This article presents a novel approach to optimise scheduling and production planning to meet seasonal demand in an industrial process using decaying catalysts, based on its formulation as a multistage mixed-integer optimal control problem (MSMIOCP). Unlike existing methodologies, the MSMIOCP formulation allows to solve this problem as a standard nonlinear optimisation problem without combinatorial optimisation methods, which can be advantageous in providing reliable, robust and efficient solutions. Using this formulation, four case studies of this problem, differing in reaction or deactivation kinetics, are investigated. Two different solution implementations are used, each having their own relative advantages. The first implementation demonstrates a bang-bang behaviour for the linear scheduling controls, consistent with a theoretical analysis, but faces integration problems and does not always produce high quality solutions. The second implementation, while not demonstrating the bang-bang property, always produces high quality solutions and shows the advantages of the MSMIOCP formulation over existing methodologies.

It is innovative and important to perform complex binary azeotrope separation via single distillation column. In the article, design and control of a novel and simple side-stream extractive distillation (SSED) column with extraction and solvent recovery function is investigated for the separation of methanol and toluene binary azeotrope with intermediate boiling triethylamine (Et3N) as solvent. The steady-state design parameters of the novel SSED column are optimized and obtained with the objective of minimal total annual cost (TAC) via conventional sequential iterative procedure. On the basis of steady-state design, four single-end temperature control structures (STCS), four dual-temperature control structures (DTCS) and four dual-composition control structures (DCCS) are developed and established successively to overcome the operation and control challenges caused by the novel scheme. To seek the robust control, the dynamic performance analysis on account of the above control structures is conducted for the SSED column, which is evaluated for feed flowrates and composition disturbances. The results show that the control performance of DCCS is significantly superior to that of STCS and DTCS while the integral squared error (ISE) and energy-consuming effect are equivalent, and can take shorter time to bring the product purities back to the original steady state in coping with specified feed disturbances.

The present work investigates the treatment of wastewater by degrading detergents and residual surfactants using individual and combined approaches based on ozone, catalyst and cavitation. The intensification of ozonation has been investigated by the addition of solid ZnO and CuO catalysts. The extent of degradation increased with catalytic ozonation as compared to non-catalytic ozonation. In comparison, the combination with cavitation did not yield any beneficial results. The study of the effect of initial pH of the solution and effect of different catalyst loadings in catalytic ozonation with ZnO established that the maximum degradation as 89.3 % was obtained at initial pH of 9 and 0.1 g L-1 of catalyst loading respectively. It was also demonstrated that the reaction followed first order kinetics with rate constant as 0.067 min-1. BOD analysis at optimized conditions demonstrated that catalytic ozonation efficiently converts non-biodegradable harmful surfactants in wastewater to easily digestible compounds, which means that this can be a complimentary process to biological oxidation. Overall the work has clearly demonstrated the efficacy of catalytic ozonation approach for treating the laundry wastewater.

The salting-out extraction (SOE) systems based on ionic liquids (ILs) have attracted extensive attention in the separation of bio-based products, in which imidazolium ILs were widely studied. However, the high cost and toxicity have hindered their further industrial application. Hydroxylammonium ILs have the characteristics of cheap raw material, simple synthesis process and low toxicity, but are rarely used in the SOE systems. In this work, five hydroxylammonium ILs (2 cations and 4 carboxylate anions) were synthesized and used in SOE of bio-chemicals. The phase forming abilities of ILs with K3PO4 and H2O were affected by the hydrophilicity of anions and cations. With the increase of carbon chain length, phase forming abilities of ILs increased, while the temperature had little influence. The partition behaviors of acetoin, ILs and 2,3-butandiol, and the selectivity of acetoin to organic acids were investigated and compared at different concentrations of ethanolammonium butyrate (EOAB) and K3PO4. In a SOE system consisted of 6% EOAB-38% K3PO4 (w/w), the recovery of acetoin, IL and 2,3-butandiol was 92.7%, 76.0% and 86.0%, respectively, and the selectivity of acetoin to lactic acid and acetic acid was 16.46 and 3.85, respectively. The ATR-IR spectra showed the hydrogen bonds formed between acetoin and O-H, N-H, -COO- of hydroxylammonium IL played an important role in the efficient extraction of acetoin from fermentation broths.

