The thermal conductivity of diamond particles reinforced copper matrix composite as an attractive thermal management material is significantly lowered by the non-wetting heterointerface.The paper investigates the heat...The thermal conductivity of diamond particles reinforced copper matrix composite as an attractive thermal management material is significantly lowered by the non-wetting heterointerface.The paper investigates the heat transport behavior between a 200-nm Cu layer and a single-crystalline diamond substrate inserted by a chromium(Cr)interlayer having a series of thicknesses from 150 nm down to 5 nm.The purpose is to detect the impact of the modifying interlayer thickness on the interfacial thermal conductance(h)between Cu and diamond.The time-domain thermoreflectance measurements suggest that the introduction of Cr interlayer dramatically improves the h between Cu and diamond owing to the enhanced interfacial adhesion and bridged dissimilar phonon states between Cu and diamond.The h value exhibits a decreasing trend as the Cr interlayer becomes thicker because of the increase in thermal resistance of Cr interlayer.The high h values are observed for the Cr interlayer thicknesses below 21 nm since phononic transport channel dominates the thermal conduction in the ultrathin Cr layer.The findings provide a way to tune the thermal conduction across the metal/nonmetal heterogeneous interface,which plays a pivotal role in designing materials and devices for thermal management applications.展开更多
Ag-Cu-In-Ti low-temperature filler was used to braze the diamond and copper,and the effects of brazing temperature and soaking time on the microstructure and mechanical properties of the joints were investigated.In ad...Ag-Cu-In-Ti low-temperature filler was used to braze the diamond and copper,and the effects of brazing temperature and soaking time on the microstructure and mechanical properties of the joints were investigated.In addition,the joint formation mechanism was discussed,and the correlation between joint microstructure and mechanical performance was established.Results show that adding appropriate amount of In into the filler can significantly reduce the filler melting point and enhance the wettability of filler on diamond.When the brazing temperature is 750°C and the soaking time is 10 min,a uniformly dense braze seam with excellent metallurgical bonding can be obtained,and its average joint shear strength reaches 322 MPa.The lower brazing temperature can mitigate the risk of diamond graphitization and also reduce the residual stresses during joining.展开更多
A Ni layer with a thickness of about 100 nm was sputtered on Cu substrates,followed by an ultrasonic seeding with nanodiamond suspension.High-quality diamond film with its crystalline grains close to thermal equilibri...A Ni layer with a thickness of about 100 nm was sputtered on Cu substrates,followed by an ultrasonic seeding with nanodiamond suspension.High-quality diamond film with its crystalline grains close to thermal equilibrium shape was deposited on Cu substrates by hot-filament chemical vapor deposition（HF-CVD）,and the sp2 carbon content was less than 5.56%.The nucleation and growth of diamond film were investigated by micro-Raman spectroscopy,scanning electron microscopy,and X-ray diffraction.The results show that the nucleation density of diamond on the Ni-modified Cu substrates is 10 times higher than that on blank Cu substrates.The enhancement mechanism of the nucleation kinetics by Ni modification layer results from two effects：namely,the nanometer rough Ni-modified surface shows an improved absorption of nanodiamond particles that act as starting points for the diamond nucleation during HF-CVD process;the strong catalytic effect of the Ni-modified surface causes the formation of graphite layer that acts as an intermediate to facilitate diamond nucleation quickly.展开更多
Effects of rare earth element La on the microstructure of Cumatrix diamond tools were researched under the conditions of variousmaterials components and the process parameters in order to improvematerials properties. ...Effects of rare earth element La on the microstructure of Cumatrix diamond tools were researched under the conditions of variousmaterials components and the process parameters in order to improvematerials properties. SEM, XPS and X-ray were used to investigate thefracture section, microstructure and the element valence inmaterials. The Results shown that the combination of rare earthelement La and transition element Ti is advantageous to the bondingstate Between diamond particles and matrix, so it can improve thematerials properties. Suitable sintering temperature is 790 deg. C.展开更多
