CN 41-1243/TG ISSN 1006-852X

2024 Vol. 44, No. 1

Display Method:
Analysis of the influence of container structure on the flow characteristics of vertical vibration polishing granular media
FENG Lidong, LI Wenhui, LI Xiuhong, ZHANG Yan, WEN Xuejie, FAN Yu
2024, 44(1): 1-8. doi: 10.13394/j.cnki.jgszz.2023.0067
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In order to explore the impact of container structure on the motion characteristics of granular media in vertical vibrating grinding equipment, ADAMS-EDEM coupling simulation was used to simulate the motion characteristics of granular media during the vibrating polishing process. Firstly, the influence of container structure on particle motion characteristics is analyzed from the perspective of particle motion trajectory and velocity vector. Secondly, the influence of container structure on particle velocity and particle force is comprehensively judged from the depth direction and radial direction. Finally, the effectiveness of the simulation is verified through dynamic force test experiments. The experimental results show that the island-like structure aids the tumbling movement of particles but hinders circumferential movement. The movement of particles in the container with islands is more violent, and the average force of particles is greater than that of islands. The existence of the island structure does not change the basic law that the particle force gradually increases with depth, but it amplifies the force increase, particularly evident in the island container. However, the existence of the island structure basically does not change the trend of a gradual increase in particle force in the radial direction. The rationality of the simulation is verified by both sets of experiments.
Diamond grown on KTN substrate and its photocatalytic performance
LUAN Yuhan, LI Tianwei, WANG Xuping, HAO Jianxin, ZHAO Hongyang, FU Qiuming, TAO Hong, GAO Deng, MA Zhibin
2024, 44(1): 9-14. doi: 10.13394/j.cnki.jgszz.2023.0007
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[Objectives] Diamond, with advantages of high melting point, good insulation, stable chemical properties, and high thermal conductivity, is a promising semiconductor material for high-power devices, sensors, and quantum computing. The best method for producing high-quality single crystal diamonds through microwave plasma chemical vapor deposition (MPCVD) is homoepitaxial growth, which requires expensive single crystal diamond substrates. Therefore, heteroepitaxial growth on foreign substrates is a compromise approach that has to be adopted, where the selection of a proper substrate becomes a major challenge for growing high-quality diamonds. To enhance the quality of heteroepitaxial growth, potassium tantalum niobate (KTa1-xNbxO3, referred to as KTN) crystals are proposed as the substrate. Their lattice parameter (0.3994 nm) is close to that of diamond (0.3567 nm). The structural similarity between them makes it possible to achieve an ideal result with small lattice mismatch and high crystal quality.

[Methods] Diamond thin films were grown on large-size, high-quality KTN single crystals using MPCVD. The effect of different growth times on diamond quality was explored by varying the duration of diamond growth. The surface morphologies, microstructures, and crystalline quality were analyzed using scanning electron microscope (SEM), X-ray diffraction (XRD) and Raman spectroscopy. Diamond samples with different growth times were used to degrade Rhodamine B (RhB) to assess their photocatalytic effect. The absorbance of RhB was measured to evaluate the degradation efficiency of diamond films as catalysts for the pollutant solution.

