scholarly journals Research on The Bonding Properties of Vitrified Bonds With Porous Diamonds and The Grinding Performance of Porous Diamond Abrasive Tools

2021 ◽  
Author(s):  
Jianwei LI ◽  
Wenjun FANG ◽  
Long WAN ◽  
Xiaopan LIU ◽  
Weida HU ◽  
...  
Keyword(s):  
Wafer Surface ◽  
Processing Efficiency ◽  
Abrasive Particles ◽  
Bonding Properties ◽  
New Type ◽  
Vitrified Bond ◽  
Abrasive Tools ◽  
Grinding Efficiency ◽  
Diamond Abrasive

Abstract Ordinary diamond presents the disadvantages of poor self-sharpening and concentrated grinding stress when it is used as an abrasive. Moreover, this kind of diamond cannot be well wetted by the vitrified bond, resulting in a lower holding force of the binder to the abrasives (i.e., the diamond is easy to detach from the binder matrix during grinding). These comprehensive factors not only reduce the surface quality of the processed workpiece, but also hinder the processing efficiency. In order to solve these problems, a new type of porous diamond with high self-sharpening properties was prepared using a thermochemical corrosion method in this study. Our results showed a great improvement in pore volume and specific surface area of the porous diamond compared with ordinary diamond abrasive particles, and the holding force and wettability of vitrified bond to the porous diamond abrasive particles were also improved. Compared with ordinary diamond abrasive tools, porous diamond abrasive tools showed a 29.6% increase in grinding efficiency, a 15.5% decreased in grinding ratio, a 27.5% reduction in workpiece surface roughness, and the scratches on the silicon wafer surface were reduced and refined.

Simulation of the metallic powder mixing process and deterministic formation of homogeneity

2021 ◽  
pp. 93-100
Author(s):  
A. V. Evseev ◽  
V. V. Preys ◽  
N. E. Proskuryakov ◽  
A. V. Lobanov
Keyword(s):  
Mathematical Model ◽  
Cross Section ◽  
Metal Layer ◽  
Mixing Process ◽  
Special Design ◽  
Powder Mixing ◽  
Abrasive Tools ◽  
The One ◽  
Diamond Abrasive

This paper describes a mathematical model simulating the process of deterministic formation of a homogeneous mixture for making diamond abrasive tools. The process of modelling was divided into a few steps: – determining the capacity of the screw feeders; – determining how far the material is thrown by the screw; – building a cross-section of the distributed material; – determining the concentration of components within the microareas of a given size and calculating the mixture quality. The model provides a detailed description of the dosing process. They are the parameters of this process that mainly determine the quality of the resultant mixtures giving them a well-organized structure so that the diamond grains were distributed in the cutting metal layer as evenly as is desired. The obtained results have been verified through a series of full-scale experiments conducted in a special-design mixer. Thanks to this process, the resultant tool has a higher performance as compared with the one produced with the help of existing techniques.

Influence of flowing parameter of magnetorheological polishing fluids (MRPFs) on the quality of processing polycrystalline glass ceramics

2011 ◽  
Vol 23 (9) ◽  
pp. 959-962 ◽  
Author(s):  
Gennadi Gorodkin ◽  
Zoya Novikova
Keyword(s):  
Glass Ceramics ◽  
Root Mean Square Roughness ◽  
Magnetorheological Finishing ◽  
Abrasive Particles ◽  
Atomic Force ◽  
Finishing Process ◽  
Surface Measurements ◽  
Magnetorheological Polishing ◽  
Diamond Abrasive

The study of rheological characteristics for two types of magnetorheological polishing fluids (MRPFs), MRPF-1 based on cerium oxide abrasive particles and MRPF-2 based on nano-diamond abrasive particles, was carried out. Experiments on polishing of a polycrystalline sitall laser mirror substrates with these fluids using magnetorheological finishing process were executed. The surface structure of the samples after the polishing was investigated with the atomic force microscope. The results of surface measurements for the samples under the study polished with both MRPF-1 and MRPF-2 fluids are reported in comparison with the existed data obtained from a regular pitch polishing method. The lowest root-mean-square roughness of 0.2–0.4 nm was obtained for the samples polished with MRPF-2.

