A new cup-type grinding wheel of the brazed monolayer diamond is developed with a defined grain pattern on the wheel surface. Grinding performance of the brazed wheel in the surface grinding of cemented carbide is stu...A new cup-type grinding wheel of the brazed monolayer diamond is developed with a defined grain pattern on the wheel surface. Grinding performance of the brazed wheel in the surface grinding of cemented carbide is studied. Experimental results show that when continuous dry grinding is employed, grits of the brazed diamond grinding wheel fail mainly in attritious wear and fracture modes and no pull-out ones are found in conventional electroplated and sintered diamond wheels. It indicates the strong retention of brazing alloy to diamond grits and the longer service life of the wheel. In addition, the ground surface has good roughness. The theoretical surface roughness agrees well with experimental results.展开更多
A specific revised HFCVD apparatus and a novel process combining HFCVD and polishing technique were presented to deposit the micro-and nano-crystalline multilayered ultra-smooth diamond（USCD） film on the interior-ho...A specific revised HFCVD apparatus and a novel process combining HFCVD and polishing technique were presented to deposit the micro-and nano-crystalline multilayered ultra-smooth diamond（USCD） film on the interior-hole surface of WC-Co drawing dies with aperture ranging from d1.0 mm to 60 mm.Characterization results indicate that the surface roughness values（Ra） in the entry zone,drawing zone and bearing zone of as-fabricated USCD coated drawing die were measured as low as 25.7,23.3 and 25.5 nm,respectively.Furthermore,the friction properties of USCD films were examined in both dry sliding and water-lubricating conditions,and the results show that the USCD film presents much superior friction properties.Its friction coefficients against ball-bearing steel,copper and silicon nitride balls（d4 mm）,is always lower than that of microcrystalline diamond（MCD） or WC-Co sample,regardless of the lubricating condition.Meanwhile,it still presents competitive wear resistance with the MCD films.Finally,the working lifetime and performance of as-fabricated USCD coated drawing dies were examined under producing low-carbon steel pipes in dry-sliding and water-lubricating conditions.Under the water-lubricating drawing condition,its production significantly increases by about 20 times compared with the conventional WC-Co drawing dies.展开更多
The wide application of high pressure laminated (HPL) flooring has an insistent need for cutting tools with an excellent performance and fine cutting quality. Chemical vapor deposition (CVD) thick film diamond is a pr...The wide application of high pressure laminated (HPL) flooring has an insistent need for cutting tools with an excellent performance and fine cutting quality. Chemical vapor deposition (CVD) thick film diamond is a promising material for the machining of HPL flooring. In the present work, CVD thick film diamond tools were used to mill the wear resistance layer of HPL flooring. Wear volumes of flank face were examined by optical microscopy, and micro wear morphologies were observed by scanning electron microscopy (SEM). The experiments revealed that the predominant wear characteristics of CVD diamond tools were transgranular cleavage wear and intergranular peeling of the CVD diamond. Experimental results also showed that twin characteristic, cavity defect, micro crack and grain size of CVD thick film diamond contributed greatly to the wear process of CVD thick film diamond tools. The effects caused by the factors were also analyzed in detail in the paper.展开更多
The failure behavior of diamond-coated die was investigated experimentally and analytically through finite element method (FEM) simulation in the present work. Diamond coatings were fabricated by straight hot filament...The failure behavior of diamond-coated die was investigated experimentally and analytically through finite element method (FEM) simulation in the present work. Diamond coatings were fabricated by straight hot filament chemical vapor deposition (CVD) passing through the interior hole of the drawing die using a mixture of hydrogen and acetone as source gases. The performance tests were made under real drawing condition. Scanning electron microscopy (SEM) was used for the study of coating wear after die service. The coating wear appears on two regions of the reduction zone: one is near the entrance where the contact begins, and the other is at the end of the reduction zone. FEM simulation was made for calculating the von Mises stresses distribution on the coating and substrate during the drawing process. The present work was of great practical significance for the improvement of drawing performance of diamond-coated drawing dies.展开更多
文摘A new cup-type grinding wheel of the brazed monolayer diamond is developed with a defined grain pattern on the wheel surface. Grinding performance of the brazed wheel in the surface grinding of cemented carbide is studied. Experimental results show that when continuous dry grinding is employed, grits of the brazed diamond grinding wheel fail mainly in attritious wear and fracture modes and no pull-out ones are found in conventional electroplated and sintered diamond wheels. It indicates the strong retention of brazing alloy to diamond grits and the longer service life of the wheel. In addition, the ground surface has good roughness. The theoretical surface roughness agrees well with experimental results.