[Results ] Analysis of plasma diagnostic spectra confirmed the presence of H groups and carbon source groups, while CN groups were absent. The H group exhibited the highest spectral line intensity, higher than that of the C2 group. This indicated that the system was well-sealed and provided sufficient reactive groups for diamond growth. The ratio of peak intensities between Hα and Hβ was high, while the ratio between C2 and Hα was low, both of which were favorable for the deposition of high-quality diamonds. Raman spectroscopy revealed structural changes in diamonds through comparing Isp3/Isp2, the relative intensities of diamond-phase characteristic peaks and non-diamond-phase characteristic peaks. The ratio gradually increased with the extension of growth time, indicating that the quality of diamonds was improving. XRD analysis of diamond films showed characteristic diamond peaks. In the 6h sample, characteristic peaks appeared at 34.8° (111), 40.5° (200), 58.6° (220) and 70.0° (311), consistent with the standard card (JCPDS No. 35-0801) as the characteristic peaks of TaC, indicating the presence of TaC in the 6h sample. However, the TaC characteristic peaks were lower in the 9h sample, and only diamond characteristic peaks were observed in the 12h sample. This indicated that TaC was only a transitional layer formed in the pre-nucleation stage, and TaC was no longer generated with the extension of growth time. From the SEM images of diamond films at different deposition time, it could be seen that the grain size of the 12h sample was much larger and more evenly distributed than those of other samples. The surface of the 12h sample was mostly composed of (100) faceted grains with a high degree of flatness, and the grains growing at the grain boundaries tended to grow significantly larger. Analysis of photocatalytic activity showed that higher diamond purity and lower non-diamond phase proportion led to better photocatalytic activity, more stable photocatalytic performance, and higher reusability.

[Conclusions] A new diamond substrate, potassium tantalum niobate (KTa1-xNbxO3), was successfully used to grow high-quality diamond films using MPCVD technology. The samples were characterized by XRD, SEM and Raman spectroscopy. Results indicate the formation of a TaC transition layer when growing diamond films on the KTN substrate, which is favorable for stable diamond growth. Moreover, with increasing growth time, the diamond grain size increases, the diamond phase content increases, and the sample quality improves. Photocatalytic results show that the sample grown for 12 hours has stronger photocatalytic ability and higher photocatalytic stability, achieving a degradation efficiency of 91.9% for RhB, which is 1.6 times higher than that of the 3h sample. These findings broaden the application of diamond and provide valuable insights for substrate selection in diamond fabrication.

Analysis of low-temperature CVD growth process of diamond films in C-H-F atmosphere
JIAN Xiaogang, LIANG Xiaowei, YAO Wenshan, ZHANG Yi, ZHANG Binhua, CHEN Zhe, CHEN Maolin
2024, 44(1): 15-21. doi: 10.13394/j.cnki.jgszz.2023.0069
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To better understand the growth mechanism of diamond films via low-temperature chemical vapor deposition in a C-H-F atmosphere, this paper employed density functional theory based on first principle. It calculated the adsorption energy, reaction heat, and reaction energy barrier of H and F atoms undergoing extraction reactions on the hydrogen-terminated diamond surface. Additionally, the analysis included the adsorption of CF3, CF2, and CF growth groups on the active site substrate. The results show that compared with H atoms, F atoms are more likely to extract H from the surface of hydrogen terminated diamond and desorb it in the form of HF. This process is advantageous for generating more active sites at low temperatures in a C-H-F atmosphere. Both the structure and the absolute value of the adsorption energy of CF3, CF2, and CF groups are more favorable for the generation of the diamond phase after adsorption. Increasing the concentration of CF3, CF2, and CF growth groups appropriately can facilitate the growth of diamond phase at a higher rate.
Preparation of Ti3SiC2/diamond composites by Ni-Al assisted microwave self-propagating sintering
SHI Shuhao, YANG Li, GUO Shenghui, GAO Jiyun, HOU Ming, LU Yuanjia
2024, 44(1): 22-30. doi: 10.13394/j.cnki.jgszz.2023.0021
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[OBJECTIVES] Low carbon economy and green economy are the strategic direction of sustainable development, in order to reduce the manufacturing cost and energy consumption of diamond grinding tools, this study aims to explore a process of preparing high-performance ceramic bond diamond grinding tools under low energy consumption, to reduce the manufacturing cost and energy consumption of diamond grinding tools. The specific objectives include preparing Ti3SiC2-based diamond composite materials, and studying the effects of combustion-supporting agent Si and diamond particle size on the phase composition, microstructure and grinding performance of the samples.

