金刚石与磨料磨具工程

LUO Shan, HU Xiaoyue, WANG Chengyong, ZHENG Lijuan, ZHAO Danna

2018, 38(2): 1-7. doi: 10.13394/j.cnkij.gszz.2018.2.0001

Abstract(466)

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Abstract:
Diamond, with excellent performance, is more and more applied in medical field. The applications of block, film and nanopowder of diamonds are detailed according to fields such as tool, material and pharmaceutical. As diamond has special advantages on hardness, wear resistance, stability and biological compatibility, it also faces problems on processing method and theoretical research. Therefore, though widely applied, there is still great possibility for diamond application and expansion.

Effect of temperature on defects in homoepitaxial single crystal diamond by MPCVD

DING Kangjun, MA Zhibin, SONG Xiuxi, XIA Yuhao, GENG Chuanwen

2018, 38(2): 8-11,19. doi: 10.13394/j.cnkij.gszz.2018.2.0002

Abstract(457)

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Abstract:
Homogeneous epitaxial growth experiments were performed by microwave plasma chemical vapor deposition (MPCVD) on seeds of single crystal diamonds with defects. The effects of temperature on such defects were studied under the same depositing parameters. The diamonds were characterized by emission spectroscopy, Raman spectroscopy, and SEM. Results show that the higher the diamond temperature is, the higher the spectral intensity ratio I(C₂)/I(H_α) in the plasma emission spectrum of the diamond surface is, and that as the electron temperature decreases, the collision between particles in the plasma become more intense. When deposited at 740℃, there appear surface cracks running through defects after homoepitaxial growth. At 780 and 820℃, the defects are inhibited and covered, whose area decreases. At 860℃, the defect area is enlarged and the protrusion is more obvious. In conclusion, the single crystal diamond grown at medium temperature has better quality, such as smaller offset of diamond characteristic peak and smaller stress. Otherwise, the peak is obviously shifted to low wave number, and the tensile stress is larger.

Influence factors of electrolytic processing diamond blocks synthesizedby high temperature and high pressure catalyst method

SHAO Jingru, LI Fangyi, LIU Yongqi, LIU Zimu, ZHAI Xiangyang, ZHU Yibo, ZHANG Songfei, DONG Pei

2018, 38(2): 12-14. doi: 10.13394/j.cnkij.gszz.2018.2.0003

Abstract(344)

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Diamond is synthesized using graphite and metal catalyst at high temperature and high pressure. However, diamond in the synthetic block is tightly wrapped by graphite, catalyst metal and etc, which is difficult to purify through general physical methods. Electrolysis is used to oxidize the metal in the synthetic block on the anode into metal ions and thus solved in the solution, and then the ions are migrated to the cathode through the solution to recover the metal, which is a more efficient and environmentally friendly method at present. Through the electrolysis experiment, the influences of the main components of electrolyte and the conditions of electrolysis process on the efficiency of electrolysis are analyzed.The results show that the best mass concentration of activator in the additives is 15-30 g/L and the best mass concentration of composite stabilizer is 25-30 g/L, the additives can significantly improve the performance of electrolyte. The pH value of the electrolyte is 2-4, electric cathode and anode distance is 50-250 mm and the current of control cabinet is 4000-4200 A, the electrolysis efficiency can be significantly improved.

Study on preparation of diamond/copper compositesby high temperature and high pressure method

ZHAO Long, SONG Pingxin, ZHANG Yingjiu, YANG Tao, MA Shanshan, WANG Caili

2018, 38(2): 15-19. doi: 10.13394/j.cnkij.gszz.2018.2.0004

Abstract(426)

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Abstract:
Diamond-copper composites were prepared by high temperature and high pressure method (HPHT). The effects of diamond volume fraction, sintering pressure, holding time, sintering temperature, surface metallization of diamond on thermal conductivity and thermal expansion coefficient of diamond-copper composites were studied. The experimental results show that when diamond volume fraction is 70%, sintering pressure is 2 GPa, sintering time is 300 s, and sintering temperature is 1200℃, the thermal conductivity of diamond-copper composite material reaches 426 W/(m·K).

