The Grinding of Workpiece Materials Exhibiting High Adhesion. Part 2: Forces

1981 ◽  
Vol 103 (2) ◽  
pp. 156-164 ◽  
Author(s):  
S. Yossifon ◽  
C. Rubenstein
Keyword(s):  
Surface Area ◽  
Large Scale ◽  
Metal Contact ◽  
Wheel Surface ◽  
Workpiece Material ◽  
Large Measure ◽  
Scale Adhesion ◽  
High Adhesion ◽  
Metal Metal ◽  
Force Components

Equations expressing the dependence of the force components on grinding parameters and on the fraction of the wheel surface area over which workpiece material adheres during the grinding of workpiece materials which exhibit high adhesion are derived. These are shown to express the experimentally observed relations between the force components for each of the three grinding mechanisms which occur when this class of workpiece is ground. When large scale adhesion of workpiece material to the wheel surface occurs and more than five percent of the wheel surface is occupied by transferred material, the force components arise in large measure as a result of the forces generated through this metal/metal contact.

The Grinding of Workpieces Exhibiting High Adhesion. Part 1: Mechanisms

1981 ◽  
Vol 103 (2) ◽  
pp. 144-155 ◽  
Author(s):  
S. Yossifon ◽  
C. Rubenstein
Keyword(s):  
Stainless Steel ◽  
Mild Steel ◽  
Large Scale ◽  
Argon Atmosphere ◽  
Grinding Wheel ◽  
Workpiece Material ◽  
Degree Of Protection ◽  
The Third ◽  
High Adhesion ◽  
First Results

Three distinct grinding mechanisms have been found to occur when 304 L stainless steel is ground by alumina wheels. The first results in the grits becoming worn by attritious wear and occurs when temperatures in the grinding zone are relatively high, the second occurs at lower grinding temperatures and results in isolated, tiny areas of workpiece material adhering to grits while the third becomes manifest at relatively low grinding temperatures and results in areas of the wheel, large in comparison to the size of a grit, being covered by adherent workpiece material. Previous proposals advanced to explain metal build-up on the grinding wheel are shown to be inadequate and the phenomenon of large-scale metal transfer to the grinding wheel is shown to be related to the ductility of the workpiece along with the degree of protection conferred by the oxide of the workpiece material. This explanation is confirmed by grinding experiments performed on a series of oxide-resistant workpieces ground in air and, in particular, by the grinding of mild steel in an argon atmosphere under which conditions large-scale transfer of workpiece material to the wheel occurred.

The entrainment interface

1972 ◽  
Vol 51 (1) ◽  
pp. 97-118 ◽  
Author(s):  
O. M. Phillips
Keyword(s):  
Velocity Field ◽  
Turbulent Flow ◽  
Surface Area ◽  
Large Scale ◽  
Positive Curvature ◽  
Lagrangian Description ◽  
Eulerian Description ◽  
Entrainment Process ◽  
Necessary And Sufficient ◽  
Small Disturbances

