Rapid sintering by thermo-compression in air using a paste containing bimodal-sized silver-coated copper particles and effects of particle size and surface finish type

ABSTRACTThe concept of 'hybrid heating with microwave (MW) energy at 2.45 GHZ.'for ultra rapid sintering of alumina is being introduced. This technique is a combination of MW - materual interaction as well as conventional radiant/conduction mechanisms, and facilitates the attainment of perhaps, the highest possible heating rates in a multimode MW cavity at 2.45 GJZz. (1500ºC in 120 sees.). Rapid sintering of pure.undoped alumina with this novel techniQue culminates in uniform, homogeneous microstructures and mechanical property enhancements vis-a-vis conventional fast firing.The role of green microstructure (particle size) on MW(hybrid) heating and processing variables (temperature, time) on the MW (hybrid) heating phenomena vs. conventional fast firing were investigated. Hybrid heated samples showed accelerated densification with comparable grain sizes when compared with the conventionally fast fired samples. The effectof particle size on the microwave (hybrid) heating phenomena was found to be analogous to conventional sintering.

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Performance Profiling of Nanoparticulate Graphite Powder as Lubricant in the Machining of AISI 1040 Steel under Variable Machining Conditions

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.984-985.15 ◽

2014 ◽

Vol 984-985 ◽

pp. 15-24 ◽

Cited By ~ 2

Author(s):

S. Srikiran ◽

K. Ramji ◽

B. Satyanarayana

Keyword(s):

Particle Size ◽

Surface Finish ◽

Cutting Forces ◽

Solid Lubricant ◽

Graphite Powder ◽

Nano Particles ◽

Chemical Degradation ◽

Work Piece ◽

Tool Temperature ◽

Cutting Zone

The generation of heat during machining at the cutting zone adversely affects the surface finish and tool life. The heat at the cutting zone, which plays a negative role due to poor thermal conductivity, resistance to wear, high strength at high temperatures and chemical degradation can be overcome by the use of proper lubrication. Advancements in the field of tribology have led to the use of solid lubricants replacing the conventional flood coolants. This work involves the use of nanoparticulate graphite powder as a lubricant in turning operations whose performance is judged in terms of cutting forces, tool temperature and surface finish of the work piece. The experimentation revealed the increase in cutting forces and the tool temperature when the solid lubricant used is decreased in particle size. The surface finish deteriorated with the decrease in particle size of the lubricant in the nanoregime.Keywords-Turning, Solid lubricant, Graphite, Minimum Quantity Lubrication, nano–particles,Weight percentage,Frictioncoefficient.

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Copper-Polyurethane Composite Materials: Particle Size Effect on the Physical-Chemical and Antibacterial Properties

Polymers ◽

10.3390/polym12091934 ◽

2020 ◽

Vol 12 (9) ◽

pp. 1934

Author(s):

Cristian Miranda ◽

Johanna Castaño ◽

Emky Valdebenito-Rolack ◽

Felipe Sanhueza ◽

Rody Toro ◽

...

Keyword(s):

Mechanical Properties ◽

Particle Size ◽

Composite Materials ◽

Thermoplastic Polyurethane ◽

Antibacterial Properties ◽

Copper Particle ◽

Copper Particles ◽

Polyurethane Composite ◽

Natural Concentration ◽

Blending Method

In this work, thermoplastic polyurethane (TPU) composites incorporated with 1.0 wt% Cu particles were synthesized by the melt blending method. The effect of the incorporated copper particle size on the antibacterial, thermal, rheological, and mechanical properties of TPU was investigated. The obtained results showed that (i) the addition of copper particles increased the thermal and mechanical properties because they acted as co-stabilizers of polyurethane (PU) (ii) copper nanoparticles decreased the viscosity of composite melts, and (iii) microparticles > 0.5 µm had a tendency to easily increase the maximum torque and formation of agglomerates. SEM micrographics showed that a good mixture between TPU and copper particles was obtained by the extrusion process. Additionally, copper-TPU composite materials effectively inhibited the growth of the Gram-negative Escherichia coli and the Gram-positive Staphylococcus aureus. Considering that the natural concentration of copper in the blood is in the range of 0.7–0.12 mg/L and that the total migration value of copper particles from TPU was 1000 times lower, the results suggested that TPU nanocomposites could be adequately employed for biomedical applications without a risk of contamination.

