Carbon Fiber Breakage Mechanism in Aluminum(Al)/Carbon Fibers(CFs) Composite Sheet during Accumulative Roll Bonding(ARB) Process

We put forward a method of fabricating Aluminum(Al)/carbon fibers(CFs) composite sheets by the accumulative roll bonding(ARB) method. The finished Al/CFs composite sheet has CFs and pure Al sheets as sandwich and surface layers. After cross-section observation of the Al/CFs composite sheet, we found that the CFs discretely distributed within the sandwich layer. Besides, the tensile test showed that the contribution of the sandwich CFs layer to tensile strength was less than 11% compared with annealed pure Al sheet. With ex-situ observation of the CFs breakage evolution with-16%,-32%, and-45% rolling reduction during the ARB process, the plastic instability of the Al layer was found to bring shear damages to the CFs. At last, the bridging strengthening mechanism introduced by CFs was sacrificed. We provide new insight into and instruction on Al/CFs composite sheet preparation method and processing parameters.

Square concrete columns strengthened with carbon fiber reinforced plastics sheets at low temperatures

Twenty-one square concrete columns were constructed and tested. The testing results indicate that bonded carbon fiber reinforced plastics(CFRP) sheets can be used to increase the strength and improve the serviceability of damaged concrete columns at low temperatures. The failure of the specimens,in most cases,takes place within the middle half of the columns. And the failure of strengthened columns is sudden and explosive. The CFRP sheets increase both the axial load capacity and the ultimate concrete compressive strain of the columns. The ultimate loads of strengthened columns at-10,0 and 10 ℃ increase averagely by 9.09%,6.63% and 17.83%,respectively,as compared with those of the control specimens. The axial compressive strength of strengthened columns is related to the curing temperatures. The improvement of axial compressive strength decreases with reducing temperature,and when the temperature drops to a certain value,the improvement increases with falling temperature.

Experimental and simulation research on thermal stamping of carbon fiber composite sheet

To improve the manufacture efficiency and promote the application of composites in the automobile industry, a new composite forming method, thermal stamping, was discussed to form composite parts directly. Experiments on two typical stamping processes, thermal bending and thermal deep drawing, were conducted to investigate the forming behavior of composite sheets and analyze the influence of forming temperature on the formed composite part. Experimental results show that the locking angle for woven composite is about 30°. The bending load is smaller than 5 N in the stamping process and decreases with the increase of temperature. The optimal temperature to form the carbon fiber composite is 170 ℃. The die temperature distribution and the deformation of composite sheet were simulated by FEA software ABAQUS. To investigate the fiber movement of carbon woven fabric during stamping, the two-node three-dimension linear Truss unit T2D3 was chosen as the fiber element. The simulation results have a good agreement to the experimental results.

Study on High Strength Concrete Confined by Continuous Carbon Fiber Sheet

Eight high strength concrete (HSC) prisms strengthened with continuous carbon fiber sheet(CFS)were tested.As a result of the confinement provided by CFS,the concrete would fail at a greater strain than the unconfined and then a significant increase in ductility can be achieved.The lateral pressure exerted by CFS would increase the compressive strength of the concrete,resulting in higher load bearing capacity.This paper proposes the stress strain curve of this kind of hybrid specimen,which agrees well with the test results.Based on the stress strain relationship and the assumptions proposed in this paper,a computer program was developed to analyze HSC columns,confined by CFS,which were subjected to axial compression and biaxial bending.The results shown in this paper indicate that the ductility of HSC column is significantly improved and the strength is also increased by some degree.

MECHANICAL PROPERTIES OF CONTINUOUS CARBON FIBER SHEET USED IN STRENGTHENING REINFORCED CONCRETE MEMBERS IN BENDING

This paper discusses the method of determining the tensile strength and modulus of elasticity of continuous carbon fiber sheet.Five simply supported beams strengthened by CFS were tested.Based on th experiment,a computer analysis program is developed and a simplified formula is proposed.The calculated results agree well with the experimental results.The design method suggested by this paper can meet the engineering requirements.