[METHODS] Ti, Si, graphite powder, and diamond abrasives are selected as raw materials. After proportioning and weighing, they are cold-pressed to prepare green bodies. Ni powder and Al powder are cold-pressed into auxiliary heating green bodies according to the proportion. The material green body is horizontally placed on the auxiliary heating green body and then placed on the graphite block, then placed in a microwave tube furnace, Ar atmosphere is introduced for protection, and the temperature is quickly raised to the thermal explosion temperature point under the condition of 3kW power. After 30 seconds, the microwave source is cut off, and the furnace is cooled to room temperature before the Ar atmosphere input is turned off. At the end of the experiment, Ti3SiC2-based diamond composite material can be obtained.

[RESULTS] Microwave pressureless sintering is more efficient than conventional heating methods below 1000 ℃. High calorific value Ni-Al alloy assistance can shorten the experimental time of sample sintering, and can control the temperature point of inducing SHS reaction below the graphitization temperature of diamond. Under the protection of Ar atmosphere, the Ti-Si-C system undergoes an SHS reaction, which can generate three phases of Ti3SiC2, TiC, and Ti5Si3. Adding a certain amount of Si as a combustion-supporting agent in the experiment will be beneficial to the generation of the target phase of Ti3SiC2. When Ti3SiC2, TiC, and Ti5Si3 are at a certain proportion of equilibrium points, they can stably combine with diamond abrasives to exert the maximum grinding performance. As the Si content increases, the Ti3SiC2 phase first increases and then decreases. When n (Ti): n (Si): n (C) = 3: 1.1: 2, the grinding performance of Ti3SiC2-based diamond composite material is the best, and the diamond particle size is 70/80 mesh. The sample has the highest wear ratio, which can reach 286.53. Through the analysis of the friction wear test section of the composite material, the overall pores of the sample are small and evenly distributed, providing a good grip for the diamond abrasive. The diamond fits tightly with the surrounding matrix, the exposed part of the diamond is slightly higher than the grinding surface of the matrix, and the remaining part is tightly wrapped by the matrix, maximizing the grinding ability of the sample. It is known from the above analysis that the size of the pores, the distribution of the pores, the ratio of the raw materials, and the particle size of the diamond are the keys to the overall grinding performance. The pores are small and evenly distributed, and the matrix is more likely to form a flat grinding plane during the grinding process, which is easy for the diamond to exert good grinding performance. Adding a combustion-supporting agent and increasing the particle size of the diamond can both improve the grinding performance of the sample. When the Si combustion-supporting agent is added to 0.1 mol and the diamond particle size is 180~212 μm, it reaches the highest.

[CONCLUSIONS] By optimizing the raw material ratio and preparation process, using Ni-Al to assist microwave sintering, an SHS reaction is induced at 482 s and 685.5 ℃, preparing a Ti3SiC2-based diamond composite material containing Ti3SiC2, TiC, and Ti5Si3, which has excellent grinding performance. By analyzing the mechanism of the difference in the wear ratio of samples under different raw material ratios, it is found that the small and evenly distributed pore structure in the matrix organization is conducive to producing a flat grinding surface and improving the grinding performance of the composite material samples. This research provides a new method for preparing diamond grinding tools for green and low-carbon circular development, and is expected to reduce energy consumption and improve efficiency in practical applications.

Exploration of ceramic binder diamond aggregated abrasives
CHENG Xiaozhe, XU Yan, MU Yunchao, HAN Jinghe, LIU Tao
2024, 44(1): 31-38. doi: 10.13394/j.cnki.jgszz.2023.0022
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The diamond powder manufacturing industry at present grapples with a large backlog of fine-grained diamond powders. To enhance its applicability, agglomerated abrasive samples were manufactured with aluminum-borosilicate binder as the bonding agent, Si powder and Ti powder as additives. These agglomerated abrasive samples were then added into an aluminum-borosilicate binder to create ceramic bond samples. The bending strength, phase composition, and microscopic morphology of the samples were analyzed. The results show that the Al-B-Si binder, when combined with Si or Ti, can agglomerate diamond. When the mass fraction of Si or Ti in the agglomerated abrasives is 10.0%, the bending strength of the ceramic bond samples prepared is the largest. The bending strength of the agglomerated abrasive sample with Si added is 43.74 MPa. When the mass fraction of Si or Ti exceeds 10.0%, a large number of Si or TiO2 peaks appear in the agglomerated abrasive samples, and its bending strength decreases sharply. Compared with the agglomerated abrasive sample added with Ti, the agglomerated abrasive sample added with Si has a larger particle size and a more uniform particle size distribution. 1~2 μm abrasives can be aggregated into 5~10 μm abrasives with the addition of Al-B-Si binder with Si.