Zwitterion polymer modified membranes have demonstrated fouling resistance in wide applications. The ubiquitous success in scientific progress, however, has not yet brought significant breakthrough in the application of such membranes in wastewater treatment. Limitation of zwitterion materials in membrane is seldomly discussed. In this paper, we aimed to bring an engineering view on the pros-and-cons of zwitterion modified microfiltration membrane in treating solutions containing humic acid (HA) and bovine serum albumin (BSA). A 3-[[3-(trimethoxysilane)-propyl] amino] propane-1-sulfonic acid (TMAPS) grafted zwitterionic PVDF membrane was selected as a model membrane. The membranes were prepared via a two-step “hydroxylation-grafting” method; surface modified PVDF membrane was transformed from hydrophobic to hydrophilic with significant improvement in pure water flux. An 87% increase was obtained in the stable flux for the grafted membrane when treating HA, but very similar flux pattern to the pristine one was found when treating BSA. The membrane resistance model showed that cake layer was the main fouling factor for both foulants. For HA, the cake layer blocking model predicted the membrane flux well; but for BSA, the intermediate blocking model fits best the experimental results. Zwitterion grafted surface failed to show improvement in the fouling resistance even at very low BSA feed concentration. Adsorption experiment indicated that the interaction of BSA to membrane is significantly stronger than HA and membranes independent from the surface characteristics. Present work clarified the limitation of zwitterion modified membranes in treating solutions containing HA-like and protein matters.

In order to reduce pollution from wastewater and recycle the valuable metal in the vanadium precipitation process, sodium polyvanadate precipitated wastewater was utilized to prepare an electrolyte for the vanadium redox flow battery after two-stage purification via solvent extraction, which removed most of the impurities, especially Mn. The concentration of impurity ions was less than 10 ppm, as obtained by using inductively coupled plasma-optical emission spectroscopy, and the electrolyte obtained from the wastewater complied with the Chinese national standard. The method applied herein can simplify the preparation process compared to the conventional method and avoid ammonia nitrogen pollution. Electrochemical analysis showed that the properties of the prepared electrolyte were similar to those of the standard electrolyte. From the charge/discharge test, the energy efficiency and coulombic efficiency of the electrolyte reached nearly 90% of those of the standard electrolyte, which indicates that the electrolyte prepared from wastewater has the potential for commercial applications.

In this work, we fabricated a sandwich-like single-walled carbon nanotubes (SWCNTs)-coated support for the preparation of high-performance antifouling thin-film composite (TFC) forward osmosis (FO) membrane. This sandwich-like support was prepared through the deposition of polydopamine modified SWCNTs (PDA-SWCNTs) on both sides of the polyethersulfone (PES) microfiltration (MF) membrane. The CNTs top layer was found to facilitate the formation of polyamide layer. The CNTs back layer provided an antifouling surface for the prevention of foulants adsorption and intrusion into the PES support. Results demonstrate that the CNTs back layer imparted superior rejection towards bovine serum albumin (BSA) (~98.1%) and enhanced hydrophilicity. The TFC FO membrane (TFC-modified) having the sandwich-like SWCNTs-coated support exhibited excellent perm-selectivity with the water flux Jw of 35.7 Lm−2 h−1 and the reverse salt flux Js of 1.42 gm−2 h−1 when tested in the mode of active layer facing to draw solution (AL-DS) using 1 M NaCl as a draw solution. Dynamic fouling experiments confirm that the TFC-modified membrane possessed effective antifouling performances with a low relative fouling degree (RFD) of 19.0% during the cross-flow run and 8.4% during the BSA adsorption test, which were much lower than the corresponding values of 36.1% and 15.4% for the TFC-control membrane.

To further refine the coarse columnar grains (CGs) in selective laser melted (SLMed) alloy, an Al-4.0Mg-0.7Sc-0.4Zr-0.5Mn alloy was fabricated by selective laser melting (SLM) and then subjected to cold rolling and annealing at 300 °C for 1 h. Microstructural details and mechanical properties were examined by SEM, EBSD, TEM, and tensile tests. The results show that the microstructure of the SLMed alloy can be further refined by cold rolling. A yield strength of 573 MPa is obtained with an average grain size of 2.4 ± 1.3 μm in the CGs areas, a reduction of approximately 30% compared with the as-fabricated alloy. The enhanced strength of the rolled alloy is derived from the refined grains and high density of Al3(Sc, Zr) phase. Additionally, the Al3(Sc, Zr) particles can enhance the microstructure stability.

A strategy was developed to circumvent the trade-off between the yield strength and strain hardening capability in Fe–30Mn–11Al-1.2C low-density steel by coupling two-step aging and intermediate pre-strain processes. The improvement of strain hardening capability is attributed to the non-shearable intragranular DO3 particles.

