Influence of Rolling Treatment on Interfacial Shear Strength of Steel-mushy Al-7graphite Bonding Plate

At room temperature, the rolling treatment of steel-mushy Al-7graphite bonding plate was carried out under different relative reduction. The influence of rolling on interfacial mechanical property of this bonding plate was studied. The results show that, for steel-mushy Al-7graphite bonding plate which is made up of 1.2 mm in thickness 08AI steel plate and 2.0 mm in thickness Al-7graphite layer, there is a nonlinear relationship between interfacial shear strength of bonding plate and relative reduction of rolling. When relative reduction of rolling is smaller than 2.59%, with the increasing of relative reduction, interfacial shear strength of bonding plate increases gradually. When relative reduction of rolling is bigger than 2.59%, with the increasing of relative reduction, interfacial shear strength of bonding plate decreases continuously. When relative reduction of rolling is 2.59%, the largest interfacial shear strength 77.0 MPa can be obtained.

Simultaneously enhanced interfacial shear strength and tensile strength of heterocyclic aramid fiber by graphene oxide

Heterocyclic aramid fibers,a typical kind of high-performance fibers,have been widely used in aerospace and protection fields because of their excellent mechanical properties.However,the application of heterocyclic aramid fibers as a reinforcement is hindered by the weak interfacial combination with matrix materials,especially epoxy.Traditional strategies enhancing the interfacial shear strength(IFSS)usually decrease the tensile strength.Therefore,simultaneous enhancement of both mechanical properties remains a challenge.Herein,we report a novel heterocyclic aramid fiber with high interfacial shear strength(49.3 MPa)and tensile strength(6.27 GPa),in which 4,4′-diamino-2′-chlorobenzanilide(DABA-Cl)and a small amount of graphene oxide(GO)are introduced through in-situ polymerization.Hydrogen bonds andπ–πinteraction between GO and polymer chains trigger the enhancement in crystallinity,orientation,and lateral interaction of the fibers,thus improving the tensile strength and interfacial shear strength of the fibers.Moreover,the interfacial interaction between fiber and epoxy is enhanced due to the improvement of the surface polarity of the fibers caused by DABA-Cl.Therefore,a method to improve both tensile strength and interfacial shear strength of heterocyclic aramid fibers was found by introducing GO and DABA-Cl,which may provide guidance for the design and preparation of other high-performance fibers.

Interfacial mechanical property of steel-mushy Al-20Sn bonding

The bonding of a steel plate to Al-20Sn slurry was conducted using thecasting rolling technique. The surface of the steel plate was defatted, descaled, immersed (inK_2ZrF_6 flux aqueous solution) and stoved. Al-20Sn slurry was prepared using the electromagneticmechanical starring method. The interfacial mechanical property of the bonding plate was researchedto determine the relationship between the diffusion time and the interfacial shear strength. Inorder to identify the mechanism of bonding, the interfacial structure of the bonding plate wasstudied. The results show that at a prebeat temperature of the steel plate of 505 deg C and a solidfraction of Al-20Sn slurry of 35 percent, the relationship between the interfacial shear strength Sand the diffusion time t is S=28.8+4.3t-0.134t^2 +0.0011t^3. When the diffusion time is 22 s, thelargest interfacial shear strength is 70.3 MPa, and the corresponding interface is a new one whichis made up of Fe-Al compound and Fe-Al solid solution alternatively and in a right proportion. Inthis interfacial structure, the interfacial embrittlement does not happen and Fe-Al compound canplay its role in strong combination adequately.

A new method based on the shear lag model for accurate determination of ice adhesion shear strength on solid surface

Accurate measurement of the interfacial shear strength between ice and solid surface has important reference significance for the design of anti-icing and de-icing functional surfaces.In this paper,a new method is proposed based on the shear lag model of a single fiber pulled out from matrix,in order to accurately determine the interfacial shear strength(ISS)between ice and metals.The maximum pull-out force at the initiation of interface debonding is well measured in the pull-out test of a metal fiber embedded in an ice matrix.A shear lag model similar to the pull-out test is established and a closed-form relation between the non-uniform interfacial shear stress and the pull-out force is achieved.When the pull-out force reaches its peak value,the ice/metal ISS can be consequently determined as the maximum interfacial shear stress.Such a method takes into account the stress concentration at the interface,which overcomes underestimation of ice/solid ISS based on the apparent strength in previous studies.The achieved ISS is proven to not only have good convergence,but also be independent of the size and embedded depth of metal fibers.Based on the present method,the enhancing effects of freezing temperature and surface roughness on the ice adhesion are further disclosed.The present research provides a simple and reliable approach to accurately calibrate the ice/solid ISS,which should be of important reference significance for the design and assessment of anti-icing functional surfaces.

