Carbon-based foams with a three-dimensional structure can serve as a lightweight template for the rational design and controllable preparation of metal oxide/carbon-based composite microwave absorption materials. In this study, a flake-like nickel cobaltate/reduced graphene oxide/melamine-derived carbon foam (FNC/RGO/MDCF) was successfully fabricated through a combination of solvothermal treatment and high-temperature pyrolysis. Results indicated that RGO was evenly distributed in the MDCF skeleton, providing effective support for the load growth of FNC on its surface. Sample S3, the FNC/RGO/MDCF composite prepared by solvothermal method for 16 h, exhibited a minimum reflection loss (RL_min) of −66.44 dB at a thickness of 2.29 mm. When the thickness was reduced to 1.50 mm, the optimal effective absorption bandwidth was 3.84 GHz. Analysis of the absorption mechanism of FNC/RGO/MDCF revealed that its excellent absorption performance was primarily attributed to the combined effects of conduction loss, multiple reflection, scattering, interface polarization, and dipole polarization.

With the booming development of electronic information science and 5G communication technology, electromagnetic radiation pollution poses a huge threat and damage to humanity. Developing novel and high-performance electromagnetic wave (EMW) absorbers is an effective method to solve the above issue and has attracted the attention of many researchers. As a typical magnetic material, ferrite plays an important role in the design of high-performance EMW absorbers, and related research focuses on diversified synthesis methods, strong absorption performance, and refined microstructure development. Herein, we focus on the synthesis of ferrites and their composites and introduce recent advances in the high-temperature solid-phase method, sol–gel method, chemical coprecipitation method, and solvent thermal method in the preparation of high-performance EMW absorbers. This review aims to help researchers understand the advantages and disadvantages of ferrite-based EMW absorbers fabricated through these methods. It also provides important guidance and reference for researchers to design high-performance EMW absorption materials based on ferrite.

Microwave absorbers have great potential for military and civil applications. Herein, Co_0.5Zn_0.5Fe₂O₄/residual carbon (CZFO/RC) composites have been successfully prepared using a hydrothermal method. RC was derived from coal gasification fine slag (CGFS) via pickling, which removes inorganic compounds. Multiple test means have been used to study the chemical composition, crystal structure, and micromorphology of the CZFO/RC composites, as well as their electromagnetic parameters and microwave absorption (MA) properties. The CZFO/RC composites exhibit excellent MA performance owing to their dielectric and magnetic losses. When the thickness of CZFO/RC-2 (FeCl₃·6H₂O of 0.007 mol, ZnCl₂ of 0.00175 mol, and CoCl₂·6H₂O of 0.00175 mol) is 1.20 mm, the minimum reflection loss (RL_min) is −56.24 dB, whereas at a thickness of 3.00 mm and 6.34 GHz, RL_min is −45.96 dB and the maximum effective absorption bandwidth is 1.83 GHz (5.53–7.36 GHz). Dielectric loss includes interface and dipole polarizations, while magnetic loss includes current and remnant magnetic loss. CZFO/RC-2 exhibits high impedance matching, allowing microwave to enter the absorber. The computer simulation technology confirms that CZFO/RC-2 considerably decreases the radar cross-section. This study can be used to promote the use of CGFS as electromagnetic wave (EMW)-absorbing materials.

The effective construction of electromagnetic (EM) wave absorption materials with thin matching thickness, broad bandwidth, and remarkable absorption is a great solution to EM pollution, which is a hot topic in current environmental governance. In this study, N-doped reduced graphene oxide (N-rGO) was first prepared using a facile hydrothermal method. Then, high-purity 1T-MoS₂ petals were homogeneously anchored to the wrinkled surface of N-rGO to fabricate 1T-MoS₂@N-rGO nanocomposites. The numerous electric di-poles and profuse heterointerfaces in 1T-MoS₂@N-rGO would induced the multiple reflection and scattering of EM waves in a distinctive multidimensional structure formed by two-dimensional N-rGO and 1T-MoS₂ microspheres with plentiful thin nanosheets, remarkable conduction loss derived from the migration of massive electrons in a well-constructed conductive network formed by 1T-MoS₂@N-rGO, and abundant polarization loss (including dipolar polarization loss and interfacial polarization loss). All of these gave the 1T-MoS₂@N-rGO nanocomposites superior EM wave absorption performances. The effective absorption bandwidth of 1T-MoS₂@N-rGO reached 6.48 GHz with a relatively thin matching thickness of 1.84 mm, and a minimum reflection loss of −52.24 dB was achieved at 3.84 mm. Additionally, the radar scattering cross-section reduction value of 1T-MoS₂@N-rGO was up to 35.42 dB·m² at 0°, which further verified the huge potential of our fabricated 1T-MoS₂@N-rGO nanocomposites in practical applications.