基金Project(51005154) supported by the National Natural Science Foundation of ChinaProject(12CG11) supported by the Chenguang Program of Shanghai Municipal Education Commission,ChinaProject(201104271) supported by the China Postdoctoral Science Foundation Special Funded Project
文摘A specific revised HFCVD apparatus and a novel process combining HFCVD and polishing technique were presented to deposit the micro-and nano-crystalline multilayered ultra-smooth diamond（USCD） film on the interior-hole surface of WC-Co drawing dies with aperture ranging from d1.0 mm to 60 mm.Characterization results indicate that the surface roughness values（Ra） in the entry zone,drawing zone and bearing zone of as-fabricated USCD coated drawing die were measured as low as 25.7,23.3 and 25.5 nm,respectively.Furthermore,the friction properties of USCD films were examined in both dry sliding and water-lubricating conditions,and the results show that the USCD film presents much superior friction properties.Its friction coefficients against ball-bearing steel,copper and silicon nitride balls（d4 mm）,is always lower than that of microcrystalline diamond（MCD） or WC-Co sample,regardless of the lubricating condition.Meanwhile,it still presents competitive wear resistance with the MCD films.Finally,the working lifetime and performance of as-fabricated USCD coated drawing dies were examined under producing low-carbon steel pipes in dry-sliding and water-lubricating conditions.Under the water-lubricating drawing condition,its production significantly increases by about 20 times compared with the conventional WC-Co drawing dies.
文摘The wide application of high pressure laminated (HPL) flooring has an insistent need for cutting tools with an excellent performance and fine cutting quality. Chemical vapor deposition (CVD) thick film diamond is a promising material for the machining of HPL flooring. In the present work, CVD thick film diamond tools were used to mill the wear resistance layer of HPL flooring. Wear volumes of flank face were examined by optical microscopy, and micro wear morphologies were observed by scanning electron microscopy (SEM). The experiments revealed that the predominant wear characteristics of CVD diamond tools were transgranular cleavage wear and intergranular peeling of the CVD diamond. Experimental results also showed that twin characteristic, cavity defect, micro crack and grain size of CVD thick film diamond contributed greatly to the wear process of CVD thick film diamond tools. The effects caused by the factors were also analyzed in detail in the paper.
基金Supported by National Natural Science Foundation of China (No. 50975177 and No. 51005154)China Postdoctoral Science Foundation (No. 20100470029)Tribology Science Fund of State Key Laboratory of Tribology (No. SKLTKF10B02)
文摘The failure behavior of diamond-coated die was investigated experimentally and analytically through finite element method (FEM) simulation in the present work. Diamond coatings were fabricated by straight hot filament chemical vapor deposition (CVD) passing through the interior hole of the drawing die using a mixture of hydrogen and acetone as source gases. The performance tests were made under real drawing condition. Scanning electron microscopy (SEM) was used for the study of coating wear after die service. The coating wear appears on two regions of the reduction zone: one is near the entrance where the contact begins, and the other is at the end of the reduction zone. FEM simulation was made for calculating the von Mises stresses distribution on the coating and substrate during the drawing process. The present work was of great practical significance for the improvement of drawing performance of diamond-coated drawing dies.