The Research into the Effect of Conditions of Combined Electric Powered Diamond Processing on Cutting Power

2017 ◽  
Vol 736 ◽  
pp. 81-85 ◽  
Author(s):  
D.V. Lobanov ◽  
Pavel V. Arkhipov ◽  
A.S. Yanyushkin ◽  
Vadim Yu. Skeeba
Keyword(s):  
Substantial Reduction ◽  
Disk Surface ◽  
Combined Method ◽  
Cutting Power ◽  
Abrasive Tools ◽  
Mechanical Cutting ◽  
Diamond Processing ◽  
Electrochemical Grinding ◽  
Diamond Abrasive

The paper presents results of the investigation into efficiency of high-tensile composite materials grinding with metal bonded diamond abrasive tools, as well as it demonstrates the necessity to stabilize diamond disks cutting properties in order to reduce cutting power, since it is one of important economic indicators of processing. The comparative analysis of preliminary studies of various diamond processing methods reveals that the minimal cutting power is observed when using the combined method of electric powered diamond processing which includes electrochemical grinding and simultaneous continuous electrochemical dressing of the grinding disk surface. Further research into the suggested method reveals relevant mathematical dependences of metal-bonded diamond disks cutting power and electric modes. The analysis of the results shows that combining of hard-alloy surface electrochemical dissolution and electrochemical dressing of the disk surface facilitates mechanical cutting with high effectiveness and little effort. This leads to substantial reduction of cutting power as compared with other methods. The reasonable electric modes are discovered which provide the minimal cutting power without reducing efficiency of the process and quality of finished product.

TRIBOLOGICAL ASPECTS OF DIAMOND-ABRASIVE PROCESSING OF SILICON CARBIDE PLATES

2020 ◽  
Author(s):  
Sergey Bishutin ◽  
Sergey Alehin
Keyword(s):  
Silicon Carbide ◽  
Electron Microscope ◽  
Brittle Fracture ◽  
Experimental Studies ◽  
Surface Layers ◽  
Abrasive Particles ◽  
Tribological System ◽  
Diamond Abrasive ◽  
Scanning Electron

The article considers diamond-abrasive grinding of silicon carbide plates as a tribological system in order to increase the productivity and quality of this processing, as well as to substantiate the directions of its improvement. The process of removing material from the workpiece is considered as a result of abrasive wear of the silicon carbide plate on the lap with loose abrasive. Based on the hypothesis of F. Preston, a dependence was obtained for calculating the rate of removal of material removed during processing from the surface of the workpiece. The results of experimental studies of the productivity and quality of processing are presented. Attention is paid to the formation of surface layers of silicon carbide plates by introducing abrasive particles into the workpiece, causing the formation of multidirectional microcracks and the removal of material mainly as a result of brittle fracture. The results of experimental studies of the state of surface layers using a digital 3-D microscope VHX-1000E, a scanning electron microscope Jeol JSM 6610 and a profiler-profilometer "Mahr GmbH" Based on the research results, recommendations were formulated to improve the efficiency of diamond-abrasive processing of silicon carbide plates.

Experimental Research on Dry Grinding of Titanium Alloy with Graphite Coated Brazed cBN Mounted Wheel

2012 ◽  
Vol 565 ◽  
pp. 160-164 ◽  
Author(s):  
Jie Wu ◽  
Yan Chen ◽  
Yu Can Fu ◽  
Lan Ying Ding ◽  
Kai Chen
Keyword(s):  
Titanium Alloy ◽  
Cubic Boron Nitride ◽  
Solid Lubricants ◽  
Polyvinyl Butyral ◽  
Grinding Temperature ◽  
Dry Grinding ◽  
New Type ◽  
Abrasive Tools ◽  
Titanium Alloy Ti6al4v

During dry grinding of titanium alloy, workpiece burn and chips adhesion phenomenon always takes place, which influences the surface quality of the machined components. In this paper, the solid lubricants, composed of graphite and polyvinyl butyral, are covered on the brazed cubic boron nitride (cBN) mounted wheels using the ultrasonic vibration method. Test of grinding of titanium alloy Ti6Al4V is carried out with the above tools. Comparative dry grinding tests are carried out to reveal the performance this new-type abrasive tools. Experimental study shows that the grinding temperature with the cBN grinding mounted wheels covered by graphite is lower than that of non-lubricant-covered wheels; the grinding surface with the cBN mounted wheels covered by graphite is remarkably improved with a roughness Ra lower than 1.5 μm. And graphite lubricant participates in grinding operation constantly.

scholarly journals Publication by association: how the COVID-19 pandemic has shown relationships between authors and editorial board members in the field of infectious diseases