High-entropy design is attracting growing interest as it offers unique structures and unprecedented application potential for materials. In this article, a novel high-entropy ferrite (CoNi) _x/2(CuZnAl)_(1−x)/3Fe₂O₄ (x = 0.25, 0.34, 0.40, 0.50) with a single spinel phase of space group

was successfully developed by the solid-state reaction method. By tuning the Co–Ni content, the magnetic properties of the material, especially the coercivity, changed regularly, and the microwave absorption properties were improved. In particular, the effective absorption bandwidth of the material increased from 4.8 to 7.2 GHz, and the matched thickness decreased from 3.9 to 2.3 mm, while the minimum reflection loss remained below −20 dB. This study provides a practical method for modifying the properties of ferrites used to absorb electromagnetic waves.

The development of high-performance functional composites has become a research hotspot in response to the hazards of overheating and electromagnetic radiation in modern electronic devices. Herein, we grew magnetic Fe₃O₄ particles in situ on the MXene layer to obtain an MXene@Fe₃O₄ composite with rich heterogeneous interfaces. Owing to the unique heterostructure and the synergistic effects of multiple electromagnetic wave absorption mechanisms, the composite achieved a minimum reflection loss of −27.14 dB and an effective absorption bandwidth of 2.05 GHz at an absorption thickness of 2 mm. Moreover, the MXene@Fe₃O₄ composite could be encapsulated in thermoplastic polyurethane (TPU) via thermal curing. The obtained composite elastomer exhibited a strong tensile strength, and its thermal diffusivity was 113% higher than that of pure TPU. Such additional mechanical properties and thermal conduction features render this composite elastomer an advanced electromagnetic absorber to adapt to the ever-changing environment for expanding practical applications.

The increase in the utilization of infrared heat detection technology in military applications necessitates research on composites with improved thermal transmission performance and microwave absorption capabilities. This study satisfactorily fabricated a series of MoS₂/BN-xyz composites (which were characterized by the weight ratio of MoS₂ to BN, denoted by xy:z) through chemical vapor deposition, which resulted in their improved thermal stability and thermal transmission performance. The results show that the remaining mass of MoS₂/BN-101 was as high as 69.25wt% at 800°C under air atmosphere, and a temperature difference of 31.7°C was maintained between the surface temperature and the heating source at a heating temperature of 200°C. Furthermore, MoS₂/BN-301 exhibited an impressive minimum reflection loss value of −32.21 dB at 4.0 mm and a wide effective attenuation bandwidth ranging from 9.32 to 18.00 GHz (8.68 GHz). Therefore, these simplified synthesized MoS₂/BN-xyz composites demonstrate great potential as highly efficient contenders for the enhancement of microwave absorption performance and thermal conductance.

Interface modulation is an important pathway for highly efficient electromagnetic wave absorption. Herein, tailored interfaces between Fe₃O₄ particles and the hexagonal-YFeO₃ (h-YFeO₃) framework were constructed via facile self-assembly. The resulting interfacial electron rearrangement at the heterojunction led to enhanced dielectric and magnetic loss synergy. Experimental results and density function theory (DFT) simulations demonstrate a transition in electrical properties from a half-metallic monophase to metallic Fe₃O₄/h-YFeO₃ composites, emphasizing the advantages of the formed heterointerface. The transformation of electron behavior is also accompanied by a redistribution of electrons at the Fe₃O₄/h-YFeO₃ heterojunction, leading to the accumulation of localized electrons around the Y–O–Fe band bridge, consequently enhancing the polarization. A minimum reflection loss of −34.0 dB can be achieved at 12.0 GHz and 2.0 mm thickness with an effective bandwidth of 3.3 GHz due to the abundant interfaces, enhanced polarization, and rational impedance. Thus, the synergistic effects endow the Fe₃O₄/h-YFeO₃ composites with high performance and tunable functional properties for efficient electromagnetic absorption.

