金刚石与磨料磨具工程

Advances in preparation and application of graphene on diamond surface

YU Wei, LI Zhengxin

2021, 41(6): 1-6. doi: 10.13394/j.cnki.jgszz.2021.6.0001

Abstract(470)

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Abstract:
In recent years, growing graphene on insulating substrate surface has attracted much attention and new strategies are put forward, some of which tried on SiO₂/Si, sapphire, GaN, glass or other insulating substrates with good progress. Diamond, who has irreplaceable advantages as graphene substrate, is less used to grow graphene directly. In this paper, the research progress of graphene grown on diamond substrate is introduced and so is the application technology of the corresponding devices. The development of graphene preparation on diamond substrate is prospected.

Robotic grinding of casing air passage and support plate surface

ZENG Qingshuang, GUO Haobang, LI Dingwei

2021, 41(6): 7-11. doi: 10.13394/j.cnki.jgszz.2021.6.0002

Abstract(361)

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Abstract:
This experiment presents the robot grinding technology for the airway and support plate surface of the aeroengine casing. A high-bandwidth and long-overhang adaptive grinding tool is developed for the airway surface and supporting plate surface of the casing. Based on the force analysis of the grinding tool, the PID force controller is further designed, and the Robotmaster is used for grinding tool path planning. A comparative experiment between the with-force controlled scheme and the without-force controlled grinding scheme was carried out on the experimental casing. The results show that the force error of the with-force controlled grinding scheme is less than ±1.5 N, and the average surface roughness is 1.450 μm. However, the force of the without-force controlled grinding scheme is 20.0 N, and the average surface roughness is 2.069 μm. The surface quality of the casing after force control grinding is higher.

Robot grinding and polishing impedance control based on environmental model optimization

WANG Jinghang, PENG Yunfeng

2021, 41(6): 12-17. doi: 10.13394/j.cnki.jgszz.2021.6.0003

Abstract(425)

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Abstract:
Compared with traditional machining machine tools, the stiffness and the positioning accuracy of robot were low. In order to improve the machining quality of robot assisted grinding, it was necessary to control the contact pressure in the machining process. Taking the depressing amount of the grinding tool as the independent variable, the contact pressure between grinding tool and workpiece as the dependent variable, the finite element simulation was carried out based on the contact characteristics of spherical elastic grinding tool during grinding. The curve fitting of the downforce contact pressure simulation results was carried out, and its accuracy was verified by the contact experiment. The impedance control model modified based on the environmental model was established, and the free-form surface force control experiment was carry out. The results show that the impedance control method based on environmental model modification can effectively improves the force control performance of the spherical elastic abrasive tools, and the free-form surface force control accuracy reaches ±0.5 N, which provides stable grinding pressure for the complex surface grinding of the spherical elastic abrasive tools.

Material removal depth model of titanium alloy ground by flap wheel

HU Zhijie, CAO Shiyu, HUANG Wenjian, WU Chaoqun

2021, 41(6): 18-23. doi: 10.13394/j.cnki.jgszz.2021.6.0004

Abstract(324)

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Abstract:
The surface removal of the titanium alloy was difficult to control when grinding with flap wheels. Therefore, a material removal depth model was established, by theoretical methods such as the Preston equation, Hertz contact theory, and line contact deformation, from the perspective of the moving process of flap wheel polishing. Firstly, by analyzing the movement of the flap wheel and the material removal process in the grinding process and simplifying the grinding process through the Preston equation, the relationship between the material removal depth and the linear velocity, the contact pressure, and the feed speed of the flap wheel was obtained. Secondly, the relationship between contact pressure and preload was obtained through Hertz contact theory and line contact deformation, and then the theoretical model of material removal depth was constructed by the preload substituted into the contact pressure. Finally, the orthogonal experiments and the single-factor experiments were used to verify the accuracy of the theoretical model. And the impact of various parameters on the flap wheel grinding and polishing removal depth was analyzed by range analysis. The results show that the material removal depth is directly proportional to the preload and the linear speed of the page wheel, inversely proportional to the feed speed of the page wheel, and the influence of various parameters on the grinding and polishing removal depth of the page wheel is basically the same. The average relative error between the material removal depth predicted by the theoretical model and the test results is 6.25%, which shows that the model can accurately predict the grinding removal depth.

