金刚石与磨料磨具工程

Mechanism and optimization of chemical-mechanically polishing ceramic glass substrate with CeO_2 slurry

BAI Linshan, WANG Jinpu, CHU Xiangfeng

2017, 37(2): 1-5,10. doi: 10.13394/j.cnki.jgszz.2017.2.0001

Abstract(464)

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Abstract:
The effects of mass fraction of abrasive,pH value,flow rate of polishing slurry,rotate speed,surfactant types and mass fraction of NH₄ F on the material removal rate and the surface roughness of the ceramic glass substrate were investigated by CeO₂ slurry.The surface roughness of the ceramic glass substrates after being polished was characterized by atomic force microscope.Resultsshow that the material removal rate(MRR)could reach 180.91nm/min and the surface roughness could reach 0.72 nm under the following conditions:the mass fraction of CeO₂3%,the flow rate of slurry 25mL/min,the rotate speed 100r/min,pH=8.0,the mass fraction of lauryl sodium sulfate 0.01%,the mass fraction of NH₄F 0.7%.

Characterization of wafer shape after grinding with diamond wheel

CHEN Xiuyi, LIU Haijun, ZHU Xianglong, KANG Renke, DONG Zhigang

2017, 37(2): 6-10. doi: 10.13394/j.cnki.jgszz.2017.2.0002

Abstract(350)

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Subsurface damage is formed in the silicon wafer during the thinning process,where residual stress causes defects.Therefore,variation law of the warping profile was studied in the silicon wafer without spark-out process.The silicon wafers were thinned to 400μm or 450μm by a diamond grinding wheel and their warping profiles were measured.The silicon surface profile was divided into five rings from the center to the edge in radial direction and the radius of curvature of each area was obtained by spherical fit respectively.By analyzing the warping profile,it is found that the deformation of the silicon wafer increases from the central area to the edge and it implies that the residual stress grows and so does the grinding damage.In addition,it is found that the crystal orientation has a significant effect on the deformation of silicon wafer,thus the deformation in the 〈110〉crystal orientation area quite different from that in the〈100〉crystal orientation area.

Investigation on pad′s conditioning technology and improving self-conditioning of fixed abrasive pad

JU Zhilan, ZHU Yongwei, ZHANG Fubao

2017, 37(2): 11-15. doi: 10.13394/j.cnki.jgszz.2017.2.0003

Abstract(313)

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The surface features of abrasive pad deform during chemical mechanical polishing and as a result the polishing ability of the pad is dramatically reduced.Pad conditioning improves the pad surface profile and consequently the wafer profile.In addition,it reduces defects on pad surface and prolongs its service life.The conditioning technologies of fixed-abrasive pad are introduced in this paper,which can be divided into two types,namely non-self-conditioning and self-conditioning.High pressure water jet,ultrasonic vibration and diamond dresser etc are non-self-conditioning methods.The methods of improving the self-conditioning of hydrophilic fixed polishing pad are emphasized.Choosing proper slurry,adding soluble and optimizing the lapping process parameters can benefit the self-conditioning process.

Effect of Fe mass fraction on diamond bit′s matrix and drilling properties

PAN Xiaoyi, SU Yu, XIE Delong, LIN Feng, XIAO Leyin, CHEN Chao, QIN Jianxin, PENG Shaobo, CHEN Jiarong

2017, 37(2): 16-19,25. doi: 10.13394/j.cnki.jgszz.2017.2.0004

Abstract(334)

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Fe-Cu matrix formulas were designed to research the effect of Fe mass fraction on diamond drill bit's matrix and drilling properties.Hardness,relative density and three-point bending strength of different formulas' sintered samples were analyzed.The fracture appearances of these sintered samples were investigated by SEM.The drilling efficiency and service life of different formulas' drill bits were analyzed by drilling simulations.The results show that each formula's sample can be well sintered,and that their relative density can reach up to more than 98% of theoretical density.The hardness increases first,and then decreases while Fe mass fraction increases.The hardness tends to be steady when the mass fraction of Fe increases to more than 45%,and it reaches the maximum as 35 HRC at 60% Fe.The three-point bending strength result shows that it does not change obviously but in a small range.The fracture appearance SEM shows that the toughness decreases and the diamond etching effect aggravates while Fe mass fraction increases.Drilling simulations show that the 30% Fe formula sample perform better,both in drilling efficiency and service life,when drilling 6to 8level drill ability stratum.