To realize the application of electromagnetic wave absorption (EWA) devices in humid marine environments, bifunctional EWA materials with better EWA capacities and anticorrosion properties have great exploration significance and systematic research requirements. By utilizing the low-cost and excellent magnetic and stable chemical characteristics of barium ferrite (BaFe₁₂O₁₉) and using the high dielectric loss and excellent chemical inertia of nanocarbon clusters, a new type of nanocomposites with carbon nanoclusters encapsulating BaFe₁₂O₁₉ was designed and synthesized by combining an impregnation method and a high-temperature calcination strategy. Furthermore, Ce–Mn ions were introduced into the BaFe₁₂O₁₉ lattice to improve the dielectric and magnetic properties of BaFe₁₂O₁₉ cores significantly, and the energy band structure of the doped lattice and the orders of Ce replacing Fe sites were calculated. Benefiting from Ce–Mn ion doping and carbon nanocluster encapsulation, the composite material exhibited excellent dual functionality of corrosion resistance and EWA. When BaCe_0.2Mn_0.3Fe_11.5O₁₉-C (BCM-C) was calcined at 600°C, the minimum reflection loss of −20.1 dB was achieved at 14.43 GHz. The Ku band’s effective absorption bandwidth of 4.25 GHz was achieved at an absorber thickness of only 1.3 mm. The BCM-C/polydimethylsiloxane coating had excellent corrosion resistance in the simulated marine environment (3.5wt% NaCl solution). The ∣Z∣_0.01Hz value of BCM-C remained at 10⁶ Ω·cm² after 12 soaking days. The successful preparation of the BaFe₁₂O₁₉ composite encapsulated with carbon nanoclusters provides new insights into the preparation of multifunctional absorbent materials and the fabrication of absorbent devices applied in humid marine environments in the future.

With the wide application of electromagnetic wave, a high performance electromagnetic shielding material is urgently needed to solve the harm caused by electromagnetic wave. Complete cross-linking strategy is adopted in this paper. Polyacrylamide (PAM) was synthesized by in-situ polymerization of acrylamide (AM) monomer. The obtained PAM was blended with polyethylene glycol (PEG) to prepare PAM/PEG hydrogels and form rigid support structures. Subsequently, the modified carbon nanotubes (S-CNTs) were incorporated into sodium alginate (SA) and PAM/PEG. Finally, Na⁺ was used to trigger SA self-assembly, which significantly improved the mechanical properties and electrical conductivity of the hydrogels, and prepared PAM/PEG/SA/S-CNTs-Na hydrogels with high toughness and strong electromagnetic interference (EMI) shielding efficiency (SE). The results showed that the compressive strength of PAM/PEG/SA/S-CNTs-Na hydrogel was 19.05 MPa, which was 7.69% higher than that of PAM/PEG hydrogel (17.69 MPa). More encouraging, the average EMI SE of PAM/PEG/SA/S-CNTs-Na hydrogels at a thickness of only 3 mm and a CNTs content of 16.53wt% was 32.92 dB, which is 113.21% higher than that of PAM/PEG hydrogels (15.44 dB).