Performance optimization of Al-based bond matrix in metallic bond diamond wheel

CHEN Kexin, LIU Yibo, CAO Caiting, LIU Wei

2018, 38(2): 20-25. doi: 10.13394/j.cnkij.gszz.2018.2.0005

Abstract(256)

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Abstract:
Commonly used alloying elements, namely Cu, Zn, Mg and Mn, were selected to strengthen aluminum with AlSi₂₀ as the main component. The factors, each with three levels, were marked as A, B, C and D, respectively. The L₉(3⁴) orthogonal test scheme was developed. Al-based bonding matrix was prepared by hot pressing sintering. The effects of alloying elements on the properties of the matrix were studied by means of Archimedes drainage method, rockwell hardness test, three-point bending strength test and scanning electron microscope. Results show that the addition of alloy elements reduces the sintering temperature of AlSi₂₀ and promotes the densification of sintering. The influence of alloy elements on hardness is Mn>Zn>Cu>Mg. The influence of bending strength is Cu>Mn>Zn>Mg. In conclusion, the combination of A₁B₂C₂D₂ and A₁B₃C₃D₃ have high hardness and bending strength, whose matrices are closely tied to diamond. The fracture mode of binding agent is brittle fracture, which can improve the self-dressing ability of diamond grinding wheel.

Crystallization of ZABS glass and its wettability on diamond abrasive

LUAN Shixun, FU Renli, ZHU Haiyang, LIU Qilong, LI Yujun

2018, 38(2): 26-31,36. doi: 10.13394/j.cnkij.gszz.2018.2.0006

Abstract(291)

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Abstract:
To modify glass-ceramic bond, ZnO-Al₂O₃-B₂O₃-SiO₂ (ZABS) glass was prepared by conventional melting method. The influence of boron-silicon ratio and sintering process on its thermal and mechanical properties, as well as crystallizing behavior was discussed. The microstructure of the glass and its wettability on diamond abrasive were studied. Results show that with increased boron content, the thermal expansion coefficient of glass increases and its thermal resistance decreases, while bending strength first increases and then decreases. Too much boron will make the bond cover the grain entirely, which is bad for grinding. It is also found that with increased silicon content, the viscosity of glass increases, thus leading to poor wettability to grains. Too much silicon leads to poor bending strength. In conclusion, the best boron-silicon ratio of ZABS glass is 1:1 in weight, and the optimized heat treatment is 710℃ for 2 h. The glass would have a thermal expansion coefficient of 5.132 7×10^-6℃^-1 and a bending strength of 78 MPa, as well as good wettability to grains.

Preparation of iron-based pre-alloyed powders by water-gas atomizationand its application in diamond tools

LIU Kunjie, LE Chen, ZHAO Fang, TANG Mingqiang, WU Chengyi

2018, 38(2): 32-36. doi: 10.13394/j.cnkij.gszz.2018.2.0007

Abstract(328)

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Abstract:
The iron-based pre-alloyed powders for diamond tools were produced by water-gas atomization. The physical properties of powders prepared by different processes including conventional water atomization and water-gas water atomization were compared, accordingly powders were sintered to segments and the fracture morphology and mechanical properties of the segments were observed, compared and analyzed respectively. The results showed that the iron-based pre-alloyed powder prepared by water-gas atomization with low oxygen content, is of spherical shape and fine particle size. The fracture morphology of TZ611 sintered segments using powders produced by water-gas atomization, exhibits typical ductile fracture and intergranular fracture characteristics.The mechanical properties, such as the relative density, hardness and bending strength of the segments, are greatly improved, which leading to better bonding force between the matrix and diamond. The circular blade made of pre-alloyed powder prepared by water-gas atomization is more sharp, and the service life is 1.62 times that of the conventional water atomization powder.

Influence of CVD diamond coating process on performance ofcarbide end mill for cutting CFRP

YANG Xiaofan, LI Yousheng, LI Lingxiang, WANG Jue, SHEN Zhihuang

2018, 38(2): 37-41. doi: 10.13394/j.cnkij.gszz.2018.2.0008

Abstract(350)

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CFRP, carbon fiber reinforced polymer, was a typical hard-to-process material that would cause serious tool wear when cut by conventional cemented carbide tools (CCTs). Therefore, the CCTs need diamond coatings. Three kinds of CCTs with different diamond coatings, namely rough-diamond, fine-diamond and compound-diamond due to depositing processes, were prepared, separately. The surface of coatings were analyzed by SEM, and the CCTs were used to cut CFRP under the same conditions to study the wear mechanism. Results show that CCTs with compound coatings have best wear resistance and longest serve life, which is almost 1.35 and 1.59 times of those of CCTs with rough-diamond coatings and fine-diamond coatings. In conclusion, CCTs coated with compound-diamond is more suitable for CFRP cutting.

Research on performance of precision grinding cemented carbidecutting tools with heavy grinding wheel

JIANG Zhijin

2018, 38(2): 42-46. doi: 10.13394/j.cnkij.gszz.2018.2.0009

Abstract(289)

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The grain shape of the heavy grinding wheel, the composition of the grinding layer, the wear of the grinding wheel, the grinding force of the grinding wheel and the appearance quality of the endmill are studied. The results show that the composition of the grinding layer has a effect on the self-sharpening of the grinding wheel. Under the same grinding condition, the crystal shape of abrasive not only affects the grinding force and wear resistance of the grinding wheel itself, but also determines the appearance and surface quality of the solid carbide cutting tools.

