Chemical Smoothing of Rough Metal Surfaces

1992 ◽  
Vol 114 (4) ◽  
pp. 421-426 ◽  
Author(s):  
D. E. Kim ◽  
N. P. Suh
Keyword(s):  
Chemical Etching ◽  
Material Removal ◽  
Metal Surfaces ◽  
Cost Effective ◽  
Simplified Model ◽  
Irregular Surface ◽  
Diffusion Controlled ◽  
Dissolved Species ◽  
Smoothing Process ◽  
Fundamental Mass

A chemical etching method is investigated as a possible approach to smoothing metal surfaces automatically. In a chemical etching process metal is removed due to chemical reaction and the dissolved species are transported away from the surface mainly by diffusion. Controlled dynamics introduced to the etchant motion provide the conditions necessary to perform preferential material removal such that an irregular surface is smoothed. A simplified model for the smoothing process based on fundamental mass transfer understandings is presented. Experimental results of smoothing electric discharge machined 440 stainless steel specimens are also presented. This work is motivated by the need to develop a cost effective way to manufacture molds during secondary processing.

scholarly journals Simplified Mathematical Modelling of Uncertainty: Cost-Effectiveness of COVID-19 Vaccines in Spain

Mathematics ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 566
Author(s):  
Julio Emilio Marco-Franco ◽  
Pedro Pita-Barros ◽  
Silvia González-de-Julián ◽  
Iryna Sabat ◽  
David Vivas-Consuelo
Keyword(s):  
Cost Effectiveness ◽  
Health Planning ◽  
Cost Effective ◽  
Incremental Cost Effectiveness Ratio ◽  
Reliable Data ◽  
Simplified Model ◽  
Fatality Rate ◽  
Cost Effectiveness Ratio ◽  
Funeral Homes ◽  
The Cost

When exceptional situations, such as the COVID-19 pandemic, arise and reliable data is not available at decision-making times, estimation using mathematical models can provide a reasonable reckoning for health planning. We present a simplified model (static but with two-time references) for estimating the cost-effectiveness of the COVID-19 vaccine. A simplified model provides a quick assessment of the upper bound of cost-effectiveness, as we illustrate with data from Spain, and allows for easy comparisons between countries. It may also provide useful comparisons among different vaccines at the marketplace, from the perspective of the buyer. From the analysis of this information, key epidemiological figures, and costs of the disease for Spain have been estimated, based on mortality. The fatality rate is robust data that can alternatively be obtained from death registers, funeral homes, cemeteries, and crematoria. Our model estimates the incremental cost-effectiveness ratio (ICER) to be 5132 € (4926–5276) as of 17 February 2021, based on the following assumptions/inputs: An estimated cost of 30 euros per dose (plus transport, storing, and administration), two doses per person, efficacy of 70% and coverage of 70% of the population. Even considering the possibility of some bias, this simplified model provides confirmation that vaccination against COVID-19 is highly cost-effective.

Grinding-aided electrochemical discharge drilling in the light of electrochemistry

2018 ◽  
Vol 233 (6) ◽  
pp. 1896-1909 ◽  
Author(s):  
VG Ladeesh ◽  
R Manu
Keyword(s):  
Material Removal Rate ◽  
Borosilicate Glass ◽  
Chemical Etching ◽  
Material Removal ◽  
Removal Rate ◽  
Machining Accuracy ◽  
Hybrid Technique ◽  
Machined Surface ◽  
Influence Of Process Parameters ◽  
Electrochemical Discharge