The thermal conductivity of diamond/copper composites with bimodal particle sizes was studied. The composites were prepared through pressure infiltration of liquid copper into diamond preforms with a mixture of 40 and...The thermal conductivity of diamond/copper composites with bimodal particle sizes was studied. The composites were prepared through pressure infiltration of liquid copper into diamond preforms with a mixture of 40 and 100 pm-size diamonds. The permeability of the preforms with different coarse-to-fine volume ratios of diamonds was investigated. The thermal conductivity of the diamond/copper composites with bimodal size distribution was compared to the theoretical value derived from an analytical model developed by Chu. It is predicted that the diamond/copper composites could reach a higher thermal conductivity and their surface roughness could be improved by applying bimodal diamond particle sizes.展开更多
Submicron diamonds were co-deposited on aluminum substrates with copper from the acid copper sulfate electrolyte by electro- lyte-suspension co-deposition. After submicron diamonds were added to the electrolyte, the s...Submicron diamonds were co-deposited on aluminum substrates with copper from the acid copper sulfate electrolyte by electro- lyte-suspension co-deposition. After submicron diamonds were added to the electrolyte, the shape of copper grains transformed from oval or round to polyhedron, the growth mode of copper grains transformed from columnar growth to gradual change in size, and the preferred ori- entation of copper grains transformed from （220） to （200）. Analyzing the variation of cathodic overpotential, it was found that the cathodic overpotential tended to remain tmchanged when copper plane （220） grew in the process of electrodepositing pure copper, while it tended to decrease with time when copper plane （200） grew in the process of co-deposition. It was inferred that copper plane （200） was propitious to the deposition of submicron diamonds.展开更多
Tungsten was plated on the surface of diamond by using thermal diffusion method.Different process parameters were employed to prepare the composites with tungsten,diamond and copper.The micro morphology of different s...Tungsten was plated on the surface of diamond by using thermal diffusion method.Different process parameters were employed to prepare the composites with tungsten,diamond and copper.The micro morphology of different samples was observed,and the thermal conductivity of samples was measured by laser flash method.The optimal process parameters for preparing diamond/copper composites with high thermal conductivity were investigated.The results indicated that plating tungsten on diamond could modify the interface bonding.When the diamond was plated for 60 min,the coating appeared intact,uniform and flat,and the thermal conductivity of the sample could reach as high as 486 W/(m·K).The integrity and uniformity were more important than thickness for the coating.When the tungsten-plated diamond was further annealed,the metallurgical bonding between the coating and the diamond was enhanced,and the thermal conductivity rose to 559 W/(m·K).展开更多
The thermal conductivity of diamond hybrid SiC/Cu,diamond/Cu and SiC/Cu composite were calculated by using the extended differential effective medium (DEM) theoretical model in this paper.The effects of the particle v...The thermal conductivity of diamond hybrid SiC/Cu,diamond/Cu and SiC/Cu composite were calculated by using the extended differential effective medium (DEM) theoretical model in this paper.The effects of the particle volume fraction,the particle size and the volume ratio of the diamond particles to the total particles on the thermal conductivity of the composite were studied.The DEM theoretical calculation results show that,for the diamond hybrid SiC/Cu composite,when the particle volume fraction is above 46% and the volume ratio of the diamond particles to the SiC particles is above 13:12,the thermal conductivity of the composite can reach 500 W·m-1·K-1.The thermal conduc-tivity of the composite has little change when the particle size is above 200μm.The experimental results show that Ti can improve the wettability of the SiC and Cu.The thermal conductivity of the diamond hybrid SiCTi/Cu is almost two times better than that of the diamond hybrid SiC/Cu.It is feasible to predict the thermal conductivity of the composite by DEM theoretical model.展开更多