As a novel 2D material, Ti₃C₂T _x–MXene has become a major area of interest in the field of microwave absorption (MA). However, the MA effect of common Ti₃C₂T _x–MXene is not prominent and often requires complex processes or combinations of other materials to achieve enhanced performance. In this context, a kind of gradient woodpile structure using common Ti₃C₂T _x–MXene as MA material was designed and manufactured through direct ink writing (DIW) 3D printing. The minimum reflection loss (RL_min) of the Ti₃C₂T _x–MXene-based gradient woodpile structures with a thickness of less than 3 mm can reach −70 dB, showing considerable improvement compared with that of a completely filled structure. In addition, the effective absorption bandwidth (EAB) reaches 7.73 GHz. This study demonstrates that a Ti₃C₂T _x–MXene material with excellent MA performance and tunable frequency band can be successfully fabricated with a macroscopic structural design and through DIW 3D printing without complex material hybridization and modification, offering broad application prospects by reducing electromagnetic wave radiation and interference.

Gels and conductive polymer composites, including hydrogen bonds (HBs), have emerged as promising materials for electromagnetic wave (EMW) absorption across various applications. However, the relationship between conduction loss in EMW-absorbing materials and charge transfer in HB remains to be fully understood. In this study, we developed a series of deep eutectic gels to fine-tune the quantity of HB by adjusting the molar ratio of choline chloride (ChCl) and ethylene glycol (EG). Owing to the unique properties of deep eutectic gels, the effects of magnetic loss and polarization loss on EMW attenuation can be disregarded. Our results indicate that the quantity of HB initially increases and then decreases with the introduction of EG, with HB-induced conductive loss following similar patterns. At a ChCl and EG molar ratio of 2.4, the gel labeled G22-CE2.4 exhibited the best EMW absorption performance, characterized by an effective absorption bandwidth of 8.50 GHz and a thickness of 2.54 mm. This superior performance is attributed to the synergistic effects of excellent conductive loss and impedance matching generated by the optimal number of HB. This work elucidates the role of HB in dielectric loss for the first time and provides valuable insights into the optimal design of supramolecular polymer absorbers.

Using SiC nanowires (SiC_NWs) as the substrate, reflux–annealing and electrodeposition–carbonization were sequentially applied to integrate SiC nanowires with magnetic Fe₃O₄ nanoparticles and amorphous nitrogen-doped carbon (NC) for the fabrication of SiC_NWs@Fe₃O₄@NC nanocomposite. Comprehensive testing and characterization of this product provided valuable insights into the impact of structural and composition changes on its electromagnetic wave absorption performances. The optimized SiC_NWs@Fe₃O₄@NC nanocomposite, which has 30wt% filler content and a corresponding thickness of 2.03 mm, demonstrates exceptional performance with the minimum reflection loss (RL_min) of −53.69 dB at 11.04 GHz and effective absorption bandwidth (EAB) of 4.4 GHz. The synergistic effects of the enhanced nanocomposite on electromagnetic wave absorption were thoroughly elucidated using the theories of multiple scattering, polarization relaxation, hysteresis loss, and eddy current loss. Furthermore, a multicomponent electromagnetic wave attenuation model was established, providing valuable insight into the design of novel absorbing materials and the enhancement of their absorption performances. This research demonstrated the significant potential of the SiC_NWs@Fe₃O₄@NC nanocomposite as a highly efficient electromagnetic wave-absorbing material with potential applications in various fields, such as stealth technology and microwave absorption.

W-type barium–nickel ferrite (BaNi₂Fe₁₆O₂₇) is a highly promising material for electromagnetic wave (EMW) absorption because of its magnetic loss capability for EMW, low cost, large-scale production potential, high-temperature resistance, and excellent chemical stability. However, the poor dielectric loss of magnetic ferrites hampers their utilization, hindering enhancement in their EMW-absorption performance. Developing efficient strategies that improve the EMW-absorption performance of ferrite is highly desired but remains challenging. Here, an efficient strategy substituting Ba²⁺ with rare earth La³⁺ in W-type ferrite was proposed for the preparation of novel La-substituted ferrites (Ba_1−xLa _xNi₂Fe_15.4O₂₇). The influences of La³⁺ substitution on ferrites’ EMW-absorption performance and the dissipative mechanism toward EMW were systematically explored and discussed. La³⁺ efficiently induced lattice defects, enhanced defect-induced polarization, and slightly reduced the ferrites’ bandgap, enhancing the dielectric properties of the ferrites. La³⁺ also enhanced the ferromagnetic resonance loss and strengthened magnetic properties. These effects considerably improved the EMW-absorption performance of Ba_1−xLa _xNi₂Fe_15.4O₂₇ compared with pure W-type ferrites. When x = 0.2, the best EMW-absorption performance was achieved with a minimum reflection loss of −55.6 dB and effective absorption bandwidth (EAB) of 3.44 GHz.