Research on new diamond tools and technology for highefficiency machining cemented carbide counterbore

ZHANG Qiankun, LI Suwang, SUN Hongding, HE Yuehui, JIANG Yao, CHEN Yuzhang, XIAO YiFeng

2018, 38(2): 47-50,56. doi: 10.13394/j.cnkij.gszz.2018.2.0010

Abstract(404)

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A new diamond tool for machining cemented carbide counterbore and its processing technology are introduced. The relationship between the machining efficiency and the service life of the diamond grinding head is studied under the conditions of different cutting depth and feed speed by using the electroplating and sintered diamond grinding head on NC milling machine. The effects of different size and groove electroplating and sintered diamond grinding head on the efficiency and the precision of the cemented carbide counterbore with different materials are studied. The micro-structure of the diamond grinding head is analyzed by SEM and optical microscope. Results show that the sintered diamond grinding head has better working life and efficiency. The processing time of the per counterbore (φ13 mm×5 mm) of the traditional cemented carbide is shortened from 2 hours to 10-15 min, and the serving life of each sintered diamond grinding head can reach 33-40. The application of hard and brittle materials with counterbore machining will be promisingly expanded.

Three-dimensional printing in the application of diamond tools manufacturing

ZHANG Shaohe, TANG Jian, ZHOU Hou, WANG Jialiang

2018, 38(2): 51-56. doi: 10.13394/j.cnkij.gszz.2018.2.0011

Abstract(407)

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Three-dimensional printing is an intelligent manufacturing technology and it's a new attempt to manufacture diamond tools with 3D printing which has distinct advantages, such as highly integrated products, precision manufacturing, easy to handle, and capable of products with complex shapes. These characteristics greatly help in the manufacturing of diamond tools. Through the 3D printing technology, the diamond tools can be further developed to a certain extent in respects of having ultra-thin, tiny and irregular shapes, which is difficult for other conventional methods. However, there are some problems, such as the lack of qualified diamond powder, as well as the carbonization, granularity and concentration of diamonds, which will be solved as 3D printing technology further develops.

Dispersion strengthened impregnated drill bits by WC nanoparticles

LIU Baochang, LI Siqi, HAN Zhe, ZHAO Xinzhe, LI Chuang, CAO Xin

2018, 38(2): 57-60. doi: 10.13394/j.cnkij.gszz.2018.2.0012

Abstract(351)

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In order to improve the drilling efficiency and serving life of impregnated diamond bits, WC nanoparticles were introduced into the matrix of traditional bit matrix. The matrix formula and preparation process were optimized to utilize the dispensation strengthening effect of WC nanoparticles, improving physical and mechanical performance of working layers. Indoor drilling experiments were carried out to compare the the enhanced and traditional bits. Results show that when adding 2.5wt% nano-WC into traditional matrix of impregnated bits, an enhanced bit is developed, with 24.93% faster drilling speed, 28.91% longer service life and steadier process.

Developing equipment for electro-depositing diamond wire saw

WANG Qihao, BI Wenbo, GE Peiqi

2018, 38(2): 61-65. doi: 10.13394/j.cnkij.gszz.2018.2.0013

Abstract(246)

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Abstract:
Electro-deposited diamond wire saw, which is easy to manufacture with high bonding strength between deposited layer and substrate, has broad prospect in the application of slicing superhard crystals. Based on the principle of electro-depositing, the process of electrode depositing material onto, and thus metallurgically bonding with, substrate surface is analyzed. New equipment is designed with rotating electrodes and gas medium through analyzing the influence of depositing method and media on deposited layer. The electrodes is set at spark discharging state through adjusting their distance to the substrate. The distance is determined according to the average voltage between electrodes and substrate, which is used to detect discharging. It is found that the equipment works reliable and that it could deposit diamond grits onto φ0.4 mm stainless wire.

Analysis on delay phenomenon of resin diamond wire when slicing silicon

GAO Wei, DONG Funing, LI Teng, MA Bojiang, WANG Dongxue

2018, 38(2): 66-70. doi: 10.13394/j.cnkij.gszz.2018.2.0014

Abstract(425)

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Abstract:
To erase the delay phenomenon of resin diamond wire slicing silicon, a slicing model was established to study the deformability of single diamond in resin layer. The relationship between shift δ and the bending arc A was analyzed. Theoretical research indicates that there is a positive correlation between δ and A. Diamond wires were then made at the same condition but with resins of different hardness and the contrast tests were implemented. After slicing, the wires were observed by SEM. It is found that at the same slicing condition, diamond wire with softer resin deforms more, and thus with bigger bending arc and longer slicing time. In conclusion, resin with high strength will add the curing strength of resin layer and decrease the deformability, thus efficiently solving the slicing delay problem.