Improved wettability and mechanical properties of metal coated carbon fiber-reinforced aluminum matrix composites by squeeze melt infiltration technique

In order to improve the wettability and bonding performance of the interface between carbon fiber and aluminum matrix,nickel-and copper-coated carbon fiber-reinforced aluminum matrix composites were fabricated by the squeeze melt infiltration technique.The interface wettability,microstructure and mechanical properties of the composites were compared and investigated.Compared with the uncoated fiber-reinforced aluminum matrix composite,the microstructure analysis indicated that the coatings significantly improved the wettability and effectively inhibited the interface reaction between carbon fiber and aluminum matrix during the process.Under the same processing condition,aluminum melt was easy to infiltrate into the copper-coated fiber bundles.Furthermore,the inhibited interface reaction was more conducive to maintain the original strength of fiber and improve the fiber−matrix interface bonding performance.The mechanical properties were evaluated by uniaxial tensile test.The yield strength,ultimate tensile strength and elastic modulus of the copper-coated carbon fiber-reinforced aluminum matrix composite were about 124 MPa,140 MPa and 82 GPa,respectively.In the case of nickel-coated carbon fiber-reinforced aluminum matrix composite,the yield strength,ultimate tensile strength and elastic modulus were about 60 MPa,70 MPa and 79 GPa,respectively.The excellent mechanical properties for copper-coated fiber-reinforced composites are attributed to better compactness of the matrix and better fiber−matrix interface bonding,which favor the load transfer ability from aluminam matrix to carbon fiber under the loading state,giving full play to the bearing role of carbon fiber.

Electroless nickel plating on the surface of carbon fibers

The electroless nickel plating on the surface of carbon fibers was prepared by pretreating the carbon fibers in order to increase their conductivity,and consequently enhance the EMI shielding effectiveness of the composites.The relationship between the performance of depositing coat and pH value,temperature,reaction time and the way of agitation was studied.Results show that the depositing quality is stable under pH between 4.5 and 5.0,temperature between 75 ℃ and 85 ℃,reaction time for 10 min and air agitation.The uniform and compact nickel layer deposited on carbon fibers was proved by XRD and SEM,and the electrical resistivity of carbon fibers with nickel coating was tested.Results indicate that the electrical resistivity of carbon fibers with electroless nickel plating is decreased by an order of magnitude compared with that of carbon fibers.It means that nickel coating can greatly improve the electromagnetic interference shielding properties of carbon fibers.

弯-剪-扭复合受力CFRP布加固RC梁抗扭性能细观数值分析

为了研究弯-剪-扭复合受力条件下碳纤维增强复合材料(carbon fiber reinforced polymer, CFRP)布加固钢筋混凝土(reinforced concrete, RC)梁的抗扭性能,建立体现混凝土材料非均质性、钢筋-混凝土黏结滑移关系和CFRP布-混凝土相互作用关系的细观数值分析模型。由于缺乏CFRP布加固RC梁在弯-剪-扭复合受力作用下失效破坏的典型物理试验,采用复合对比验证法对数值模型的合理性进行验证,即分别与单独受剪、单独受扭以及受弯-扭复合作用下RC梁和CFRP布加固RC梁的试验结果进行对比验证。进而,基于建立的细观数值分析模型探究了配纤率和扭弯比对CFRP布加固RC梁在弯-剪-扭复合受力作用下抗扭力学性能的影响。结果表明:1)采用CFRP布加固能够显著提高RC梁的峰值扭矩;2)随配纤率增加,RC梁损伤分布范围逐渐变大,CFRP布应变逐渐减小,梁整体峰值扭矩增大,但其增大幅度减小;3)随扭弯比增加,RC梁裂缝分布愈加集中,裂缝与水平方向夹角逐渐减小,梁整体峰值扭矩增大,CFRP布应变减小。建立的考虑弯-剪-扭复合受力作用的数值模拟方法可为后续研究复杂应力状态下CFRP布加固RC梁尺寸效应行为等奠定基础。

钢渣基CO_(2)矿化板材的制备与性能研究

采用铺浆注模、压制脱水成型、CO_(2)养护等工艺措施制备钢渣板材,考察了原材料掺量、脱水压力、养护方式等对钢渣板材力学性能的影响。试验结果表明:水胶比0.35抗折强度最高;随着水泥、熟石灰以及木质纤维掺量的增加,板材的抗折强度均提高;随脱水压力的增加,板材的抗折强度先提高后降低;养护时间延长,板材的抗折强度提高;耐碱玻璃纤维长度减小,板材的抗折强度提高,耐碱玻璃纤维掺量为1.5%时,板材抗折强度最高。

自成核行为在CF/PPS复合材料中的差异性与普适性

以半结晶高分子为基体的碳纤维增强热塑性复合材料,其基体的结晶行为将受到碳纤维表面性质与热历史的共同影响。当这种材料在经历反复加热冷却的热循环过程时,基体会产生自成核行为,其结晶过程变得更加复杂。通过三种T300级碳纤维分别制备了碳纤维增强聚苯硫醚(CF/PPS)复合材料,并探究了二次熔融温度与CF/PPS复合材料结晶行为的关系,揭示了不同碳纤维表面性质对CF/PPS复合材料自成核行为的影响。在此基础上阐明了CF/PPS复合材料基体自成核与CF异相成核的竞争关系。最后,通过冲压成型制得具有自成核行为的CF/PPS复合材料角片,验证了自成核对于CF/PPS复合材料二次热成型技术的有效性与重要性。

