Abstract: Solid-state nanopores have drawn the interest of numerous researchers due to their excellent mechanical properties, stability, and shape control, which have demonstrated tremendous potential in gene detection, protein detection, energy conversion, material separation, and water purification. And shape-controlled and efficient solid-state nanopore manufacturing technology is the prerequisite for the application of solid-state nanopore. At present, the high energy beam manufacturing method has the advantages of high efficiency, high precision and high manufacturing controllability among the conventional solid state nanopore manufacturing methods. This paper provides an overview of four solid state nanopore fabrication methods including high energy electron beam, focused ion beam, laser etching and ion track etching and their fundamental principles. The benefits and drawbacks of these methods, as well as their feasibility for large-scale controlled fabrication are discussed.
Under the background of the comprehensive implementation of the National Carbon Peak Carbon Neutralization Action, the superhard material industry energy consumption research was carried out. It aims to promote the superhard material industry to make new contributions to the green, low-carbon and high-quality development of the country. The energy consumption data of superhard material and product enterprises were summarized and analyzed, and the energy consumption of typical products in the inorganic non-metallic field was compared. The results show that from 2019 to 2021, the energy consumption per unit of gross industrial output value of superhard materials is 0.11, 0.10, and 0.08 tce/10 000¥; and that the energy consumption per unit of gross industrial output value of superhard materials products is 0.08, 0.07 and 0.05 tce/10 000¥ respectively. The reduction rate of energy consumption in superhard materials industry is far greater than the reduction percentage of national GDP energy consumption index. Compared with the typical products in the inorganic non-metallic field such as cement, ceramics and ordinary abrasives, the energy consumption in the superhard material industry is at a lower level. Finally, the paper makes suggestions on superhard industry policies and enterprise carbon reduction.
Abstract: PDC bit has become the preferred type of drill bits in the field of oil and gas exploration. The ever-increasing performance requirements of PDC bits, especially the drilling efficiency, have brought great challenges to the drill bits. The improvement of the drill bit working face structure is crucial to the efficient rock breaking of PDC bits. However, this brings great difficulties to the manufacture of drill bits. 3D printing technology is a new type of rapid prototyping technology which has the advantages of manufacturing any complex shape structures, personalized customization and creative design. It is an inevitable trend to apply 3D printing technology to the production of PDC bits. This paper focuses on the basic principles of 3D printing technologies currently used to prepare PDC bits, including photolithography (SLA), fused deposition (FDM), selective laser sintering (SLS), selective laser melting (SLM) and three dimensional printing (3DP), etc. And then it summarizes the research progress of the existing 3D printing technology in the manufacture of PDC and PDC bits, and gives an outlook on the development of 3D printing PDC and PDC bits in the future.
Abstract: The characteristics of rock cuttings are important factors affecting their annulus upward return. The indoor micro drilling experiment was carried out to study the characteristics of rock cuttings produced by impregnated diamond bit breaking granite. It is found that the rock cuttings produced by broken rock show single peak distribution in a certain range, and that the distribution is related to drilling parameters such as WOB and rotating speed. To some extent, the peak particle size of cuttings increases with the increase of WOB and decreases with the increase of rotating speed. Further microscopic observation on the morphological characteristics of rock cuttings shows that the particle size of rock cuttings is basically smaller than that of original minerals, and that most of the rock cuttings are of single mineral composition. Further observation on the morphology characteristics of rock cuttings and rock surface shows that the impregnated diamond bit drilling granite is mainly in the form of volume crushing, supplemented by plastic micro cutting.
Abstract: FeCoCu pre-alloy powder was added into tungsten carbide matrix to find out the influence law of FeCoCu content and sintering temperature on matrix performance, aiming to improve the adaptability between bit matrix wear resistance and formation abradability and to enhance the self-sharpening ability of the bits. The ratio of FeCoCu to WC powder was adjusted and the matrix were sintered at different sintering temperatures. The test results show that with the increase of FeCoCu content, the performances of the matrix decrease, namely relative density, hardness, bending strength and wear resistance. It is also found that the sintering temperature has a significant impact on the wear resistance of the matrix, the maximum change of which reaches 310%; but it has small impact on other performances such as relative density, hardness and bending strength. In conclusion, the coupling effect of FeCoCu pre-alloy and sintering temperature provides a wide adjusting range for the wear resistance of the bits, whose adaptability to formations could be improved through the two-way adjustment of the two parameters.
Abstract: PDC bits have been working in a worn state for a long time. To explore its cutting performance and avoid premature failure of the bit, this paper analyzes the load on the worn teeth and the drilling characteristics of the bit through single tooth cutting experiment and full-scale wear bit drilling experiment. The result shows that the worn teeth bear larger load compared with the new teeth, and the phenomenon of blunt rubbing is common in the process of rock cutting after the cutting teeth are “rounded”. Under the same depth, the greater the wear height is, the more obvious the load fluctuation appears. Through the full-scale bit drilling experiment, it is found that compared with the new bit, the worn bit can produce a smoother bottom hole, which is not beneficial for PDC bits' teeth intruding into the rock. With the increase of wear degree, the mechanical rate of penetration decreases and the mechanical specific energy increases. When the wear is greater than 3 mm, the mechanical specific energy and mechanical rate of penetration are not sensitive to weight on bit. With the increase of wear degree, the vibration degree of the bit decreases, and there is little difference in the radial acceleration value of the bit regardless of the wear degree.