Study on swarf when sawing granite with diamond wire

WU Hairong, GUO Hua, ZHAO Ruyi, HUANG Hui

2018, 38(2): 71-77. doi: 10.13394/j.cnkij.gszz.2018.2.0015

Abstract(265)

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The diamond wire-sawing process was developed to cut granite in both quarries and block processing plants. In this paper, swarf was collected from different areas along the sawing arc when sawing three granites. The particle size distribution and the morphology of the swarf were investigated systematically, along with the swarf formation mechanism in sawing. Granite swarf formation was dominated by transgranular fractures based on the morphology of sawn granite chips and the analysis of sawn chip size. A long cutting arc increased the movement among the swarf, tool, and workpiece, thereby inducing a secondary fracture in the sawn chip.

Compositions of slurry used in chemical-mechanically polishing 304 stainless steel

LIU Zhenhui, CHEN Shaokun, PENG Yanan, LI Jiejing, SU Jianxiu

2018, 38(2): 78-81,88. doi: 10.13394/j.cnkij.gszz.2018.2.0016

Abstract(334)

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304 stainless steel will become one of the main materials of flexible display substrate due to its excellent characteristics. In order to improve the rate and quality of chemical mechanical polishing of 304 stainless steel, the influences of different oxidants on material removal rate and surface roughness under different mass concentration or volume concentration and pH value are mainly studied. The results show that the oxidants of Fe₂O₃, H₂O₂, and FeCl₃ achieved the best polishing effects in pH=2, and that KMnO₄ achieved the best polishing effect in pH=10. The best surface roughness is 4 nm when the volume concentration of H₂O₂ is 10 mL/L, and the highest material removal rate is 209 nm/min when the mass concentration of FeCl₃ is 4.0 g/L at their optimum pH.

Experiment on optimization of lapping cylindrical roller

SU Jia, Yuan Julong, ZHANG Sen, CAO Linlin, LV Binghai, YAO Weifeng

2018, 38(2): 82-88. doi: 10.13394/j.cnkij.gszz.2018.2.0017

Abstract(323)

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To optimize OD grinding cylindrical roller process, orthogonal experiment is designed on the influences of workpiece deflection angle, workpiece position and rotation speeds, namely rotation speed of both polishing disks, eccentric wheel and outer gear ring, on material removal rate, surface roughness and roundness. Results show that the angle has most significant effect on material removal rate, followed by rotation speeds and workpiece position. As with surface roughness, the sequence should be rotation speed, angle and position. Workpiece position influences the roundness most, then rotation speeds and angle. The best processing parameters are deflection angle 0°, workpiece position 0.8, and rotation spees of up & down polishing disks, eccentric wheel and outer gear ring are -76, 84, 80 and 48 r/min, respectively. After machining for 15 min, the material removal rate could reach 0.541 μm/min, with surface roughness from 0.078 to 0.045 μm, decreasing 42.3%, and roundness from 0.74 to 0.41 μm, decreasing 44.6%.

Analysis on model of grain depth-of-cut of wafer rotational grinding

LIN Bin, CAO Zhihe, ZHOU Ping, KANG Renke

2018, 38(2): 89-93. doi: 10.13394/j.cnkij.gszz.2018.2.0018

Abstract(365)

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Grain depth-of-cut has a significant impact on surface- or subsurface-damage (SSD) of the ultra-ground parts of hard and brittle materials. Thus, to better simulate and predict the depth-of-cut, the differences between prediction and result are analyzed, mainly about why prediction is smaller than result. The model is fixed according to deviation analysis on grain numbers and test result of single-grain scratch. However, the fixed model, though more accurate, still could not meet the results. Some other factors that might influence the simulation are put forward, such as radius of cutting and minimum thickness of chip, to provide reference for further development and promote the optimization of grinding parameters.

Development of ultrasonic vibration polishing method on workpiece surface

WAN Hongqiang, HAN Peiying, GE Shuai, LI Fancong, LIU Zhihao

2018, 38(2): 94-100. doi: 10.13394/j.cnkij.gszz.2018.2.0019

Abstract(644)

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In this paper, the principle and development of ultrasonic vibration polishing on workpiece surface and the research progress of ultrasonic vibration polishing method and composite ultrasonic vibration polishing method at home and abroad in recent years are described. The comparative analysis is made and the development direction of ultrasonic vibration polishing on the surface of the workpiece is pointed out.

2018 Vol. 38, No. 2

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