Electrochemical performance of Ag-coated micron diamond

MENG Weimin, HUANG Hao, GUO Song, MA Xilong

2017, 37(2): 20-25. doi: 10.13394/j.cnki.jgszz.2017.2.0005

Abstract(293)

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Micro diamond possesses excellent physical and chemical properties.In order to expand its application field,nano silver particles were coated on the surface of micro diamond by glucose reducing complexation Ag+in silver ammonia solution. The morphology,composition and structure of composites were characterized by SEM,TEM,EDS and XRD.The properties of oxygen reduction and oxygen evolution of diamond with different content of coated Ag were studied by using rotating disk electrodes.Resultsshow that the limiting current density of oxygen reduction reaction is 4.1mA/cm²,while the limiting current density of oxygen evolution reaction is 27.5 mA/cm² when the silver mass fraction is 10%.

Mechanically polish gadolinium gallium garnet crystal with polyurethane polishing pad

ZHANG Haoran, JIN Zhuji, WANG Ziguang, HAN Xiaolong

2017, 37(2): 26-30. doi: 10.13394/j.cnki.jgszz.2017.2.0006

Abstract(341)

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GGG(gadolinium gallium garnet)wafer is an excellent kind of laser material.However,its surface is easily scratched and the efficiency low during the polishing process.In order to avoid the scarification and improve polishing effect,polyurethane polishing pad was used to mechanically polish the GGG wafer.The influences of working pressure and plate speed on the flatness and surface quality were researched.Resultsshow that the polyurethane polishing pad could avoid the appearance of scarification efficiently and that smaller abrasive is better for the flatness.Under the optimized parameters(70r/min and 127g/cm²),the flatness could reach 226 nm,with surface roughness RMS36.3nm and the defects of the surface could be easily eliminated by chemical mechanical polishing.

Burns prediction of TC4-Ti-alloy based on scaled conjugate gradient neutral networks

DENG Chaohui, XIAO Lanxiang, DENG Hui, LIU Wei

2017, 37(2): 31-35,40. doi: 10.13394/j.cnki.jgszz.2017.2.0007

Abstract(307)

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In order to predict the degree of TC4 titanium alloy after high-speed cylindrical grinding,surface hardness is used to differentiate grinding burns of the workpiece based on surface hardness value change resulted by phase transformation after grinding burn.Surface hardness of TC4 titanium alloy after high-speed cylindrical grinding is forecasted using the scaled conjugate gradient algorithm of neural network.Correspondence relationship between the surface hardness value and the degree of grinding burn is used to predict grinding burns.Validation experiment indicates that the error between the experiments and the predictions is within 5%,which means that the model prediction effect is good.

Uniform wear of the wheel in grinding axisymmetric aspheric

ZHOU Xuguang, YAN Qiusheng, KONG Lingye

2017, 37(2): 36-40. doi: 10.13394/j.cnki.jgszz.2017.2.0008

Abstract(292)

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Abstract:
In order to realize uniform wear of the wheel when grinding axisymmetric aspheric,constant removal grinding in parallel grinding is investigated.Firstly,the relation between the angular velocity of the grinding point,the feed rate of the grinding wheel and the line speed of the grinding point are analyzed.Then a new mathematical model of grinding volume is obtained by accurate calculating removal in grinding with any time,and relational expression of removal is derived between the position of the grinding point and the feed rate within unit time in parallel grinding.Finally,axisymmetric aspheric constant removal grinding is realized through sub-feed control wheel feed rate in parallel grinding,and tests are conducted on constant removal grinding.Experimental results indicate that the wear in wheel edge parts is significantly decreased in in parallel grinding,and constant removal grinding can basically achieve uniform wear of the wheel by sub-feed control wheel feed rate.