Effect of pore density on thermal conductivity of CVD diamond foam

LI Songbo, YU Yanglei, JIAO Zengkai, KANG Huiyuan, KANG Aolong, WEI Qiuping, ZHOU Kechao, YU Zhiming, MA Li

2021, 41(6): 24-30. doi: 10.13394/j.cnki.jgszz.2021.6.0005

Abstract(407)

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Abstract:
Copper foams with different pore densities were chosen as the substrate to deposit the continuous diamond film on the surface by chemical vapor deposition (CVD) technology. The influence of the pore density of the foam skeleton on the overall heat transfer effect of the diamond film was explained by finite element simulation. The scanning electron microscope, the Raman spectrum and the infrared thermal imager were used to compare and analyze the micro morphology, the film composition and the thermal diffusivity of diamond foam with different pore densities. The results show that high pore density foam substrate is more conducive to heat transfer, but its tiny pore size limits the flow of free radicals in the pores, and the size of diamond grains deposited by CVD is significantly reduced, with only 2~3 μm. The grain quality is also slightly inferior to that of medium and low pore density samples. In the infrared thermal imaging with the same heating time, the surface heating rate of the medium pore density diamond foam is higher than that of the high and low void density samples, which increases by 43.4% and 12.7%, respectively. In summary, the diamond foam with excellent three-dimensional connectivity and excellent diamond quality has excellent thermal conductivity, and is a better choice of heat conduction reinforcement.

Preparation technology of diamond film by MPCVD method

LI Sijia, FENG Shuguang, GUO Shenghui, YANG Li, GAO Jiyun

2021, 41(6): 31-37. doi: 10.13394/j.cnki.jgszz.2021.6.0006

Abstract(771)

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Abstract:
With 3 kW/2 450 MHz microwave plasma chemical vapor deposition (MPCVD) system, the growth process of micron diamond film was studied by single factor experimental method with monocrystalline silicon as the substrate. The effects of substrate temperature, cavity pressure and methane volume concentration on the diamond film forming process were investigated and the optimal growth process of micron diamond film was obtained. The results show that the growth rate of diamond film is positively correlated with substrate temperature, cavity pressure and methane volume concentration. There is the best critical value of substrate temperature and cavity pressure for the quality of diamond film. The too high methane volume concentration is not conducive to the formation of diamond phase. The optimum parameters of diamond film growth are determined as follows. The power is 2 200 W, substrate temperature is 850 ℃, cavity pressure is 14 kPa, and methane volume concentration is 2.5%. In this case, growth rate of diamond film is 1.706 μm/h, and diamond phase content is 87.92%.

Effect of holding time on Pr₆O₁₁ etching diamond single crystal

ZHU Zhendong, MA Jinming, CHEN Bingwei, XIAO Changjiang, LI Zhengxin

2021, 41(6): 38-43. doi: 10.13394/j.cnki.jgszz.2021.6.0007

Abstract(310)

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Abstract:
To study the effect of holding time on the etching of diamond single crystal by Pr₆O₁₁, the mixture of Pr₆O₁₁and diamond was heated at different holding time in 900 ℃ and N₂ atmosphere to etch the diamond single crystal. The etching effect was characterized by the surface morphology, the etching depth and the single particle compressive strength of the diamond single crystal after etching. The results show that Pr₆O₁₁ can promote the etching of the diamond surface, and the etching degree and the maximum etching depth increase with the increase of holding time. When the holding time is 120 min, the etching pits on the {111} surface and {100} surface of the diamond are stepped inverted pyramid and honeycomb respectively, and the maximum etching depth is 15.07 μm and 4.27 μm. The compressive strength of single diamond particle also decreases with the prolongation of holding time, but the compressive strength of single diamond particle etched by Pr₆O₁₁ is higher than that of diamond etched without adding etchant and directly etched in air.

Nickel plating method and process on diamond surface with rotating electrode

ZHANG Yang, CUI Zhongming, FENG Changcai, YANG Tianbiao, ZHANG Yunhe, XU Benchao

2021, 41(6): 44-50. doi: 10.13394/j.cnki.jgszz.2021.6.0008

Abstract(549)