The preparation of carbon-based electromagnetic wave (EMW) absorbers possessing thin matching thickness, wide absorption bandwidth, strong absorption intensity, and low filling ratio remains a huge challenge. Metal–organic frameworks (MOFs) are ideal self-sacrificing templates for the construction of carbon-based EMW absorbers. In this work, bimetallic FeMn–MOF-derived MnFe₂O₄/C/graphene composites were fabricated via a two-step route of solvothermal reaction and the following pyrolysis treatment. The results reveal the evolution of the microscopic morphology of carbon skeletons from loofah-like to octahedral and then to polyhedron and pomegranate after the adjustment of the Fe³⁺ to Mn²⁺ molar ratio. Furthermore, at the Fe³⁺ to Mn²⁺ molar ratio of 2:1, the obtained MnFe₂O₄/C/graphene composite exhibited the highest EMW absorption capacity. Specifically, a minimum reflection loss of −72.7 dB and a maximum effective absorption bandwidth of 5.1 GHz were achieved at a low filling ratio of 10wt%. In addition, the possible EMW absorption mechanism of MnFe₂O₄/C/graphene composites was proposed. Therefore, the results of this work will contribute to the construction of broadband and efficient carbon-based EMW absorbers derived from MOFs.

Traditional stealth materials do not fulfill the requirements of high absorption for radar waves and low emissivity for infrared waves. Furthermore, they can be detected by various technologies, considerably threatening weapon safety. Therefore, a stealth material compatible with radar and infrared was designed based on the photonic bandgap characteristics of photonic crystals. The radar stealth layer (bottom layer) is a composite of carbonyl iron/silicon dioxide/epoxy resin, and the infrared stealth layer (top layer) is a 1D photonic crystal with alternately and periodically stacked germanium and silicon nitride. Through composition optimization and structural adjustment, the effective absorption bandwidth of the compatible stealth material with a reflection loss of less than −10 dB has reached 4.95 GHz. The average infrared emissivity of the proposed design is 0.1063, indicating good stealth performance. The theoretical analysis proves that photonic crystals with this structural design can produce infrared waves within the photonic bandgap, achieving high radar wave transmittance and low infrared emissivity. Infrared stealth is achieved without affecting the absorption performance of the radar stealth layer, and the conflict between radar and infrared stealth performance is resolved. This work aims to promote the application of photonic crystals in compatible stealth materials and the development of stealth technology and to provide a design and theoretical foundation for related experiments and research.

Herein, an external crosslinker facilitated the hypercrosslinking of ferrocene and a nitrogen heterocyclic compound (either melamine or imidazole) through a direct Friedel–Crafts reaction, which led to the formation of nitrogen-containing hypercrosslinked ferrocene polymer precursors (HCP-FCs). Subsequent carbonization of these precursors results in the production of iron–nitrogen-doped porous carbon absorbers (Fe–NPCs). The Fe–NPCs demonstrate a porous structure comprising aggregated nanotubes and nanospheres. The porosity of this structure can be modulated by adjusting the iron and nitrogen contents to optimize impedance matching. The uniform distribution of Fe–N _xC, N dipoles, and α-Fe within the carbon matrix can be ensured by using hypercrosslinked ferrocenes in constructing porous carbon, providing the absorber with numerous polarization sites and a conductive network. The electromagnetic wave absorption performance of the specially designed Fe–NPC-M₂ absorbers is satisfactory, revealing a minimum reflection loss of −55.3 dB at 2.5 mm and an effective absorption bandwidth of 6.00 GHz at 2.0 mm. By utilizing hypercrosslinked polymers (HCPs) as precursors, a novel method for developing highly efficient carbon-based absorbing agents is introduced in this research.