Improved damage tolerance and oxidation resistance of (Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))B_(2)–SiC by introducing chopped carbon fibers

High-entropy diborides(HEBs)are considered as promising high-temperature structure materials owing to their high melting point and excellent thermal stability.However,the intrinsic brittleness is the main obstacle that seriously limits their practical applications.To overcome with this obstacle,carbon fibers(Cf)with outstanding mechanical properties are used in the present work as a first attempt to improve the damage tolerance of HEBs.The as-prepared C_(f)/(Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))B_(2)–SiC composite(C_(f)/HEB–SiC)shows high relative density(97.9%)and good mechanical properties with flexural strength of 411±3 MPa and fracture toughness of 6.15±0.11 MPa·m^(1/2).More importantly,the damage tolerance parameter(Dt)has increased from 0.10 m^(1/2) for HEB–SiC to 0.29 m^(1/2) for C_(f)/HEB–SiC.Through microstructural analysis and Vickers indentation of the composite,the toughening mechanisms are disclosed.The carbon fibers coated with carbon coatings demonstrate unique capacity for prolonging the crack propagation path,which promotes the reliability of the composite effectively.Moreover,the C_(f)/(Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))B_(2)–SiC composite also exhibits good static oxidation resistance in the temperature range of 1100–1500℃in air due to the formation of the protective oxide layer constituting of multicomponent oxides(Zr)HfTiO4 and(Zr)Hf_(6)Ta_(2)O_(17) embedded in a continuous SiO_(2) glass.These results are promising,and this primary work can be used as a reference to the synthesis of C_(f)/HEBs for thermal protection materials under hightemperature serving conditions.

环氧树脂/碳纤维复合材料模压制品力学性能影响因素分析

通过正交实验研究模压工艺参数对环氧树脂/碳纤维(EP/CF)片状模塑料SMC模压成型制品力学性能的影响,分析了各工艺参数对制品拉伸强度和弯曲强度的影响趋势。通过方差分析,得到工艺参数对于拉伸强度的影响大小为合模速度>模压温度>模压压力>保压时间,工艺参数对于弯曲强度的影响大小为合模速度>模压压力>模压温度>保压时间,同时得到了对拉伸强度和弯曲强度的显著性因素;研究了拉伸破坏模式及失效机理,采用K-均值方法并选取典型试样观察,发现环氧树脂与基体的结合程度是影响拉伸强度的原因。

往复水平力作用下CFS约束混凝土柱变形能力试验研究

介绍了8根碳纤维布(CFS)约束的混凝土柱和1根混凝土柱在竖向力和往复水平力作用下的试验。研究缠绕CFS的混凝土 柱的屈服后变形能力。结果表明,缠绕CFS,可以使混凝土柱具有良好的屈服后变形能力;增大纤维特征值能增大变形能 力;为了达到同样大的变形能力,轴压比大的混凝土柱的纤维特征值应比轴压比小的混凝土柱大;但纤维特征值大于一定值 后,增大纤维特征值对提高混凝土柱屈服后变形能力的作用不大,轴压比对CFS约束混凝土柱的变形能力的影响也不大。

无机酸掺杂聚苯胺/碳纤维复合海洋电场传感器电极

碳纤维电极具有成本低、化学稳定性好、性能可调控等优点,可用于开发高性能海洋电场传感器.利用电化学原位聚合法制备盐酸、硫酸、磷酸掺杂的聚苯胺/碳纤维(PANI/CF)复合电场电极,提高其电化学性能与电场响应性能.结果表明:碳纤维表面生成致密的导电聚苯胺膜,并在循环伏安测试中出现特征氧化还原峰;电化学阻抗分析显示PANI/CF复合电极低频(0.01 Hz)阻抗值至少降低为空白电极的1/118,利于对水下微弱电场信号进行响应.在电场响应性能测试中,盐酸掺杂PANI/CF复合电极电位漂移量最低达1.77 mV/d;能够较好地响应1 mV/10 mHz的低频率低强度电场信号;误差线性度最小值为0.111%,在同类电极中具有最好响应灵敏度.该新型复合电场电极制备方法简单、成本低廉,有助开发新一代低成本、高性能海洋电场传感器.