Preparation of Ni-W alloy disc for dynamic friction polishing of diamond
NIU Hao, JIN Zhuji, SHEN Yu, YANG Huipeng
2024, 44(1): 39-49. doi: 10.13394/j.cnki.jgszz.2023.0042
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To investigate the impact of bath composition and process conditions on Ni-W alloy coating, Ni-W alloy discs with low internal stress and high hardness were prepared for dynamic friction polishing of diamonds. The effects of complexing agent concentration, solution pH, and saccharin sodium concentration on the internal stress, tungsten content, hardness, and deposition rate of the coating were investigated by single experiments. Additionally, the effects of different additives on the surface leveling of the coating were also investigated. Finally, salicylaldehyde was selected as the leveling agent, and the reverse pulse current was applied to reduce the surface roughness of the coating. A Ni-W alloy disc with a hardness of HV 713 and a coating thickness of about 0.66 mm was prepared. Diamond dynamic friction polishing was carried out using these alloy discs to explore appropriate polishing process parameters. The best polishing effects were achieved at a disc speed of 8000 r/min and a pressure of 40 N, yielding a removal rate of 5.56 μm/min, a grinding ratio of 0.394, and a surface roughness (Ra) of 3.7 nm. Comparing wear parameters revealed that Ni-W alloy discs can achieve better polishing effects using traditional cast iron discs in friction chemical polishing of diamonds.
Development of multilayer brazed diamond grinding wheel for ceramic precision grinding
ZHOU Hao, XIAO Bing, ZHOU Liyong, WANG Su, HE Xu
2024, 44(1): 50-56. doi: 10.13394/j.cnki.jgszz.2023.0020
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To address the issues of low grinding efficiency and the tendency of blockage and burning of the grinding wheel when working with ceramic materials using traditional resin and electroplated diamond grinding wheels, the feasibility of using brazed diamond technology to prepare a multilayer brazed diamond grinding wheel for ceramic grinding is analyzed. Combined with the optimization of filler metal composition, a multilayer brazed diamond grinding wheel with a slotted structure is prepared, and the grinding performance of 99.9% high-purity Al2O3 ceramics is tested. The results show that resin and electroplated diamond grinding wheels suffer from low grinding efficiency and insufficient grinding life, respectively. Single-layer brazed diamond grinding wheels exhibit high grinding efficiency but have limited grinding life. Multilayer brazed diamond grinding wheels show obvious advantages in terms of grinding life while maintaining high grinding efficiency, being about 60% higher than that of single-layer brazed diamond grinding wheels. During the ceramic material grinding process, the multilayer brazed diamond grinding wheel demonstrates remarkable grinding effectiveness. Despite the limited exposed height of abrasive particles, the slotting design significantly enhances chip removal, preventing the wheel's surface from bonding and blocking with ceramic powder.
