金刚石与磨料磨具工程

2021, 41(2): 1-3.

Abstract(99)

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Preparation of titanium-aluminum-carbon bond diamond composite material by microwave-induced thermal explosion

DAI Zhen, ZHANG Wangxi, LIANG Baoyan, YANG Li

2021, 41(2): 4-8. doi: 10.13394/j.cnki.jgszz.2021.2.0001

Abstract(139)

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Using Ti, Al, graphite and diamond powder as raw materials, the titanium-aluminum-carbon bond/diamond composite material was prepared by the microwave-induced thermal explosion method, and the effect of diamond content and particle size on the phase composition and microscopic morphology of the composite material was studied. The results show that under a nitrogen atmosphere, the raw material powder undergoes thermal explosion reaction, which can generate Ti₂AlC, Ti₃AlC₂, TiC, TiN, AlN and Al₃Ti phases. When a lower diamond content or a thicker diamond is used, it is easy to obtain more titanium, aluminum, and carbon content in the product, and the interface between the matrix and the diamond is denser. The content and particle size of diamond have a significant effect on the wear ratio performance of composite materials. With the increase of diamond content or particle size, the wear specific properties of the samples increased significantly. When the mass fraction of diamond (170/200) is 30%, the wear ratio of the sample reaches 53.8. Higher diamond content or coarser particle size can promote the significant improvement of the grinding performance of the composite material.

Strength analysis of axial rotating heat pipe grinding wheel under thermo-mechanical coupling

JIANG Huafei, CHEN Jiajia, FU Yucan, XU Youlin

2021, 41(2): 9-16. doi: 10.13394/j.cnki.jgszz.2021.2.0002

Abstract(182)

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To study the matrix strength of the axial rotating heat pipe grinding wheel (HPGW) in the process of high efficiency profile grinding, and considering that HPGW has the characteristics of heat transfer enhancement, ANSYS workbench was used to perform finite element analysis on the HPGW under the thermo-mechanical coupling. At the rotating speed of 30 000 r/min, the maximum equivalent stress of HPGW is 26.481 MPa, and the maximum deformation is 0.014 8 mm, all of which meet the allowable requirements. The influence of rotating speed on maximum equivalent stress and deformation under the conditions of different grinding parameters, matrix materials and workpiece materials was discussed respectively. The results show that at the same feed rate and cutting depth, with the increase of the rotating speed, the maximum equivalent stress of HPGW decreases first and then increases, and the maximum deformation decreases continuously. HPGW with 2Cr13 as the matrix material adopts the creep feed deep grinding process to grind the titanium alloy, which can minimize the stress and deformation. The best parameters in this condition was rotating speed of n=10 000 r/min, workpiece speed of v_w=80 mm/min, and cutting depth of a_p=0.10 mm.

Study on optimal method of induction brazing temperature for single-layer CBN grinding wheel

LI Qilin, DING Kai, LEI Weining, SHAN Daping

2021, 41(2): 17-22. doi: 10.13394/j.cnki.jgszz.2021.2.0003

Abstract(1278)

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The traditional optimizing methods of brazing temperature for CBN grinding wheels were adopting one of a discrete temperature sequence. In order to acquire the exact optimal temperature during brazing of CBN wheels, a newly optimizing method of induction brazing temperature was proposed. A mathematical evaluation model, which took brazing temperature as independent variable, was established to evaluate the grinding performance. The sharpness of grains and service life of the wheel were both taken into account in this mathematical model. Grinding tests of TC4 titanium were carried out with a group of induction brazed CBN wheels. The temperature evaluation function of brazed CBN wheel was obtained based on the cubic spline interpolation of the experimental data. The optimal brazing temperature for CBN grinding wheels was 936.5 ℃ according to the evaluation function. Experimental results of the evaluation function showed about 3.4% larger than that of theoretical value. It was implied that the brazing temperature evaluation model and the optimizing method were both reliable.

Development of suitable CuSnZnNi pre-alloyed powder for diamond tools

YU Qi, MA Jia, LONG Weimin, ZHONG Sujuan, YU Xinquan, PAN Jianjun

2021, 41(2): 23-27. doi: 10.13394/j.cnki.jgszz.2021.2.0004

Abstract(197)