Abstract: In order to obtain better drilling effect in the conglomerate layer, it is necessary to optimize the tooth shape and caster angle of PDC bit for the conglomerate layer. Single tooth rock breaking experiments are conducted on ordinary plane teeth, conical teeth and axe teeth in the conglomerate rock sample. Then the simulation analysis is conducted on the optimized axe teeth to optimize the optimal tooth surface angle of axe teeth. And the cutting simulation is conducted with ordinary plane teeth to verify the experimental results. The results show that the axe tooth has the highest cutting efficiency and the most stable stress in the conglomerate layer; the drilling effect of 140° axe tooth in conglomerate is better; and the cutting efficiency is the highest when 140° axe teeth are matched with 30° caster angle. Therefore, when optimizing the cutting tools for the conglomerate layer, it is necessary to reasonably select the teeth according to the formation characteristics. When applying axe teeth, in order to achieve high cutting efficiency, it is necessary to optimize the combination of tooth surface angle and caster angle.
The direct ink writing (DIW) technology of slurry is a 3D printing technology based on slurry extrusion. It has the advantages of low energy consumption, low cost, fast printing speed and no structural design restrictions. On the basis of summarizing the advantages of the application of DIW technology to ceramic-based diamond tools, key steps in the application process, such as the raw material selection, the slurry preparation, the printing suitability, the degreasing and the sintering process, are discussed and the powder agglomeration problem that needs to be given attention to in the slurry preparation process is pointed out. At the same time, some research examples of DIW manufacturing process are analyzed. Finally, it points out the key problems that should be solved in DIW manufacturing ceramic-based diamond tools.
Abstract: To study the microstructure and the thermodynamic properties of lubricants, as well as their effects on the structure and mechanical property of wet-forming or sintered materials, different lubrication release agents are added into metal abrasive tools which are fabricated with wet forming and degreasing sintering process. Synchronous thermal analyzer, scanning electron microscope and X-ray diffractometer are used to analyze the performance of the samples. The results indicate that the the residual degreasing amount of zinc stearate is about 20.00% while that of HV1 lubricant is only 3.00%. The residue of zinc stearate is the aggregate of nanometer particles and the counterpart of HV1 is ～10 μm interlocking irregular particles. Both HV1 and zinc stearate lubricant have better release effect on wet molding. However, adding HV1 or zinc stearate lubricant reduces the density of the compact by 0.5% or 5%, the density of sintered samples by 1.5% or 3.4%, and the bending strength by 4.4% or 9.1%, respectively. Compared with zinc stearate lubricant, HV1 has good demoulding effect and less influence on the properties of the compact and the sample, which is more suitable for metal abrasives of wet forming applications.
Abstract: In order to integrate various processes in composite dressing method more systematically and improve dressing efficiency of forming grinding wheel, a CAM system was developed by combining self-developed laser and mechanical composite dressing equipment. According to different grinding wheel section shapes, the system can automatically plan dressing trajectory under multi-process and multi-dressing strategy, calculate planar three-axis linkage dressing tool path, automatically generate machining code, and design visual interface to simulate machining process. The dressing experiment of bronze bonded diamond grinding wheel was completed. The results show that the system can generate laser rough repair, semi-finishing repair and mechanical finishing machining program without collision and overcutting, and greatly improve the programming efficiency of composite dressing method. After dressing, the grinding wheel profile error was within 9.1 µm and the runout error was 6.1 µm.
Abstract: The thin-wall shell parts manufactured by quartz fiber reinforced ceramic matrix composites have low machining efficiency and bigger cutting force, which can easily lead to broken parts and bad surface roughness not meeting the requirements. To solve these problems and seek feasible cutting tool and process parameters, based on the principles of micro cutting, the feasibility study of SiO2f/SiO2 was carried out by using the developed integral multi-edge PCD tool and electroplated diamond grinding tool. The experimental results show that the integral multi-edge PCD tool, designed based on the micro-edge cutting principle, can achieve a large cutting depth and a large cutting efficiency, but its cutting force is relatively huge. Compared with the integral multi-edge PCD tool, electroplated diamond grinding tool have lower cutting force, better surface quality and lower surface roughness.
