金刚石与磨料磨具工程

Research status and prospect of additive manufacturing diamond tools

TAO Yakun, GAN Jie, ZHOU Yan, DUAN Longchen

2022, 42(5): 511-517. doi: 10.13394/j.cnki.jgszz.2022.3004

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In recent years, diamond tools are developing in new directions such as complex shape, precise structure and high-end performance. However, limited by the forming principle, it is difficult to meet the above requirements through conventional manufacturing processes. Therefore, there is an urgent need to seek new methods. As an emerging manufacturing technology, additive manufacturing technology has been applied to the manufacture of diamond tools with complex structures in recent years owing to its characteristics of turning three-dimensional manufacturing into two-dimensional manufacturing. This paper reviews the research progress of the current mainstream means to fabricate diamond tools through additive manufacturing processes, such as selective laser melting, selective laser sintering and stereo lithography appearance. The forming principles of the three methods are introduced in detail, focusing on the interface combination of diamond and matrix material under different processes. At the same time, the differences of the three additive manufacturing methods for forming diamond tools are briefly compared. Finally, the future research priorities are prospected and some suggestions are put forward.

Research of diamond bit in Wulong Gold Mine, Liaoning Province

WANG Luzhao, WU Haixia

2022, 42(5): 518-522. doi: 10.13394/j.cnki.jgszz.2022.3010

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The Wulong gold deposit is located in the ore-concentrated district of eastern Liaoning Province. It is a large quartz vein type mine hosting more than 80 tons of gold. However, with the increase of mining volume, the mining depth of the deposit is nearly 1 km, and the retained reserves are decreasing. Therefore, it is urgent to carry out deep prospecting research in the mining area. On the basis of previous studies, a high matrix diamond coring bit was developed through the study of bit matrix formula, diamond parameters and bit structure. The field test indicates that the bit effect is remarkable and that the problems of low drilling efficiency and short service life of original bits in this mining area have been solved.

Report on operation of Chinese superhard industry in 2021

LI Lijuan, ZHANG Beibei, ZHAO Xinghao, LI Zhihong, SUN Zhaoda

2022, 42(5): 523-526. doi: 10.13394/j.cnki.jgszz.2022.4001

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A overall reflection of Chinese superhard industry in 2021 is presented with China’s macroeconomic indicators. The development of the industry is analyzed. It is found that despite the general background of increased pressure on the manufacturing industry, the superhard industry achieves outstanding results in both international and domestic circulation, whose industrial output and profit growth rate are both higher than the national average. However, the achievements mainly results from the macroeconomic environment, while the development in management and technology of enterprises is relatively slow. In conclusion, the overall situation for the industry is still not optimistic with significantly increased development pressure.

Configuration design and thermal conductivity of diamond-SiC/Al composites

KANG Huiyuan, KANG Aolong, JIAO Zengkai, WANG Xi, ZHOU Kechao, MA Li, DENG Zejun, WANG Yijia, YU Zhiming, WEI Qiuping

2022, 42(5): 527-534. doi: 10.13394/j.cnki.jgszz.2022.0015

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The preforms were prepared with SiC and W-coated diamond reinforcements, and the diamond-SiC/Al composites were prepared by gas pressure infiltration technology at 800 ℃ and 5 MPa. The properties of composite materials were analyzed by scanning electron microscope, infrared thermal imager and laser thermal conductivity meter. The influences of the content and the particle size ratio R of SiC and diamond on the configuration of composites were investigated to optimize the thermal conductivity of the composites. The results show that with the same SiC particle size, the thermal conductivity of the composites will be significantly improved with the increase of diamond volume fraction. When the volume fraction of diamond is 30%, the thermal conductivity of the composites containing F100 SiC is the best, which reaches 344 W/(m∙K). When the volume fraction of diamond is the same and the particle size ratio R increases from 0.07 to 0.65, the thermal conductivity of the composite increases in turn. Moreover, the thermal conductivity of composites with diamond volume fraction of 15% increases from 174 W/(m∙K) to 274 W/(m∙K), which achieves the largest increase of 57%.Therefore, by improving the content and the particle size ratio of reinforcements in the diamond-SiC/Al composites, the configuration of composites can be regulated to realize full potential of thermal conductivity.

First-principles calculations of diamond/copper (silver, titanium carbide) interface properties

HAN Jinjiang, CHEN Bingwei, LU Pengxian, LI Ying, LI Zhengxin

2022, 42(5): 535-542. doi: 10.13394/j.cnki.jgszz.2022.5002

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The structure, electrical structure, and heat transmission of diamond/copper, diamond/silver, and diamond/titanium carbide surfaces have been investigated using first-principles calculations. The results show that the diamond/titanium carbide interfacial structure is the most stable, with the shortest interfacial distance (1.990 Å), the greatest interfacial adhesion effort (5.578 J/m²), and the best bond strength. The results of the electronic density of states, mulliken population analysis ,charge density difference, and radial distribution function indicate the presence of more charge transfer and stronger bonding in diamond/titanium carbide. According to the results of the phonon density calculation, the interfacial thermal resistance of diamond/titanium carbide is low.