Optimization of dry compression molding process parameters for magnetic abrasive grains based on discrete element method
CUI Zihan, GAO Huimin, CHEN Yan, CHENG Haidong, HAN Bing
2024, 44(1): 57-65. doi: 10.13394/j.cnki.jgszz.2023.0075
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In order to explore the influence of various process parameters in the pressing stage of magnetic abrasive grain bodies on their forming quality, optimize the sintering preparation parameters of magnetic abrasive grains, and prepare high-quality magnetic abrasive grains, the dispersion element model of dry pressing forming of magnetic abrasive grains was established with iron-based alumina magnetic abrasive grains as the research object. By changing the pressing force, pressing mode, friction coefficient, die height-diameter ratio and other process parameters, the influence of each process parameter on the forming quality of the magnetic abrasive grain bodies was explored, and the optimization of process parameters in the pressing process was realized. The results show that the larger the pressing force, the smaller the porosity of the green body. However, if the pressing force is too large, cracks will appear on the outer surface of the green body, affecting the integrity of the surface morphology of the green body. Therefore, a pressing force of 75 to 125 MPa should be selected. The density of the green body obtained by two-way pressing is more uniform, and the mechanical properties are better. The higher the height-diameter ratio of the mold, the higher the porosity of the green body, and the smaller the axial stress of the green body. The smaller the friction coefficient between particles and between the side wall and particles, the smaller the porosity, the better the density and the better the homogeneity of the green body. When adding an appropriate amount of lubricant in the mixing stage of the magnetic abrasive particles, the friction coefficient between the magnetic abrasive particles and between the particles and the side wall of the mold can be appropriately reduced, thereby improving the quality of the abrasive body.
Calibration of emissivity value of 18CrNiMo7-6 steel and study on cylindrical grinding temperature
WANG Dong, ZHAO Rui, ZHANG Zhipeng, ZHANG Yinxia, QIAO Ruiyong
2024, 44(1): 66-72. doi: 10.13394/j.cnki.jgszz.2023.0013
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To study the variation rule of workpiece temperature concerning machining parameters in the cylindrical transverse grinding process of gear steel, 18CrNiMo7-6 gear steel was selected as the workpiece material, and a CBN grinding wheel was used as the grinding tool. An infrared thermal imaging instrument was used to detect the temperature during the grinding process. A calibration scheme of thermal emissivity value, incorporating an additional air curtain device, was proposed. The high-speed airflow generated by the air curtain was used to slow down the entry of external air into the heating furnace, preventing the oxidation of samples during calibration, thus ensuring the accuracy of the emissivity value calibrated under high-temperature conditions. Based on the test results, the influence of workpiece speed ${v_{\text{w}}}$, workpiece grinding depth per revolution ${f_{\text{a}}}$, grinding wheel grain size ${d_{\text{g}}}$, grinding wheel diameter ${d_{\text{s}}}$ and grinding width $b$ on the temperature was analyzed. The workpiece grinding depth per revolution ${f_{\text{a}}}$ was identified as the most significant factor affecting the temperature change. The empirical formula between grinding temperature and aforementioned test parameters was obtained by fitting, with an error of 9.27%. The test measurement results of grinding temperature were compared with those derived from the theory of a moving heat source, Rayleigh distribution model and dry grinding heat distribution ratio model, resulting in a deviation of 8.51%.
On line prediction of roll grinding chatter based on EMD component and wavelet packet energy entropy
ZHU Huanhuan, CHI Yulun, ZHANG Mengmeng, XIONG Li, YING Xiaoang
2024, 44(1): 73-84. doi: 10.13394/j.cnki.jgszz.2022.0198
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To address the issue of partial feature loss in the single processing method within the time-frequency domain for roll grinding chatter, a combined time-frequency domain method is proposed to process signal feature. An intelligent algorithm is used to achieve online prediction of roll grinding chatter. Firstly, the empirical mode decomposition (EMD) method is utilized to decompose the vibration sensor signals, extrating the intrinsic mode function (IMF) while removing "spurious components" to calculate time domain characteristics associated with roll grinding chatter. Then, wavelet packet energy entropy is used to solve the frequency band node energy entropy values of acoustic emission sensor signals, obtaining frequency domain features characterizing the roll grinding chatter. Finally, the time-frequency domain features after dimension reduction is substituted into the intelligent algorithm model for online prediction of the roller grinding process. The results show that the the LV-SVM model achieves an average classification accuracy of 92.75%, with an average response time of 0.776 5 s. This verifies the validity of EMD and LV-SVM based on wavelet packet energy entropy in the time-frequency domain for online prediction of roller grinding chatter.