The electroless copper deposition on both pure and Cr-coated diamond particles was stud- ied to produce copper/diamond composites for electronic packaging materials. The particles were characterized and the mechanism ...The electroless copper deposition on both pure and Cr-coated diamond particles was stud- ied to produce copper/diamond composites for electronic packaging materials. The particles were characterized and the mechanism of product formation was investigated through scanning electron microscopy （SEM）, energy dispersive spectroscopy （EDS）, X-ray diffraction （XRD）, and X-ray photoelectron spectra （XPS）. The particle coating thickness was measured using optical micro- graphs. The diamond particles got uniform coating thickness of copper crystals layers. This method provided an excellent base for the fabrication of metal-based composites using cheap equipments, and was less time consuming, nature friendly and economical compared with other methods of dia- mond surface metallization.展开更多
The scratch test is used for quality control mostly in phenomenological ways,and whether fracture toughness can be obtained from this test is still a matter of debate requiring further elucidation.In this paper,values...The scratch test is used for quality control mostly in phenomenological ways,and whether fracture toughness can be obtained from this test is still a matter of debate requiring further elucidation.In this paper,values of the fracture toughness of copper obtained by different scratch-based approaches are compared in order to examine the applicability of scratch-based methodologies to characterize the fracture toughness of soft metals.The scratch response of copper to a Rockwell C diamond indenter is studied under a constant normal load condition.The variations of penetration depth,residual depth,and residual scratch width with applied normal load are quantified from spherical to sphero-conical contact regimes by piecewise functions.A newly proposed size effect law is found to be the most suitable for scratch-based approaches to characterizing the fracture toughness of soft metallic materials with significant plasticity.A simple expression relating the nominal stress to the penetration depth is proposed for the spherical contact regime and gives almost the same value of fracture toughness.The residual scratch width provides useful information on pile-up of material and on the spherical tip radius of the indenter.It is found that the values of the fracture toughness obtained from the microscratch test are influenced by the data range for analysis.展开更多
The direct deposition of diamond films on copper substrate has been suffered fromadhesion problems due to the mismatch of the thermal expansion coefficients of diamond andcopper. In this paper nuclei with valuable den...The direct deposition of diamond films on copper substrate has been suffered fromadhesion problems due to the mismatch of the thermal expansion coefficients of diamond andcopper. In this paper nuclei with valuable density were directly introduced thirough a submicrondiamond powder layer. The diamond grits partially were buried in the copper substrate leadingto better adhesion. Another method with nickel intermediate layer for enhancing the adhesionwas studied here in detail. It was suggested that Cu-Ni eutectic between the copper substrate andNi interlayer might contribute to the adhesion improvement. The quality of the diamond filmsdeposited wlth rnckel interlayer was investigated by scanning electron microscopy and Ramanspectroscopy.展开更多
Formation of diamond particles was investigated in an energy-controlled CH4/H2 radio-frequency (RF) discharge plasma. Here, in particular, it was examined how diamond particles grew on a nickel substrate under an infl...Formation of diamond particles was investigated in an energy-controlled CH4/H2 radio-frequency (RF) discharge plasma. Here, in particular, it was examined how diamond particles grew on a nickel substrate under an influence of Cu vapor that was supplied from a heated Cu wire. Here, the plasma was generated by a hollow-magnetron-type (HMT) RF plasma source at the frequency of 13.56 MHz. Total pressure was kept at 100 mTorr. Diamond particles grew besides Ni and Cu particles. From Raman spectrum the substrate surface was covered with thin graphite film deposited as a background layer. It was shown that diamond could grow in a self-organized manner even when the other atomic gas species such as Ni and Cu were contained in the gas at the same time during the growth process.展开更多
