of composites were investigated. The change of the mechanical properties of composites with the Al content was in line with the mixed rule. With an increase in the Al content, the fracture toughness increased, the Vickers hardness and the flexural strength decreased. The toughen mechanism of composites included ductile rupture and microcrack toughening. The avoiding of excessive interface reaction between AlN and Al was beneficial to the mechanical properties of composites. With an increase in the heat treatment temperature, the stress and the dislocation due to mismatch in the coefficients of thermal expansion increased, the fracture toughness decreased, the vickers hardness and the flexural strength increased.
|
| 12 |
Through in situ reaction synthesis with Ti, Al, Sn and TiC, the porous Ti3AlC2 was prepared as prefabricated part, which was later applied to the fabrication of co-continuous Ti3AlC2/Cu composite by vacuum non-pressure infiltration. The result of observing the microstructure of this composite by scanning electron microscope (SEM) and X-ray diffraction (XRD), together with tests on its compressive strength and fracture mechanism, show that the porous Ti3AlC2 prefabricated part with 54.3% apparent porosity can be prepared by the in situ reaction synthesis, and the vacuum non-pressure infiltration performs effectively in fabricating dense co-continuous Ti3AlC2/Cu composite materials in which the ceramic skeleton and metal skeleton form three-dimensional network structure and reveals close interface bonding, thus resulting in its high strength and good ductility. Moreover, considering the compressive strength 753.8 MPa and the fracture strain 17.8%, it also testifies better mechanical properties.
URL
[本文引用:1]
|
| 13 |
URL
[本文引用:1]
|
| 14 |
[本文引用:1]
|
| 15 |
A pentagonal dodecahedron model of metal foam with open cells was considered for calculation of specific surface area. of the high porosity metals. According to the pentagonal dodecahedron model the authors calculate the specific surface area of nickel foam samples with the cell size of similar to 200 mu m and find it approximate agreement with the results obtained by other methods, and the specific surface area of metal foams is correlated with cell size and the width of cell wall.
|