Mechanical analysis on diamond saw blade based on ANSYS Workbench

LI Yang, WANG Yanjun, QIN Ke

2017, 37(2): 41-45. doi: 10.13394/j.cnki.jgszz.2017.2.0009

Abstract(364)

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An analysis model for dry cutting saw blades was estbalished.The status of saw blade's stress was analyzed by means of finite element software ANSYS Workbench.The magnitude and distribution of the stress were concluded under the action of centrifugal force,cutting force and thermal load of the diamond saw blade.Resultsshow that the stress produced by dry cutting is 535 MPa,which is beyond its permissible stress according to the third strength theory.Therefore,the biggest factor affecting the life of saw blade is the thermal stress caused by sawing heat.It is also found that the radial thermal stress is reduced by about 3%,and the compressive stress of the tangential thermal stress increased by about 0.4% under the combined action of the centrifugal force and cutting force.

Effect of heat preservation on the property and structure of low-temperature vitrified/Cu-Sn-Fe-based bond diamond tool

LI Guangfeng, HOU Yonggai, GAO Yuan, LI Wenfeng, HUANG Qingfei, DING Zhijing

2017, 37(2): 46-49. doi: 10.13394/j.cnki.jgszz.2017.2.0010

Abstract(278)

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Low-temperature vitrified/Cu-Fe-Sn-based bond diamond tool was prepared by the method of powder metallurgy.Bending strength and impact strength of samples were tested by using mechanical tester and their micro-topography were analyzed by using XRD and SEM.Resultsshow that when the heat preservation is 8 min,the mechanical property of vitrified/Cu-Fe-Sn-based bond diamond tool reaches its maximum value,namely bending strength 285.6 MPa and impact strength 10.88kJ/m².Prolonged holding time could promote low-temperature ceramic spreading on diamond surface.When the holding time is 8 min,the low temperature ceramic/Cu-Fe-Sn based binder can achieve the best mechanical fit and improve the bonding strength.

Simulation and experimental study on a cylindrical single-mode microwave plasma CVD device

LIU Fan, WENG Jun, WANG Jianhua, SUN Qi

2017, 37(2): 50-54. doi: 10.13394/j.cnki.jgszz.2017.2.0011

Abstract(437)

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Microwave plasma chemical vapor deposition(MPCVD)is considered to be an important method for the high quality diamond films deposition due to its unique advantages.The electric field distribution and strength in the cylindrical single-mode cavity are numerical simulated,meanwhile the study on the plasma discharge and the diamond films deposition are carried out on the MPCVD device.The results show that the simulated maximum electric field strength of the cylindrical single mode MPCVD device is 3.0×10⁵ V/m when the input power is only 100 W,which shows that the cavity possesses excellent focusing capability,and the design of quartz window can avoids plasma etching at the same time.In addition,High quality micro and nano diamond films are obtained on the diameter of 50 mm silicon wafer.The results provide theoretical guidance for the development of MPCVD devices.

Influence factors of pre-dressing and oxide film forming when ELID grinding silicon nitride ceramic

WAN Linlin, LIU Zhijian, DENG Chaohui, LIU Wei

2017, 37(2): 55-61. doi: 10.13394/j.cnki.jgszz.2017.2.0012

Abstract(289)

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According to the machining requirements of high efficiency and low damage of silicon nitride ceramic rotary surface parts,an electrolytic in-process dressing(ELID)grinding experiment device is designed,which is suitable for rotary surface machining.Pre-dressing experiment is carried out on CNC coordinate grinder.Based on the parallel electrode electrolytic cell model,a model of the relationship between pre-dressing time and oxide film thickness is established,and the influence of the duty cycle and the pole clearance on the film formation is analyzed as well.Resultsshow that duty cycle influences pre-conditioning time most,followed by electrolyte flow rate,grinding wheel speed and pulse frequency.In conclusion,the optimal process parameters are duty cycle 0.75,pulse frequency 50 kHz,wheel speed 9 000r/min,and electrolyte flow rate 1.0L/min through Taguchi method.

Effect of magnetic susceptibility of diamond micropowder on performance of plated diamond wire saw

HE Jingyuan, LI Zhengxin, HE Weichun, DAI Xiaonan

2017, 37(2): 62-64. doi: 10.13394/j.cnki.jgszz.2017.2.0013

Abstract(409)

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Magnetic susceptibility and ash content of various diamond micropowders were tested.The powders were then made into electroplated diamond wire saw to implement glass cutting experiments.Resultsshow that the magnetic susceptibility affects on the ash content and the performance of wire saw significantly.The diamond wire saw cutting performance becomes better with lower magnetic susceptibility,and the maximum cutting depth can reach 31.4mm.

