Electrochemical atomic force microscopy (EC-AFM), a branch of a scanning probe microscopy (SPM), can image substrate topography with high resolution. Since its inception, it was extended to a wide range of research areas through continuous improvement. The presence of an electrolytic cell and a potentiostat makes it possible to observe the topographical changes of the sample surface in real time. EC-AFM is used in in situ corrosion research because the samples are not required to be electrically conductive. It is widely used in passive film properties, surface dissolution, early-stage corrosion initiation, inhibitor efficiency, and many other branches of corrosion science. This review provides the research progress of EC-AFM and summarizes the extensive applications and investigations using EC-AFM in corrosion science.

Inhomogeneous structures with carbon nanotubes (CNTs), reinforced with Cu composite foams as the reinforcing skeletons (CNTs/Cu_f^®Cu), have been designed to overcome the paradox between strength and ductility or conductivity in copper matrix composites. The interface between CNTs and the copper matrix is usually weak, due to poor wettability and interaction. In this study, nickel nanoparticles are decorated onto CNTs to improve interfacial bonding. The broader interface transition area between CNTs and copper with Ni₃C interfacial products formed, and a combination of improved electrical conductivity (95.6% IACS), tensile strength (364.9 MPa), and elongation (40.6%) was achieved for the Ni-decorated CNTs/Cu_f^®Cu (Ni-CNTs/Cu_f^®Cu). In addition, the strengthening mechanisms are discussed in this study.

Copper matrix composites reinforced by copper foams with uniformly embedded carbon nanotubes (CNTs) were prepared by electrodeposition and spark plasma sintering (SPS). The microstructure and mechanical properties of the composite foams and bulk composites were characterized or tested by Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and tensile tester, respectively. The results show that the CNTs are uniformly dispersed and embedded in the copper foams by electrodeposition, which preserve as reinforcing skeletons in the subsequent SPS sintered composites. Significant improvements of the tensile strength up to 341.32 MPa and the elongation value of 35.59% are obtained for the CNTs/Cu foam reinforced copper composites, showing a simultaneous achievement of high strength and high ductility with such a three-dimensional skeleton reinforced composite structure. The strengthening mechanisms are also discussed.

Alkaline Al-air batteries (AABs) have attracted numerous attention due to their high theoretical capacity density and energy density with intrinsic safety and low cost. However, severe hydrogen evolution reaction (HER) decreases the discharge performance and increases usage risk, which restricts the development of AABs. In this comprehensive review, a systematic overview of progress in inhibition methods of HER was provided, including anodic alloying, structural treatment, surface modification, additives and non-aqueous electrolyte. Among them, the most efficient method was additives, which was simple and provided the highest inhibition rate. Finally, suggestions and perspectives for future research are offered on improving the commercial application potential of AABs, which provide advice for aqueous metal-air batteries.

In this study, carbon nanotube-reinforced silver composites (CNT/Ag) were prepared by the powder metallurgy process via spark plasma sintering (SPS) and hot pressing sintering (HP) with composite powders through an improved electroless plating method assisted by ultrasonic spray atomization. The dispersion of CNTs was effectively improved by ultrasonic spray atomization, and uniform silver layers were deposited on the surface of CNTs by electroless deposition. The property testing results showed significant improvements of the electrical conductivity, hardness, and tensile strength in the samples prepared by SPS, as compared to their HP sintered counterparts. When the volume fraction of CNTs reached 2.5%, the tensile strength reached a maximum value of 221 MPa, which was more than twice that of the pure silver samples. The structural analysis indicated different degrees of CNT agglomeration and matrix mean grain sizes in the composites prepared by SPS and HP, which are responsible for the differences in properties.

During the laser-based directed energy deposition (DED-LB) processing, a WC-12Co composite coating with high hardness and strong wear resistance was successfully prepared on a 316L stainless steel substrate by adopting a high-precision coaxial powder feeding system using a spherical WC-12Co composite powder, which showed a large number of dendritic carbides and herringbone planar crystals on the substrate-binding interface. The influences of laser power on microstructural and mechanical properties (e.g., hardness, friction resistance) of WC-12Co composite surfaces were investigated. The results show that laser power has a significant effect on determining the degree of Co phase melting around the WC particles and the adhesion strength between the matrix and the coating. Lower laser power does not meet the melting requirements of WC particles, thus weakening the molding quality of the composite coating. At high laser power, it is possible to dissolve the WC particles and melt the metal powder between the particles, thus improving the material properties. The laser power increased from 700 W to 1000 W and the average hardness of the coating surface gradually increased from 1166.33 HV to 1395.70 HV, which is about 4–5 times higher than the average hardness of the substrate (about 281.76 HV). In addition, the coatings deposited at 1000 W showed better wear resistance. This work shows that the processing parameters during laser-directed energy deposition can be optimized to prepare WC-12Co composite coatings with excellent mechanical properties.