The deposition of high-quality diamond films and their adhesion on cemented carbides are strongly influenced by the catalytic effect of cobalt under typical deposition conditions. Decreasing Co content on the surface...The deposition of high-quality diamond films and their adhesion on cemented carbides are strongly influenced by the catalytic effect of cobalt under typical deposition conditions. Decreasing Co content on the surface of the cemented carbide is often used for the diamond film deposition. But the leaching of Co from the WC-Co substrate leading to a mechanical weak surface often causes a poor adhesion. In this paper we adopted an implant copper layer prepared by vaporization to improve the mechanical properties of the Co-leached substrate. The diamond films were grown by microwave plasma chemical vapor deposition from CH4:H2 gas mixture. The cross section and the morphology of the diamond film were characterized by scanning electron microscopy (SEM). The non-diamond content in the film was analyzed by Raman spectroscopy. The effects of pretreatment on the concentrations of Co and Cu near the interfacial region were examined by energy dispersive spectrum (EDS) equipped with SEM. The adhesion of the diamond on the substrate was evaluated with a Rockwell-type hardness tester. The results indicate that the diamond films prepared with implant copper layer have a good adhesion to the cemented carbide substrate due to the recovery of the mechanical properties of the Co-depleted substrate after the copper implantation and the formation of less amorphous carbon between the substrate and the diamond film.展开更多
Copper is a transition metal and an essential element for the organism,as alterations in its homeostasis leading to metal accumulation or deficiency have pathological effects in several organs,including the central ne...Copper is a transition metal and an essential element for the organism,as alterations in its homeostasis leading to metal accumulation or deficiency have pathological effects in several organs,including the central nervous system.Central copper dysregulations have been evidenced in two genetic disorders characterized by mutations in the copper-ATPases ATP7A and ATP7B,Menkes disease and Wilson’s disease,respectively,and also in multifactorial neurological disorders such as Alzheimer’s disease,Parkinson’s disease,amyotrophic lateral sclerosis,and multiple sclerosis.This review summarizes current knowledge about the role of copper in central nervous system physiology and pathology,reports about unbalances in copper levels and/or distribution under disease,describes relevant animal models for human disorders where copper metabolism genes are dysregulated,and discusses relevant therapeutic approaches modulating copper availability.Overall,alterations in copper metabolism may contribute to the etiology of central nervous system disorders and represent relevant therapeutic targets to restore tissue homeostasis.展开更多
The role of copper element has been an increasingly relevant topic in recent years in the fields of human and animal health, for both the study of new drugs and innovative food and feed supplements. This metal plays a...The role of copper element has been an increasingly relevant topic in recent years in the fields of human and animal health, for both the study of new drugs and innovative food and feed supplements. This metal plays an important role in the central nervous system, where it is associated with glutamatergic signaling, and it is widely involved in inflammatory processes. Thus, diseases involving copper(Ⅱ) dyshomeostasis often have neurological symptoms, as exemplified by Alzheimer's and other diseases(such as Parkinson's and Wilson's diseases). Moreover, imbalanced copper ion concentrations have also been associated with diabetes and certain types of cancer, including glioma. In this paper, we propose a comprehensive overview of recent results that show the importance of these metal ions in several pathologies, mainly Alzheimer's disease, through the lens of the development and use of copper chelators as research compounds and potential therapeutics if included in multi-target hybrid drugs. Seeing how copper homeostasis is important for the well-being of animals as well as humans, we shortly describe the state of the art regarding the effects of copper and its chelators in agriculture, livestock rearing, and aquaculture, as ingredients for the formulation of feed supplements as well as to prevent the effects of pollution on animal productions.展开更多