A theory is developed to describe the evolution of the entrainment interface in turbulent flow, in which the surface is convoluted by the large-scale eddies of the motion and at the same time advances relative to the fluid as a result of the micro-scale entrainment process. A pseudo-Lagrangian description of the process indicates that the interface is characterized by the appearance of ‘billows’ of negative curvature, over which surface area is, on average, being generated, separated by re-entrant wedges (lines of very large positive curvature) where surface area is consumed. An alternative Eulerian description allows calculation of the development of the interfacial configuration when the velocity field is prescribed. Several examples are considered in which the prescribed velocity field in the z direction is of the general form w = Wf(x – Ut), where the maximum value of the function f is unity. These indicate the importance of leading points on the surface which are such that small disturbances in the vicinity will move away from the point in all directions. The necessary and sufficient condition for the existence of one or more leading points on the surface is that U [les ] V, the speed of advance of an element of the surface relative to the fluid element at the same point. The existence of leading points is accompanied by the appearance of line discontinuities in the surface slope re-entrant wedges, In these circumstances, the overall speed of advance of the convoluted surface is found to be W + (V2 – U2)½, where W is the maximum outwards velocity in the region; this result is independent of the distribution f.When the speed U with which an ‘eddy’ moves relative to the outside fluid is greater than the speed of advance V of an element of the front, the interface develops neither leading points nor discontinuities in slope; the amplitude of the surface convolutions and the overall entrainment speed are both reduced greatly. In a turbulent flow, therefore, the large-scale motions influencing entrainment are primarily those that move slowly relative to the outside fluid (with relative speed less than V). The experimental results of Kovasznay, Kibens & Blackwelder (1970) are reviewed in the light of these conclusions. It appears that in their experiments the entrainment speed V is of the order fifteen times the Kolmogorov velocity, the large constant of proportionality being apparently the result of augmentation by micro-convolutions of the interface associated with small and meso-scale eddies of the turbulence.

Facile and large-scale synthesis of poly(m-phenylenediamine) nanobelts with high surface area and superior dye adsorption ability

RSC Advances ◽  
2014 ◽  
Vol 4 (85) ◽  
pp. 45244-45250 ◽  
Author(s):  
Yun Meng ◽  
Liyuan Zhang ◽  
Liyuan Chai ◽  
Wanting Yu ◽  
Ting Wang ◽  
...  
Keyword(s):  
Surface Area ◽  
Large Scale ◽  
High Surface ◽  
High Surface Area ◽  
Dye Adsorption ◽  
High Adsorption ◽  
Adsorption Ability ◽  
Adsorption Performance ◽  
Large Scale Synthesis

PmPD nanobelts with high adsorption performance have been synthesized by using CTAP as oxidants.

scholarly journals A New Method of Manufacturing Thin-Walled Tube Made of AZ61 Magnesium Alloy Including Direct Extrusion And Corrugated Equal Channel Angular Extrusion

2021 ◽  
Author(s):  
H-J Hu ◽  
Ou Zhang ◽  
Gang Hu ◽  
Hui Zhao ◽  
Zhongwen OU
Keyword(s):  
Plastic Deformation ◽  
Magnesium Alloy ◽  
Large Scale ◽  
Equal Channel Angular Extrusion ◽  
Process Conditions ◽  
Workpiece Material ◽  
Plastic Deformation Behavior ◽  
Angular Extrusion ◽  
Thin Walled Tube ◽  
Thin Walled

Abstract Due to demand of strong toughness of thin walled tube, and good secondary forming properties and high-precision dimension, New plastic forming method should be researched to achieve a complete filling, uniform deformation and microstructure evolution during forming process.To obtain the deformation mechanisms of a new composite extrusion for thin walled tube fabricated by tube corrugated equal channel angular extrusion has been researched which is shorten as “TC-ECAE” in this paper. Finite element DEFORMTM-3D software to investigate the plastic deformation behavior of magnesium billet during TC-ECAE process has been employed. Computed parameters including workpiece material characteristics and process conditions have been taken into consideration. The pridictions of strains distributions and damage distributions and effective stress distributions and flow velocities distributions and microstructures evolutions have been explored. The results proved that the TC-ECAE process is a forming method for magnesium alloy tube which is suitable for large scale industrial application. The TC-ECAE process would cause serve plastic deformation and improve the dynamic recrystallization of magnesium alloy during TC-ECAE process.

