Ultra wear resistant TiC-Fe coating prepared by high efficient and economic plasma cladding method

The key components of engineering machinery frequently failed due to working in the high load and high wear operating envir-onment.And the performance of the Fe-based alloy coatings typically employed need to be improved for fulfilling the service requirements.Herein,a TiC strengthened Fe-based alloy cladding layer,named TiC-Fe coating,was designed and prepared by plasma cladding technology.The frictional wear performance of coating under various loads was tested.The wear morphology of the coating was observed,and its wear mechanism was examined.The results indicated that the TiC-Fe coating was well formed and metallurgically bonded to the Q345C substrate.Its microstructure mainly consisted of Fe-Cr solid solution,α-Fe phase,(Fe,Cr)_(7)C_(3) phase and TiC phase.The coating exhibited an average microhardness of 980 HV0.2,which was about 5.4 times that of the Q345C substrate.The wear mass loss of the TiC-Fe coatings was much smaller than that of the Q345C substrate,which indicated that the wear resistance of the Q345C coating was superior to the substrate,and the wear mechanism of the coating was mainly attributed to the abrasive wear.

Preparation of Cu@Ag Nanoparticles for Conductive Ink

In order to overcome the shortcomings of low-cost anti-oxidation conductive ink and its preparation method in the field of printing electronics, core-shell coated Cu@Ag nanoparticles were used to prepare conductive ink, and a printed circuit was obtained by inkjet printing. Copper nanoparticles were prepared by a chemical reduction method and then coated with Cu@Ag particles by a copper-based self-catalytic reaction. Conductive ink was prepared by ball milling and dispersion and printed on PI film to form a conductive coating. After characterization and analysis, the particle size and dispersion of the obtained Cu@Ag meet the requirements and can be stored stably under normal atmospheric conditions. The resistivity of the conductive film sintered at 300˚C is only 10.6 μΩ∙cm.

Progress in Light-weight High Entropy Alloys

High entropy alloys(HEAs)possess good mechanical properties and a wide range of industrial applications.In this paper,phase formation prediction theory,microstructure,properties and preparation methods of light-weight HEAs(LWHEAs)were reviewed.The problems and challenges faced by LWHEAs development were analyzed.The results showed that many aspects are still weak and require investigation for future advanced alloys,such as clarification of the role of entropy in phase formation and properties of HEAs,improved definition and different generations division of HEAs,close-packed hexagonal(HCP)phase structure prediction and corresponding alloy design and fabrication.Finally,some suggestions were presented in this paper including in-depth research on formation mechanism of multi-component alloy phase and strengthening of large-scale HEA preparation methods via technology compounding and 3D printing technology.Also,there is a need for more research on the in-situ preparation of HEA coatings and films,as well as developing LWHEAs with superior strength and elevated temperature resistance or ultra-low temperature resistance to meet the requirements of future engineering applications.

Research on automatic high velocity arc spraying technique and metastable coating materials

Into the 21st century, remanufacturing engineering has been accepted by more and more people in China. Remanufacturing is an industrial maintenance technology for worn or waste electro-mechanical products using advanced technology, which means the high-level stage for the maintenance and surface engineering. In this paper, a new automotive high velocity arc spraying system was introduced. And three kinds of advanced amorphous and nanocrystalline metastable coatings were developed, including Fe, Ni and Al-based amorphous and nanocrystalline composite coatings. Their research development and applications were introduced. And the development trends of high velocity arc spraying system and advanced metastable surface protective coating materials on the remanu- facturing engineering were indicated.

High Velocity Electric Arc Sprayed Fe-Al-Nb-B Composite Coating and Its Wear Behavior

A type of Fe-Al-Nb-B cored wire was designed and the coating was prepared using a robot-based electric wire arc spraying process. The Fe-Al binary cored wire and coating were also prepared as comparison. The phase composition and structure of the coatings were investigated using X-ray diffraction （XRD）, scanning electron microscopy （SEM） coupled with energy dispersive X-ray spectroscopy （EDS） and transmission electron microscopy （TEM）. The coating tribological properties were evaluated with the micromotion wear tester under different conditions. The results show that, although typical lamellar structure was performed for both the arc sprayed Fe-Al-Nb-B coating and Fe-Al coating, the structure composition, mechanical and wear properties of the former are quite different from those of latter. The Fe-Al-Nb-B coating is a typical composite coating, which is distributed inhomogeneously with α-Fe crystalline, FeAl and Fe3Al intermetallics, amorphous and nanocrystallines as well as locally existed oxide phases. As a result, the mircrohardness and wear resistance of the Fe-Al-Nb-B composite coating increased significantly. Finally the mechanism of the coating wear resistant behavior was discussed based on the experimental results such as friction coefficient, two dimensional and three dimensional worn surface profiles.