The relationship between mechanical properties and microstructures of a metastable dual-phase high entropy alloy Fe50Mn30Co10Cr10 under uniaxial tensile testing at different strain rates (10-3 s-1∼103 s-1) has been studied systematically. As the strain rate increases, yield strength, ultimate tensile strength and uniform elongation decrease first and then increase. Namely, when the strain rate is 10-3 s-1, yield strength and ultimate tensile strength are 280 MPa and 720 MPa, respectively, with the uniform elongation of 64.2%. When the strain rate is increased to 1 s-1, yield strength and ultimate tensile strength are 300 MPa and 672 MPa, respectively, and uniform elongation decreases to 49.2%. When the strain rate reaches 103 s-1, yield strength and ultimate tensile strength increase to 380 MPa and 810 MPa, respectively, while uniform elongation is elevated to 67%. As dynamic deformation is affected by the adiabatic heating, the stacking fault energy of the alloy is increased by ∼13 mJ m-2 at a strain rate of 103 s-1 compared with that in the quasi-static condition. Under quasi-static loading, martensitic transformation is the dominant deformation mechanism. Under dynamic loading, when the strain is low the deformation induced phase transformation dominates, whereas as the loading proceeds mechanical twinning becomes the dominant deformation mode. At the same time, the adiabatic temperature rise under dynamic tests also causes a reverse transformation from ε-martensite to austenite. Accordingly, the release of internal stress and the formation of soft and ductile austenite jointly contribute to the elevated uniform elongation of the material. Both mechanical twinning and martensitic reverse transformation promote the microstructure to be dynamically refined, so that the alloy shows the good plasticity while maintaining the high ultimate tensile strength at dynamic strain rates.

The thought of designing Al–based composites with attractive comprehensive properties, by using various particles as reinforcements simultaneously, has been put forward and verified in this paper. By in–situ synthesizing Al2O3 (<1 μm), ZrB2 (<300 nm) and AlN (<100 nm) particles, a novel (Al2O3+ZrB2+AlN)/Al composite has been prepared. It was found that the ultimate tensile strength of the composite is as high as 540 MPa at 25 °C and 200 MPa at 350 °C, while the elasticity modulus of the composite is 101 GPa. Besides, the composite also performs attractive thermal stability and the coefficient of thermal expansion is 15.8×10–6 K–1 at 500 °C. It is regarded that the synergistic effect of the multi–scale Al2O3, ZrB2 and AlN particles are responsible for the improved performance. This paper may be referred for designing multiphase reinforced composites to achieve various properties.

Controlled in situ SEM tensile tests have been carried out between 200 and 300 °C at a constant strain rate of 5.10-5 s-1 to investigate the effect of temperature on deformation mechanisms operating in an Mg–3Al–1Zn (AZ31) Mg-alloy. Fiducial microgrids deposited using electron beam lithography are used to evidence grain boundary sliding as well as to determine the spatial strain heterogeneities as a function of temperature. Dislocation creep and grain boundary sliding coexist between 200 and 300 °C but their respective activity varies significantly as shown by the strain rate sensitivity value m which is about 0.2 at 200 °C but about 0.5 at both 250 and 300 °C. In addition, grain boundary sliding becomes predominant at 250 and 300 °C whereas its occurrence is relatively limited at 200 °C. Slip trace analysis shows that at 200 °C prism and pyramidal slip already exhibit a great activity. Spatial strain heterogeneities determined by digital image correlation (DIC) based on microgrid displacements develop during the early stage of plastic deformation and persist at larger strains. It is shown that the strain in the vicinity of grain boundaries intensifies when the temperature rises from 200 to 300 °C while the core of grains accommodates less deformation in agreement with the fact that grain boundary sliding is predominant at 250 and 300 °C.

