Mechanics of Polishing

1998 ◽  
Vol 65 (2) ◽  
pp. 410-416 ◽  
Author(s):  
V. H. Bulsara ◽  
Y. Ahn ◽  
S. Chandrasekar ◽  
T. N. Farris
Keyword(s):  
Particle Size ◽  
Material Removal ◽  
Indentation Hardness ◽  
Particle Sizes ◽  
Size Distributions ◽  
Polishing Process ◽  
Average Force ◽  
Abrasive Particles ◽  
Effect Of Particle Size ◽  
Micro Indentation

A model has been developed to determine the number and sizes of abrasive particles involved in material removal in polishing, and the forces acting on these particles. The effect of particle size on these parameters has been simulated for a range of particle sizes. It is shown that when polishing with abrasive powders having relatively broad size distributions, only a very small percentage of the particles are involved in material removal. Further, these particles are comprised of the larger particles occurring in the tail end of the particle size distribution. The average force on a particle is found to be in the range of 5–200 mN under typical polishing conditions, which is of the order of loads used in micro-indentation hardness testing. These predictions of the model are consistent with observations pertaining to polished surfaces and the polishing process.

Effect of Particle Size on the Oil Yield and Catechin Compound Using Accelerated Solvent Extraction

2013 ◽  
Vol 60 (1) ◽  
Author(s):  
Mohd Azizi Che Yunus ◽  
Manzurudin Hasan ◽  
Norasikin Othman ◽  
Siti Hamidah Mohd-Setapar ◽  
Liza Md.-Salleh ◽  
...  
Keyword(s):  
Particle Size ◽  
Solvent Extraction ◽  
Accelerated Solvent Extraction ◽  
Extraction Time ◽  
Oil Yield ◽  
Particle Sizes ◽  
Experimental Range ◽  
Areca Catechu ◽  
Effect Of Particle Size ◽  
Extraction Cycle

Kajian ini bertujuan untuk mengkaji kesan saiz zarah ke atas pengekstrakan sebatian catechin daripada biji Areca catechu L. dengan menggunakan Pengekstrakan Pelarut Terpecut (PPT). Saiz zarah biji Areca catechu dipelbagaikan dari 75 μm sehingga 500 μm. Pengekstrakan telah dijalankan padaparameter tetap iaitu suhu (140oC), tekanan (1500 psi), masa (10 minit), isipadu semburan (60%) dan satu kitaran pengekstrakan, masing-masing. Hasil minyak peratusan yang lebih tinggi adalah 300 mg minyak / gram sampel (30.00% pati minyak) ditemui pada 125 μm. Walaubagaimanapun, kandungan catechin dalam pati minyak hanya 0.0375 mg catechin / gram sampel. Saiz zarah yang terbaik dalam julat uji kaji ini telah dikenal pasti pada 500 μm yang memberikan kandungan catechin yang tinggi iaitu 0.0515 mg catechin / gram sampel dari 247.5 mg minyak / gram sampel (24.75% pati minyak). Kata kunci: Saiz zarah; catechin; LC-MS-TOF; pengekstrakan pelarut terpecut The purpose of this work is to investigate the effects of particle size on the extraction of catechincompound from Areca catechu L. seeds by using Accelerated Solvent Extraction (ASE). The particle sizes of Areca catechu L. seeds are varied from 75 µm until 500 µm. The extraction is conducted at fixed parameters which are temperature (140oC), pressure (1500 psi), extraction time (10 minutes), flush volume (60%) and the static cycle is done for 1 extraction cycle respectively. Higher percentage oil yield of 300mg oil/gram of sample (30.00% oil yield) is found at 125 µm. However, the amount of catechin in oil yields is only 0.0375 mg of catechin/gram of sample. The best of particle size within the experimental range has been identified at 500 µm which gives a high content of catechin with 0.0515 mg Catechin/gram of sample from 247.5 mg oil/gram of sample (24.75% oil yield). Keywords: Particle size; catechin; LC-MS-TOF; accelerated solvent extraction

scholarly journals A Gentle Sedimentation Process for Size-Selecting Porous Silicon Microparticles to Be Used for Drug Delivery Via Fine Gauge Needle Administration