Preparation methods of boron-doped diamond electrode and its research progresses

LI Lianlian, CHEN Guanqin

2022, 42(5): 543-551. doi: 10.13394/j.cnki.jgszz.2021.5005

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The common two-dimensional boron doped diamond flat plate electrode in the practical wastewater treatment application shows the disadvantages of small reactive area and low degradation efficiency. In order to realize excellent degradation efficiency towards wastewater, it is expected that boron doped diamond electrode has high specific surface area so as to enhance the reactive area and has special surface structure so as to enhance its oxidative and catalytic ability. However, there still exists problems such as the complexity of preparation process and expensive equipment for such boron-doped diamond electrode. In order to address above problem, this article focuses on the preparation methods of the boron doped diamond electrode, analyze the merits and demerit of these methods, and discusses its industrial application prospect in wastewater treatment.

Effect of B₂O₃ content on the structure and properties of SiO₂–B₂O₃–Al₂O₃–Na₂O system ceramic binder

WANG Zhao, XU Sankui, HUANG Wei, XU Tianbing, HAN Ping, YAN Guojin, CHEN Zhaoqi, WU Tanyang

2022, 42(5): 552-559. doi: 10.13394/j.cnki.jgszz.2022.0041

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The SiO₂–B₂O₃–Al₂O₃–Na₂O system glass samples and the ceramic binder samples with different B₂O₃ contents were prepared. The density and the microhardness of different glass samples, the bending strength, the micro morphology and the thermal expansion coefficient of ceramic binder samples were measured by electronic multifunctional experimental machine, scanning electron microscope, microhardness instrument, plane flow method and thermal expansion coefficient tester. The structures and the compositions of the ceramic binder were analyzed by X-ray diffractometer and Fourier transform infrared spectrometer. The results show that the introduction of B₂O₃ into the ceramic binder can effectively reduce its sintering temperature, improve its thermal stability and adjust its thermal expansion coefficient. When B₂O₃ with mole fraction of 15% is added to the ceramic binder, the maximum bending strength of the spline is 78.11 MPa, and the maximum density and hardness are 2.45 g/cm³ and 856 MPa respectively, and the thermal expansion coefficient of the ceramic binder is the best match with that of diamond. The results of X-ray diffraction analysis show that the ceramic binder is a typical glass phase structure and has a good coating effect on the abrasives.

Effect of Y₂O₃ on properties of iron-based diamond tools

WEN Lu, ZHOU Qiang, LUO Li, PAN Xixiang, WU Jinpin

2022, 42(5): 560-566. doi: 10.13394/j.cnki.jgszz.2022.0046

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The effects of hot pressing pressure, sintering temperature and Y₂O₃ content on the hardness, the density, the flexural strength and the fracture morphology of the iron-based matrix were studied by orthogonal test, and the better sintering process parameters were obtained. On this basis, the iron-based diamond tool containing Y₂O₃ was prepared, and its fracture morphology, wear resistance and sharpness were detected and analyzed.The results show that the order of factors affecting the relative density and the hardness of the iron-based binder matrix containing Y₂O₃ is Y₂O₃ content, followed by the sintering temperature and the hot pressing pressure, and the influencing factor order of the flexural strength is sintering temperature, Y₂O₃ content and hot pressing pressure. Y₂O₃ can promote the densification of iron-based diamond matrix structure and reduces its sintering temperature. Under the better sintering process with sintering temperature of 780 ℃ and hot pressing pressure of 51 kN, an appropriate amount of Y₂O₃ can reduce the porosity of diamond tools, improve the bonding condition, and enhance the holding ability of binder to diamond abrasive particles.

Experimental study on grinding force in axial feed grinding of cemented carbide with diamond grinding wheel

REN Xiaoke, HUANG Hui, SU Zhenfa

2022, 42(5): 567-577. doi: 10.13394/j.cnki.jgszz.2022.0040

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In order to study the grinding force of diamond wheel in axial feed grinding of cemented carbide, the transformation models of horizontal grinding force, vertical grinding force, normal force and tangential force are established, the variation of grinding force under different process parameters was measured, the effects of process parameters on normal force, tangential force and axial force are analyzed, the empirical formula of grinding force is established. The results show that in the process of axial feed grinding, the maximum grinding force is the normal force, and the axial force is slightly less than the tangential force. The influence of grinding wheel linear speed on grinding force in three directions is roughly the same. The influence of grinding depth on grinding force in three directions is obviously different. The effect of feed rate on grinding force is not significant.

