Study on Interface Microstructure and Bonding Properties of Hot-Rolled Nickel-Based Composite Plate

In this paper, the interface microstructure, elements’ diffusion features at the interface, and bonding properties in nickel-based alloy/carbon steel clad composite prepared by vacuum hot-roll bonding were investigated, comprehensively. The influence of element distribution on the interface bonding strength was revealed as well. The results showed that there was a 13 μm thick diffusion layer at the interface of nickel-based alloy/carbon steel composite plate, which was beneficial to a strong bond between nickel-based alloy and carbon steel, as well as the stable transition of mechanical properties in the thickness direction. Kirkendall voids and fine-grained structure (the grain size is about 41.5 nm) were observable by peeling off the nickel-based alloy cladding, which greatly promoted element diffusion and enhanced the interfacial bonding strength of the nickel-based alloy/carbon steel composite plate. The diffusion coefficient of Ni at the interface was about 2 orders of magnitude larger than that of nanocrystalline Fe. The shear strength reached up to 453 MPa, which was much higher than the minimum of 140 MPa defined in ASTM A-264 specifications. Furthermore, in the shear test, the fracture occurred on the X52 carbon steel side at the contact rather than at the composite plate interface.

Surface Optimization of ZrC–SiC Inner Layer to Enhance Ablation Property of SiC/ZrC–SiC Multi-Layer Coating for C/C Composites

A ZrC–SiC inner layer was fabricated on carbon/carbon composites by pack cementation at different temperatures, aiming to prepare a transition layer for subsequent deposition of SiC and ZrC–SiC layer by chemical vapor deposition and plasma spray. Results show that the structure and phase composition of the inner layer significantly affected the interface bonding strength and thermal shock resistance of the multilayer, which played a vital role in resisting ablation. The jagged and porous surface of the inner layer led to forming a root-like pinning interface, generating a sawtooth combination between the layers. Moreover, the inner layer with high SiC content decreased the coefficient of thermal expansion mismatch between the inner and outer layers. Therefore, the enhanced ablation resistance of the optimum coating was attributed to the improved interface bonding strength and thermal shock resistance caused by the ZrC–SiC inner layer with rough and porous surface structure.

Laboratory Investigation on the Interface Bonding between Portland Cement Concrete Pavement and Asphalt Overlay

The interface bonding between Portland cement concrete (PCC) pavement and hot-mix asphalt (HMA) overlay plays an important role in the performance of the composite pavement. This research conducted a series of comprehensive laboratory studies to investigate the influence factors of the interface bonding strength using a self-designed direct shear test apparatus that can simultaneously apply normal stress and shear stress on a specimen. Four kinds of commonly used tack coat materials were systematically tested and compared under various combinations of normal stress and temperature. Then, coupling effects of the normal stress and temperature on the interface bonding between PCC and HMA were analyzed. The test results show that temperature has a significant impact on the adhesion of the tack coat. Emulsified asphalt was considered the optimal tack coat material because of its simple construction method. In addition, it was found that a damaged interface could still provide considerable bonding strength. Normal stress generated by traffic loads was beneficial to the interface bonding strength, especially at lower temperatures. The temperature had a significant effect on interface bonding and played a leading role in the failure mode of interface bonding.

Interface Bonding Behavior of Concrete-Filled Steel Tube Blended with Circulating Fluidized Bed Bottom Ash

The interface bonding behavior between the steel tube and the concrete of concrete-filled steel tube (CFST) blended with circulating fluidized bed bottom ash (CFB-BA) was investigated in this study. A total of 8 groups of CFSTs stub columns were prepared with different dosage of CFB-BA, water-binder ratio (W/B), and interface bonding length. A series of push-out tests were carried out to acquire the data representing the interface bonding behavior. The results show that the dosage of CFB-BA has a direct effect on interface bonding behavior of CFST. CFB-BA can improve the interface bonding behavior of CFST. The highest ultimate bonding load and strength are achieved when the dosage of CFB-BA is 30%. When the dosage of CFB-BA increases to 50%, its interface bonding behavior decreases, but is still better than that of CFST without CFB-BA. W/B has a negative correlation with the interface bonding behavior of CFST. While the W/B increases, the interface bonding load and strength of CFST decreases. The increase of the interface bonding length can improve the interface bonding load, but cannot improve the interface bonding strength.

Effect of Pulse Current-Assisted Rolling on the Interface Bonding Strength and Microstructure of Cu/Al Laminated Composite

In this paper, Cu/Al laminated composite was prepared by adopting the pulse current-assisted rolling method, and the microstructure and mechanical properties of the material were investigated. The results showed that the Cu/Al laminated composite with pulsed current was significantly strengthened. The composite interface of Cu/Al laminated composite with pulse current-assisted rolling was found without intermetallic phase, and its bonding mode was mainly mechanical combined. The number of reticulated ridges increased at the shear interface. The small cracks on the copper surface were firmly embedded in the aluminum metal. There were obvious folds on the copper surface without aluminum embedding. The structural change of the bonding interface increases the contact area between copper sheet and aluminum sheet, thereby enhancing the bonding strength of the Cu/Al laminated composite.