Freeze casting is a versatile approach for the design of lamellar metal−ceramic composites with unique combination of strength and toughness. However, previous studies mainly focused on ceramic factors such as content and lamellae structure, seldom concerning the effects of metal property and interfacial structures, which, in practice, are key factors in determining the mechanical performances of the composites. In this work, we prepared three kinds of Al/TiC lamellar-interpenetrated composites with different matrix compositions (pure Al, 6061Al (Al−0.4Cu−1.0Mg−0.6Si) and ZL107 (Al–7Si–5Cu)) via freeze casting and pressure infiltration, aiming at clarifying the roles of matrix property and interfacial reaction on the mechanical properties and fracture mechanisms of the composites. The flexural strengths of pure Al/TiC, 6061Al/TiC and ZL107/TiC composites reached 355 ± 10, 415 ± 15 and 459 ± 18 MPa, while the toughness values (characterized by crack-growth toughness) were 81.0 ± 2.0, 57.6 ± 1.2 and 43.4 ± 1.5 MPa m1/2, respectively. The exceptional damage tolerance of these lamellar composites was attributed to multiple toughening mechanisms such as crack deflection, uncracked-ligament bridging of ductile layers and plastic deformation of the metal matrix. However, the presence of Si in the 6061Al and ZL107 alloys weakened the stability of TiC and promoted interfacial reaction, leading to the formation of a certain number of (Al1-m, Sim)3Ti and Al4C3, which greatly weakened the toughness of the composites. Due to the combined effects of alloy plasticity, lamellar-interpenetrated structure and interfacial reaction, the fracture of the materials changed from a multiple cracking mode in the Al/TiC composite to a single crack propagating mode in the 6061Al/TiC and ZL107/TiC composites.

This study investigates the mechanical properties of the second phase particles and Mg-matrix in a Mg–8Al-0.5Zn cast alloy by compression of machined micropillars. The stress-strain behavior showed that the Mg17Al12 particles exhibited a sudden and unusual failure after a significant strain burst. The Al8Mn5 particles were much more ductile, but also much stronger.

It was observed that low level of yttrium (Y) has a modifying effect on the Mg17Al12 phase in the binary Mg-6wt%Al casting alloy. Scanning/transmission electron microscopy, mechanical testing and thermodynamic calculations were employed to understand the modification mechanism. It is found that Y at trace level refines the β-Mg17Al12 phase leading to increased tensile elongation and compressive strain to fracture. The refinement effect is lost with further increase in the Y level. Thermodynamic calculations (Scheil cooling) indicate that the formation temperature of the Al4MgY phase changes with the Y level. At trace levels, its nucleation temperature is the same as that of Mg17Al12, producing a co-precipitation/nucleation effect. As Y increases, Al4MgY forms at increasingly higher temperatures than β-Mg17Al12 with a loss of the refinement due to the disappearance of co-precipitation.

The microstructure and texture evolution of as-extruded Mg-0.96 wt%Al-5.82 wt%Y (denoted as Mg–1Al–6Y) alloy with strain at a temperature of 350 °C and a strain rate of 0.1 s−1 were studied using ex-situ electron backscatter diffraction (EBSD). Moreover, the deformation mechanism was systematically analyzed. The results shown that weak <2-1-11> rare-earth texture and no twinning were observed in the as-extruded Mg–1Al–6Y alloy. The hot compression curve exhibited obvious work-hardening characteristics with a yield strength of 98 MPa. In the initial stage of deformation, {10–12} extension twinning was formed in some grains. As the strain increased, the number of {10–12} extension twinning and texture intensity gradually decreased, whereas the amount of low-angle grain boundaries increased. The Schmid factor (SF) of pyramidal slip remained at ∼0.4. In addition, the TEM characterization revealed that as the strain increased, dislocations multiplied, and the pyramidal dislocation was always observed. Therefore, the reduction of twinning and activation of pyramidal slip lead to the dominance of slip during the deformation. Hence, work hardening appeared in the compression curve of Mg–1Al–6Y alloy.

The growth of eutectic colonies in Sn–Cu, Sn–Zn and Sn–Ag–Cu eutectic alloys has already been reported in the literature. However, relationships between this kind of microstructure and mechanical properties remain undetermined for solders. The use of water-cooled copper (Cu) and AISI 1020 low-C steel molds and the eutectic Sn-9 wt.%Zn alloy make it possible to address this matter. The samples grown in the Cu mold demonstrated higher solidification rates than those developed in the low-C steel mold. Overall, the microstructure is constituted by Zn-lamellae embedded in a Sn-rich matrix. The Zn lamellae are not only uneven in thickness but also irregularly perforated. Due to Cu dissolution into the alloy, a small fraction of Cu5Zn8 intermetallic particles formed during solidification of the Sn-9 wt.%Zn alloy in the Cu mold. The contamination with Cu appears to be responsible for the improvement in the distribution of Zn-lamellae. The decrease in spacing between broken lamellae measured from SEM images, as well as a higher number of Zn particles per area, explain such occurrence. Ductility and tensile strength of different samples could allow the establishment of relationships among properties vs. eutectic colony spacing. For the Cu mold, the motion of Cu towards the alloy as well as higher solidification rates, allowed microstructures to be formed combining 60% of strain to fracture and 52 MPa of ultimate tensile strength. These achievements are mainly due to the finest spacings of both the eutectic colony (λχ = 36 μm) and the Zn lamellae (λL=0.9 μm), besides homogeneous distribution of Cu across the resulting microstructure.