Potential of Thai Bast Fibers for Injection Molded PLA Composites

Thailand has a huge variability of bast fiber plants,some of which have been little researched regarding their applicability in composites.Bast fiber(bundle)s from different species were investigated and incorporated into a polylactide(PLA)matrix by injection molding.Hemp and kenaf were used as well-studied fibers,while roselle,Fryxell and paper mulberry are less extensively characterized.Tensile strength,tensile modulus and interfacial shear strength(IFSS)of single fiber(bundle)s were highest for hemp,followed by kenaf,roselle,Fryxell and paper mulberry.Despite the lower tensile strength and IFSS of paper mulberry,the highest tensile strength was achieved for the paper mulberry/PLA composite followed by hemp/PLA.Scanning electron microscope(SEM)analyses showed that the single cells in paper mulberry fiber bundles,in contrast to the other fiber types investigated,were only partially bonded to each other,which explains the lower strength of the fiber bundles.The higher aspect ratio of fiber(bundle)s of paper mulberry in the PLA composite can explain the good composite characteristics.Apart from hemp,paper mulberry shows the best reinforcing effect in the PLA matrix and offers interesting potential for composite applications.Compared to neat PLA,the tensile strength could be increased by 24%and the tensile modulus by 54%.

Bridging Effect and Efficiency of Partly-Cured Z-pin Reinforced Composite Laminates

To study the bridging effect of partly-cured Z-pin,Z-pins with different curing degrees are manufactured by controlling pultrusion parameters.A unit cell is selected to analyze the stress of Z-pinned laminates and the quantitative relationship between the maximum bridging force and Z-pin diameter,embedded length,interfacial shear strength and tensile strength is acquired.The Z-pin″bridging law″test and Z-pin tensile test are carried out to study the effect of Z-pin′s curing degree on bridging effect,and the bridging efficiency is defined to evaluate the reinforcement effect of Z-pin.The modeⅠinterlaminar fracture toughness(G_(ⅠC))is measured by the double cantilever beam test.The experimental results show that Z-pin′s co-curing with laminate matrix can improve the bridging force significantly and the fitting results show a linear relationship between Z-pin curing degree and interfacial shear strength.The three-dimensional images of the surface of pullout Z-pins indicate that the failure mode changed from totally interfacial debonding to a mixed mode.Finally,the reinforcement by partly-cured Z-pin can be used to further enhance the interlaminar toughness.Compared with completely-cured Z-pin,G_(ⅠC) of Z-pin with 67.6% curing degree increases by 47.0%.

Influence of diffusion time on property of steel-aluminum solid to liquid bonding

The bonding of solid steel to liquid aluminum was conducted using rapidsolidification. The influence of diffusion time on interfacial shear strength was studied. Theresults show that when the temperature of aluminum liquid is 700℃ and the preheat temperature ofsteel plate is 250℃, the relationship between diffusion time (t) and interfacial shear strength(σ) is σ =15.1+8.14t-037t^2 +0.005t^3, and the maximum interfacial shear strength is 71.1 MPa.

Study on Mechanical Property in Steel-Aluminum Solid to Liquid Bonding

The bonding of solid steel plate to liquid Al was conducted using rapid solidification. The influence of thickness of Fe-Al compound layer at the interface on interfacial shear strength of bonding plate was studied. The results show that the relationship between thickness of Fe-AI compound layer and interfacial shear strength is 5=30.4+8.51 h-0.51 h2 +0.007 h3 (where h is thickness of Fe-AI compound layer, S is interfacial shear strength). When thickness of Fe-AI compound layer is 10.7 um, the largest interfacial shear strength is 71.6 MPa.

Effect of Interface on Mechanical Property of Steel-mushy Al-20Sn Bonding Plate

The ratio of Fe-Al compound at interace, which could determine the quarttity of Fe-Al compound at the interace of steel-mushy Al- 20 Sn bonding plate, was used to characterize the interfacial structure of steel-mushy Al-20 Sn bonding plate quantitatively. The effect of ratio of Fe-Al compound at interface on interacial shear strength was investigated perfectly. The results show that the relationship between ratio of Fe-Al compound at interace and interfacial shear strength is S = 3.3 ＋ 1.91 t - 0.0135t^2 （ where t is ratio of Fe-Al compound at in- terface and S is interfacial shear strength ）. When the ratio of Fe-Al compound at interface is 71%, the largest interfacial shear strength 70.9 MPa is got. This reasonable ratio of Fe-Al compound at interface is a quarttitative criterion of interfacial embrittlement. When the ratio of Fe-Al compound at interface is higher than 71% , interfacial embrittlement will occur.