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Effects of Nano-scale Colloidal Abrasive Particle Size on SiO2 by Chemical Mechanical Polishing

MRS Proceedings ◽

10.1557/proc-671-m1.6 ◽

2001 ◽

Vol 671 ◽

Cited By ~ 6

Author(s):

Chunhong Zhou ◽

Lei Shan ◽

S.H. Ng ◽

Robert Hight ◽

Andrew. J. Paszkowski ◽

...

Keyword(s):

Particle Size ◽

Material Removal Rate ◽

Surface Finish ◽

Material Removal ◽

Removal Rate ◽

Abrasive Particle ◽

Single Crystal Silicon ◽

Weight Percent ◽

Crystal Silicon ◽

P Type

ABSTRACTThis paper reports on the effect of colloidal abrasive particle size in the polishing of thermally grown silicon dioxide on 100mm diameter, P-type, (100), single crystal silicon wafers. The abrasive particle sizes were varied in six (6) slurries with pH values of 10.97 ± 0.08. The abrasive sizes were 10, 20, 50, 80, 110 and 140nm in diameter, and the slurry contained 30 weight percent abrasives. The experimental results indicate that the material removal rate (MRR) varies with the volume of the particle size. Results also confirm that there exists an optimum abrasive particle size with respect to material removal rate and surface finish. For a pad surface roughness of 5.2μm (Ra), the slurry containing 80nm particles resulted in the highest material removal rate and best surface finish. A nano-film model based on the pad roughness is used to explain the results.

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Micro Ultrasonic Machining Using Oil Based Abrasive Slurry

ASME 2008 International Manufacturing Science and Engineering Conference, Volume 2 ◽

10.1115/msec_icmp2008-72138 ◽

2008 ◽

Cited By ~ 4

Author(s):

Murali M. Sundaram ◽

Sreenidhi Cherku ◽

K. P. Rajurkar

Keyword(s):

Particle Size ◽

Material Removal Rate ◽

Surface Finish ◽

Material Removal ◽

Removal Rate ◽

Abrasive Particle ◽

High Wear Resistance ◽

Ultrasonic Machining ◽

Influence Of Process Parameters ◽

Slurry Concentration

Advanced engineering materials posses excellent properties such as high wear resistance, and inertness to corrosion and chemical reactions. Since these materials are usually hard, brittle, chemically inert, and electrically nonconductive, they pose serious machinability challenges. Micro ultrasonic machining (Micro USM) is an emerging method for the micromachining of hard and brittle materials without any thermal damage. This paper presents the results of micro ultrasonic machining using oil based abrasive slurry. Details of the in-house built experimental setup used to conduct the experiments are explained. The influence of process parameters such as slurry medium, slurry concentration, and abrasive particle size on the performance of micro USM are reported. It was noticed that the evidence of three body material removal mechanism is predominant for micro USM using oil based slurry. In general, the material removal rate increases with the increase in the abrasive particle size for both aqueous abrasive slurry and oil based abrasive slurry. Further, material removal rate is consistently higher for experiments conducted with aqueous abrasive slurry medium. On the other hand, it is noticed that the oil based slurry medium provides better surface finish. It is also noticed that the smaller abrasive grains provide better surface finish for both aqueous, and oil based abrasive slurry mediums. Role of slurry concentration is ambiguous, as no clear trend of its effect of on process performance is evident in the available experimental results.

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Tunable Optical Absorption of Composites of Nanocrystalline Copper Prepared by in situ Chemical Reduction within a Cu2+-Polymer Complex

MRS Proceedings ◽

10.1557/proc-789-n3.30 ◽

2003 ◽

Vol 789 ◽

Author(s):

Cheng Huang ◽

Gang Huang ◽

C. Z. Yang

Keyword(s):

