Good Bending Research Articles

In-situ synthesis and microstructural evolution of a SiC reinforced Al-50Si composite exhibiting exceptional thermal properties

Incorporating carbon nanotubes (CNTs) into Al-Si alloy to prepare in-situ SiC/Al-Si composites enhances thermal conductivity (TC) and reduces the coefficient of thermal expansion (CTE). However, challenges include CNTs aggregation and uneven SiC distribution. This study uses fluidized bed chemical vapor deposition (FBCVD) to achieve uniform CNTs coverage on Al-50Si powder. Subsequent powder hot extrusion and heat treatment above the eutectic temperature enable a gradual reaction between CNTs and Al/Si atoms, resulting in uniformly dispersed SiC within the SiC/Al-50Si composite. The formation mechanism of in-situ SiC particles and their impact on the microstructure, thermal and mechanical properties of the composite are further investigated. The formation process involves a two-step chemical reaction: lamellar Al4C3 phases transform into lamellar eutectic SiC + Al phases, which then transition into polyhedral SiC particles through epitaxial growth. This in-situ formation of SiC particles also impedes Si growth during heat treatment, refining Si particles and enhancing the composite’s properties. The resulting in-situ SiC/Al-50Si composite exhibits excellent thermal and mechanical properties, including a high TC of ∼162 Wm-1K−1, a low CTE of ∼ 8.7 × 10-6/K, and a good bending strength of approximately 253 MPa at room temperature.

Preparation mechanism and characterization of PET/Cu composite foils

PET/Cu composite foils are expected to have widespread applications due to their lightweight, good bendability and excellent electrical conductivity. However, efficiently and stably preparing copper cladding layers on the surface of PET film with good bonding to the substrate remains a challenge. In this study, by optimizing the process route and adopting a synergistic method involving electroless plating and electroplating, PET/Cu composite foils with excellent conductivity and robust bonding can be successfully prepared. The experimental results indicate that the optimal performance of PET/Cu composite foils is achieved when the PET substrate is roughened with KMnO4/H+ solution, activated with salt-based colloidal palladium, subsequently treated with a weak alkaline electroless nickel plating solution for 5 min, and plated copper at a current density of 0.4 A·dm−2. The adhesion strength of the PET/Cu composite foils meets the ASTM 5B standard and the electrical conductivity reaches up to 4.17 × 107 S/m. The method proposed in this study offers an efficient and concise approach for preparing high-quality PET/Cu composite foils that hold great potential for diverse applications in flexible copper clad laminates.

Rapid-annealed FeSiBPCu nanocrystalline alloy with high Bs approaching 1.9 T and good bendability

To promote energy savings, high efficiency and miniaturization of power electronic devices, Fe–Si–B–P–Cu nanocrystalline soft magnetic materials with high saturation magnetization (Bs) parallel to that of the 6.5 wt% Si steel and low coercivity (Hc) are desired. In this work, 30 μm-thick Fe84Si3B10P2Cu1 and Fe84.5Si3B9.5P2Cu1 (at.%) amorphous/nanocrystalline precursor ribbons were melt-spun, which has high Fe contents comparable to that of the 6.5 wt% Si steel. These ribbons consist of an amorphous matrix and pre-existing α-Fe of approximately 28–30 nm in size possessed relatively low and similar-value activation energy of nucleation and growth in the range of 224–249 kJ/mol. Which could induce strong crystallization competition and effectively suppress coarsening of the pre-existing α-Fe. The Fe84Si3B10P2Cu1 nanocrystalline alloy obtained by rapid-annealing (∼100 °C/s) the amorphous/nanocrystalline precursor at 480 °C for 30 s (Fe84-480) exhibited a fine and uniform nanostructure containing α-Fe with small average grain size of approximately 23.1 nm and high volume fraction. The Fe84-480 alloy possessed a high Bs of approximately 1.88 T, a low Hc of 8.6 A/m, and good bendability revealed by relatively large bending fracture strain of ∼1.65%, making it a promising soft magnetic material for power electronic devices.

Ti3C2T x MXene Based Electro-Ionic Soft Actuator with Potential for Wearable Finger Straps.