Different morphologies of carbide-free bainite were obtained through a series of isothermal heat treatments of a new medium-carbon bainitic steel, and the evolution of microstructures during tensile deformation was then observed. The results showed that the strength-ductility balance could reach its highest value near 350 °C. The retained austenite sustaining martensitic transformation, long bainite ferrite sheaf, and phase transformation dynamics were the main factors that caused high plasticity of the steel at 350 °C isothermal transformation. It is noteworthy that 350 °C is also a phase change sensitive point for most bainitic steels. Maintaining high work hardening rate at high strain is beneficial to increase elongation, which is attributed to the continuous martensitic transformation of the retained austenite with high volume fraction. The (200) austenite peak was separated using the Gaussian multi-peaks fitting method. It was found that the (200) austenite peak moves to the left with the increase of strain. The proportion of low angle peaks also increased with strain. This indicates that the transformation of the retained austenite always occurs in the low carbon region.

A novel method was designed to fabricated Ti/steel clad plates via cold spray additive manufacturing (CSAM) and hot-rolling. In order to study the influence of annealing on the microstructure and mechanical properties of the Ti/steel clad plates, the as-rolled clad plates were subjected to different annealing temperatures in the order: 450, 550 and 650 °C. It was revealed that CSAM and hot-rolling promote metallurgical bonding between Ti/Ti as well as Ti/steel interfaces, thus resulting in Ti/steel clad plates with excellent mechanical properties. The annealing treatment promotes inter-diffusion of Ti and Fe across the Ti/steel interface and improves the microstructures of the as-rolled Ti/steel clad plates. The results show that when the annealing temperature is low (i.e. 450 °C), the elongation of the specimen increases while the ultimate tensile strength and shear strength both decrease through recovery and recrystallization mechanisms. However, when the annealing temperature is too high (i.e. 650 °C), the elongation and strength of the specimen decrease sharply due to the nucleation and growth of brittle TiC and FeTi compounds. The annealing, at 550 °C for 3 h, was pin-pointed as the optimum post-spray treatment to achieve superior ultimate tensile strength (564 Mpa), shear strength (280 Mpa) and elongation (18%) in the clad plate.

Outcrop and core observations show that discontinuities are well developed in unconventional reservoirs. Presence of these discontinuities can have beneficial or detrimental effect on hydraulic fracturing behaviors. Previous studies summarized several interaction modes between hydraulic fracture and a single-weak plane based on a large number of laboratory tests and theoretical analysis. In some cases, the reservoir contains a considerable number of parallel weak planes that make the fracture propagation more complex. The interaction mechanisms between hydraulic fracture and parallel weak planes remain unclear. In the present study, a bonded-particle model (BPM) coupling fluid-mechanical is used to study the driven force of these interactions. Moment tensor inversion is used to analyze the failure mechanisms of those weak planes. The results indicate that as the number of weak plane increases, the interaction mode becomes complex. Several modes (e.g. arrested, arrested with offsetting, crossing, and crossing with offsetting) are observed in the multiple parallel weak planes contained models. The interaction mode is closely related to a stress concentration around the intersection area between hydraulic fracture and weak planes. The arrested or crossing with offsetting mode is mainly caused by the shear slippage of the weak plane through moment tensor inversion analysis.

This study proposes a transient gas-liquid-solid multiphase flow model for gas kick during MPD, considering the effect of dynamic wellhead back-pressure, temperature field, and velocity relation of different phases. Based on this model, the gas kick control strategies and outflow response characteristics during MPD are thoroughly investigated. The simulated results reveal that, with the upward migration and expansion of the invading gas, the hydrostatic pressure and frictional pressure in the annulus changes accordingly, resulting in a non-linear relationship between the wellbore back-pressure and the bottom-hole pressure. Moreover, the effects of an under-balance pressure at the bottom hole, the pressure balance relationship between the formation and the bottom hole, the kick detection level, the well depth on the wellhead back-pressure control and the response behaviors of the outlet flow rate are discussed. The results of this investigation can provide engineering guidance for MPD to address the issue of gas kick.