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Abstract:
Aiming at the problems of low plating efficiency and uneven coating in the current fixed electrode barrel plating method, a method of barrel plating on diamond surface based on rotating electrode was proposed, while the corresponding barrel plating device was developed. The mechanism of diamond rotary electrode barrel plating was analyzed, and the effects of plating parameters on deposition rate and morphology of diamond coating were studied by experiments. The results show that the rotating electrode can drive the abrasive stack to increase its overturning frequency and dispersing ability, and improve the contact uniformity between the abrasive stack with the electrode and plating solution, so as to improve the uniformity and surface quality of the coating. The results show that the best process parameters of rotating electrode barrel plating method are as follows: barrel plating current 4 A, cathode rotating speed 20 r/min, cathode rotor diameter 22.5 mm, grain size code of diamond 70/80. In addition, with the increase of rolling frequency of abrasive pile, the contact uniformity between abrasive particles is improved, which allows the increase of barrel plating space and electrode size, thus increasing the loading capacity of single plating. The results show that the maximum loading capacity of rotating electrode barrel plating method in 2 L capacity plating bottle can reach 700 g, which is about twice of the fixed electrode loading capacity under the same conditions, and the production efficiency is significantly improved.

Effect of TiH₂ on structure and properties of Cu60Zn40 alloy metal bond

HAN Ping, LIU Hengyuan, XU Sankui, HUANG Wei, XU Tianbing

2021, 41(6): 51-55. doi: 10.13394/j.cnki.jgszz.2021.6.0009

Abstract(327)

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Abstract:
The effects of TiH₂ volume concentration and sintering temperature on the mechanical properties and microstructure of Cu60Zn40 binder were studied with Cu60Zn40 alloy powder as raw material and TiH₂ as additive. TiH₂ can activate sintering and the mechanical properties of Cu60Zn40 were improved. When the sintering temperature is 680 ℃ and the volume concentration of TiH₂ increases from 0 to 10%, the flexural strength increases from 225 MPa to 445 MPa while the impact strength increases from 28.3 kJ/m² to 54.3 kJ/m². When the sintering temperature is 560 ℃ and the volume concentration of TiH₂ increases from 0 to 5%, the hardness increases from 46 HRB to 88 HRB. The porosity increases with the increase of TiH₂ volume concentration. When the volume concentration of TiH₂ is 20%, the porosity is 6.2%. The addition of TiH₂ is beneficial to the grinding performance of Cu60Zn40 bonded diamond grinding tool. The wear ratio increases from 28.50 to 61.67 and that the surface burn of workpiece is reduced when volume concentration of TiH₂ increases from 0 to 10%.

Optimization of processing parameters during electrical discharge diamond grindingof RB-SiC ceramics based on grey relational theory

HUANG Shuqiang, WEI Zongze, RAO Xiaoshuang, LI Chen, ZHANG Feihu

2021, 41(6): 56-62. doi: 10.13394/j.cnki.jgszz.2021.6.0010

Abstract(520)

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Abstract:
The electrical discharge diamond grinding tests of RB-SiC ceramics were performed. The influence of wheel parameters, grinding parameters and discharge parameters on surface roughness, material removal rate, wheel wear rate and normal grinding force were analyzed. The results indicated that electrical discharge diamond grinding could effectively improve the material removal rate and reduce the normal grinding force compared with the traditional grinding. However, too high discharge energy would result in serious wheel wear and reduce the material removal rate and ground surface quality. The process parameters were optimized based on grey relational theory and orthogonal experiment, and verification experiments were carried out to verify the optimization results. The results demonstrated that the optimized processing parameters could effectively improve the material removal rate and ground surface quality, and reduce the normal grinding force and wheel wear rate.

Surface roughness prediction based on stepwise regression analysis

ZHANG Jiayou, SONG Wanwan, BAI Yuzhen, HAN Bing, LI Lujie, ZHU Huining

2021, 41(6): 63-67. doi: 10.13394/j.cnki.jgszz.2021.6.0011

Abstract(483)

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Abstract:
To reduce the magnetic resistance of the carbon steel shaft on the method of processing the carbon steel shaft of the magnetic particles, the abrasive is stored in a circular vessel in which a plurality of magnetic poles is contained, and the magnetic particles taken away by the workpiece can be in the magnetic pole for cyclic utilization. Although the self-update of magnetic abrasive is in a single magnetic pole, it is possible to prevent the loss of magnetic abrasives. Further, in the test of the axial part of the 20CrMnTi material, the particle size of the magnetic abrasive particles is independent variable with the mass ratio of the machining time, the workpiece rotation speed, the magnetic abrasive and the polishing liquid, and the surface roughness as the dependent variable. The prediction model of surface roughness is established by stepwise regression analysis. The accuracy of the prediction result is found through the test, and it is found that the absolute value of relative error of surface roughness can be controlled within 7%, which has good prediction ability.