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Based on the composition of CuSn alloy, Zn and Ni elements were added to develop CuSnZnNi pre-alloyed powder, which would overcome the problems of low hardness, weak holding power of diamond and poor universality of CuSn10. CuSnZn alloy was prepared by adding 20% zinc element. Compared with CuSn10 alloy, the temperature difference between solid and liquid phase decreased from 170 ℃ to 34 ℃, and the fluidity of the alloy was significantly improved.The microstructure of CuSn eutectoid phase (α+δ) increased significantly with the addition of Zn element. Meanwhile, α -(Cu, Sn) phase gradually transformed into α -(Cu, Zn) phase in the sintered matrix. XRD analysis showed that δ phase of Cu₆Sn₅, Cu₄₁Sn₁₁, Cu_5.6Sn and γ phase of Cu₅Zn₈ were formed in the alloy. The results show that the grain size of the alloy could be refined and the density of sintered body improved by adding nickel element continuously. At the same time, Ni could strengthen the phase structure and prevent the crack growth. Solid solution of α-(Cu, Ni) and intermetallic compound Ni₃Sn appeared in the alloy. The results show that the pre-alloyed powder could improve the sintering performance of diamond tools, which have excellent adaptability.

Latest development of static high pressure technology in China and abroad

WANG Yipeng, KOU Zili, JIANG Mingquan

2021, 41(2): 28-34. doi: 10.13394/j.cnki.jgszz.2021.2.0005

Abstract(378)

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High pressure is divided into dynamic (shock wave) high pressure and static high pressure, while static high pressure is divided into small volume press like as diamond anvil cell (DAC) and large volume press (LVP). Under high pressure, materials exhibit completely different properties under normal temperature and pressure. Through high pressure research, we can systematically understand the phase transition and compression behavior of various materials under pressure. Therefore, high pressure has been widely used in materials science, geophysics, planetary science, national defense and other fields. According to the survey, the current foreign DAC can exceed the pressure of 500 GPa, the pressure in large volume press (LVP) can reach the pressure of 125 GPa, and the domestic pressure can reach the pressure of 35 GPa. This paper systematically summarizes the temperature, pressure range and design principles of high-pressure devices at home and abroad to reveal the development history of static high-pressure science. Summarizing the temperature and pressure limits of various static high-pressure equipment at home and abroad not only allows us to have a clearer understanding of international and domestic high-pressure development trends.

Analysis and early warning of pressure leakage in diamond synthesis process

LIU Qiankun, HE Wenjiang, DU Huanlong, SHEN Xingwei, HAN Changyu, LU Yang, WANG Chenyang

2021, 41(2): 35-38. doi: 10.13394/j.cnki.jgszz.2021.2.0006

Abstract(242)

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In the synthesis of man-made diamond, the surrounding heating material would deform before the ultra-high pressure leakage occurs. The change of resistance and current, caused by the deformation, was analyzed to warn about the leakage. The current change was simulated and calculated by models, and an early warning scheme was formulated according to the actual statistics. The scheme, when applied in production, would achieve its expected effect, thus effectively avoiding such accidents and reducing the production cost.

Preparation of diamond films by low power MPCVD

ZHU Haifeng, WANG Yankun, DING Wenming, LIANG Linda

2021, 41(2): 39-45. doi: 10.13394/j.cnki.jgszz.2021.2.0007

Abstract(308)

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High-quality diamond films are prepared using CH₄/H₂ gas by the microwave plasma chemical vapor deposition (MPCVD) method. Under 150 W low microwave power, the influences of the substrate pretreatment method, deposition pressure, and volume ratio for preparing high-quality diamond films are studied. The results show that the high volume ratio is not conducive to the size control of diamond particles, and the presence of secondary nucleation can obtain diamond films with near nanometer particle size; the larger deposition pressure is conducive to the preparation of dense and uniform diamond films. The impact of substrate pretreatment for the film deposition is obvious, and the ultrasonic treatment with a methanol suspension containing diamond powder is the most effective seeding method.

Preparation of high thermal conductivity diamond/aluminum composites by vacuum hot pressing

XU Yang, SHEN Weixia, FAN Jingzhe, HOU Ling, ZHANG Zhuangfei, HUANG Guofeng, LI Kenan

2021, 41(2): 46-52. doi: 10.13394/j.cnki.jgszz.2021.2.0008

Abstract(196)

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A high heat-conducting diamond/aluminum composite material with thermal conductivity of 677 W/(m·K) was prepared by vacuum hot-pressing solid-phase sintering. The properties of the diamond/aluminum composite were characterized by laser thermal conductivity instrument and thermal expansion instrument. The preparation process was optimized by modifying the preparation temperature, holding time and diamond particle size. It was noted that the density and relative density of diamond/aluminum composite increased with the increase of the preparation temperature, and the thermal conductivity first rose and then fell. When the preparation temperature was 650 ℃, the thermal conductivity reached 526.2 W/(m·K). When the heat preservation time increased from 30 minutes to 120 minutes, the density, the relative density and the thermal conductivity of diamond/aluminum composite materials all increased to the density of 99.1% and the thermal conductivity of 566.7 W/(m·K). When the size of diamond particle increased from 20 μm to 500 μm, the density and relative density of diamond/aluminum composite first increased and then decreased. When the size of diamond particle is 200 μm, the density and relative density reached their maximum values, namely 3.06 g/cm³ and 98.4%. The thermal conductivity increased with the increase of diamond size, and the thermal conductivity reached the highest 677.5 W/(m·K) when using 500 μm diamond particles as thermal conductive fillers. Therefore, high-density diamond/aluminum composite material prepared by vacuum hot pressing method can effectively improve the combination of aluminum matrix and diamond through process control, reduce interfacial void, and then prepare high thermal conductivity diamond/aluminum composite material.