Study on the machining performance of electric antirust grinding
CAI Zhongwei, SUN Yuli, CHEN Fayu, SHENG Yi, ZUO Dunwen
2024, 44(1): 85-91. doi: 10.13394/j.cnki.jgszz.2023.0011
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In view of the issues of environmental pollution, harm to human health, and increase in production and processing costs caused by the use of grinding fluid in traditional grinding, this paper proposes an electric antirust grinding method that utilizes tap water instead of traditional grinding fluid, The self-made electric antirust grinding system is employed to carry out research on processing performance. The differences in grinding force, grinding force ratio, grinding specific energy, grinding temperature and surface roughness between electric antirust grinding, dry grinding, and wet grinding are compared and analyzed. The results show that the average difference between electric antirust grinding and dry grinding is about 19.2%, and the average difference between electric antirust grinding and wet grinding is about 7.7%. Its processing performance surpasses dry grinding and is close to the level of wet grinding. Therefore, the electric antirust grinding method demonstrates a certain level of applicability.
Investigation on mechanism of nano-machining of single-crystal silicon carbide on non-continuous surface with diamond abrasive
WANG Yifan, TANG Wenzhi, HE Yan, GAO Xingjun, FAN Lin, SONG Shuyuan
2024, 44(1): 92-100. doi: 10.13394/j.cnki.jgszz.2023.0057
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The molecular dynamics model of nano-machining a single-crystal silicon carbide substrate with a diamond abrasive is established. The effect of scratch on the atomic removal process and the material removal mechanism of the scratch wall were studied, considering vector displacement, cutting force, crystal structure transformation, and defects. The results show that the main methods for removing atoms in the scratched area are cutting and extrusion. The wall deformation of the scratch inlet zone invloves elastic and plastic mixed deformation, while the wall deformation of the scratch outlet zone is mainly plastic deformation. Increasing machining depth improves the removal of atoms. The presence of scratches on the substrate surface reduces both tangential and normal cutting forces in the nano-machining process, with the maximum difference being about 300 nN and 600 nN, respectively. The absence of atoms in the scratch area is the main reason for the decrease in tangential forces. The crystal structure of silicon carbide atoms is transformed by the shear and extrusion of the abrasive, resulting in a large number of atoms without a complete lattice. Moreover, atoms on the substrate surface form a stable structure by bonding with neighboring atoms. The affected area of substrate temperature is mainly concentrated under the abrasive and transferred to the depth of the substrate, with a difference of about 100 K between the substrate temperature at 2 Å, 5 Å, and 8 Å nano-machining depths.
Preliminary investigation of dry tribochemical mechanical polishing of single crystal SiC substrates
XUE Mingpu, XIAO Wen, LI Zongtang, WANG Zhankui, SU Jianxiu
2024, 44(1): 101-108. doi: 10.13394/j.cnki.jgszz.2023.0052
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Aiming at the issues of low efficiency, high cost, and environmental pollution associated with silicon carbide (SiC) substrates in the polishing process, a method of tribochemical mechanical polishing of SiC substrates in the dry state (Dry Tribochemical Mechanical Polishing, DTCMP) is proposed. The effect of different process parameters (abrasive type, abrasive size, abrasive content, polishing plate speed, polishing load, solid phase oxidant content) on the polishing efficiency and surface quality of single-crystal silicon carbide substrates was investigated. The results show that diamond abrasive is more suitable for the tribochemical mechanical polishing of silicon carbide. Optimal test parameters are achieved when the abrasive size is W1, the abrasive content is 4 g, the polishing plate speed is 70 r/min, the polishing load is 20.685 kPa, and the solid phase oxidant sodium percarbonate is added at 10 g. Single-crystal 6H-SiC substrates with a surface roughness of approximately 20 nm were polished using the optimal process parameters, finanlly resulting in a surface roughness of Ra of 3.214 nm. The DTCMP method for polishing SiC substrate has less heat loss than water-based polishing method, enabling higher interface temperature and lower activation energy required for reactions. This method can realize green, efficient and high-quality polishing of SiC substrates.