Venturi is one of the most commonly used flowmeters for measuring gas-liquid flow at the natural gas wellhead. A better understanding of the flow mechanism and the causes for pressure drop is necessary for the establishment of the measurement model. In this study, a one-dimensional pressure drop model between the two pressure taps of Venturi has been proposed for vertical annular-mist flow. The relations between the liquid film, entrainment rate, void fraction, and velocity slip have been revealed when the annular flow went through Venturi. We consider the gas acceleration in the throat of Venturi. The proportions of various pressure drops are given. The experimental results show that the relative errors of the pressure drop have a confidence probability of 98.5% within 10%. The predicted results are also in good agreement with the on-site data. It proves that the new pressure drop model has good performance.

When gas dissolves into a liquid, interface resistance can limit the mass flux. Increasing or decreasing interface resistance by means of surface-active agents is of interest in applications ranging from biomedicine to petroleum recovery. This paper describes a pressure-decay methodthat allows systematic investigation of both interface resistance and internal (diffusive) resistance during gas-to-liquid mass transfer; introduces a mathematical modeling approach that determines both resistances simultaneously; and provides experiments in which only the interface resistance varies. In the pressure decay method, the system pressure is recorded as gas transfers across the gas/liquid interface and diffuses within the liquid. It allows initiating the experiment at a prescribed pressure with high reproducibility, facilitating the interpretation of a series of experiments. The exact solution of the 1D resistance-in-series model is derived. An accurate approximation is further reported to analyze experiments conveniently. The interface resistance is systematically varied in a static nitrogen/water system by adding small concentrations of oleic acid. As the concentration of oleic acid increases, the mass transfer coefficient decreases or the interface resistance increases. The effect is significant: at a concentration of 2 ppm, at which concentration the interface resistance is almost four times greater than that for pure water. The oleic acid has little effect on the diffusion coefficient of nitrogen in water due to its low concentration. The model comparison indicates the range of Biot number when the interface resistance or internal resistance must be accounted for. The characteristic chart can effectively contribute to a qualitative analysis of the gas-liquid mass transfer process when the effect of surface-active agents is considered.

T-jet reactors have been widely used in micro/mini reactors for their simple geometries and rapid mixing. Following our previous report (Zhang et al., Chem. Eng. J., vol. 358, 2019, 1561-1573), the present study describes the flow regimes in T-jet reactors with different geometrical parameters at 50≤Re≤400 by using planar laser induced fluorescence (PLIF). The influences of the headspace height (H/h), the outlet aspect ratio (W/w), and the depth of the reactor (w/h) on the origination and evolution of steady and unsteady engulfment flow have been investigated in detail, where h is the inlet height, w is the reactor depth, W is the outlet width, and H is the headspace height. A comparison of the critical Reynolds number (Re) of steady engulfment flow between current work and previous investigations in the literature is presented. The mixing performance of various T-jet channels has also been analyzed using the Intensity of Segregation (IOS). Results show that, the intertwinement of two inlet streams is weakened as the headspace height increases, and the unsteady engulfment flow disappears for H/h≥0.3. The outlet aspect ratio influence the evolution of engulfment flow in the chamber and the unsteady engulfment flow vanishes as W/w reaches 8. Besides, the engulfment of two inlet streams decreases and the unsteady engulfment flow disappears whether the reactor depth increases to w/h=2 or decreases to w/h=0.5.

The development of broadband and high-efficiency electromagnetic wave absorbing materials in the gigahertz is highly crucial and challenging. Here, typical magnetic-carbon composites were successfully obtained, which involves a controlled reduction process from a semiconductor to magnetic materials under reducing atmosphere. Due to the huge difference in lattice constants, yolk-shell Fe3O4@C and [email protected]@C powders were developed from core-shell a-Fe2O3@PDA precursor. The chemical composition, magnetic property, and morphology of the final [email protected]@C powders were discussed comprehensively. Related electromagnetic parameters of all samples were tested to analyze the storage and loss ability toward electromagnetic wave energy. Inspiringly, both the Fe3O4@C and [email protected]@C composites exhibited high-performance energy absorption in the microwave band. The minimal reflection loss (RLmin) value of Fe3O4@C is -45.4 dB at the absorber thickness only at 1.5 mm and the efficient absorption (RL≤-10 dB) frequency up to 5.5 GHz at 2.0 mm thickness. Meanwhile, the RLmin value of [email protected]@C is -66.5 dB at the absorber thickness of only 1.6 mm and show broadband responding arrange, covering almost all the Ku-band. The synthesized magnetic-carbon composites display excellent electromagnetic properties and high-efficient energy conversion behaviors, meeting to the high requirements for modern microwave absorption materials.