The coating of Ni W P was deposited as base layer, and then the composite coating of Ni Ti(particles) Re(rare earth) was deposited subsequently on the surface of diamond using electroless plating by adding 2...The coating of Ni W P was deposited as base layer, and then the composite coating of Ni Ti(particles) Re(rare earth) was deposited subsequently on the surface of diamond using electroless plating by adding 2～3 μm Ti particles and trace rare earth salt to bath solution. Ti particles deposited on the surface of diamond were found by SEM and formation of TiC was verified by X ray diffraction analysis after heat treatment of the coatings in vacuum at 900 ℃. The binding strength between the coated diamond and the metal matrix was improved effectively in the diamond composite based on metal cement.展开更多
Effects of sintering temperature in hot pressing, t yp es, states and amounts of rare earth as well as TiH 2 on the transverse rupture strength (TRS) of Fe-based composites are studied by means of orthogonal test and ...Effects of sintering temperature in hot pressing, t yp es, states and amounts of rare earth as well as TiH 2 on the transverse rupture strength (TRS) of Fe-based composites are studied by means of orthogonal test and variance analysis in this paper. It is found that sintering temperature has a significant effect on the TRS of Fe-based diamond composites. The optimal sin tering temperature is 780～860 ℃. On the contrary, the effects of RE additi v es on values of TRS of the diamond composites have on distinct difference no mat ter the RE is in the state of mixture or compound or oxidization. Experimental r esults demonstrate that Fe-based diamond composites with RE additives exhibit h igher TRS, which results in an increase in diamond retention capacity. The degre e of increment of TRS is different at different sintering temperatures. The opti mal amount of rare earth was found to be about 1% in weight. The effect of RE is more significant at lower sintering temperature. The experimental results also reveal that TiH 2 additive has a negative effect on the TRS of Fe-based compos ites. Microscope observations demonstrate that specimen without TiH 2 additives , shows fewer pores and denser structures in the base metal. It can also be seen from the SEM observation of the resulting fracturing surface of bending test sp ecimens that the bonding of the diamond-matrix interface is better in the speci men without TiH 2 than in the specimen with TiH 2. Also the fracture surface o f the specimen without TiH 2 reveals ductile cup and cone behavior.展开更多
We perform synthesis, characterization, and application of nanostructured diamond composites. The enhancements of the thermomechanical performance of bulk diamond compacts in terms of hardness, fracture toughness, wea...We perform synthesis, characterization, and application of nanostructured diamond composites. The enhancements of the thermomechanical performance of bulk diamond compacts in terms of hardness, fracture toughness, wear resistance, impact strength, and thermal stability are our project objectives. It is to aim at applying an advanced nanosynthesis process for the manufac-turing of superhard and ultratough diamond/SiC nanocomposites with the implementation of nanofiber reinforcement. The R&D re-sults can be used in multi-industrial applications, particularly, for drill bits designed to encounter dynamic impacts for high speed oil/gas drillings, thus to achieve high efficiency and energy saving. Science and technology (S&T) researches on precursors, cata-lyst, reactive sintering, and in-situ/real-time characterization of high P-T neutron/X-ray diffraction studies on phase stability, syn-thesis kinetics, residual strain, and yield strength have been applied to help optimizing the nanomanufacturing process. Our R&D ef-fort in high P-T nanosynthesis of TSP diamond/SiC composites is to achieve superior performance of nanomechanics in resisting dy-namic impact and thermal degradation, while still maintaining the super-hardness and super-abrasiveness of diamond and silicon-car-bide. The improved polycrystalline diamond compact (PDC) bit inserts for drilling, boring, and cutting will be applied in harsh envi-ronments so as to meet the demands of the mining, petroleum, and machinery industries. With success of the proposed project, the expected energy savings and reduction of CO2 emission will be significant and the economic advantages are going to be enormous.展开更多