Atomic surfaces are strictly required by high-performance devices of diamond.Nevertheless,diamond is the hardest material in nature,leading to the low material removal rate(MRR)and high surface roughness during machin...Atomic surfaces are strictly required by high-performance devices of diamond.Nevertheless,diamond is the hardest material in nature,leading to the low material removal rate(MRR)and high surface roughness during machining.Noxious slurries are widely used in conventional chemical mechanical polishing(CMP),resulting in the possible pollution to the environment.Moreover,the traditional slurries normally contain more than four ingredients,causing difficulties to control the process and quality of CMP.To solve these challenges,a novel green CMP for single crystal diamond was developed,consisting of only hydrogen peroxide,diamond abrasive and Prussian blue(PB)/titania catalyst.After CMP,atomic surface is achieved with surface roughness Sa of 0.079 nm,and the MRR is 1168 nm·h^(-1).Thickness of damaged layer is merely 0.66 nm confirmed by transmission electron microscopy(TEM).X-ray photoelectron spectroscopy,electron paramagnetic resonance and TEM reveal that·OH radicals form under ultraviolet irradiation on PB/titania catalyst.The·OH radicals oxidize diamond,transforming it from monocrystalline to amorphous atomic structure,generating a soft amorphous layer.This contributes the high MRR and formation of atomic surface on diamond.The developed novel green CMP offers new insights to achieve atomic surface of diamond for potential use in their high-performance devices.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos. 51871014, 51571015)the National Youth Science Foundation, China (No. 51606193)
文摘The thermal conductivity of diamond particles reinforced copper matrix composite as an attractive thermal management material is significantly lowered by the non-wetting heterointerface.The paper investigates the heat transport behavior between a 200-nm Cu layer and a single-crystalline diamond substrate inserted by a chromium(Cr)interlayer having a series of thicknesses from 150 nm down to 5 nm.The purpose is to detect the impact of the modifying interlayer thickness on the interfacial thermal conductance(h)between Cu and diamond.The time-domain thermoreflectance measurements suggest that the introduction of Cr interlayer dramatically improves the h between Cu and diamond owing to the enhanced interfacial adhesion and bridged dissimilar phonon states between Cu and diamond.The h value exhibits a decreasing trend as the Cr interlayer becomes thicker because of the increase in thermal resistance of Cr interlayer.The high h values are observed for the Cr interlayer thicknesses below 21 nm since phononic transport channel dominates the thermal conduction in the ultrathin Cr layer.The findings provide a way to tune the thermal conduction across the metal/nonmetal heterogeneous interface,which plays a pivotal role in designing materials and devices for thermal management applications.
基金National MCF Energy R&D Program(2019YFE03100400)。
文摘Ag-Cu-In-Ti low-temperature filler was used to braze the diamond and copper,and the effects of brazing temperature and soaking time on the microstructure and mechanical properties of the joints were investigated.In addition,the joint formation mechanism was discussed,and the correlation between joint microstructure and mechanical performance was established.Results show that adding appropriate amount of In into the filler can significantly reduce the filler melting point and enhance the wettability of filler on diamond.When the brazing temperature is 750°C and the soaking time is 10 min,a uniformly dense braze seam with excellent metallurgical bonding can be obtained,and its average joint shear strength reaches 322 MPa.The lower brazing temperature can mitigate the risk of diamond graphitization and also reduce the residual stresses during joining.
基金Project(20110933K) supported by the State Key Laboratory of Powder Metallurgy,ChinaProject(2012QNZT002) supported by the Freedom Explore Program of Central South University,ChinaProject(CSUZC2012024) supported by the Open-End Fund for the Valuable and Precision Instruments of Central South University,China
文摘A Ni layer with a thickness of about 100 nm was sputtered on Cu substrates,followed by an ultrasonic seeding with nanodiamond suspension.High-quality diamond film with its crystalline grains close to thermal equilibrium shape was deposited on Cu substrates by hot-filament chemical vapor deposition（HF-CVD）,and the sp2 carbon content was less than 5.56%.The nucleation and growth of diamond film were investigated by micro-Raman spectroscopy,scanning electron microscopy,and X-ray diffraction.The results show that the nucleation density of diamond on the Ni-modified Cu substrates is 10 times higher than that on blank Cu substrates.The enhancement mechanism of the nucleation kinetics by Ni modification layer results from two effects：namely,the nanometer rough Ni-modified surface shows an improved absorption of nanodiamond particles that act as starting points for the diamond nucleation during HF-CVD process;the strong catalytic effect of the Ni-modified surface causes the formation of graphite layer that acts as an intermediate to facilitate diamond nucleation quickly.