Design parameters and modal optimization of radial vibration matching layer transducer

GUO Shuaihong, LI Jun, WANG Huantao

2021, 41(6): 68-73. doi: 10.13394/j.cnki.jgszz.2021.6.0012

Abstract(555)

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Abstract:
The radial vibration transducer based on the matching layer shell was designed. The influences of the material of the matching layer, the diameter of the transducer and the thickness of the piezoelectric vibrator on the modal shape of the transducer were investigated. Due to the optimal modal shape at the design frequency, the design parameters of the transducer were optimized. The results show that the emission efficiency of the transducer in air medium is greatly improved by the resin based matching layer. As the diameter of transducer decreases and the thickness of piezoelectric vibrator increases, the excitation efficiency of radial vibration transducer increases. The optimized transducer diameter is 100 mm, and the thickness of piezoelectric vibrator is 10 mm. It can achieve high efficiency and high quality vibration assisted lapping when it works at the third resonance frequency of 34 729 Hz.

Experimental analysis on application performance of electroplated diamond wire saw

ZHANG Chenzheng, GE Peiqi, CHEN Zibin, ZHENG Chuxi, BI Wenbo

2021, 41(6): 74-79. doi: 10.13394/j.cnki.jgszz.2021.6.0013

Abstract(421)

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Abstract:
The unique test device with constant force feed is set up to evaluate the application performance of diamond wire saws, and the experiment of cutting single crystal silicon is carried out with two different electroplated diamond wire saws Ⅰ and Ⅱ. In the experiment, the surface roughness, kerf width and abrasive shedding rate are observed and measured with related instruments, and the sawing efficiency is calculated by recording machining time. The results show that the performance of diamond wire saw could be evaluated by the test device, quantitatively. It is also found that the sawing efficiency of wire saw Ⅰ is 13.6% higher than that of wire saw Ⅱ. In addition, the surface roughness of wafer sliced in feeding direction and movement direction by wire saw Ⅱ is 17.5% and 10.8% smaller than that of wafer sliced by wire saw Ⅰ. The kerf width of wire saw Ⅰ is 3.8% lower than that of wire saw Ⅱ. Finally, the service life of wire saw Ⅱ is longer than that of wire saw Ⅰ. The abrasive shedding rate of wire saw Ⅰ is 2.1 times that of wire saw Ⅱ.

Effect of abrasive mass fraction on grinding performance of diamond grindingwheel for grinding silicon wafer

LUO Miaodi, ZHAO Jinwei, DING Yulong, MIAO Weipeng, BAO Hua, ZHANG Yunhe

2021, 41(6): 80-84. doi: 10.13394/j.cnki.jgszz.2021.6.0014

Abstract(433)

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Abstract:
The porous vitrified-bond ultrafine diamond grinding wheel was fabricated through a modified gel casting technique in this study. Meanwhile, the microstructure and grinding performance of porous vitrified-bond ultrafine diamond grinding wheels, were evaluated at six different abrasive fractions (27%, 30%, 33%, 36%, 39%, 42% in mass percentage, respectively). The abrasive fraction was found to play an important influence directly on the grinding current, wheel wear rate and hence affected the surface integrity of Si wafers. Results revealed that a smooth surface with roughness of 4.8 nm was achieved by using the grinding wheel with abrasive fraction of 39%.

Rock breaking modes under different cutting edge angles of axe drill teeth

LI Shangjie, ZHAO Xing, HUANG Jiqing, LIU Wei

2021, 41(6): 85-90. doi: 10.13394/j.cnki.jgszz.2021.6.0015

Abstract(558)

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Abstract:
To further study the rock-breaking mechanism of the axe blade PDC cutter, a 3D finite element model of the dynamic rock breaking of the PDC cutter was established, and a comparative study of three axe cutters with different angles was evaluated. The result shows that the blade with 135° has higher shearing force and cutting force compared to those of cutters with 150° and 165°, which results in a higher efficiency on rock breaking. It is also found that with the same back rake angle, cutting depth and cutting force, the axe blade with 165° cutting edge shows a smaller fluctuation than those of others. Compared with the data collected from vertical lathe (VTL), the trend of simulation results matches with the experiment one and the deviations between experiment and finite element analysis (FEA) can be accepted.

2021 Vol. 41, No. 6

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