It remains a popular question whether rare earth oxides encourage reinforcing phases to the uniform distribution in cermet coating to improve the mechanical properties. This study applied laser ...cladding to prepare the TiAl/WC/CeO2 MMC cermet coatings on the TC21 alloy substrate. The effects of CeO2 content on the phase composition, microstructure formation, evolution mechanism, and properties of cermet coatings were investigated. Results show that the incorporation of CeO2 did not change the phase of composite coating, but the shape of the TiC phase has a close relation to the CeO2 content. CeO2 enhanced the fluidity of the molten pool, which further encouraged the TiC/Ti2AlC core-shell reinforcement phase. With the increase in CeO2 content, the optimized coating contributed to homogenous microstructure distribution and fine grain size. Owing to the hard phases strengthening and dispersion strengthening effects of CeO2, the microhardness of the composite coatings was all significantly higher (almost 1.6 times) than that of the substrate. Importantly, the addition of CeO2 significantly improved the wear resistance of the composite coating. This work provides a certain reference value for the study of surface strengthening of key parts in the aerospace field.
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•Surface finishing and modification of 65 steel were achieved by continuous electron beam process.•A smooth surface was attained and the surface roughness decreased significantly with ...appropriate scanning frequency.•The microstructure was homogeneous acicular martensite as quenched completely, when the frequency was 400 Hz.•Microhardness and wear resistance of 65 steel surface could be improved greatly.
Environmental-friendly and efficient surface polishing of high carbon steel components remains challenging. In this study, continuous electron beam process (CEBP) was used to surface finishing and modification of 65 steel. The effect of different scanning frequency on surface roughness, microstructure, microhardness and wear resistance of the modified layer were evaluated after surface scanned by CEBP. Results indicated that a smooth surface was achieved and the surface roughness decreased significantly, no defects were discovered under the scanning frequency 400 Hz. Moreover, the microstructure was homogeneous acicular martensite as quenched completely. Microhardness and wear resistance of 65 steel surface were improved greatly by CEBP. This study demonstrated the potential of using CEBP for efficient and impurity-free surface strengthening of high carbon steel.
•The category of electron beam (EB) in lithium ion batteries (LIBS) was outlined.•Review on progress in electrode/separator materials modification/synthesized by EB.•Mechanisms of EB to enhance the ...electrode/separator properties were discussed.•The future challenges/directions of EB and its application in LIBs were proposed.
Lithium ion batteries (LIBs) have been recognized as an indispensable option for substantially reducing fossil fuel consumption in industrial production and daily life. Given that the electrode and separator are pivotal components of LIBs, their properties notably impact the electrochemical performance of the entire system. Consequently, the efficient synthesis and modification of electrode or separator using versatile and cost-effective methods are the key for a wide range of LIBs applications. Currently, electron beam technology has emerged as a potent choice for synthesizing and modifying electrode and separator materials. Herein, we categorize electron beam technology and outline its vital roles in material processing. Additionally, the advancements on the synthesis and modification of anode, cathode as well as separator materials with the assistance of electron beam is highlighted, and the mechanisms of electron beam to enhance the electrochemical properties for electrode/separator are negotiated. Finally, we examine the challenges and prospects associated with the application of electron beam technology in the context of LIBs.
Ti
3
Al matrix composite coatings were synthesized on a TC4 titanium alloy with Ti, Al and BN mixed powder by in situ laser cladding. Then, the effect of ZrO
2
addition to the composite coatings was ...investigated. The phase composition, microstructure and element distribution of the composite coatings were characterized by scanning electron microscopy, x-ray diffraction and electron probe microanalysis. Results showed that the Ti
3
Al matrix composite coatings were reinforced by TiB
2
, TiB and TiN phases. The quality and mechanical properties of the composite coating can be significantly improved with ZrO
2
addition under optimum laser power of 1000 W. The microhardness of the composite coatings was 2-3 times higher than that of the substrate, and the wear resistance of the composite coating without and with ZrO
2
addition was enhanced by nearly 4 and 7 times compared to the substrate. The better properties of the composite coating with ZrO
2
addition were mainly attributed to the formation of a ZrO
2
network. The network-like distribution of ZrO
2
provided dispersion strengthening and grain refinement effects. This research is expected to provide a new coating material to obtain high-performance Ti
3
Al matrix composite coating.
The effect of TiN addition on the high temperature oxidation behavior of Ti-Al-Cr coating was investigated. Results revealed that the coating with 4 wt.% TiN addition exhibited superior oxidation ...resistance. The minimum mass gain after being oxidized at 850 ℃ was 0.56 mg/cm2, which was 40.1% less than that of the TiN-free coating. The mechanisms for TiN addition can enhance the high-temperature oxidation resistance of Ti-Al-Cr coating include the dispersed TiN resulting in more grain boundaries and prolonging the diffusion paths of oxygen and contributing to the generation of a protective CrAlN layer to diminish the inward oxygen diffusion, as well as facilitating the formation of the dense internal oxide layer Al2O3 and Cr2O3.
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•Ti-Al-Cr coatings with TiN addition were fabricated on TC21 for the first time.•TiN addition can promote the formation of core-ring microstructure.•The addition of TiN in the Ti-Al-Cr coating decreased oxidation rate.•TiN addition can change the oxide scale of Ti-Al-Cr coating.•The presence of CrAlN phase inhibited the internal diffusion of O in the oxide scales.