文摘Effects of rare earth element La on the microstructure of Cumatrix diamond tools were researched under the conditions of variousmaterials components and the process parameters in order to improvematerials properties. SEM, XPS and X-ray were used to investigate thefracture section, microstructure and the element valence inmaterials. The Results shown that the combination of rare earthelement La and transition element Ti is advantageous to the bondingstate Between diamond particles and matrix, so it can improve thematerials properties. Suitable sintering temperature is 790 deg. C.
基金supported by the National Natural Science Foundation of China (No. 50971020)the National High-Tech Research and Development Program of China (No. 2008AA03Z505)
文摘The thermal conductivity of diamond/copper composites with bimodal particle sizes was studied. The composites were prepared through pressure infiltration of liquid copper into diamond preforms with a mixture of 40 and 100 pm-size diamonds. The permeability of the preforms with different coarse-to-fine volume ratios of diamonds was investigated. The thermal conductivity of the diamond/copper composites with bimodal size distribution was compared to the theoretical value derived from an analytical model developed by Chu. It is predicted that the diamond/copper composites could reach a higher thermal conductivity and their surface roughness could be improved by applying bimodal diamond particle sizes.
文摘Submicron diamonds were co-deposited on aluminum substrates with copper from the acid copper sulfate electrolyte by electro- lyte-suspension co-deposition. After submicron diamonds were added to the electrolyte, the shape of copper grains transformed from oval or round to polyhedron, the growth mode of copper grains transformed from columnar growth to gradual change in size, and the preferred ori- entation of copper grains transformed from （220） to （200）. Analyzing the variation of cathodic overpotential, it was found that the cathodic overpotential tended to remain tmchanged when copper plane （220） grew in the process of electrodepositing pure copper, while it tended to decrease with time when copper plane （200） grew in the process of co-deposition. It was inferred that copper plane （200） was propitious to the deposition of submicron diamonds.
基金supported by the National Natural Science Foundation of China(No.11802125)。
文摘Tungsten was plated on the surface of diamond by using thermal diffusion method.Different process parameters were employed to prepare the composites with tungsten,diamond and copper.The micro morphology of different samples was observed,and the thermal conductivity of samples was measured by laser flash method.The optimal process parameters for preparing diamond/copper composites with high thermal conductivity were investigated.The results indicated that plating tungsten on diamond could modify the interface bonding.When the diamond was plated for 60 min,the coating appeared intact,uniform and flat,and the thermal conductivity of the sample could reach as high as 486 W/(m·K).The integrity and uniformity were more important than thickness for the coating.When the tungsten-plated diamond was further annealed,the metallurgical bonding between the coating and the diamond was enhanced,and the thermal conductivity rose to 559 W/(m·K).
基金financially supported by High-Technology Research and Development Program of China (No.2008AA03Z505)
文摘The thermal conductivity of diamond hybrid SiC/Cu,diamond/Cu and SiC/Cu composite were calculated by using the extended differential effective medium (DEM) theoretical model in this paper.The effects of the particle volume fraction,the particle size and the volume ratio of the diamond particles to the total particles on the thermal conductivity of the composite were studied.The DEM theoretical calculation results show that,for the diamond hybrid SiC/Cu composite,when the particle volume fraction is above 46% and the volume ratio of the diamond particles to the SiC particles is above 13:12,the thermal conductivity of the composite can reach 500 W·m-1·K-1.The thermal conduc-tivity of the composite has little change when the particle size is above 200μm.The experimental results show that Ti can improve the wettability of the SiC and Cu.The thermal conductivity of the diamond hybrid SiCTi/Cu is almost two times better than that of the diamond hybrid SiC/Cu.It is feasible to predict the thermal conductivity of the composite by DEM theoretical model.