Recent progress in microwave absorption materials stimulates the extensive exploration of rare earth oxide materials. Herein, we report the synthesis of a hollow sphere-based carbon material compounded with rare earth oxides. Hollow N-doped carbon nanospheres loaded ceria composites (H-NC@CeO₂) were designed and prepared by the template method, combined with in-situ coating, pyrolysis and chemical etching. By controlling the loading content of H-NC@CeO₂ and adjusting the impedance matching of the material, the H-NC@CeO₂/PS (polystyrene) composite exhibited a minimum reflection loss (RL) of −50.8 dB and an effective absorption bandwidth (EAB) of 4.64 GHz at a filler ratio of 20wt% and a thickness of 2 mm. In accordance with measured electromagnetic parameters, simulations using the high frequency structure simulator (HFSS) software were conducted to investigate the impact of the honeycomb structure on the electromagnetic wave performance of H-NC@CeO₂/PS. By calculating the surface electric field and the material’s bulk loss density, the mechanism of electromagnetic loss for the honeycomb structure was elaborated. A method for structural design and manufacturing of broadband absorbing devices was proposed and a broadband absorber with an EAB of 11.9 GHz was prepared. This study presents an innovative approach to designing advanced electromagnetic (EM) wave absorbing materials with broad absorption bandwidths.

The rapid development of 5G communication technology and smart electronic and electrical equipment will inevitably lead to electromagnetic radiation pollution. Enriching heterointerface polarization relaxation through nanostructure design and interface modification has proven to be an effective strategy to obtain efficient electromagnetic wave absorption. Here, this work implements an innovative method that combines biomimetic honeycomb superstructure to constrain hierarchical porous heterostructure composed of Co/CoO nano-particles to improve the interfacial polarization intensity. The method effectively controlled the absorption efficiency of Co²⁺ through de-lignification modification of bamboo, and combined with the bionic carbon-based natural hierarchical porous structure to achieve uniform dispersion of nanoparticles, which is conducive to the in-depth construction of heterogeneous interfaces. In addition, the multiphase structure brought about by high-temperature pyrolysis provides the best dielectric loss and impedance matching for the material. Therefore, the obtained bamboo-based Co/CoO multiphase composite showed excellent electromagnetic wave absorption performance, achieving excellent reflection loss (RL) of −79 dB and effective absorption band width of 4.12 GHz (6.84–10.96 GHz) at low load of 15wt%. Among them, the material’s optimal radar cross-section (RCS) reduction value can reach 31.9 dB·m². This work provides a new approach to the micro-control and comprehensive optimization of macro-design of microwave absorbers, and offers new ideas for the high-value utilization of biomass materials.

Non-stoichiometric carbides have been proven to be effective electromagnetic wave (EMW) absorbing materials. In this study, phase and morphology of XZnC (X = Fe/Co/Cu) loaded on a three dimensional (3D) network structure melamine sponge (MS) carbon composites were investigated through vacuum filtration followed by calcination. The FeZnC/CoZnC/CuZnC with carbon nanotubes (CNTs) were uniformly dispersed on the surface of melamine sponge carbon skeleton and Co-containing sample exhibits the highest CNTs concentration. The minimum reflection loss (RL_min) of the CoZnC/MS composite (m _composite: m _paraffin = 1:1, m represents mass) reached −33.60 dB, and the effective absorption bandwidth (EAB) reached 9.60 GHz. The outstanding electromagnetic wave absorption (EMWA) properties of the CoZnC/MS composite can be attributed to its unique hollow structure, which leads to multiple reflections and scattering. The formed conductive network improves dielectric and conductive loss. The incorporation of Co enhances the magnetic loss capability and optimizes interfacial polarization and dipole polarization. By simultaneously improving dielectric and magnetic losses, excellent impedance matching performance is achieved. The clarification of element replacement in XZnC/MS composites provides an efficient design perspective for high-performance non-stoichiometric carbide EMW absorbers.