Particle Size ◽

Optical Absorption ◽

Chemical Reduction ◽

Nonlinear Susceptibility ◽

Polymer Complex ◽

Present System ◽

Absorption Bands ◽

Quantum Sphere ◽

Copper Particles

ABSTRACTResearch on nanocrystalline materials and the physics behind their properties have attracted considerable attention. A number of physical and chemical techniques have been used to synthesize different nanomaterials and nanocomposites. Optical absorption characteristics of composites containing nanosized metals or semiconductors have been investigated for potential applications in nonlinear optics and photonic crystals and also to understand the effect of particle size on the band gap of the material concerned. These materials show a large third-order nonlinear susceptibility. A polymer-matrix nanocomposite containing copper particles has been prepared by in situ chemical reduction within a polymer-metal complex solid film. The copper particle size in the order of 10 nm is controlled by the initial content of the metal ions in the complex. Their fractal pattern and the value of the fractal dimension indicate that there exists a cluster-cluster aggregation (CCA) process in the present system. Optical absorption spectra of copper-polymer nanocomposites show distinct plasma absorption bands and quantum size effect in the samples. More studies on optical properties of composites containing nanosized metals are within the Drudeframe on the basis of Mie theory, but the electrons behave in a wavelike rather than a particlelike way as the particle size decreases to below 10 nm, and the classical Drude model should be modified considering the quantum confinement effect. In this paper, the calculated blueshift of the resonance peak based on a quantum-sphere model (QSM) proposed by Huang and Lue, gives remarkable agreement with the experimental data as the size of copper particles embedded in the polymer becomes smaller.

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Evaluation of Rheological Properties of Magnetorheological Polishing Fluid and Their Effect on Surface Finish in Ultra Precision Finishing Processes

World Tribology Congress III, Volume 1 ◽

10.1115/wtc2005-64260 ◽

2005 ◽

Author(s):

Sunil Jha ◽

V. K. Jain

Keyword(s):

Particle Size ◽

Rheological Properties ◽

Surface Finish ◽

Iron Particle ◽

Abrasive Particles ◽

Ultra Precision ◽

Effect Of Particle Size ◽

Finishing Processes ◽

Polishing Fluid ◽

Magnetorheological Polishing Fluid

Magnetorheological finishing (MRF) process for automated lens finishing and Magnetorheological abrasive flow finishing (MRAFF) for internal geometries rely on unique smart behavior of MRP-fluid. The rheological properties of MRP-fluid depend on carbonyl iron particle (CIP) and silicon carbide (SiC) particle size, their volume concentration, magnetic properties and applied magnetic field strength. To study the effect of particle size on rheological properties of MRP-fluid, a hydraulically driven specially designed capillary rheometer is fabricated. The best surface finish improvement was obtained with MRP-fluid containing approximately equal diameter of abrasive particles and CIPs. Least improvement was noticed with smaller CIPs and bigger abrasive combinations used. This is because the smaller size CIPs are incapable of providing the necessary finishing forces for bigger abrasive particles, which results in weak bonding strength.

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Surface Finish Assessment of Polishing Process of Tool Steels by Abrasion, Using Diamond and Alumina Particles

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.716.423 ◽

2013 ◽

Vol 716 ◽

pp. 423-429 ◽

Cited By ~ 1

Author(s):

André Marcon Zanatta ◽

José Divo Bressan ◽

Jefferson de Oliveira Gomes ◽

Fábio Dondeo Origo ◽

Alvaro José Damião

Keyword(s):

Particle Size ◽

Surface Finish ◽

Roughness Parameter ◽

Surface Finishing ◽

Diffuse Light ◽

Tool Steels ◽

Polishing Process ◽

Automatic Polishing ◽

Light Reflectance ◽

Versus Particle

The present work investigates the surface finishing of two mould tool steels (WNr 1.2738~P20 and WNr 1. 4305) after polishing by conventional method and automatic laboratory equipment. These steels are employed in the fabrication of polymer injection moulds due to its good machinability, homogeneous microstructure and hardness. The polishing process was performed in laboratory by manual and automated processes. The surface finishing was measured by mechanical and optical methods. In the manual polishing, SiC paper grit 320, 600 and 1200 was used. Final polishing was carried out with polishing cloth containing 0.3 μm alumina suspension or 6 μm and 1 μm diamond suspension. Alternately, polishing of steel specimens in the specially developed laboratory automatic equipment was performed using a large rotating disc at 140 rpm, nominal pressures of 0.013 Pa, 0.139 Pa and 0.244 Pa and diamond paste with particle size 1 μm. Surface finish of specimens were compared as a function of the particle size and polishing time by three methods: the roughness parameter Rz (mean of maximum roughness depth) using a stylus probe, light reflectance with an integrating sphere connected to a spectrophotometer, and reflected diffuse light intensity analysis of a He-Ne laser. Specimen surface images were also obtained by an optical microscope to compare the topography after polishing. From the plot of roughness measurements versus particle size and intensity of diffuse light versus particle size, it was observed that both roughness parameter Rz and the intensity of diffuse light decreased linearly with the abrasive particle size for the manual polishing method. The method of light reflectance measurements shows an approximately constant value of 55 % for all particle size. Therefore, the better methods to assess surface finish of tool steels are the roughness parameter Rz and the intensity of diffuse light by laser method. For the automatic polishing, the results show that there is an optimized time for minimum roughness which is 5 minute. Other relevant aspects of surface finish by particle abrasion are also discussed.