Three-Dimensional MoS2/Graphene Hybrid Aerogel as Free-Standing, High-Performance Electrode for Supercapacitor

NANO ◽  
2020 ◽  
Vol 15 (05) ◽  
pp. 2050062
Author(s):  
Zhaolei Meng ◽  
Xiaojian He ◽  
Song Han ◽  
Zijian Hu
Keyword(s):  
Porous Structure ◽  
Surface Area ◽  
High Performance ◽  
Large Scale ◽  
Low Cost ◽  
Hydrothermal Process ◽  
Three Dimensional ◽  
Rate Capability ◽  
Free Standing ◽  
Hybrid Aerogel

Carbon materials are generally employed as supercapacitor electrodes due to their low- cost, high-chemical stability and environmental friendliness. However, the design of carbon structures with large surface area and controllable porous structure remains a daunt challenge. In this work, a three-dimensional (3D) hybrid aerogel with different contents of MoS2 nanosheets in 3D graphene aerogel (MoS2-GA) was synthesized through a facial hydrothermal process. The influences of MoS2 content on microstructure and subsequently on electrochemical properties of MoS2-GA are systematically investigated and an optimized mass ratio with MoS2: GA of 1:2 is chosen to achieve high mechanical robustness and outstanding electrochemical performance in the hybrid structure. Due to the large specific surface area, porous structure and continuous charge transfer network, such MoS2-GA electrodes exhibit high specific capacitance, good rate capability and excellent cyclic stability, showing great potential in large-scale and low-cost fabrication of high-performance supercapacitors.

scholarly journals Quantifying the Polygenic Architecture of the Human Cerebral Cortex: Extensive Genetic Overlap between Cortical Thickness and Surface Area

2020 ◽  
Vol 30 (10) ◽  
pp. 5597-5603 ◽  
Author(s):  
Dennis van der Meer ◽  
Oleksandr Frei ◽  
Tobias Kaufmann ◽  
Chi-Hua Chen ◽  
Wesley K Thompson ◽  
...  
Keyword(s):  
Surface Area ◽  
Cortical Thickness ◽  
Large Scale ◽  
Gaussian Mixture ◽  
Total Surface Area ◽  
Brain Morphology ◽  
Genetic Determinants ◽  
Genetic Predictors ◽  
Genetic Overlap ◽  
Causal Variants

Abstract The thickness of the cerebral cortical sheet and its surface area are highly heritable traits thought to have largely distinct polygenic architectures. Despite large-scale efforts, the majority of their genetic determinants remain unknown. Our ability to identify causal genetic variants can be improved by employing brain measures that better map onto the biology we seek to understand. Such measures may have fewer variants but with larger effects, that is, lower polygenicity and higher discoverability. Using Gaussian mixture modeling, we estimated the number of causal variants shared between mean cortical thickness and total surface area, as well as the polygenicity and discoverability of regional measures. We made use of UK Biobank data from 30 880 healthy White European individuals (mean age 64.3, standard deviation 7.5, 52.1% female). We found large genetic overlap between total surface area and mean thickness, sharing 4016 out of 7941 causal variants. Regional surface area was more discoverable (P = 2.6 × 10−6) and less polygenic (P = 0.004) than regional thickness measures. These findings may serve as a roadmap for improved future GWAS studies; knowledge of which measures are most discoverable may be used to boost identification of genetic predictors and thereby gain a better understanding of brain morphology.

Directed self-assembly of dual metal ions with ligands: towards the synthesis of noble metal/metal oxide composites with controlled facets

2018 ◽  
Vol 54 (16) ◽  
pp. 2044-2047 ◽  
Author(s):  
Fang Cui ◽  
Jiajia Zhang ◽  
Qing Shao ◽  
Linxu Xu ◽  
Xinzi Pan ◽  
...  
Keyword(s):  
Metal Oxide ◽  
Metal Ions ◽  
Noble Metal ◽  
Self Assembly ◽  
Large Scale ◽  
Assembly Strategy ◽  
Metal Metal ◽  
Exposed Facet ◽  
Dual Metal ◽  
Oxide Composites

Despite numerous reports on noble metal/metal oxide composites, the control of the exposed facet is still a great challenge. Here, the large-scale synthesis of noble metal/metal oxide spheres with controlled facets is enabled by making use of a bottom-up self-assembly strategy.

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