Exploring high-efficiency and broadband microwave absorption (MA) materials with corrosion resistance and low cost is urgently needed for wide practical applications. Herein, the natural porous attapulgite (ATP) nanorods embedded with TiO₂ and polyaniline (PANI) nanoparticles are synthesized via heterogeneous precipitation and in-situ polymerization. The obtained PANI–TiO₂–ATP one-dimensional (1D) nanostructures can intertwine into three-dimensional (3D) conductive network, which favors energy dissipation. The minimum reflection loss (RL_min) of the PANI–TiO₂–ATP coating (20wt%) reaches −49.36 dB at 9.53 GHz, and the effective absorption bandwidth (EAB) can reach 6.53 GHz with a thickness of 2.1 mm. The excellent MA properties are attributed to interfacial polarization, multiple loss mechanisms, and good impedance matching induced by the synergistic effect of PANI–TiO₂ nanoparticle shells and ATP nanorods. In addition, salt spray and Tafel polarization curve tests reveal that the PANI–TiO₂–ATP coating shows outstanding corrosion resistance performance. This study provides a low-cost and high-efficiency strategy for constructing 1D nanonetwork composites for MA and corrosion resistance applications using natural porous ATP nanorods as carriers.

Pitting corrosion of 316L stainless steel in NaCl solution was investigated by means of staircase potential electrochemical impedance spectroscopy (SPEIS). The investigation focused on the transition of stainless steel from the passive state to pitting corrosion. Based on the evolution of electrical parameters of the equivalent electrical circuit, it is suggested that the most probable mechanism of pit creation is the film breaking model. The result demonstrates that staircase potential electrochemical impedance spectroscopy is an effective method for the investigation of pitting corrosion.

316L stainless steel (SS 316L) is quite attractive as bipolar plates in proton exchange membrane fuel cells (PEMFC). In this study, graphite-polypyrrole was coated on SS 316L by the method of cyclic voltammetry. The surface morphology and chemical composition of the graphite-polypyrrole composite coating were investigated by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). A simulated working environment of PEMFC was applied for testing the corrosion properties of graphite-polypyrrole coated SS 316L. The current densities in the simulated PEMFC anode and cathode conditions are around 3×10⁻⁹ and 9×10⁻⁵ A·cm⁻², respectively. In addition, the interfacial contact resistance (ICR) was also investigated. The ICR value of graphite-polypyrrole coated SS 316L is much lower than that of bare SS 316L. Therefore, graphite-polypyrrole coated SS 316L indicates a great potential for the application in PEMFC.

The oxidation behavior of different SiAlON phases (β-SiAlON, X-phase SiAlON and 12H powders) synthesized from coal gangue in air atmosphere was investigated using isothermal thermogravimetry (TG) and field-emission scanning electron microscopy (FE-SEM). The effect of ferric oxide impurities in coal gangue was studied. The results show that ferric oxide contributes to the growth of SiAlON crystalline during the synthesis process. In the oxidation experiment, the existence of ferric oxide decreases the oxidation resistance of SiAlON. The reason is that the impurity causes the formation of a liquid phase at a higher temperature. At 1423–1623 K, the oxidation of SiAlON powders is diffusion controlled and it can be described by Chou’s model. A fair agreement is found between theoretical calculations and the experimental data.

A comparative study of the dissolution kinetics of galena ore in binary solutions of FeCl₃/HCl and H₂O₂/HCl has been undertaken. The dissolution kinetics of the galena was found to depend on leachant concentration, reaction temperature, stirring speed, solid-to-liquid ratio, and particle diameter. The dissolution rate of galena ore increases with the increase of leachant concentration, reaction temperature, and stirring speed, while it decreases with the increase of solid-to-liquid ratio and particle diameter. The activation energy (E _a) of 26.5 kJ/mol was obtained for galena ore dissolution in 0.3 M FeCl₃/8.06 M HCl, and it suggests the surface diffusion model for the leaching reaction, while the E _a value of 40.6 kJ/mol was obtained for its dissolution in 8.06 M H₂O₂/8.06 M HCl, which suggests the surface chemical reaction model for the leaching reaction. Furthermore, the linear relationship between rate constants and the reciprocal of particle radius supports the fact that dissolution is controlled by the surface reaction in the two cases. Finally, the rate of reaction based on the reaction-controlled process has been described by a semiempirical mathematical model. The Arrhenius and reaction constants of 11.023 s⁻¹, 1.25×10⁴ and 3.65×10² s⁻¹, 8.02×10⁶ were calculated for the 0.3 M FeCl₃/8.06 M HCl and 8.06 M H₂O₂/8.06 M HCl binary solutions, respectively.