The processing damages such as delamination and tearing were easily produced during the drilling of the sleeve holes of GFRP, which were directly related to the axial drilling force. In order to improve the quality of GFRP hole-making, a new diamond thin-wall trepanning tool was adopted; and combined with the low-frequency axial vibration machining technology, the kinematic model and the dynamic model of single abrasive particle were established. The variation law of axial force in GFRP hole-making was experimentally studied. The burning probability and the automatic blanking rate of trepanning tool were analyzed. The results show that the instantaneous feed rate and the axial force of low-frequency vibration drilling are larger than that of conventional drilling. Besides, the axial force increases with the increase of amplitude, and the axial forces of the low-frequency vibration drilling and the conventional drilling increase with the increase of feed speed and decrease with the increase of spindle speed. At the same time, the abrasive particles participate in drilling intermittently, which greatly reduces the burning probability of the trepanning drill and improves its automatic blanking rate. The automatic blanking rate during low-frequency vibration drilling is up to 88.24%, which can realize the continuous batch hole-making of GFRP.
Six kinds of diamond electroplated bits, whose diameters were 0.280～0.440 mm and the basic particle sizes of diamond were 20～30, 36～54 and 63～75 μm, were used to drill micro holes of three-dimensional needle-punched felt-based C/SiC composite materials. The optimum processing parameters of the six kinds of bits were tested, and the influences of the process parameters, the diamond basic particle size and the bit diameter on the processing quality and efficiency of micro holes were analyzed. The results show that at the same drilling speed, the lower the feed speed is, the better the micro-hole quality is. The larger the basic particle size of electroplated diamond grains on the bit is, the higher the drilling efficiency is. In the six kinds of bits, the better drilling performances can be obtained by electroplating 63～75 μm abrasive particles on 0.300 mm diameter substrate and 36～54 μm abrasive particles on 0.200 mm diameter substrate.
In order to improve the efficiency and quality of diamond wire saw cutting and meet the demand of real-time monitoring of saw wire wear, a detection algorithm based on improved YOLOv5 was proposed. The algorithm combined coordinate attention mechanism and BiFPN module on the basis of YOLOv5. The detection accuracy, recall rate and average accuracy were increased by 1.7%, 3.7% and 3.2% respectively. Abrasive particles with different wear degrees can be effectively detected. Besides, the DeepSORT multi-target tracking algorithm was connected to set up a virtual detection line, count the number of abrasive particles with different wear degrees, and monitor the wear of diamond saw wire.
To investigate the influence of the installation angle of specimens on the finishing effect of the cross hole connecting part, vibration finishing technology of cross hole specimens is simulated and analyzed based on the discrete element method. The results show that the machining uniformity of the cross hole connecting part is better and the minimum wear depth of the connecting part is greater when the installation angle is 45° compared with that under 0° and 90°. Based on the single factor test method, ZLC100 horizontal vibration finishing equipment is used to carry out finishing test on cross hole specimens with different installation angles. The results show that the burr removal effect of the cross hole connecting part is better and the fillet effect of the cross hole connecting part is more obvious when the installation angle is 45° compared with that under 0° and 90°. The measured fillet radius is within the range of 0.3～0.7 mm at the connecting part and the normalized surface roughness Ra* has a significant downward trend in 8 regions of the inner surface of large and small holes when the installation angle is 45°. The experimental results are consistent with the simulation results.
Abstract: The internal multi cooling channels of aviation turbine blades, mostly processed by lost foam casting, have high surface roughness, low cooling efficiency, small internal channel section and S-shaped bending and narrow distribution, and are not easy to polish. The Polyflow software is used to simulate the internal cooling channel of blade, and the changes of internal pressure field and velocity field are studied. The workpiece with S-shaped inner runner was machined and tested to study the variation law of surface roughness and material removal in four typical areas of the workpiece. The results show that the pressure drop decreases along the flow direction and the velocity decreases from the center of the channel to the wall; under the same test conditions, the surface roughness at the turning of S-shaped channel is lower than that at the straight channel; there is pressure loss along the flow path, and the material removal in area A is 4～5 times greater than that in area D.
Abstract: In order to explore the surface grinding quality and subsurface damage law of the grinding depth on the diamond material, the model of diamond workpiece ground by multi grits is established by molecular dynamics (MD) method. The effect of different grinding depths on the grinding force, the grinding quality of the surface and the subsurface damage characteristics of the material is studied. The analysis shows that the chip atoms accumulated between the grits have the effect of micro-grinding, and that the amorphous area between the grits is gradually fused together under the action of grinding to form the processing surface of the diamond material. The grinding depths of h = 0.36 nm, 0.71 nm, 1.07 nm and 1.43 nm are used respectively. The springback of diamond crystal material can be effectively inhibited only when the grinding depth exceeds 0.71 nm. However, increasing the grinding depth will increase the accumulation of atoms on the surface of diamond workpiece, which cannot improve the grinding quality. At the same time, the increase of the grinding depth will intensify the subsurface damage to the diamond workpiece. The subsurface damage of the material with a grinding depth below 0.71 nm is small and stable. However, the damage increases rapidly when the grinding depth exceeds 0.71 nm and large-depth damage over 3 nm appears on the subsurface.
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