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Experimental characterization of conformal hydrodynamic nanopolishing of a machined single crystal sapphire cavity

Journal of Micromanufacturing ◽

10.1177/25165984211015372 ◽

2021 ◽

pp. 251659842110153

Author(s):

Prashant Kumar ◽

Rinku Mittal ◽

Ramesh K. Singh ◽

Suhas S. Joshi

Keyword(s):

Particle Size ◽

Single Crystal ◽

Surface Finish ◽

Abrasive Particle ◽

Diamond Turning ◽

Initial Surface ◽

Workpiece Surface ◽

Abrasive Particles ◽

Single Crystal Sapphire

Sapphire is an important ceramic material which finds applications in fields such as temperature sensing, optics, electronics, and ceramic bearings. Polishing of sapphire has always been a difficult task for industries and research communities. Hydrodynamic polishing (HDP) is one of the prominent methods used for polishing of hard and profiled surfaces, whereas rigid tool-based methods such as diamond turning, grinding, and honing have many limitations. The HDP process involves deterministic flow of abrasive particles in the slurry between the workpiece surface and a rotating soft tool to obtain the desired surface finish. A novel experimental setup has been fabricated to realize the conformal hydrodynamic nanopolishing on single crystal sapphire cavity. In this study, the experiments were conducted to understand the effect of abrasive particle size, basicity of slurry, and change in temperature of slurry on the polishing of machined sapphire cavity. The effect of the initial surface roughness of the machined cavity on conformal hydrodynamic nanopolishing has also been investigated. A microcrack/pit-free surface has been found after the final polishing of the sapphire cavity. An improvement of 21% is found in surface finish after the final polishing using abrasive particle size of 0.06 µm. Abrasive slurry with higher basicity (pH 13) does not improve the surface finish. By heating the abrasive slurry to a temperature of 70°C–75°C, surface finish improves by ∼26% as compared to improvement of ∼ 21% at room temperature polishing.

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Microstructural characterization of laser-melted/roller-quenched dicalcium silicate

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100104972 ◽

1988 ◽

Vol 46 ◽

pp. 582-583

Author(s):

C. J. Chan ◽

K. R. Venkatachari ◽

W. M. Kriven ◽

J. F. Young

Keyword(s):

Particle Size ◽

Raw Materials ◽

Shape Change ◽

Microstructural Characterization ◽

Particle Size Effect ◽

Dicalcium Silicate ◽

Laser Melting ◽

Uniform Size ◽

Cell Shape Change ◽

Wide Range

Dicalcium silicate (Ca2SiO4) is a major component of Portland cement. It has also been investigated as a potential transformation toughener alternative to zirconia. It has five polymorphs: α, α'H, α'L, β and γ. Of interest is the β-to-γ transformation on cooling at about 490°C. This transformation, accompanied by a 12% volume increase and a 4.6° unit cell shape change, is analogous to the tetragonal-to-monoclinic transformation in zirconia. Due to the processing methods used, previous studies into the particle size effect were limited by a wide range of particle size distribution. In an attempt to obtain a more uniform size, a fast quench rate involving a laser-melting/roller-quenching technique was investigated.The laser-melting/roller-quenching experiment used precompacted bars of stoichiometric γ-Ca2SiO4 powder, which were synthesized from AR grade CaCO3 and SiO2xH2O. The raw materials were mixed by conventional ceramic processing techniques, and sintered at 1450°C. The dusted γ-Ca2SiO4 powder was uniaxially pressed into 0.4 cm x 0.4 cm x 4 cm bars under 34 MPa and cold isostatically pressed under 172 MPa. The γ-Ca2SiO4 bars were melted by a 10 KW-CO2 laser.

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