A study on the GA-BP neural network model for surface roughness of basswood-veneered medium-density fiberboard

Roughness is an important property of wood surface and has a significant influence on the interface bonding strength and surface coating quality. However, there are no theoretical models for basswood-veneered medium-density fiberboard (MDF) by fine sanding from existing research work. In this paper, the basswood-veneered MDF was fine sanded with an air drum. Orthogonal experiment was implemented to study the effects of abrasive granularity, feed rate, belt speed, air drum deformation and air drum pressure on the surface roughness of basswood-veneered MDF. The simulation models of the parallel-grain roughness and the vertical-grain roughness of the sanded surface were conducted based on the BP (error back propagation) neural network, which was optimized by a genetic algorithm (GA) (GA-BP neural network), and these models were verified by extensive experimental data. The results showed that the influence of sanding parameters on parallel-grain roughness was similar to that on vertical-grain roughness. The order of influence was that: abrasive granularity > belt speed > feed speed > air drum deformation and air drum pressure. Based on the work, the parallel-grain roughness and vertical-grain roughness of basswood-veneered MDF could be well predicted by the GA-BP neural network. The average relative errors on parallel-grain roughness and vertical-grain roughness were 3.4% and 1.9%, respectively.

A new strategy of reusing abandoned carbon fiber reinforced plastic: Microstructures and properties of C/C composites based on recycled carbon fiber

A new strategy of recycling and reusing abandoned carbon fiber reinforced plastics (CFRP) is proposed: CFRPs are first fully carbonized to CF reinforced carbon (C/C) preforms, and then are manufactured into high value-added C/C composites. The results showed that the carbon residue rate of epoxy-resin (EP) matrix was fully recovered as the decomposition route of EP matrix was changed by charring agent. The recycled CF (rCF) was not markedly oxidized or thermally damaged, and possessed comparable properties with those of the virgin CF (vCF) after pyrolysis. The pyrolytic char had no obvious negative effect on the densification efficiency of the rCF reinforced carbon (rCF/C) composites. Both of the rCF/C and vCF reinforced carbon (vCF/C) composite bodies were quite dense, and exhibited almost no difference in their microstructures. The rCF/C and vCF/C composites therefore had quite close interface bonding strength (12.6 MPa and 13.0 MPa, respectively), and bending strength (106.4 MPa and 111.5 MPa, respectively). Furthermore, the rCF/C composites possessed comparable ablative rate with that of the vCF/C composites. The rCF/C composites derived from abandoned CF/EP composites present a great potential to be used as substitutes for vCF/C composites owing to their indistinguishable properties.

Influence of Layer Thickness and Continuous Carbon Fiber on the Mechanical Property of 3D Printed Polyamide

3D printed carbon fiber reinforced composites (CFRP) have shown great potential in lightweight application. Here, we report a prepreg carbon fiber reinforced polyamide composite by fused filament fabrication 3D printing process. The influence of layer thickness and carbon fiber layers on mechanical properties of 3D printed parts was well studied. With the incorporation of prepreg carbon fibers, the value of tension and flexural strengths of 3D printed CFRP parts could achieve 2.7 and 13.6 times compared to neat polyamide, respectively. Result illustrates that with the prepreg process the carbon fiber have good interface bonding strength with neat polyimide. This work could also be used for more 3D printing composite systems.

Study on the Interface Constitutive Relation between Carbon Fiber Fabric and Steel

Peeling failure at the interface is one of the main failure modes for CFRP (Carbon Fiber-Reinforced Polymer)-reinforced steel structures. However, there are very few reported studies on the bond-slip relationship at the CFRP-steel interface. A series of simple shear tests were carried out in the present paper. The influence of the fiber fabric’s width and thickness, the surface roughness of the steel sheet, and the thickness of the adhesive layer on the bonding performance of the CFRP fabric to steel interface was considered. The interface constitutive model and bonding strength model were further established under multiple factors. The results show that with the decrease of the surface roughness, the interface’ ultimate peeling load increases gradually, and the failure has a tendency to develop from a glue-steel interface to a glue-CFRP interface. The test pieces that were subjected to sand blasting obtained the peak value of the ultimate peeling load. This indicates that sand blasting can effectively enhance the interface bonding strength. The theoretical values obtained via the interface prediction model are consistent with the experimental values. This proves that the newly developed interface prediction model can effectively predict the local bonding slip and bonding strength of the interface.