Electroformed diamond tools have been used for many years in grinding and cutting fields while electrodeposited diamond composite coatings have been widely studied due to their desirable hardness,wear and corrosion re...Electroformed diamond tools have been used for many years in grinding and cutting fields while electrodeposited diamond composite coatings have been widely studied due to their desirable hardness,wear and corrosion resistance.This article reports the detrimental impact of diamond magnetism on the composites microstructure and gives explanations.Microstructure differences between composites that,respectively,contained no-further-treated diamond,magnetism-strengthening treated diamond and magnetism weakening treated diamond were carefully observed.It is shown that diamond magnetization treatment drastically harms the composite microstructure(e.g.,roughening the coating surface,coarsening the matrix grain,and more seriously,reducing the mechanical retention of diamond grains in the matrix) while demagnetization treatment does the opposite.All the observed facts could be explained by the electromagnetic interaction between magnetic fields produced by magnetic diamond grains and electric current(moving cations) during the electrodeposition process.展开更多
Nanocrystalline diamond films were deposited on Co-cemented carbide substrates using acetone/ H<sub>2</sub>/Ar gas mixture by bias-enhanced hot filament chemical vapor deposition（HFCVD） technique.The evi...Nanocrystalline diamond films were deposited on Co-cemented carbide substrates using acetone/ H<sub>2</sub>/Ar gas mixture by bias-enhanced hot filament chemical vapor deposition（HFCVD） technique.The evidence of nanocrystallinity,smoothness and purity was obtained by characterizing the sample with scanning electron microscopy（SEM）,X-ray diffraction（XRD）,Raman spectroscopy,atomic force microscopy （AFM ）,and field emission transmission electron microscopy（FE-TEM ）.The results show that nanocrystalline diamond films consists of nanocrystalline diamond grains with sizes range from 20 to 80 nm and contain a large amount of grain boundaries.The surface roughness of the films is measured as R<sub>a</sub>【50nm.The Raman spectroscopy,XRD pattern,and FE-TEM image of the films indicate the presence of nanocrystalline diamond.A new process is used to deposit composite diamond coatings by a two-step chemical vapor deposition procedure,including first the deposition of the rough polycrystalline diamond and then the smooth fine-grained nanocrystalline diamond film.Such composite diamond coatings not only display good adhesion and wear resistant properties,but also have smooth surfaces that are liable to polishing.This coating technology can not only meet the requirement of the adhesion of diamond coatings,but also reduce surface roughness of diamond coatings effectively,thus remove the obstacles for the industrialization of CVD diamond coatings.The diamondcoated dies with these composite coatings show obvious effect in the practical application.展开更多
文摘The coating of Ni W P was deposited as base layer, and then the composite coating of Ni Ti(particles) Re(rare earth) was deposited subsequently on the surface of diamond using electroless plating by adding 2～3 μm Ti particles and trace rare earth salt to bath solution. Ti particles deposited on the surface of diamond were found by SEM and formation of TiC was verified by X ray diffraction analysis after heat treatment of the coatings in vacuum at 900 ℃. The binding strength between the coated diamond and the metal matrix was improved effectively in the diamond composite based on metal cement.
文摘Effects of sintering temperature in hot pressing, t yp es, states and amounts of rare earth as well as TiH 2 on the transverse rupture strength (TRS) of Fe-based composites are studied by means of orthogonal test and variance analysis in this paper. It is found that sintering temperature has a significant effect on the TRS of Fe-based diamond composites. The optimal sin tering temperature is 780～860 ℃. On the contrary, the effects of RE additi v es on values of TRS of the diamond composites have on distinct difference no mat ter the RE is in the state of mixture or compound or oxidization. Experimental r esults demonstrate that Fe-based diamond composites with RE additives exhibit h igher TRS, which results in an increase in diamond retention capacity. The degre e of increment of TRS is different at different sintering temperatures. The opti mal amount of rare earth was found to be about 1% in weight. The effect of RE is more significant at lower sintering temperature. The experimental results also reveal that TiH 2 additive has a negative effect on the TRS of Fe-based compos ites. Microscope observations demonstrate that specimen without TiH 2 additives , shows fewer pores and denser structures in the base metal. It can also be seen from the SEM observation of the resulting fracturing surface of bending test sp ecimens that the bonding of the diamond-matrix interface is better in the speci men without TiH 2 than in the specimen with TiH 2. Also the fracture surface o f the specimen without TiH 2 reveals ductile cup and cone behavior.