Silicon ◽  
2020 ◽  
Author(s):  
Elida Nekovic ◽  
Catherine J. Storey ◽  
Andre Kaplan ◽  
Wolfgang Theis ◽  
Leigh T. Canham
Keyword(s):  
Drug Delivery ◽  
Particle Size ◽  
Porous Silicon ◽  
Particle Sizes ◽  
Size Distributions ◽  
Particle Agglomeration ◽  
Gas Generation ◽  
Intravitreal Drug Delivery ◽  
Median Diameter ◽  
Experimental Values

AbstractBiodegradable porous silicon (pSi) particles are under development for drug delivery applications. The optimum particle size very much depends on medical use, and microparticles can outperform nanoparticles in specific instances. Here we demonstrate the ability of sedimentation to size-select ultrasmall (1–10 μm) nanoporous microparticles in common solvents. Size tunability is quantified for 1–24 h of sedimentation. Experimental values of settling times in ethanol and water are compared to those calculated using Stokes’ Law. Differences can arise due to particle agglomeration, internal gas generation and incomplete wetting. Air-dried and supercritically-dried pSi powders are shown to have, for example, their median diameter d (0.5) particle sizes reduced from 13 to 1 μm and from 20 to 3 μm, using sedimentation times of 6 and 2 h respectively. Such filtered microparticles also have much narrower size distributions and are hence suitable for administration in 27 gauge microneedles, commonly used in intravitreal drug delivery.

The use of hollow sphere pigments as strength additives in paper and paperboard coatings—Part 1: The predictive nature of packing models on coating properties

TAPPI Journal ◽  
2020 ◽  
Vol 19 (11) ◽  
pp. 585-593
Author(s):  
ETHAN GLOR ◽  
BRIAN EINSLA ◽  
JOHN ROPER ◽  
JIAN YANG ◽  
VALERIY GINZBURG
Keyword(s):  
Particle Size ◽  
Hollow Sphere ◽  
Particle Packing ◽  
Particle Sizes ◽  
Coating Properties ◽  
Ideal System ◽  
Thermal Paper ◽  
Effect Of Particle Size ◽  
Low Levels ◽  
Better Than

Hollow sphere pigments (HSPs) are widely used at low levels in coated paper to increase coating bulk and to provide gloss to the final sheet. However, HSPs also provide an ideal system through which one can examine the effect of pigment size and particle packing within a coating due to their unimodal and tunable particle sizes. The work presented in Part 1 and Part 2 of this study will discuss the use of blends of traditional inorganic pigments and HSPs in coating formulations across a variety of applications for improved coating strength. Part 1 of this study focuses on the theory of bimodal spherical packing and demonstrates the predictive nature of packing models on the properties of coating systems containing HSPs of two different sizes. This study also examines conditions where the model fails by examining the effect of particle size on coating strength in sytems like thermal paper basecoats where the non-HSP component has a broad particle size distribution, and how these surprising trends can be used to generate better-than-expected thermal printing performance in systems with low HSP/clay ratios. Part 2 of this study focuses on the incorporation of HSPs of different particle sizes into paperboard formulations to affect coating strength and opacity.

Material Removal and Application by Chemical Impact Reaction in Nano-Abrasive Jet Polishing

2013 ◽  
Vol 631-632 ◽  
pp. 550-555
Author(s):  
Wen Qiang Peng ◽  
Sheng Yi Li ◽  
Chao Liang Guan ◽  
Xin Min Shen
Keyword(s):  
Material Removal ◽  
Abrasive Particle ◽  
Precision Machining ◽  
Optical Surface ◽  
Polishing Process ◽  
Abrasive Particles ◽  
Mechanical Process ◽  
Abrasive Jet Polishing ◽  
Ultra Precision ◽  
Machining Properties

Material removed by mechanical process inevitably causes surface or subsurface damage containing cracks, plastic scratch, residual stress or dislocations. In nano-abrasive jet polishing (NAJP) the material is removed by chemical impact reaction. The chemical impact reaction is validated by contrast experiment with traditional lap polishing process in which the material is mainly removed through mechanical process. Experiment results show the dependence of the abrasive particles on the choice of materials. Even if the abrasive particle and the workpiece are composed of similar components, the machining properties are remarkably different due to slight differences in their physical properties or crystallography etc. Plastic scratches on the sample which was polished by the traditional mechanical process are completely removed by NAJP process, and the surface root-square-mean roughness has decreased from 1.403nm to 0.611nm. The NAJP process will become a promising method for ultra precision machining method for ultrasmooth optical surface.