The electrically non-conductive materials like glass, ceramics, quartz, etc. are of great interest for many applications in modern industries. Machining them with high quality and at a faster rate is a challenging task. In this study, a novel technique called grinding aided electrochemical discharge drilling (G-ECDD) is demonstrated which uses a hollow diamond core drill as the tool for performing electrochemical discharge machining of borosilicate glass. The new hybrid technique enhances the material removal rate and machining accuracy to several folds by combining the thermal melting action of discharges and grinding action of the abrasive tool. This paper presents the experimental investigation on the material removal rate during G-ECDD of glass while using different electrolytes. An attempt has been made to explore the influence of electrolyte temperature on G-ECDD performance by maintaining the electrolyte at different temperatures. Experiments were conducted using three different electrolytes which include NaOH, KOH, and the mixture of both. The results obtained from this study revealed that an increase in temperature will favor chemical etching as well as electrochemical reaction rate. Also, it was observed that heating the electrolyte leads to an increase in the bubble density and enhances the ion mobility. This causes the formation of gas film at a faster rate and thereby improving the discharge activity. Thus, machining will be done at a faster rate. Better results are obtained while using a mixture of NaOH and KOH. From the microscopic images of the machined surface, it was observed that material removal mechanism in G-ECDD is a combination of grinding action, electrochemical discharges, and chemical etching. Response surface methodology was adopted for studying the influence of process parameters on the performance of G-ECDD. The new technique of grinding aided electrochemical discharge drilling proved its potential to machine borosilicate glass and simultaneously offers good material removal rate, repeatability, and accuracy.

In Vitro Gene Delivery with Large Porous Silicon Nanoparticles Fabricated Using Cost-Effective, Metal-Assisted Chemical Etching

Small ◽  
2016 ◽  
Vol 13 (3) ◽  
pp. 1602739 ◽  
Author(s):  
Nancy Wareing ◽  
Kyle Szymanski ◽  
Giridhar R. Akkaraju ◽  
Armando Loni ◽  
Leigh T. Canham ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Gene Delivery ◽  
Chemical Etching ◽  
Silicon Nanoparticles ◽  
Cost Effective ◽  
Porous Silicon Nanoparticles ◽  
Metal Assisted Chemical Etching

Microstructural Evolution during Sintering of the P/M Blended Elemental Ti-5Al-2.5Fe Alloy

2005 ◽  
Vol 498-499 ◽  
pp. 55-60 ◽  
Author(s):  
Rodrigo P. Siqueira ◽  
Hugo Ricardo Zschommler Sandim ◽  
Vinicius André Rodrigues Henriques ◽  
J.F.C. Lins
Keyword(s):  
Microstructural Evolution ◽  
Cost Effective ◽  
X Ray Diffraction ◽  
Blended Elemental ◽  
Surgical Implants ◽  
Diffusion Controlled ◽  
Effective Option ◽  
Temperature Homogenization ◽  
Increasing Temperature ◽  
Cold Pressed

The alpha-beta Ti-5%Al-2.5Fe (wt-%) alloy was developed as a cost-effective option to replace the traditional Ti-6%Al-4%V alloy in the manufacture of surgical implants because of its larger biocompatibility (V-free alloy). Samples of this alloy were prepared using the blended elemental (BE) technique. The isochronal sintering of the cold pressed compacts was carried out at 700, 1000, and 1400°C in vacuum. In this work, the preliminary results of the behavior of elementary powders during sintering and the corresponding microstructural evolution are shown. The alloy was characterized by means of scanning electron microscopy (SEM) in the backscattered mode, X-ray diffraction (XRD), energy-dispersive spectrometry (EDS), and density measurements. The results indicate that the homogenization of the alloy is diffusion-controlled. Non-equilibrium Ti-Al phases as well as Fe-Al compounds were identified in samples sintered at lower temperatures (700oC). With increasing temperature, homogenization of the alloy takes place and a structure consisting of coarse plate-like alpha and intergranular beta is present.

