Cubic boron nitride particles coated by titanium nitride (TiN/cBN) as well as diamond particles coated by titanium carbide (TiC/diamond) were prepared by Ti molten salt deposition followed by heat-treatment process. c...Cubic boron nitride particles coated by titanium nitride (TiN/cBN) as well as diamond particles coated by titanium carbide (TiC/diamond) were prepared by Ti molten salt deposition followed by heat-treatment process. cBN or diamond particles were mixed separately with Ti powders and molten salts (KCl, NaCl and K<sub>2</sub>TiF<sub>6</sub>). The mixture was heated at 900 °C under argon atmosphere. The produced particles were heat-treated under hydrogen at 1000 °C. The morphologies and chemical compositions of the produced particles were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and focused ion beam (FIB). The results show that the cBN and the diamond particles are coated by nano-sized Ti layers. By heat-treatment of the Ti/cBN and TiC/diamond coated particles under hydrogen atmosphere, the deposited Ti layers were interacted by the in-situ transformation reaction with the surfaces of cBN and diamond particles and converted to titanium compounds (TiN and TiC), respectively.展开更多
The further electrification of various fields in production and daily life makes it a topic worthy of exploration to improve the performance of capacitors for a long time,including thin-film capacitors.The discharge e...The further electrification of various fields in production and daily life makes it a topic worthy of exploration to improve the performance of capacitors for a long time,including thin-film capacitors.The discharge energy density of thin-film capacitors that serves as one of the important types directly depends on electric field strength and the dielectric constant of the insulation material.However,it has long been a great challenge to improve the breakdown strength and dielectric constant simultaneously.Considering that boron nitride nanosheets(BNNS)possess superior insulation and thermal conductivity owing to wide band gap and 2-dimensional structure,a bilayer polymer film is prepared via coating BNNS by solution casting on surface of polyethylene terephthalate(PET)films.By revealing the bandgap and insulating behavior with UV absorption spectrum,leakage current,and finite element calculation,it is manifested that nanocoating contributes to enhance the bandgap of polymer films,thereby suppressing the charge injection by redirecting their transport from electrodes.Worthy to note that an ultrahigh breakdown field strength(~736 MV m^(−1)),an excellent discharge energy density(~8.77 J cm^(−3))and a prominent charge-discharge efficiency(~96.51%)are achieved concurrently,which is ascribed to the contribution of BNNS ultrathin layer.In addition,the modified PET films also have superior comprehensive performance at high temperatures(~120°C).The materials and methods here selected are easily accessible and facile,which are suitable for large-scale roll-to-roll process production,and are of certain significance to explore the methods about film modification suitable for commercial promotion.展开更多
A series of high solid content(30 wt%)epoxy resin(EP)composite coatings reinforced with differently sized cubic boron nitride(CBN)particles were fabricated successfully on 304 L stainless steel.Polydopamine(PDA)was us...A series of high solid content(30 wt%)epoxy resin(EP)composite coatings reinforced with differently sized cubic boron nitride(CBN)particles were fabricated successfully on 304 L stainless steel.Polydopamine(PDA)was used to improve the dispersibility of CBN particles in EP.The structural and morphological features of the CBN particles and the composite coatings were characterized by Raman spectroscopy,scanning electron microscopy(SEM),and transmission electron microscopy(TEM).Moreover,a UMT-3 tribometer and surface profiler were used to investigate the tribological behaviors of the as-prepared composite coatings.Electrochemical impedance spectroscopy(EIS)and Tafel analysis were used to investigate the coatings'anti-corrosion performance.The results demonstrated that the CBN fillers could effectively enhance the tribological and anti-corrosion properties of the EP composite coatings.In addition,when the additive proportion of the microsized(5μm)and nanosized(550 nm)CBN particles was 1:1,the tribological property of the EP composite coatings was optimal for dry sliding,which was attributed to the load carrying capability of the microsized CBN particles and the toughening effect of the nanosized CBN particles.However,when the additive proportion of the microsized and nanosized CBN particles was 2:1,the tribology and corrosion resistance performance were optimal in seawater conditions.We ascribed this to the load-carrying capacity of the microparticles,which played a more important role under the seawater lubrication condition,and the more compact structure,which improved the electrolyte barrier ability for the composite coatings.展开更多
文摘Cubic boron nitride particles coated by titanium nitride (TiN/cBN) as well as diamond particles coated by titanium carbide (TiC/diamond) were prepared by Ti molten salt deposition followed by heat-treatment process. cBN or diamond particles were mixed separately with Ti powders and molten salts (KCl, NaCl and K<sub>2</sub>TiF<sub>6</sub>). The mixture was heated at 900 °C under argon atmosphere. The produced particles were heat-treated under hydrogen at 1000 °C. The morphologies and chemical compositions of the produced particles were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and focused ion beam (FIB). The results show that the cBN and the diamond particles are coated by nano-sized Ti layers. By heat-treatment of the Ti/cBN and TiC/diamond coated particles under hydrogen atmosphere, the deposited Ti layers were interacted by the in-situ transformation reaction with the surfaces of cBN and diamond particles and converted to titanium compounds (TiN and TiC), respectively.