Soft electro-ionic actuators have received extensive research and attention due to their advantages such as low voltage response and adjustable deformation. However, they have not been able to enter the actual industry application like traditional rigid actuators; one of the reasons may be that the kinematic properties of actuators have been less studied. The electro-ionic actuator based on Ti3C2T x MXene-CNT/PPy electrode prepared in this paper shows good bending displacement (18.8 mm) and strain (0.63%) under 4 V voltage. In this article, the overlapping nature and exponential function relationship of the actuator end-point trajectories are preliminarily discussed, and the morphology change and cubic polynomial function relationship of the actuator body are considered. Moreover, in application, a novel proof-of-concept model of smart wearable finger straps is proposed. This study is a unique attempt and is hoped to provide a new research perspective in the field of soft electro-ionic actuators.

High-precision silver electrode based on PEN substrate with robust mechanical performance

Wearable electronics are becoming more and more popular, and in order to ensure the safety and accuracy of wearable electronics, the requirements for the refinement and stability of flexible electrodes are getting higher and higher. The reduction of the amount of ink jet and the reduction of surface charge density and electrostatic stress near the nozzle hole can significantly improve the jetting state of the ink. And nozzle voltage is a key factor that affects them. The spreading of ink droplets on the substrate and the formation of a specific pattern is a dynamic process, which is closely related to the properties of the substrate and the state of the ink droplets. In this paper, PEN is used as the substrate to print silver electrode, with its good thermal stability and good mechanical properties. In order to solve these problems and improve the accuracy of the electrode pattern on PEN substrate, a joint control method of ink drop spacing and nozzle voltage is proposed. It is found that the accuracy of the pattern increases with the increase of the drop spacing. At 45 μm, 90.91 % of the pattern accuracy with the ideal pattern can be achieved. As the nozzle voltage decreases, so does the satellite spot. And at 25 V, it can achieve satellite-free spot printing. Because this method avoids the adjustment of ink properties and the regulation of voltage waveform, this advancement provides a simpler solution for patterned high-precision printed silver electrodes based on flexible substrates. In addition, a silver electrode with a resistivity of 3.43 μΩ·cm was obtained at an annealing temperature of 160 °C. The resistivity change of the electrode only 7.58 % under 5000 times of bending. This is very rare in flexible electrodes.The silver film on the PEN substrate exhibited excellent adhesion under the tape test. XPS depth profiling was used to characterize the elemental states of the films at different depths. The results indicated that the coordination bond between the PEN substrate and the Ag film resulted in good bending resistance, which gives a persuasive explanation for the first time. This result is also due to the precise handling of the film, which also results in a homogeneous distribution of the film. It solves the problem of poor adhesion of silver electrodes based on other substrates or other preparation methods. Therefore, silver electrodes based on PEN substrates have a broad application prospect in the field of flexible wearable electronics.

Experimental investigation of comprehensive performance by tailoring the proportion of late transition metals in quinary Fe-Co-Ni-Si-B amorphous alloys

We fabricated the Fe-Co-Ni-Si-B multi-principal element alloys by vacuum melt-spinning method. The effects of late transition metals proportion in quinary alloy ribbons on the formation, phase structure, thermal stability, microhardness, corrosion resistance and soft magnetic properties were investigated. The melt-spun structure consists of an amorphous single phase for all the specimens. The surfaces of glassy ribbons are rather flat and flawless and the average surface roughness is 0.351 nm or below. The initial crystallization temperature (Tx) and supercooled liquid region (ΔTx) of alloy system decrease by degrees with increasing Co and Ni content, showing the maximum values of 753.0 K and 60.0 K for Fe60Co10Ni10Si6B14 alloy. But the glass transition temperature (Tg) seems to barely change and maintain approximately 692.0 K. All the as-received alloy ribbons exhibit good bending ductility and acceptable Vickers microhardness ranging from 671 to 785 HV0.5. The amorphous alloy ribbons present a gradually wide passive potential range (ΔE) with the decrease of Fe content, but the corrosion current density (Icorr) becomes larger. The smallest Icorr value is 1.785 μA·cm-2 for Fe60Co10Ni10Si6B14 alloy and the widest ΔE value is about 0.272 V for Fe26Co27Ni27Si6B14 alloy. The saturation magnetization of these glassy alloys reduces from 165.0 to 112.0 emu/g as the Fe content decreases. Meanwhile, the coercivity also changes from 14.25 to 6.70 A/m. This paper offers a brand-new perspective to understand the role of late transition metals on the various physicochemical properties of quinary Fe-Co-Ni-Si-B amorphous alloys.