Fabrication of diamond-WC-Co composites at high temperature and high pressure

YANG Yanan, WANG Haikuo, HOU Zhiqiang, WU Jiakun, WANG Chao

2021, 41(2): 53-58. doi: 10.13394/j.cnki.jgszz.2021.2.0009

Abstract(218)

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Diamond-WC-Co composites is prepared by using the high pressure cubic cell at 5.50 GPa and 1 100~1 500 °C for 2 min, with mass fraction of 5% diamond powder (average grain size 7 μm), 90% WC powder (average grain size 150 nm), 5% Co powder (average grain size 0.9 μm) as the starting materials. The sample characterization is performed through the X-ray diffraction, Raman spectrum, scanning electron microscope and Vickers hardness tester. The synthesized diamond-WC-Co composites has a uniform phase distribution, and the diamond particles are well bonded with the cemented carbide matrix. The sample has the best performance under the thermodynamic conditions of 5.50 GPa and 1 250 ℃ for 2 min, with a relative density of 96% and a Vickers hardness of 23.60 GPa.

Application of metal/diamond composite abrasive in resin abrasive tools

LIU Hengyuan, XU Sankui, HAN Zhijing, HAN Ping, ZOU Wenjun

2021, 41(2): 59-63. doi: 10.13394/j.cnki.jgszz.2021.2.0010

Abstract(187)

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To modify the grinding effect of rails, superhard composite abrasive grains were used to make resin bond test specimens through processes of press-sintering and then curing. The effects of the grain type on the bending strength, the impact strength and the abrasive wear ratio of the specimens were studied and the ground surfaces of the abrasives and rails were observed by using SEM to characterize the quality of ground surface. Results show that after the grain and metal bond are granulated, all three types of mentioned performance of the specimens are significantly improved, i.e. bending strength 50% higher, impact strength nearly 2 times larger and wear ratio about 12.6 times larger. In conclusion, superabrasive, when added as composite grains, could enhance the bonding force of the tool on its grains and reduce the phenomenons such as bluing and burning, thus achieving a better surface quality of the rail.

Multi-camera visual inspection of abrasives distribution density on electroplated diamond wire saw surface

ZHAO Yukang, BI Wenbo, GE Peiqi

2021, 41(2): 64-68. doi: 10.13394/j.cnki.jgszz.2021.2.0011

Abstract(236)

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Electroplated diamond wire saw is widely used in slicing of hard and brittle materials, such as monocrystalline silicon, sapphire, single crystal silicon carbide, and ceramics. The abrasive distribution density on the surface of electroplated diamond wire saw will directly affect its slicing performance, which is the main index of diamond wire saw quality inspection. Four CCD cameras were used to acquire the surface images of diamond wire saw at the same time, and the images were preprocessed by Gaussian filter. The images were expanded based on the cylindrical model, and the image mosaic was completed through the steps of feature point matching, feature point screening, registration model solving, image resampling, and image overlapping area removal. Then the number of abrasives in the whole image was extracted by using the connected region labeling. The results show that the proposed method for detecting the abrasive particle distribution density of the full-surface image of the electroplated diamond wire saw can improve the accuracy of the online detection of the abrasive particle distribution density. Compared with the half surface image results detected by a single camera, the maximum relative error of the detection results of the abrasive distribution density decreases by 29.6%, and the average relative error decreases by 17.3%.

Research on PCBN cutting tool for high speed cutting hardened steel

YE Zhibiao, JIANG Wenqing, LUO Tao

2021, 41(2): 69-74. doi: 10.13394/j.cnki.jgszz.2021.2.0012

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PCBN composites was used as the tool material, its related mechanical properties were analyzed. Then, it was made into SNGN120408 type tool and the hardened steel cutting experiment was carried out on the tool machine. The analysis results show that the binders of the PCBN composites are mainly TiN and TiB₂. The internal structure is evenly distributed and has good compactness. Cutting experiments show that in the hard cutting process, the cutting speed and cutting feed rate have a more obvious impact on tool wear than the cutting depth. Compared with cutting speed, the feed rate has a greater influence on the surface roughness of hardened steel workpiece. The wear of PCBN tool high-speed cutting hardened steel is the result of multiple wear such as bond wear, local spalling and diffusion wear.