基金supported by the National Natural Science Foundation of China(Grant Nos.51937007,and 51921005)National Key Research and Development Program of China(No.2021YFB2401502).
文摘The further electrification of various fields in production and daily life makes it a topic worthy of exploration to improve the performance of capacitors for a long time,including thin-film capacitors.The discharge energy density of thin-film capacitors that serves as one of the important types directly depends on electric field strength and the dielectric constant of the insulation material.However,it has long been a great challenge to improve the breakdown strength and dielectric constant simultaneously.Considering that boron nitride nanosheets(BNNS)possess superior insulation and thermal conductivity owing to wide band gap and 2-dimensional structure,a bilayer polymer film is prepared via coating BNNS by solution casting on surface of polyethylene terephthalate(PET)films.By revealing the bandgap and insulating behavior with UV absorption spectrum,leakage current,and finite element calculation,it is manifested that nanocoating contributes to enhance the bandgap of polymer films,thereby suppressing the charge injection by redirecting their transport from electrodes.Worthy to note that an ultrahigh breakdown field strength(~736 MV m^(−1)),an excellent discharge energy density(~8.77 J cm^(−3))and a prominent charge-discharge efficiency(~96.51%)are achieved concurrently,which is ascribed to the contribution of BNNS ultrathin layer.In addition,the modified PET films also have superior comprehensive performance at high temperatures(~120°C).The materials and methods here selected are easily accessible and facile,which are suitable for large-scale roll-to-roll process production,and are of certain significance to explore the methods about film modification suitable for commercial promotion.
基金the National Natural Science Foundation of China(No.51775540)Key Research Program of Frontier Sciences of the Chinese Academy of Science(No.QYZDY-SSW-JSC009)the Youth Innovation Promotion Association,CAS(No.2017338)。
文摘A series of high solid content(30 wt%)epoxy resin(EP)composite coatings reinforced with differently sized cubic boron nitride(CBN)particles were fabricated successfully on 304 L stainless steel.Polydopamine(PDA)was used to improve the dispersibility of CBN particles in EP.The structural and morphological features of the CBN particles and the composite coatings were characterized by Raman spectroscopy,scanning electron microscopy(SEM),and transmission electron microscopy(TEM).Moreover,a UMT-3 tribometer and surface profiler were used to investigate the tribological behaviors of the as-prepared composite coatings.Electrochemical impedance spectroscopy(EIS)and Tafel analysis were used to investigate the coatings'anti-corrosion performance.The results demonstrated that the CBN fillers could effectively enhance the tribological and anti-corrosion properties of the EP composite coatings.In addition,when the additive proportion of the microsized(5μm)and nanosized(550 nm)CBN particles was 1:1,the tribological property of the EP composite coatings was optimal for dry sliding,which was attributed to the load carrying capability of the microsized CBN particles and the toughening effect of the nanosized CBN particles.However,when the additive proportion of the microsized and nanosized CBN particles was 2:1,the tribology and corrosion resistance performance were optimal in seawater conditions.We ascribed this to the load-carrying capacity of the microparticles,which played a more important role under the seawater lubrication condition,and the more compact structure,which improved the electrolyte barrier ability for the composite coatings.