Evaluation of grinding performance for micromotor rotor shaft by microcrystalline ceramic corundum grinding wheel

ZHANG Bisheng, WU Yao, QU Meina

2022, 42(5): 578-584. doi: 10.13394/j.cnki.jgszz.2021.5004

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In view of frequent dressing of grinding wheel in process of centerless cylindrical grinding of micromotor rotor shaft, this paper proposes to use microcrystalline ceramic corundum grinding wheel instead of traditional corundum grinding wheel to grind micromotor rotor shaft. By building a surface grinding process platform and referring to the dressing and grinding parameters of centerless grinding wheel, grinding performance of microcrystalline ceramic corundum grinding wheel and corundum grinding wheel was compared and analyzed in grinding temperature, surface processing quality, and grinding ratio. Compared with corundum grinding wheel, microcrystalline ceramic corundum grinding wheel can not only effectively improve the grinding temperature (reduce 38.5%), improve the surface processing quality (reduce the surface roughness by 78.6%), but also has a higher grinding ratio (increase 2.2 times). In addition, microcrystalline ceramic corundum grinding wheel was selected to verify centerless grinding production of micromotor rotor shaft. The test results of centerless grinding sample of micromotor rotor shaft meet requirements of actual production index, and dressing cycle is twice longer than that of traditional corundum grinding wheel, which improves processing quality and production efficiency significantly.

Optimizing process parameters of ultrasonic vibration assisted grinding CFRP based on response surface method

JI Daohang, CHEN Yan, GUO Nan, LIANG Yuhong, JI Junjie, WANG Yongqing

2022, 42(5): 585-594. doi: 10.13394/j.cnki.jgszz.2022.0019

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To solve the contradiction between high quality and high efficiency of CFRP machining surface, the quadratic regression models of 3D surface roughness S_a and surface damage layer depth D_d were established by using the response surface method, and the genetic algorithm was used for multi-objective optimization to obtain small S_a, D_d and maximum material removal rate V_MRR. The results show that the regression models of S_a and D_d are explicit and reliable, and the feed speed v_f has the most significant influence on S_a and D_d, followed by the grinding depth a_p, the spindle speed n and the ultrasonic amplitude A. The results of response surface analysis show that the interactions of n and A, v_f and a_p, v_f and A have significant effects on S_a. The interactions of n and A, v_f and A, v_f and a_p, a_p and A have significant effects on D_d. When the weight ratios of S_a, D_d and V_MRR are 1/5, 1/5 and 3/5 respectively, compared with the central point results, the optimized S_a decreases by 11.01%, D_d decreases by 10.08%, and V_MRR increases by 62.02%. The absolute values of the relative errors between the experimental and the predicted values of S_a and D_d under the optimized process parameters are 8.25% and 9.41% respectively, indicating that the prediction model has high accuracy and can be used for the optimization and prediction of the process parameters of CRFP ultrasonic vibration grinding.

End face wear of small brazed diamond grinding head for 3C ceramics

ZHOU Yu, HUANG Guoqin

2022, 42(5): 595-601. doi: 10.13394/j.cnki.jgszz.2022.0030

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The diamond micro-milling head is widely used in the processing of advanced ceramic components of 3C products. Through the grinding tests on the zirconia ceramic workpiece most commonly used in 3C products, the morphology evolution of the brazed diamond micro milling head was observed, and the corresponding relationship between the accumulated removal volume of zirconia ceramics and the wear amount of diamond abrasive grains on the grinding head was counted. The wear failure and the service life of the copper-based and the nickel-based brazed diamond micro milling heads were compared and analyzed. The results show that under the same processing parameters, the life of the copper-based grinding head is longer, which is 1.2 times that of the nickel-based grinding head. In the process of grinding, there are three main failure modes of grinding particles on the end face of diamond grinding head: crushing, flattening and falling off. The wear of grinding head mainly starts from the edge of the end face of the grinding head and gradually spreads to the center until the abrasive wear is serious and the grinding head fails.

Optimization of laser sharpening parameters for diamond grinding wheel based on CNN

GAO Mengyang, CHEN Genyu, LI Wei, ZHOU Wei, LI Jie

2022, 42(5): 602-609. doi: 10.13394/j.cnki.jgszz.2022.0018

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To optimize laser sharpening parameters for bronze diamond grinding wheels, the laser sharpening test was carried out on the bronze diamond grinding wheel using the orthogonal test method.The convolutional neural network (CNN) is used to identify the diamond abrasive grains at the pixel level. The protruding height of abrasive grains is obtained by extracting the area information of abrasive grains. Two laser sharpening quality evaluation indicators, the protruding height score and the optimal interval ratio, are obtained by using the statistical distribution law. The quality of the grinding wheel laser sharpening effect obtained by the test is evaluated by the evaluation index proposed and the range method is performed. The results show that the average power is the biggest factor affecting the quality of trimming. The optimal trimming process parameters are as follows: the average power is 35 W; the repetition frequency is 100 kHz; the rotational speed is 300 r/min; the scanning speed is 1.0 mm/min.