2021 ◽  
pp. bmjebm-2021-111670
Author(s):  
Clara Locher ◽  
David Moher ◽  
Ioana Alina Cristea ◽  
Florian Naudet
Keyword(s):  
Infectious Diseases ◽  
Evidence Based Medicine ◽  
Medical Community ◽  
Board Members ◽  
Evidence Based ◽  
Ripple Effect ◽  
New Type ◽  
Based Medicine

During the COVID-19 pandemic, the rush to scientific and political judgements on the merits of hydroxychloroquine was fuelled by dubious papers which may have been published because the authors were not independent from the practices of the journals in which they appeared. This example leads us to consider a new type of illegitimate publishing entity, ‘self-promotion journals’ which could be deployed to serve the instrumentalisation of productivity-based metrics, with a ripple effect on decisions about promotion, tenure and grant funding, but also on the quality of manuscripts that are disseminated to the medical community and form the foundation of evidence-based medicine.

Study on the Behavior of the Cast-Iron Bonded Grinding Wheel to Machining Properties of Hard and Brittle Materials

2007 ◽  
Vol 24-25 ◽  
pp. 229-232
Author(s):  
S.L. Ma ◽  
Wei Li ◽  
Cong Rong Zhu ◽  
J. Zhang ◽  
H.C. Ye
Keyword(s):  
Grain Size ◽  
Cast Iron ◽  
Tungsten Carbide ◽  
Surface Quality ◽  
Ground Surface ◽  
Grinding Wheel ◽  
Different Grain Size ◽  
Grinding Efficiency ◽  
Machining Properties

Tungsten carbide which is a hard and brittle material was ground by cast-iron bonded diamond wheel with ELID (Electrolytic In-Process Dressing) technique, for the purpose of getting high efficiency, super-precision machining. Three kinds of cast-iron bonded diamond wheels with different grain size were adopted to get different grinding efficiency and surface quality of workpieces. The grinding properties of cast-iron bonded grinding wheels with different grain size and the ground surface quality of tungsten carbide are discussed in this paper. The experiment results indicate that, under the same feeding amount, the grinding efficiency of the wheel with bigger grain size is higher, and it could make the dimension accuracy of the workpiece controllable, but the wheel with smaller grain size could get better ground surface quality. The two grinding phases are decided by the ratio between the size of abrasive grain and the thickness of the oxide layer on the grinding wheel.

scholarly journals Development of a New Type Saw Wire Fixed Diamond Abrasive Grains with Solder and Ni Electroplating and Its Application to Slicing of Silicon and Sapphire Ingots

2015 ◽  
Vol 62 (12) ◽  
pp. 559-566 ◽  
Author(s):  
Atsushi NAKAHIRA ◽  
Atsushi OKIMURA ◽  
Yasuhito HAGIWARA ◽  
Takashi NAKANISHI ◽  
Masaru YOKOTA ◽  
...  
Keyword(s):  
Abrasive Grains ◽  
New Type ◽  
Diamond Abrasive

Observation in the Surface Roughness of Silicon Wafer during Semi-Fixed Abrasive Machining with Large Grains

2009 ◽  
Vol 69-70 ◽  
pp. 253-257
Author(s):  
Ping Zhao ◽  
Jia Jie Chen ◽  
Fan Yang ◽  
K.F. Tang ◽  
Ju Long Yuan ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Surface Quality ◽  
Silicon Wafer ◽  
Processing Parameters ◽  
Wafer Surface ◽  
Abrasive Machining ◽  
Fixed Abrasive ◽  
Is Failure ◽  
Better Than

Semi-fixed abrasive is a novel abrasive. It has a ‘trap’ effect on the hard large grains that can prevent defect effectively on the surface of the workpiece which is caused by large grains. In this paper, some relevant experiments towards silicon wafers are carried out under the different processing parameters on the semi-fixed abrasive plates, and 180# SiC is used as large grains. The processed workpieces’ surface roughness Rv are measured. The experimental results show that the surface quality of wafer will be worse because of higher load and faster rotating velocity. And it can make a conclusion that the higher proportion of bond of the plate, the weaker of the ‘trap’ effect it has. Furthermore the wet environment is better than dry for the wafer surface in machining. The practice shows that the ‘trap’ effect is failure when the workpiece is machined by abrasive plate which is 4.5wt% proportion of bond in dry lapping.

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