Flexural behavior of high-strength steel-precast prestressed concrete composite beams with grouped demountable bolts under hogging moment

To study the bending behavior of high-strength steel (HSS)-precast reinforced concrete (PRC) slab composite beams with grouped demountable bolts under hogging moment, single-point loading tests were carried out to evaluate the bending behavior of the five prefabricated composite beams, and the key parameters are shear connection degree, shear pocket spacing in the PRC slab, and applying precompression to the concrete or not. The test results indicate that the HSS composite beams have good overall bending behavior, and two failure modes are recorded including the flexural failure, and the concrete damage in the shear pocket region. The prestressing force can effectively increase the anti-cracking performance of the slab and slightly improve the bending behavior, while increasing the shear connection degree from 1.80 to 3.61 or the shear pocket spacing from 360 mm to 800 mm (the limit value in the AASHTO LRFD Bridge Design Specifications is 610 mm) under the same shear connection degree has a limited influence on the bending behavior, and the composite beams still have the effective composite action. The existing formulas are conservative in calculating the bending capacity of HSS composite beams but have a high degree of consistency in stiffness.

Cerium rare-earth ions reinforced built-in electric field to enable efficient carrier extraction for highly efficient and stable perovskite solar cells

Perovskite solar cells prepared by inorganic-organic three-dimensional hybrid have good power conversion efficiency, but their operational stability remains a major challenge for commercialization. The defect of perovskite is an important factor restricting its charge dynamics and stability. Here, the rare earth metal chloride CeCl3 is introduced into perovskite solution to passivate the defects, where the Pb2+ part of the B position is replaced by Ce3+. The prepared films have the characteristics of increasing grain size, enhancing carrier mobility and excellent crystallinity. Meanwhile, via passivating interface defects and improving carrier transport capacity, the generation of non-radiative recombination is reduced, the carrier migration length is extended, and the device performance is improved. The results show that the PCE of the standard device is only 65 % after 2880 h of N2 atmosphere at room temperature, while the efficiency of the device doped with CeCl3 can remain at 93 %. When the unencapsulated sample was placed in an air environment (40–60 % humidity), the control sample was reduced to 72 % at 1060 h, while the CeCl3 was maintained at 87 %. Additionally, the reduction of residual stress in the perovskite layer also provides good bending stability for the flexible target device. These results show that the incorporation of rare earth metal ions is an effective way to stabilize and improve the efficiency of the device.

The flexible transparent N-doped CuI/AgI pn junction towards enhanced photovoltaic conversion via interface transition of in situ iodization

The flexible transparent pn junction of N-doped CuI/AgI with interface transition is prepared via approach of continuous sputtering-in situ iodization method. N-doped CuI/AgI flexible pn junction exhibits transmittance of ∼85 %, photovoltaic enhancement of ∼1.3 × 104-folds, stable output during 10 weeks’ cycle, and good flexible bending stability (1500 bending, ∼83.5 %). It's mainly attributed to that the appropriate flat-band potentials gradient and increased carrier injection achieved through N-doping, as well as ameliorating interface carrier immigration/diffusion through in situ iodization, both contribute significantly to carrier kinetic equilibrium, while the N-doping can balance a high transparency via stable-wide bandgap and optimizing inner crystallinity interface scattering. Additionally, the inorganic monoiodides and PEN substrate can provide a decent flexible stability for its actual applications.

Mechanical performance study of PVA fiber-reinforced seawater and sea sand cement-based composite materials

Due to the swift progress in the construction sector, there is a global concern about the potential scarcity of river sand and freshwater resources. The development of new construction materials is considered an inevitable trend for industry growth. PVA fibers, known for their strong corrosion resistance, cost-effectiveness, and high toughness, have the potential to enhance the corrosion resistance and seismic performance of structures in marine environments. However, their mechanical properties and durability in the seawater and sea sand environment are not well understood. Therefore, the investigation of the impact of seawater and sea sand on the mechanical properties and durability of PVA fiber-reinforced cement composites is considered crucial. A mechanical performance analysis of PVA fiber-reinforced seawater and sea sand fiber cement composites was conducted in this study. PVA fiber volume fractions of 0%, 0.75%, and 1.5%, cement composite matrix strength grades of C30 and C50, and curing periods of 28 days, 90 days, and 180 days were examined, investigating their influence on the bending toughness of PVA fiber-reinforced seawater and sea sand cement composites. Specific conclusions include the addition of fibers increased the peak bending load, had a less corrosive effect in seawater, and improved the flexural toughness of the material. The most significant improvement was observed at 1.5% fiber content, where the load-deflection curve was fuller and the energy absorption capacity of the material increased by 33–109%, maintaining good bending toughness. Furthermore, higher fiber contents are required for high-strength cementitious composites to improve flexural toughness and durability. The formulation of calculation formulas for predicting bending strength and corresponding deflection, which fit well with the experimental results; and the development of a calculation model for the bending toughness index of PVA fiber-reinforced seawater and sea sand cement composites, providing an effective prediction of material bending toughness.