Fenton reaction chemical mechanical polishing liquid composition optimization of polishing GaN wafer

YAN Jiewen, LU Jiabin, HUANG Yinli, PAN Jisheng, YAN Qiusheng

2022, 42(5): 610-616. doi: 10.13394/j.cnki.jgszz.2022.5001

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Aiming at the polishing liquid used for polishing GaN wafers by Fenton reaction CMP, a parameter optimization experiment was carried out with the surface quality as the evaluation index, and the optimal ratio of the polishing liquid components was found out. The results show that when the mass fraction of H₂O₂ is 7.5%, the surface of GaN wafer processing is the best, and the surface roughness reaches 3.2 nm; the catalyst can effectively adjust the rate of the Fenton reaction. Compared with the liquid catalyst FeSO₄ solution and the solid catalyst Fe₃O₄ powder, the solid catalyst Fe₃O₄ powder can continuously ionize Fe²⁺ in the solution, so that the Fenton reaction can continue to work throughout the process. When the particle size of Fe₃O₄ powder is 20 nm, the polishing surface is the best, and the surface roughness reaches 3.0 nm; compared with alumina, cerium oxide, and silica sol abrasives, the best surface polishing effect can be achieved while using the silica sol abrasives, and the surface roughness reaches 3.3 nm; when the mass fraction of silica sol abrasive is 20.0% and the abrasive particle size is 60 nm for polishing, the surface roughness reaches 1.5 nm. After optimizing the composition of the polishing liquid, the GaN wafer was polished with the optimal composition parameters of the polishing liquid, and a smooth surface with a surface roughness of 0.9 nm could be obtained.

Simulation analysis of particle mechanical behavior in rotary-assisted horizontal vibration polishing of blisk

WANG Zhicheng, LI Wenhui, LI Xiuhong, ZHANG Yan, WEN Xuejie

2022, 42(5): 617-625. doi: 10.13394/j.cnki.jgszz.2022.0051

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To solve the problems of low efficiency and poor uniformity in polishing blisk, a rotary-assisted horizontal vibration mass finishing process was adopted. Based on the discrete element method, the behavior of particles in the process was simulated to study the characteristics of the particle behavior on the blisk, and the variation law and the distribution of the particle acting force. The results show that the particles have different movement feature in the flow passage area and the non-work-piece area, and the particles on both sides, where there is no workpiece, can only act on the two sides of the blisk. During the rotating process of the blisk, the blade would experience some sudden forces when entering or exiting the particle flow field. The force on blade surface increases at first and then decreases along the rotating direction. Moreover, changing the rotating direction affects the fluctuation range of the forces acting on the back surface and the basin surface of blade. The effect of particle on the blade surface is obviously different, whose RSD value is between 30% and 60%, and the strong force of the back surface of blade mainly appears in the areas of inlet and tip while at the basin surface of blade is generally focused in the areas of exhaust and tip.

Study on removal mechanism of steel bonded cemented carbide material GT35 in cutting process

CHEN Bochuan, SHAO Mengbo, GAO Xiaoxing, LI Qilin, YUAN Songmei

2022, 42(5): 626-636. doi: 10.13394/j.cnki.jgszz.2022.0038

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Single particle diamond cutting experiments are designed to research the micro scratching process and material removal mechanism of GT35 steel bonded cemented carbide. The value of linear scale coefficient k is estimated as well. The exact value of k is further confirmed by equal depth cutting experiment. Furthermore, the material removal approaches at different cutting depths are discussed by microscopic observation and three-dimensional morphology modeling by SEM and laser confocal microscope. It is observed that there is a linear functional relationship between cutting force and groove cross-sectional area. k (F_x) is 0.026 29 N/μm²(R₂=0.990 46) and k (F_z) is 0.046 42 N/μm²(R₂=0.994 08) after fitting. The quenched and tempered GT35 material is mainly plastic removal under various cutting depths, in which the bottom surface of the groove shows an obvious plastic shear removal state, and the edge shows a certain brittle removal state. During the cutting process, there will form a material stacking dead zone at the tool tip, causing tool edge collapse and wear. The formation of the surface morphology is closely related to tool wear.

2022 Vol. 42, No. 5

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