Synergy between Chemical Dissolution and Mechanical Abrasion during Chemical Mechanical Polishing of Copper

2005 ◽  
Vol 867 ◽  
Author(s):  
Wei Che ◽  
Ashraf Bastawros ◽  
Abhijit Chandra
Keyword(s):  
Residual Stress ◽  
Chemical Etching ◽  
Material Removal ◽  
Wear Test ◽  
Wear Depth ◽  
Chemical Dissolution ◽  
Removal Mechanism ◽  
Material Removal Mechanism ◽  
Soft Layer ◽  
Mechanical Abrasion

AbstractThe synergistic roles of chemical dissolution and mechanical abrasion on the material removal mechanism during CMP process are explored. A set of nano-wear experiments are conducted on electro-plated copper surfaces with systematic exposure to active slurries. Initial results of in situ wear test in chemically active slurry showed an increased material removal rate (MRR) relative to a dry wear test. To understand the synergistic effects of chemical dissolution and mechanical abrasion, we have investigated two plausible mechanisms of material removal. Mechanism-I is based on chemical dissolution enhanced mechanical abrasion. A soft layer of chemical products is assumed to be formed on top of the polished surface due to chemical reaction with a rate much faster than the mechanical abrasion rate. It is then followed by a gentle mechanical abrasion of that soft layer. An increase in the MRR of up to 100% is identified based on the etching time and the down force. Mechanism-II is based on mechanical abrasion accelerated chemical etching. In this case, the nano-wear experiments are first performed to generate local variation of the residual stress levels, and then followed by chemical etching to investigate the variation of the wear depth and the evolution of surface topography due to etching. It is found that the residual stress caused by the mechanical wear enhances the chemical etching rate, as manifested by the increase of wear depth. The developed understanding from these experiments can be used in future studies to control the rates of chemical dissolution and mechanical abrasion as well as investigating the various process-induced defects.

scholarly journals Surface Texture Evolution of Fused Silica in a Combined Process of Atmospheric Pressure Plasma Processing and Bonnet Polishing

Coatings ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 676
Author(s):  
Xing Su ◽  
Chenglong Ji ◽  
Yang Xu ◽  
Duo Li ◽  
David Walker ◽  
...  
Keyword(s):  
Surface Texture ◽  
Atmospheric Pressure ◽  
Influence Function ◽  
Chemical Etching ◽  
Material Removal ◽  
Texture Evolution ◽  
Plasma Processing ◽  
Atmospheric Pressure Plasma ◽  
Combined Process ◽  
Bonnet Polishing

The increasing demand for precision optical components invokes the requirement of advanced fabrication techniques with high efficiency. Atmospheric pressure plasma processing (APPP), based on chemical etching, has a high material removal rate and a Gaussian-shaped influence function, which is suitable to generate complex structures and correct form errors. Because of the pure chemical etching, an optically smooth surface cannot be achieved using only APPP. Thus, bonnet polishing (BP) with a flexible membrane tool, also delivering a Gaussian influence-function, is introduced to smooth the surface after APPP. In this paper, the surface texture evolution in the combined process of APPP and BP is studied. The etched texture with increased removal depth of APPP is presented and analyzed. Subsequently, the processed substrates are smoothed by BP. The texture smoothing and the roughness improvement is investigated in detail. The experimental results show that the APPP etched pits coalesce with each other and transform into irregular convex-concave structures, with roughness degraded to about 25 nm arithmetical mean deviation (Ra). The APPP etched texture can be successfully smoothed to 1.5 nm Ra, with 0.2–1 μm material removal of BP.

Modeling and Analysis of the Dynamics of a Drill Penetrating a Thin Plate

1986 ◽  
Vol 53 (3) ◽  
pp. 690-694 ◽  
Author(s):  
P. G. Reinhall ◽  
D. W. Storti
Keyword(s):  
Numerical Methods ◽  
Circular Hole ◽  
Composite Plate ◽  
Material Removal ◽  
Simplified Model ◽  
Drilling Process ◽  
Rigid Plate ◽  
Soft Or ◽  
Modeling And Analysis ◽  
Speed Selection

We propose a simplified model of the drilling process which is useful in understanding the problem of noncircular hole production. The dynamics of a drill penetrating a circular hole in a rigid plate are studied analytically, and numerical methods are then used to include the effects of material removal. We show that certain drill trajectories which lead to noncircular holes can be stabilized by material removal. Based on these findings, we recommend careful drill speed selection as a means of minimizing the probability of noncircular hole production, and explain why even this solution may not be sufficient for the case of very soft or composite plate materials.

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