Abrasive Effects in Oxide Chemical Mechanical Polishing

1999 ◽  
Vol 566 ◽  
Author(s):  
Uday Mahajan ◽  
Marc Bielmann ◽  
Rajiv K. Singh
Keyword(s):  
Particle Size ◽  
Surface Morphology ◽  
Surface Area ◽  
Chemical Mechanical Polishing ◽  
Material Removal ◽  
Sol Gel ◽  
Mechanical Polishing ◽  
Size Distributions ◽  
Abrasive Properties

In this study, we have characterized the effects of abrasive properties, primarily particle size, on the Chemical Mechanical Polishing (CMP) of oxide films. Sol-gel silica particles with very narrow size distributions were used for preparing the polishing slurries. The results indicate that as particle size increases, there is a transition in the mechanism of material removal from a surface area based mechanism to an indentation-based mechanism. In addition, the surface morphology of the polished samples was characterized, with the results showing that particles larger than 0.5 μm are detrimental to the quality of the SiO2 surface.

On the Lapping Mechanism of Optical Fiber End-Surfaces Using Fixed Diamond Abrasive Films

2011 ◽  
Vol 133 (2) ◽  
Author(s):  
JiAn Duan ◽  
DeFu Liu
Keyword(s):  
Particle Size ◽  
Optical Fiber ◽  
Material Removal ◽  
Abrasive Particle ◽  
Particle Sizes ◽  
Material Removal Mechanisms ◽  
Ductile Mode ◽  
Deformed Layer ◽  
Diamond Abrasive ◽  
Scanning Electron

The purpose of this paper is to reveal material removal mechanisms of optical fiber end-surface in lapping processes. The lapping process experiments are conducted using fixed diamond abrasive lapping films with various particle sizes of 6 μm, 3 μm, 1 μm, and 0.5 μm. The micrographs of the optical fiber end-surfaces are observed using a scanning electron microscope. The experimental results show that there exist three material removal modes in the lapping processes: brittle fracture mode, semibrittle and semiductile mode, and ductile mode. These modes are mainly controlled by abrasive particle size, and there appears a brittle-ductile transition’s critical point when lapping films with a particle size of 3 μm are used to lap optical fiber end-surfaces. An interpretation is proposed for the formation mechanism of the plastic deformed layer on the optical fiber end-surfaces.

scholarly journals Effect of Particle Size on the HDS Activity of Molybdenum Sulfide

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Carola Contreras ◽  
Fernanda Isquierdo ◽  
Pedro Pereira-Almao ◽  
Carlos E. Scott
Keyword(s):  
Particle Size ◽  
Heavy Oil ◽  
Molybdenum Sulfide ◽  
Vacuum Gas Oil ◽  
Particle Sizes ◽  
Heavy Oils ◽  
Gas Oil ◽  
Oil Reserves ◽  
Effect Of Particle Size

More than half of the total world oil reserves are heavy oil, extra heavy oil, and bitumen; however their catalytic conversion to more valuable products is challenging. The use of submicronic particles or nanoparticles of catalysts suspended in the feedstock may be a viable alternative to the conversion of heavy oils at refinery level or downhole (in situ upgrading). In the present work, molybdenum sulfide (MoS2) particles with varying diameters (10000–10 nm) were prepared using polyvinylpyrrolidone as capping agent. The prepared particles were characterized by DLS, TEM, XRD, and XPS and tested in the hydrodesulfurization (HDS) of a vacuum gas oil (VGO). A correlation between particle size and activity is presented. It was found that particles with diameters around 13 nm show double the HDS activity compared with the material with micrometric particle sizes (diameter ≈ 10,000 nm).

Effect of particle size distributions of activated sludges on cross-flow microfiltration flux for submerged membranes

1997 ◽  
Vol 83 (6) ◽  
pp. 583-589 ◽  
Author(s):  
Yasutoshi Shimizu ◽  
Katsushi Uryu ◽  
Yu-Ichi Okuno ◽  
Sadami Ohtubo ◽  
Atsuo Watanabe
Keyword(s):  
Particle Size ◽  
Cross Flow ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Effect Of Particle Size
Sign in / Sign up

Export Citation Format

Share Document