Significantly improved sintering shrinkage of heavy calcium carbonate ceramic cores by binder jetting using Al powder additive

In this study, the ceramic cores were printed with heavy calcium carbonate (HCC, CaMg(CO3)2) powder as raw material and Al powder as additive by binder jetting (BJ). The ceramic cores were impregnated with nano-ZrO2 dispersion solution and then sintered at high temperature to prepare the ceramic cores with low sintering shrinkage. The effects of different Al powder contents (20 wt%∼40 wt%) on the properties and sintering shrinkage of the ceramic cores were studied. It was found that with the increase of Al powder content (20 wt%∼40 wt%), the bending strength of the ceramic core gradually decreased from 35.82 MPa to 11.89 MPa, and the porosity continuously increased from 8.94 % to 46.4 %. The sintering shrinkage rate of the ceramic core also gradually decreased, and even slightly expanded. This is because the oxidation of the Al powder to Al2O3 produced a large volume expansion, and the Al2O3 reacted with the CaO and MgO generated by the decomposition of HCC to produce calcium hexaluminate (CA6), calcium dialuminate (CA2), MgAl2O4 (MA) and other substances, and these reaction processes also produced a certain volume expansion. When the amount of the Al powder was 40 %, the dimensional change rates of X, Y and Z axis of the ceramic core were 2.48 %, 2.35 % and −0.6 %, respectively. Compared with the ceramic core without Al powder, the sintering shrinkage rate decreased by 91.2 %, and the dimensional accuracy of the ceramic core was improved significantly. By observing the microstructure of the ceramic cores, it is found that various substances inside the ceramic core formed a network distribution structure, which achieved a good toughening effect and ensured that the ceramic core had a good bending strength under large porosity.

Flexible LaNiO3 film with both high electrical conductivity and mechanical robustness

Lanthanum nickel oxide (LaNiO3, LNO) films exhibit excellent electrical conductivity but poor mechanical properties, considerably limiting their further development in the field of flexible electronics. In this study, flexible LNO thin films of different thicknesses were fabricated on a unique two-dimensional (2D) mica platform using a simple metal organic deposition technique. The obtained LNO films exhibited a pseudocubic phase without impurities. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) characterisations proved that the films were well-crystallised, dense, and flat, with controllable thickness. In addition, the flexible LNO/mica element possesses low resistivity (5 × 10−4 Ω cm), translucency, and good bending resistance. The electrical resistivity can remain stable under various bending radii (r = 10∼2 mm), thousands of bending cycles, and a wide temperature range (28–200 °C), demonstrating good durability, mechanical stability and temperature resistance. Furthermore, a ferroelectric BiFeO3 film was constructed based on the obtained conductive LNO electrode, which exhibited typical ferroelectric characteristics. This excellent performance suggests that the flexible LNO electrode is promising for flexible electronic applications.

Influence of varying matrix/fiber concentration on mechanical properties of bi-directional carbon fiber reinforced polymer composite

The polymer composites comprising bi-directional carbon fabric incorporated in the epoxy matrix have been developed for various advanced applications in the field of automobile and aerospace sectors. The distinct advantages of using epoxy material with hardener are good adhesion, high tensile, compression and bending strengths, good corrosion, and heat resistance properties. Using carbon fiber enhances the stiffness, reduces the weight, and improves the chemical resistance apart from possessing high thermal conductivity and low coefficient of thermal expansion. Considering all the above aspects, the present work proposes to investigate the mechanical properties of carbon-reinforced epoxy composites with fiber matrix ratios of 40:60, 50:50, and 60:40 by wt% as these particular combinations have been limitedly addressed so far. The well-known hand lay-up technique has produced the laminates and the test samples prepared from the laminate are subjected to tensile, flexural, hardness, and impact strength properties. Based on the experimental work of the composites made in the laboratory, the fiber matrix ratio of 60:40 has revealed the best attributes in terms of higher mechanical strengths compared to the composites with fiber matrix ratio of 40:60 and 50:50 and the data obtained have been substantiated using scanning electron microscope analysis.