Surface modification of wollastonite particles using titanate as a modification agent incorporated by simultaneous wet ultra-fine grinding in a laboratory stirred mill was investigated. The physical, physic-chemical and application properties of the modified wollastonite were measured and evaluated. The results showed that grinding intensity markedly influences the modification effect because of the mechano chemical effect. The hydrophilic surface of wollastonite was turned into a hydrophobic one after modification. The interaction between titanate and wollastonite under wet grinding circumstances was studied. It was suggested that physical adsorption and chemical adsorption of titanate coexisted on the wollastonite surface. The mechanical properties of polyethylene (PE) filled with the modified wollastonite powder were markedly improved.

Gold telluride ores are important gold refractory ores due to the presence of sulfides and other gangue materials. The classification and main physical properties of gold telluride ores were described, and possible treatment methods including flotation, leaching, and oxidation were reviewed. The results show that flotation procedures are much easier for gold tellurides compared to other refractory gold-bearing ores. For the conventional cyanide leaching process, pretreatment such as oxidation is required to achieve high gold recovery. Roasting is a relatively simple but not environment-friendly method; bio-oxidation technology seems to be more suitable for the oxidation of flotation concentrate. Other treatment methods involve cyanide leaching, thiourea leaching, ammoniacal thiosulfate leaching, carbon-in-pulp, and resin-in-pulp, all of which are less commonly utilized.

The modification of MgO·Al₂O₃ spinel inclusions in Al-killed steel by Ca-treatment has been studied by industrial trials and thermodynamic calculations. In the industrial trials, samples were taken systematically during the refining process in which the molten steel was treated by calcium, and the characters of the inclusions were analyzed using scanning electron microscopy (SEM) and energy dispersive spectra (EDS). The effects of Ca-treatment were evaluated by tracking the compositions of the inclusions. The results show that the modification of MgO·Al₂O₃ spinel inclusions by Ca-treatment is effective and the transformation sequence of the inclusions during the refining is Al₂O₃→MgO·Al₂O₃→liquid complex inclusions. The modification of spinel inclusions by Ca-treatment was calculated by FactSage6.0 utilizing its free-energy minimization routines. The results of thermodynamic calculations indicate that spinel inclusions are easier to be modified than Al₂O₃ inclusions and the spinel inclusions in 30CrMo steel would transform to liquid complex inclusions when the content of dissolved Ca in the molten steel exceeds 1×10⁻⁶. Also, the results show that adding more calcium into the molten steel would lower the contents of Al₂O₃ and MgO and increase the CaO content of the inclusions, while the change in SiO₂ content is little.

In order to get the controlled methods of microstructure homogenization and high strengthening-toughening combination by compact strip production (CSP) rolling, the dynamic recrystallization characteristics of each pass were obtained during CSP rolling using a Gleeble-1500 thermal mechanical simulator. Then, the CSP process was simulated by laboratory rolling experiment. Through thermal mechanical simulation experiment and laboratory rolling experiment, a design idea of Nb-bearing pipeline steel by CSP can be obtained as the following: the level of dynamic recrystallization behavior should be increased through the reasonable balance of high deformation temperature and deformation amount in F1 and F2 passes, and F3-F7 passes should be controlled in the austenite non-recrystallization zone. Finally, X65 pipeline steel with microstructure uniformity and good properties was produced by CSP. The yield strength is up to 497 MPa, the tensile strength is up to 563 MPa, the elongation is 30% on average, and the toughness is very good whose Charpy impact value is 110 J on average and drop-weight tear test shearing areas are all 100% at −60, −40, −20, 0, and 20°C.