Quantitative analysis and research on the dressing parameter of vitrified CBN wheel

HUANG Zhen, AN Zhengwei, ZHAO Jinwei

2017, 37(2): 65-68. doi: 10.13394/j.cnki.jgszz.2017.2.0014

Abstract(389)

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Orthogonal test is designed to quantitatively analyze dressing parameters of vitrified CBN wheel on the surface quality of machined part.The results indicate that the feed speed has strong influence on surface roughness and material ratio of the profile and that dressing depth has less influence on roughness but much on material ratio.Wheel is sharper as the reciprocating time is less.The speed difference between roller and grinding wheel influence the surface quality least.In the production practice,larger feed speed,lower dressing depth and more reciprocating times will enhance the surface roughness after dressing,prolong the dressing interval and finally improve the using life of CBN wheel.

Effect of Cr powder on thermal conductivity and mechanical property of diamond tool

TAN Cui, ZHAO Mingyong, YE Fangjian

2017, 37(2): 69-72,77. doi: 10.13394/j.cnki.jgszz.2017.2.0015

Abstract(328)

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Diamond powder,Cu-Sn alloy,graphite and vinyl acetate polymer were used the main raw material to prepare,Cu-matrix bonding diamond tool by hot-pressing sintering technique.The effect of Cr powder on thermal conductivity and mechanical property of diamond tool was investigated.Resultsshow that diamond tool with Cr powder has better thermal conductivity and mechanical property when compared to that without Cr powder:the relative density and thermal conductivity are about 98.46%and 110.43 W/(m·K);mechanical properties including flexural strength,compression strength and impact strength are 77.54 MPa,108.10 MPa and 4.06J/cm²,respectively.Both diamond tools show obvious characteristics of brittle fracture in their compressive and flexural load-displacement curves.

Quality inspection method for diamond wire saw

ZHOU Bo, MAO Jianbo

2017, 37(2): 73-77. doi: 10.13394/j.cnki.jgszz.2017.2.0016

Abstract(352)

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To inspect the quality of diamond wire saw,mathematics three-dimensional modeling method is proposed based on the microscopic image analysis to quantitatively analyze parameters such as protrusion height,protrusion rate and area ratio of the grits,and diameters of wire,saw and grits.Five samples are chosen to compare and analyze.Resultsshow that this method could reflect the change of the product quality well,which is an effective guidance for wire saw product quality inspection and control.

Design of intelligent device to detect mechanical properties of metallic matrix of diamond bits

HU Yule, LIU Naipeng, ZHAO Xiaojun, YU Xi

2017, 37(2): 78-81. doi: 10.13394/j.cnki.jgszz.2017.2.0017

Abstract(342)

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Holding force and bending strength are the main mechanical properties of matrix.There are many methods to calculate them,but there still exists errors compared with actual strength.We design a device to intelligently detect the mechanical properties of matrix,which uses pressure sensor and displacement sensor as the data detection sensor to test the ultimate pressures and loading rates at different temperatures. At the same time,digital display is used to show processed data and communicate with computer.Then the LabVIEW software programming is used display the real-time data and analyze the properties of matrix.On-site tests show that there is little difference between results of the device and prior equipment,namely 19.36 MPa(2.16%).In the end the function of the device and its shortcomings are analyzed.

Application of wide abrasive belt grinding process on the large surface of metal workpiece

XU Yingjun

2017, 37(2): 82-86. doi: 10.13394/j.cnki.jgszz.2017.2.0018

Abstract(302)

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Abstract:
The article introduces the application of wide belt sanding technology in metal processing industry,such as polishing and deburring of metal plate and steel belt,grinding of hot-rolled steel plate,etc.For better promotion of wide belt sanding technology,it also analyzes the elements related from perspective of processing cost,processing precision,components pattern,etc.In the end,the author shares his understanding on how to adapt wide belt sanding technology to different types of metal material.

2017 Vol. 37, No. 2

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