Effect of composition on abrasion-corrosion behavior of WC-based matrix material for impregnated diamond bits

LIU Zhijiang, YAO Yuanji, WANG Wenzheng, PAN Bingsuo

2021, 41(2): 75-81. doi: 10.13394/j.cnki.jgszz.2021.2.0013

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To study the influence of the component (WC, Fe and 663Cu) contents on the abrasion-corrosion properties of impregnated diamond bit matrix, abrasion-corrosion tests, static corrosion tests and electrochemical tests were carried out in 20% NaCl slurry with pH value of 10. The surface morphology and corrosion products were observed and analyzed by SEM and Raman spectroscopy. The results show that mechanical wear plays a dominant role in abrasion-corrosion process in salt water environment, and pure corrosion has no obvious effect. However, the synergistic effect of these two components cannot be ignored. With the decrease in corrosion resistance of the matrix, the synergistic effect was more significant. Furthermore, the anti-corrosion property of the matrix deteriorated with the increase of WC and Fe contents, but the opposite was true for 663Cu. The dominant corrosive products have been detected as a mixture of oxides and hydroxy chloride. Due to the potential difference between different matrix components, Fe and other binder phases were formed as anode and WC as cathode in the process of abrasion-corrosion. The micro galvanic couple between WC and binder removed binder material preferentially. And WC particles were removed more easily under mechanical action after losing support from the binder. During the process of test, the exposure and passivation of the fresh surface will reach a balance. After the abrasion-corrosion test, the sample surface will be passivated rapidly.

Optimization of CMP solution for yttrium aluminum garnet crystal

ZHANG Zili, JIN Zhuji, MU Qing, YANG Huipeng, HAN Xiaolong

2021, 41(2): 82-88. doi: 10.13394/j.cnki.jgszz.2021.2.0014

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Yttrium aluminum garnet (YAG) crystal is widely used as gain medium in laser device due to its excellent physical, chemical and optical properties. However, current process can hardly satisfy the requirements of high efficiency and high quality in YAG crystal processing. Based on the material remove mechanism of silica sol, new slurry for chemical mechanical polishing (CMP) of YAG crystal was invented, and its composition was optimized by orthogonal experiment. The material removal rate of CMP was increased to 34 nm/min, and the surface roughness of YAG crystal was 0.5 nm after the CMP process by using the proposed slurry. Compared with the traditional silicon sol, the new slurry improves the polishing efficiency by 240% and reduces the surface roughness by 17%. After comparing the performances of both slurries, the effect of interacting mode at CMP surface on material removal mechanism is proposed.

Prediction and optimization of process parameters in chemical mechanical polishing for 304 stainless steel based on response surface methodology

LIU Haixu, WU Qingdong, CAO Xiaojun, QI Wanting, SU Jianxiu

2021, 41(2): 89-95. doi: 10.13394/j.cnki.jgszz.2021.2.0015

Abstract(249)

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Response surface methodology was used to study the effects of three parameters (rotating speed, pressure and time) on material removal rate R_MRR and surface roughness R_a in polishing process. According to the results of polishing test, the regression model of material removal rate and surface roughness was established, the response surface and contour map were obtained, and analyzed in detail. The results show that the regression model is significant, which proves the feasibility and reliability of the response surface method to predict and optimize the process parameters of 304 stainless steel chemical mechanical polishing. The optimum process parameters of surface roughness and material removal rate were obtained. The experimental values of R_a and R_MRR were compared with the predicted values, and the relative error was within ±10%. The results show that the precision of the model is high, and it can be used to optimize the process parameters and predict the results.

Adaptive cutting casting riser with grinding wheel

WANG Weixin, MENG Guangyao, WANG Zhe, SUN Yingnuan

2021, 41(2): 96-101. doi: 10.13394/j.cnki.jgszz.2021.2.0016

Abstract(197)

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To solve the problems of low automation and high labor intensity during casting riser removal in current casting industry, an adaptive cutting method using grinding wheel was studied. The automatic removal of casting riser was realized by the movement coordination of cutting machine and fixture. To ensure the cutting quality, the cutting machine compensated for the wear of the grinding wheel through automatic feeding so that the wheel always cut at its best cutting point. At the same time, a cutting model was established in SolidWorks and then imported into Adams to simulate the cutting process. The simulation results show that the cutting device can automatically remove the casting riser at the best cutting point, which verifies the rationality of the adaptive cutting method.

2021 Vol. 41, No. 2

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