文摘We perform synthesis, characterization, and application of nanostructured diamond composites. The enhancements of the thermomechanical performance of bulk diamond compacts in terms of hardness, fracture toughness, wear resistance, impact strength, and thermal stability are our project objectives. It is to aim at applying an advanced nanosynthesis process for the manufac-turing of superhard and ultratough diamond/SiC nanocomposites with the implementation of nanofiber reinforcement. The R&D re-sults can be used in multi-industrial applications, particularly, for drill bits designed to encounter dynamic impacts for high speed oil/gas drillings, thus to achieve high efficiency and energy saving. Science and technology (S&T) researches on precursors, cata-lyst, reactive sintering, and in-situ/real-time characterization of high P-T neutron/X-ray diffraction studies on phase stability, syn-thesis kinetics, residual strain, and yield strength have been applied to help optimizing the nanomanufacturing process. Our R&D ef-fort in high P-T nanosynthesis of TSP diamond/SiC composites is to achieve superior performance of nanomechanics in resisting dy-namic impact and thermal degradation, while still maintaining the super-hardness and super-abrasiveness of diamond and silicon-car-bide. The improved polycrystalline diamond compact (PDC) bit inserts for drilling, boring, and cutting will be applied in harsh envi-ronments so as to meet the demands of the mining, petroleum, and machinery industries. With success of the proposed project, the expected energy savings and reduction of CO2 emission will be significant and the economic advantages are going to be enormous.
基金This work was supported by Henan Agricultural University,the Natural Science Foundation of Henan Province(0411051300)the Project for Excel-lent University Teachers under the supervision of Henan Provincial Bureau of Education.
文摘Electroformed diamond tools have been used for many years in grinding and cutting fields while electrodeposited diamond composite coatings have been widely studied due to their desirable hardness,wear and corrosion resistance.This article reports the detrimental impact of diamond magnetism on the composites microstructure and gives explanations.Microstructure differences between composites that,respectively,contained no-further-treated diamond,magnetism-strengthening treated diamond and magnetism weakening treated diamond were carefully observed.It is shown that diamond magnetization treatment drastically harms the composite microstructure(e.g.,roughening the coating surface,coarsening the matrix grain,and more seriously,reducing the mechanical retention of diamond grains in the matrix) while demagnetization treatment does the opposite.All the observed facts could be explained by the electromagnetic interaction between magnetic fields produced by magnetic diamond grains and electric current(moving cations) during the electrodeposition process.
基金Supported by the National Natural Science Foundation of China(50575135)
文摘Nanocrystalline diamond films were deposited on Co-cemented carbide substrates using acetone/ H<sub>2</sub>/Ar gas mixture by bias-enhanced hot filament chemical vapor deposition（HFCVD） technique.The evidence of nanocrystallinity,smoothness and purity was obtained by characterizing the sample with scanning electron microscopy（SEM）,X-ray diffraction（XRD）,Raman spectroscopy,atomic force microscopy （AFM ）,and field emission transmission electron microscopy（FE-TEM ）.The results show that nanocrystalline diamond films consists of nanocrystalline diamond grains with sizes range from 20 to 80 nm and contain a large amount of grain boundaries.The surface roughness of the films is measured as R<sub>a</sub>【50nm.The Raman spectroscopy,XRD pattern,and FE-TEM image of the films indicate the presence of nanocrystalline diamond.A new process is used to deposit composite diamond coatings by a two-step chemical vapor deposition procedure,including first the deposition of the rough polycrystalline diamond and then the smooth fine-grained nanocrystalline diamond film.Such composite diamond coatings not only display good adhesion and wear resistant properties,but also have smooth surfaces that are liable to polishing.This coating technology can not only meet the requirement of the adhesion of diamond coatings,but also reduce surface roughness of diamond coatings effectively,thus remove the obstacles for the industrialization of CVD diamond coatings.The diamondcoated dies with these composite coatings show obvious effect in the practical application.