考虑二次受力CFS加固RC梁受弯承载力分析

推导了碳纤维布加固钢筋混凝土梁在考虑和不考虑二次受力及各种破坏情形下的正截面抗弯承载力计算公式 ,定量。

碳纤维-聚醚醚酮改性促进材料成骨活性和抗菌性能的研究进展

碳纤维-聚醚醚酮(carbon fiber-polyetheretherketone,CF-PEEK)因生物安全性、射线可穿透性、与皮质骨弹性模量的高匹配度等诸多优异性能,而被认为是骨科及牙科领域极具潜力的植入材料。如何增强CF-PEEK的生物活性和抗菌性,提高其与骨组织的结合能力,是CF-PEEK表面改性中的研究热问题。本文就碳纤维-聚醚醚酮改性促进材料成骨活性和抗菌性能的研究进展及应用前景进行综述。

CFS加固混凝土墩柱温度自应力弹性解及影响参数研究

考虑到碳纤维布(C FS)与混凝土的热胀系数不同,建立了CFS加固的任意形状横截面混凝土构件因日照辐射或骤然降温引起的温度自约束变形求解方程。进而推导了CFS加固混凝土矩形、箱形墩柱在指数和均匀温度梯度下的温度自应力弹性解。最后就弹性解讨论了CFS厚度、热胀系数、弹性模量和混凝土强度等级(弹性模量)、截面宽度、高度等因素对C FS加固混凝土矩形墩柱温度自应力的影响。

Permeable carbon fiber based thermoelectric film with exceptional EMI shielding performance and sensor capabilities

Thermoelectric(TE)technologies offer a promising approach for directly converting skin heat into electricity for wearable electronics.Recognizing p-type Sb2Tes and n-type BizTes as top-performing materials at room temperature,their rigid inorganic structure,with ultralow moisture permeability,poses challenges in warm and humid conditions,fostering bacterial growth and potential skin issues.To address this issue,we developed a cross-linked core-shell structure by electrodepositing Sb_(2)Te_(3)(Bi_(2)Te_(3))onto carbon fiber(CF).This architecture significantly improved the electrical conductivity and the Seebeck coefficient,resulting in a remarkable 300-fold increase in the power factor compared to that of pure CF.The CF/Sb_(2)Te_(3) and CF/Bi2Te films demonstrated optimal power factors of 450 and 121μW·m^(-1)·K^(-2),respectively.Moreover,the fabricated films exhibited outstanding moisture permeability,over 3000 g·m^(-2)·d^(-1),exceptional electromagnetic interference shielding efficiency approaching 93 dB,and versatility as sensors for language assistance and respiratory monitoring.These attributes underline their broad applicability,emphasizing their suitability for human health protection in diverse scenarios.

CFS抗剪加固钢筋混凝土梁的耐火性能研究(英文)

采用厚型防火涂料对3根碳纤维布抗剪加固钢筋混凝土梁和1根对比梁进行ISO834标准升温条件下的恒载升温耐火性能试验,得到试验梁的测点温度随时间增加的分布关系。分析不同加载方式、剪跨比、加固量和防火保护层厚度对高温下CFRP抗剪加固梁的破坏形态及耐火极限的影响。试验研究表明:剪跨比是高温下影响CFRP抗剪加固梁耐火极限和破坏形态的主要因素;抗剪加固防火涂料的厚度可以提高剪切破坏的耐火极限,但不改变弯曲破坏的耐火极限。编制了设有厚型防火涂料保护的碳纤维抗剪加固混凝土梁的截面温度场计算程序,通过试验结果验证程序的正确性。为全面考虑影响高温下碳纤维抗剪加固钢筋混凝土梁耐火极限的因素提供补充。

碳纤维/双马树脂复合材料初始热损伤的影响规律

针对碳纤维/双马树脂(CF/BMI)复合材料的初始热损伤问题,以常用的CCF300/QY891复合材料为研究对象,采用实验方法,研究加热温度和加热时间对力学性能的影响规律、初始热损伤的损伤机理,分析硬度与初始热损伤程度之间的关系。结果表明:拉伸强度、压缩强度和剪切强度随加热温度的升高、加热时间的增加而呈下降趋势;除360℃下加热60 min时的拉伸模量、300℃下加热5 min时的压缩模量略有下降外,弹性模量在其他加热温度和时间时,基本保持不变;洛氏和巴氏硬度随加热温度、加热时间的变化趋势,与力学性能的变化基本同步。因此可通过测定硬度的方法确定CF/BMI复合材料的初始热损伤程度。