•TiN/Ti3AlN-Ti3Al coatings were investigated with varied laser specific energy.•The dilution rate of the coatings increased with laser specific energy.•TiN particles core-rim structure was generated ...in the coatings.•Dispersion strengthening and grain refinement were notable with 58.3 J/mm2.•The optimum laser specific energy for the composite coating was proposed.
Tremendous studies were focused on the influence of single parameter on the properties of cladded coating, while scarce efforts have been devoted to investigate the coating performance affected by specific energy. Herein, the effects of laser specific energy in the range 40.0–88.9 J/mm2 on the morphology, microstructure and properties of TiN/Ti3AlN-Ti3Al composite coating were analyzed. Results revealed that the dilution rate of the coating increased with increasing of specific energy, the coating at 58.3 J/mm2 exhibited the least defects with dilution rate was about 14.0%. The coating was mainly composed of TiN, Ti3AlN and Ti3Al phases, the amount of Ti3Al and TiN decreased slightly as the specific energy increased to 58.3 J/mm2, whereas the Ti3Al and TiN decreased remarkable when the specific energy increased further. Comparatively, when the specific energy reached 58.3 J/mm2, the coating exhibited uniform distribution of TiN and finer microstructure, and core-rim structure formed in the coating. As a result, the microhardness of the composite coating was approximately 3 times higher than that of the substrate and the wear resistance was improved remarkably under optimum specific energy 58.3 J/mm2. This study provided an insight for the development of high-performance Ti3Al matrix composite coating.
Titanium alloys have high specific strength and excellent high temperature and corrosion resistance but low hardness and poor wear resistance. In this study, TiC-reinforced Ti2Ni/Ti5Si3 eutectic ...matrix composite coatings were fabricated on TC21 titanium alloy substrates by laser cladding. The phase composition and microstructure of the coating with micro- or nano-sized SiC addition as well as the microhardness and wear resistance of the coatings were evaluated. The analysis showed that the composite coatings were mainly made up of TiC, TiNi, Ti5Si3, and Ti2Ni phases, the TiC phase being distributed on the eutectic Ti2Ni/Ti5Si3 phase. The coatings with nano-SiC addition exhibited better coating quality, and higher microhardness and wear resistance than the coatings with micro-SiC addition. The better properties of the coating with nano-SiC addition were mainly attributed to the larger amount of the TiC hard-reinforcing phase and a more compact microstructure. The predominant wear mechanism of the coating with micro-SiC addition was adhesive wear, while it was abrasive wear for the coating with nano-SiC addition. This study should provide an insight into the development of Ti2Ni/Ti5Si3 eutectic matrix coatings.
Surface nanocrystallization is a highly effective approach for enhancing the surface wear resistance of stainless steel. However, the attainment of fast nanocrystallization on stainless steel ...surfaces remains a significant obstacle. Thus, a novel form for high-voltage electron beam radiation with a rapid response time of 50 ms is proposed to break through this bottleneck. The results revealed the presence of significant quantities of nanocrystals and an amorphous structure in the modified layer of stainless-steel surfaces. A large number of dislocation lines resulted in an interplane distance increase in the (110) planes of Fe-Cr. In addition, the dislocation walls can inhibit the growth of the crystal, contributing to a remarkable enhancement in their surface wear resistance. Significantly, the wear volume of the modified layer decreased from 0.0124 mm3 to 0.0013 mm3, a remarkable reduction of 90 % compared to the initial state due to surface nanocrystallization, dispersion strengthening, and dislocation walls. This study provides novel concepts for the production of surface nanocrystals in ultra-wear-resistant stainless steel.
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•A novel form for high-voltage electron beam radiation with a rapid response time of 50 ms•Stainless steel with ultra-wear-resistant was fabricated by EB irradiation.•The process of nanograins generation and the underlying mechanism of strengthening have been elucidated.•Rapid fabrication via EB irradiation advances the wear resistance to 9.5 times higher than that of matrix
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•Ultrafast in-situ transformation of graphite into graphene nanosheets by HCPEB direct irradiation is developed for the first time.•Impurity-free graphene with thickness less than 10 ...layers reaches 95%.•The transformation mechanism is ascribed to the transient internal expansion of graphite.•The effective transformation is due to the equal thermal stress and deformation of adjacent layers in graphite.
Environmental-friendly and efficient transformation of graphite to obtain impurity-free graphene remains challenging. Herein, a novel approach for in-situ transformation of graphite into graphene is proposed. The graphite particles were irradiated directly by high current pulsed electron beam (HCPEB) with pulse duration of 2 μs. The morphology and microstructure changes were characterized by Raman spectrum, X-ray diffraction, confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscope (AFM) methods. It is revealed that the surface layer on graphite particles of thickness ∼ 10 μm was transformed to graphene nanosheets effectively, where the content of graphene with thickness less than 10 atom layers reached 95%. The numerical simulation results showed that the heating temperature in the subsurface layer would be 3246 ℃ and the thermal stress amplitude ∼ 110 MPa, which leads to the instantaneous expansion and breakdown of interlayer combination and realizes the transformation of graphite into graphene microstructure. This study demonstrated the potential of using HCPEB for ultrafast in-situ transformation of graphite into graphene nanosheets.