Effect of abrasive vibration on microstructure evolution and material removal of SiC CMP
TANG Ailing, YUAN Zewei, TANG Meiling, WANG Ying
2024, 44(1): 109-122. doi: 10.13394/j.cnki.jgszz.2023.0053
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To address issues related to abrasion, agglomeration, and the challenges of mechanical and chemical release during chemical mechanical polishing (CMP), a vibration-assisted CMP method is employed. Molecular dynamics simulation analyze the dynamic evolution of frequency, amplitude, and indentation depth, along with the dicing speed of abrasive vibration on the workpiece's surface. It reveals the mechanism behind enhanced material removal and improved surface quality facilitated by vibration. The effectiveness and removal mechanism of vibration-assisted CMP are validated through process testing and surface composition analysis. The results show that atomic potential energy and temperature on the workpiece surface can be effectively improved by appropriately increasing vibration frequency, vibration amplitude, indentation depth, and abrasive particle cutting speed. Abrasive vibration contributes to increased atomic disorder on the workpiece surface, facilitating the participation of silicon carbide in oxidation reactions. This process results in the formation of an oxide layer, which is mechanically removed. Polishing tests and composition analyses also confirms that vibration can improve material removal rates by about 50.5% and improve the surface quality by about 25.4%.
Analysis and optimization of traveling wave vibration of five kinds of diamond circular saw blades
GAO Xianyi, ZHANG Dechen, MA Guoqing, LIU Xingdong, WANG Yubo
2024, 44(1): 123-132. doi: 10.13394/j.cnki.jgszz.2023.0008
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In order to reduce the sawing noise generated by diamond circular saw blades during stone processing, five typical diamond circular saw blades were selected for modal analysis and traveling wave vibration analysis by using Workbench software. The study explored the impact of various saw blade designs, including conventional saw blades, perforated saw blades, slit saw blades, and saw blades with nose-shaped radial grooves, holes, and interlayers, on traveling wave vibrations. The results show that the traveling wave resonance occurs in the conventional saw blades with diameters of 180 mm and 230 mm, causing strong noise. Conventional saw blades with diameters of 115 mm, 350 mm and 105 mm do not show traveling wave resonance. The δ value for the 180 mm and 230 mm saw blades is too large, which effectively presents traveling wave resonance. The δ value for the 115 mm and 350 mm saw blade is too small, which does not reduce noise very well. The δ value for the 105 mm sandwich saw blade is too large and has a significant effect on noise reduction. To avoid traveling wave resonance and enhance noise reduction, five design schemes incorporating radial grooves, raindrop holes, and damping interlayers are proposed for various blade diameters. The resulting δ values are 8.13 %, 7.21 %, 6.01 %, 6.39 %, and 7.00 %, respectively.
Wear experiment on underwater drilling of P110 steel using superhard abrasive core drill
2024, 44(1): 133-142. doi: 10.13394/j.cnki.jgszz.2023.0044
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P110 steel, renowed for its good comprehensive mechanical properties, is widely used as casing in oil and gas wells. However, it is seriously worn when using cemented carbide tools to drill it underwater. The study delves into the experimental exploration of the wear ratio of P110 steel during underwater drilling using three different kinds of super-hard abrasive grains and binders. The investigation includes tracking and observing the morphological changes of abrasive grains on the core drill's surface, along with the analysis of graphitization on the surface of diamond abrasive grains. The results show that under the same processing conditions, the end wear of the three different core drills is roughly the same. However, the side wear of the core drill using diamond abrasive particles is significantly less than that using cubic Boron Nitride (cBN) abrasive particles. Under the condition of underwater machining, the end face diamond abrasive grains will produce graphitization. Despite this, the diamond abrasive grains still maintain a certain cutting ability. The hardness of the bonding agent affects the exposure of abrasive particles, which results in the difference in the performance of the core drill under different working conditions.