The Influence of Preheat Temperature of Steel Plate on Steel-mushy Cu-graphite Bonding

The pressing bonding of steel plate to QTi3.5-3.5 graphite slurry was conducted. Under the conditions of 530 ℃ for the preheat temperature of dies, 45% for the solid fraction of QTi3.5- 3.5 graphite slurry, 50 MPa for the pressure and 2 min for the pressing time, the relationship between the preheat temperature of steel plate and interfacial mechanical property of bonding plate was studied. The results show that when the preheat temperature of steel plate is lower titan 618 ℃ , the interfacial shear strength of bonding plate increases with the increasing of the preheat temperature of steel plate. When the preheat temperature of steel plate is higher than 618 ℃ , the interfacial shear strength decreases with the increasing of the preheat temperature of steel plate. When the preheat temperature of steel plate is 618 ℃ , the highest interfacial shear strength of bonding plate of 127.8 MPa can be got.

Influence of aluminum solid fraction on property of steel-mushy aluminum bonding plate

The interfacial shear property of steel-mushy aluminum bonding plate was studied, and the relationship between aluminum solid fraction and the interfacial shear strength of bonding plate was determined. The results showed that when aluminum solid fraction is 34.3 %, the maximum interfacial shear strength of bonding plate is 71 .0 MPa.

Study on Bonding of Steel-mushy Al-7graphite

The bonding of steel-mushy Al-7graphite was studied. The relationship between interfacial shear strength of bonding plate and solid fraction of Al-7graphite mushy was obtained, and the interfacial structure of bonding plate was determined. The results showed that: under the condition of 500 degreesC for preheat temperature of steel plate and 10 mm/s for rolling speed, the largest interfacial shear strength of bonding plate was 70.1 MPa when solid fraction of Al-7graphite mushy was 34.6%.

Improvement in Impact Energy Absorption of UD-CFRP by Sub-Micron Glass Fiber into Its Matrix

CFRPs have high strength despite low density, but little impact resistance. In addition, the debonding of the interface between reinforcement fiber and matrix causes one of the fractures of FRPs. Therefore, the purpose of this study is to investigate the interfacial bonding characteristics between the reinforcement fiber and matrix of FRPs, not only under static loading but also under dynamic loading. Moreover, an effective method to improve the impact resistance of FRPs from the viewpoint of interfacial bonding characteristics was proposed. First, two types of UD-FRPs in which the reinforcement fiber was glass fiber or carbon fiber, were prepared to investigate the energy absorption under a bending load. A bending load was applied to the specimen statically and dynamically to measure the energy absorption until failure. The interfacial bonding characteristics between the reinforcement fiber and matrix were measured using a fragmentation method with a single fiber-embedded specimen. A dynamic tensile load was applied to the specimen using a tensile-type split Hopkinson pressure bar apparatus. Test results showed that the energy absorption of UD-CFRP decreased with an increase in strain rate, whereas that of UD-GFRP increased with an increase in strain rate. When the epoxy resin was modified by adding sub-micron glass fiber, both the interfacial shear strength between the carbon fiber and matrix, and the energy absorption of UD-CFRP improved.

Influence of processing temperature on interfacial behavior of HKT800 carbon fiber with BMI and epoxy matrices

This paper aims to study the effect of processing temperature on interfacial behavior of HKT800 carbon fiber composites with epoxy and Bismaleimide（BMI） matrix.Referring to the processing conditions of the composite, various processing-heat treatments were conducted on HKT800 and the extracted sizing content declines with increasing temperature.Chemical analysis shows that the HKT800 sizing is epoxy-type and reactive at 200 C.The interfacial shear strength（IFSS） of HKT800/epoxy and HKT800/BMI was investigated by micro-droplet method, for which the composites were fabricated with modeling temperature schemes referring to different diffusion, cure and post-cure stages.It shows that diffusion temperature and conversion degree of the resin both enhance the interfacial adhesion of HKT800/epoxy composite.For the HKT800/BMI composite,the diffusion temperature shows a insignificant effect on the IFSS.FTIR analysis indicates that sufficient reactions are achieved between HKT800-sizing and epoxy resin, however only partial reactions are observed between the sizing and BMI.Moreover, the presence of the sizing can evidently improve the wettability of HKT800 with epoxy resin but is unfavorable for HKT800 with BMI.