文摘The electroless copper deposition on both pure and Cr-coated diamond particles was stud- ied to produce copper/diamond composites for electronic packaging materials. The particles were characterized and the mechanism of product formation was investigated through scanning electron microscopy （SEM）, energy dispersive spectroscopy （EDS）, X-ray diffraction （XRD）, and X-ray photoelectron spectra （XPS）. The particle coating thickness was measured using optical micro- graphs. The diamond particles got uniform coating thickness of copper crystals layers. This method provided an excellent base for the fabrication of metal-based composites using cheap equipments, and was less time consuming, nature friendly and economical compared with other methods of dia- mond surface metallization.
基金This work was supported by the National Natural Science Foundation of China(No.51705082)the Engineering Research Center for CAD/CAM of Fujian Provincial Colleges and Universities(No.K201705)+1 种基金the Development Center of Scientific and Educational Park of Fuzhou University in the City of Jinjiang(No.2019-JJFDKY-11)Fuzhou University Testing Fund of Precious Apparatus(No.2020T017).
文摘The scratch test is used for quality control mostly in phenomenological ways,and whether fracture toughness can be obtained from this test is still a matter of debate requiring further elucidation.In this paper,values of the fracture toughness of copper obtained by different scratch-based approaches are compared in order to examine the applicability of scratch-based methodologies to characterize the fracture toughness of soft metals.The scratch response of copper to a Rockwell C diamond indenter is studied under a constant normal load condition.The variations of penetration depth,residual depth,and residual scratch width with applied normal load are quantified from spherical to sphero-conical contact regimes by piecewise functions.A newly proposed size effect law is found to be the most suitable for scratch-based approaches to characterizing the fracture toughness of soft metallic materials with significant plasticity.A simple expression relating the nominal stress to the penetration depth is proposed for the spherical contact regime and gives almost the same value of fracture toughness.The residual scratch width provides useful information on pile-up of material and on the spherical tip radius of the indenter.It is found that the values of the fracture toughness obtained from the microscratch test are influenced by the data range for analysis.
文摘The direct deposition of diamond films on copper substrate has been suffered fromadhesion problems due to the mismatch of the thermal expansion coefficients of diamond andcopper. In this paper nuclei with valuable density were directly introduced thirough a submicrondiamond powder layer. The diamond grits partially were buried in the copper substrate leadingto better adhesion. Another method with nickel intermediate layer for enhancing the adhesionwas studied here in detail. It was suggested that Cu-Ni eutectic between the copper substrate andNi interlayer might contribute to the adhesion improvement. The quality of the diamond filmsdeposited wlth rnckel interlayer was investigated by scanning electron microscopy and Ramanspectroscopy.
文摘Formation of diamond particles was investigated in an energy-controlled CH4/H2 radio-frequency (RF) discharge plasma. Here, in particular, it was examined how diamond particles grew on a nickel substrate under an influence of Cu vapor that was supplied from a heated Cu wire. Here, the plasma was generated by a hollow-magnetron-type (HMT) RF plasma source at the frequency of 13.56 MHz. Total pressure was kept at 100 mTorr. Diamond particles grew besides Ni and Cu particles. From Raman spectrum the substrate surface was covered with thin graphite film deposited as a background layer. It was shown that diamond could grow in a self-organized manner even when the other atomic gas species such as Ni and Cu were contained in the gas at the same time during the growth process.
文摘The deposition of high-quality diamond films and their adhesion on cemented carbides are strongly influenced by the catalytic effect of cobalt under typical deposition conditions. Decreasing Co content on the surface of the cemented carbide is often used for the diamond film deposition. But the leaching of Co from the WC-Co substrate leading to a mechanical weak surface often causes a poor adhesion. In this paper we adopted an implant copper layer prepared by vaporization to improve the mechanical properties of the Co-leached substrate. The diamond films were grown by microwave plasma chemical vapor deposition from CH4:H2 gas mixture. The cross section and the morphology of the diamond film were characterized by scanning electron microscopy (SEM). The non-diamond content in the film was analyzed by Raman spectroscopy. The effects of pretreatment on the concentrations of Co and Cu near the interfacial region were examined by energy dispersive spectrum (EDS) equipped with SEM. The adhesion of the diamond on the substrate was evaluated with a Rockwell-type hardness tester. The results indicate that the diamond films prepared with implant copper layer have a good adhesion to the cemented carbide substrate due to the recovery of the mechanical properties of the Co-depleted substrate after the copper implantation and the formation of less amorphous carbon between the substrate and the diamond film.