Development of flexible multi-phase barium titanate piezoelectric sensor for physiological health and action behavior monitoring

Self-powered wearable piezoelectric sensing devices demand flexibility and high voltage electrical properties to meet personalized health and safety management needs. Aiming at the characteristics of piezoceramics with high piezoelectricity and low flexibility, this study designs a high-performance piezoelectric sensor based on multi-phase barium titanate (BTO) flexible piezoceramic film, namely multi-phase BTO sensor. The substrate-less self-supported multi-phase BTO films had excellent flexibility and could be bent 180° at a thickness of 33 μm, and exhibited good bending fatigue resistance in 1 × 10 4 bending cycles at a thickness of 5 μm. The prepared multi-phase BTO sensor could maintain good piezoelectric stability after 1.2 × 10 4 piezoelectric cycle tests. Based on the flexibility, high piezoelectricity, wearability, portability and battery-free self-powered characteristics of this sensor, the developed smart mask could monitor the respiratory signals of different frequencies and amplitudes in real time. In addition, by mounting the sensor on the hand or shoulder, different gestures and arm movements could also be detected. In summary, the multi-phase BTO sensor developed in this paper is expected to develop convenient and efficient wearable sensing devices for physiological health and behavioral activity monitoring applications.

Anti-Resonant Hollow-Core Fibers with High Birefringence and Low Loss for Terahertz Propagation

A new type of anti-resonant hollow-core fiber for terahertz waveguides is proposed. By introducing central support pillars and an elliptical structure, the fiber achieves high birefringence while maintaining low confinement loss and low material absorption loss. The fiber structure is optimized through simulation using the finite element method. The optimized fiber exhibits a birefringence of up to 1.22 × 10−2 at a frequency of 1 THz, with a confinement loss of 8.34 × 10−6 dB/cm and a material absorption loss of 7.17 × 10−3 dB/cm. Furthermore, when the bending radius of the fiber is greater than 12 cm, the bending loss of the anti-resonant optical fiber at 1 THz is less than 1.36 × 10−4 dB/cm, demonstrating good bending resistance and high practical value. It is expected to play a significant role in optical communication systems.

Investigations on porous silicon nitride ceramics prepared by the gel-casting method

Abstract Due to their special structure and many excellent properties, porous Si3N4 ceramics have a wide range of potential applications as a new structural and functional integrated material. In the present study, porous Si3N4 ceramics with excellent bending properties and satisfactory porosity were prepared by the gel-casting method. The variations in porosity, bending strength, fracture morphology and phase composition of the porous Si3N4 ceramics with different weight fractions of La2O3–MgO sintering additive were investigated. The results showed that the density of porous Si3N4 ceramics increased linearly with the increase of sintering additive content. When the content of sintering additive increased from 2.5 wt.% to 10 wt.%, the porosity of porous ceramics decreased from 30 % to 10 %. With the increase of sintering additive content, the bending strength of the samples first increased and then decreased. When the sintering additive content was 5.0 wt.%, the average bending strength of the samples reached a maximum of 240.88 MPa, and scanning electron microscopy and X-ray diffractometry results showed that β-Si3N4 particles with well-developed pores and a maximum aspect ratio of 5.8 were formed in the porous silicon nitride ceramics. This study provides a reference for the preparation of porous Si3N4 ceramics with good bending properties and porosity.

Experimental investigation on flexural performance of concrete beams strengthened with SMA-GFRP-ECC smart composite materials

The structural performance improvement of concrete members is by far a crucial theoretical issue for engineers, and the development of modern smart and composite materials makes it possible to gradually enhance the durability design of the concrete structure. In this study, six beams of the same size and reinforcement ratio, the proposed composite beam (SMA-GFRP-ECC) and five comparative beams (RC, R-ECC, SS-ECC, GFRP-ECC, SMA-ECC), were designed and tested under low-cycle unidirectional cyclic loading and unloading conditions. The energy dissipation capacity, displacement ductility, residual deformation, and self-repairing performance of each concrete beam were evaluated. Afterward, a concise calculation model for the studied composite beam is deduced and developed based on the existing relevant constitutive models and concrete assumptions. The test results indicate that compared with RC beams, the composite reinforced ECC beams show obvious multi-cracking and smaller crack width during the loading process and have good bending ductility. The innovative SMA-GFRP-ECC beam is capable of a high bearing capacity, ductility, and damage self-repairing. The new proposed beam has more than 80% of the maximum crack width recovery capacity during unloading. Hence, the proposed SMA-GFRP-ECC beam is a rather good first attempt of strengthened beams, combining the advantages of SMA, GFRP, and ECC.