文摘Copper is a transition metal and an essential element for the organism,as alterations in its homeostasis leading to metal accumulation or deficiency have pathological effects in several organs,including the central nervous system.Central copper dysregulations have been evidenced in two genetic disorders characterized by mutations in the copper-ATPases ATP7A and ATP7B,Menkes disease and Wilson’s disease,respectively,and also in multifactorial neurological disorders such as Alzheimer’s disease,Parkinson’s disease,amyotrophic lateral sclerosis,and multiple sclerosis.This review summarizes current knowledge about the role of copper in central nervous system physiology and pathology,reports about unbalances in copper levels and/or distribution under disease,describes relevant animal models for human disorders where copper metabolism genes are dysregulated,and discusses relevant therapeutic approaches modulating copper availability.Overall,alterations in copper metabolism may contribute to the etiology of central nervous system disorders and represent relevant therapeutic targets to restore tissue homeostasis.
文摘The role of copper element has been an increasingly relevant topic in recent years in the fields of human and animal health, for both the study of new drugs and innovative food and feed supplements. This metal plays an important role in the central nervous system, where it is associated with glutamatergic signaling, and it is widely involved in inflammatory processes. Thus, diseases involving copper(Ⅱ) dyshomeostasis often have neurological symptoms, as exemplified by Alzheimer's and other diseases(such as Parkinson's and Wilson's diseases). Moreover, imbalanced copper ion concentrations have also been associated with diabetes and certain types of cancer, including glioma. In this paper, we propose a comprehensive overview of recent results that show the importance of these metal ions in several pathologies, mainly Alzheimer's disease, through the lens of the development and use of copper chelators as research compounds and potential therapeutics if included in multi-target hybrid drugs. Seeing how copper homeostasis is important for the well-being of animals as well as humans, we shortly describe the state of the art regarding the effects of copper and its chelators in agriculture, livestock rearing, and aquaculture, as ingredients for the formulation of feed supplements as well as to prevent the effects of pollution on animal productions.
基金financial support from the National Key Research and Development Program of China(2018YFA0703400)the Fundamental Research Funds for the Provincial Universities of Zhejiang(GK239909299001021)+1 种基金the Ninth China Association for Science and Technology Youth Talent Lift Project Support Plan(KYZ015324002)the Changjiang Scholars Program of Chinese Ministry of Education。
文摘Atomic surfaces are strictly required by high-performance devices of diamond.Nevertheless,diamond is the hardest material in nature,leading to the low material removal rate(MRR)and high surface roughness during machining.Noxious slurries are widely used in conventional chemical mechanical polishing(CMP),resulting in the possible pollution to the environment.Moreover,the traditional slurries normally contain more than four ingredients,causing difficulties to control the process and quality of CMP.To solve these challenges,a novel green CMP for single crystal diamond was developed,consisting of only hydrogen peroxide,diamond abrasive and Prussian blue(PB)/titania catalyst.After CMP,atomic surface is achieved with surface roughness Sa of 0.079 nm,and the MRR is 1168 nm·h^(-1).Thickness of damaged layer is merely 0.66 nm confirmed by transmission electron microscopy(TEM).X-ray photoelectron spectroscopy,electron paramagnetic resonance and TEM reveal that·OH radicals form under ultraviolet irradiation on PB/titania catalyst.The·OH radicals oxidize diamond,transforming it from monocrystalline to amorphous atomic structure,generating a soft amorphous layer.This contributes the high MRR and formation of atomic surface on diamond.The developed novel green CMP offers new insights to achieve atomic surface of diamond for potential use in their high-performance devices.