Plastic quasicrystal-containing alloys prepared by annealing pseudo-high entropy Zr70–75(Al, Ni, Cu, Ag)25–30 glassy alloys

A glassy (G) phase was formed for Zr-rich Zr70–75(Al, Ni, Cu, Ag)25–30 (atomic percent, at.%) melt-spun alloy ribbons. These glassy alloys exhibit the glass transition, followed by a supercooled liquid region and then three-stage crystallization. The glass transition temperature and the onset temperature for the first-stage crystallization (Tx1) decrease from 630 to 668 K, respectively for the 70Zr alloy to 619 and 652 K, respectively for the 75Zr alloy. The first-stage exothermic peak is due to the precipitation of an icosahedral quasicrystal (IQ) phase. The IQ particle size decreases from 10 nm to 6 nm with increasing Zr content from 70at.% to 74at.%. The [G + IQ] phases change to Zr2Ni + Zr2(Cu, Ag) phases after the second exothermic peak and then Zr2Ni + Zr2(Cu, Ag) + Zr5Al3 phases after the third stage. It is noticed that the as-spun glassy alloy ribbons as well as the annealed [G + IQ] phase ribbons exhibit good bending plasticity. Furthermore, the 70Zr thicker ribbons also exhibit high tensile fracture strength of 1090–1187 MPa and plastic elongation of 0.17 %–0.42 %. The fracture mode is similar to that of ordinary bulk metallic glasses. The Vickers hardness (Hv) is 480 for 70Zr alloy and decreases to 436 for 75Zr alloy. The precipitation of IQ phase causes a significant increase in Hv to about 554. The formations of glassy alloys with high Zr contents of 70at.%–75at.% by melt spinning as well as the [G + IQ] phase alloys with good bending plasticity by annealing hold promise for the creation of a new type of engineering material, transcending mere academic novelty.

Bending behavior of segmental precast diaphragm walls using bolted sleeve joints

AbstractTo study the bending behavior of segmental precast diaphragm walls using bolted sleeve joints, 2 full size specimens were tested. Both BC and EC specimens were connected using bolts with steel sleeves as positioner. BC specimen was consisted of two fully RC plates while EC specimen had precast holes in the concrete walls for lightweight treatment. Ultimate strengths, deformations, strains and failure modes were obtained from the test results. Finite element models were developed using ABAQUS and verified against the test results. The verified finite element models were used to further analyze the stress state of specimens under different loading. It indicated that the bolted sleeve joint exhibited good bearing capacity and bending stiffness. The lightweight treatment in the concrete part had minor effect and the design requirement could be satisfied.

Flexible SERS substrates with gradient porous Cu structure dealloying from the thermal diffusion couples of Al/Cu stacking foils

Accurate and sensitive surface-enhanced Raman scattering (SERS) substrates are urgently demanded for the various analytic techniques. The SERS substrates with multimodal and gradient porous structure, utilized for the Rhodamine 6G (R6G) detection, have been designed and successfully fabricated from the thermal diffusion couples of Al and Cu foils via chemical dealloying. The structural inheritance of the initial microstructure of thermal diffusion couple precursors governs the formation of the final layer-by-layer gradient porous Cu with different characteristic pore sizes and morphology. An outmost surface layer of disordered lipstick-like porous structure on the SERS substrates enhances SERS effects as has been expected. The SERS activity of R6G Raman probes on gradient porous Cu is evaluated as a SERS enhancement factor of 6.63 × 1012 and limit of detection of 2.10 × 10−17 mol/L, higher than other porous SERS substrates. Meanwhile, the present SERS substrates are flexible and exhibit good bending properties due to the unreacted Cu layer as a supporting skeleton and other gradient porous Cu layers. The superior SERS performances are considered to result from the synergetic effects of the surface scattering of porous Cu rods and enhancements of the high electromagnetic fields between the small gaps between the nanopores.