Effect of microarc oxidation by short-pulse mode parameters on composition, coating properties and process productivity

2021 ◽  
Vol 5 ◽  
pp. 82-88
Author(s):  
P. I. Butyagin ◽  
Keyword(s):  
Pulse Duration ◽  
Crystalline Phase ◽  
Short Pulse ◽  
Formation Rate ◽  
Microarc Oxidation ◽  
Pulse Mode ◽  
Coating Properties ◽  
Composition Properties ◽  
Oxidation Parameters ◽  
Process Productivity

This article presents the results of study of the influence of microarc oxidation parameters — ferquency and pulse duration — on the composition, properties of the coating, and also on the productivity of the microarc oxidation (MAO) process. It was found that the frequency in the range from 100 to 500 Hz significantly increases the formation rate of the MAO coating. A change in the composition and properties of the MAO coatings at pulse durations from 50 to 200 μs is observed. Starting with a pulse duration of 50 μs and a frequency of 400 Hz, the γ-Al2O3 crystalline phase is detected in the coating, the elemental composition, morphology, and microhardness of the coating change significantly.

scholarly journals INFLUENCE OF ELECTRICAL PARAMETERS ON THE ROUGHNESS OF THE COATING OBTAINED IN A SHORT-PULSE MODE OF MICRO-ARC OXIDATION

2021 ◽  
pp. 29-33
Author(s):  
Pavel I. Butyagin ◽  
Keyword(s):  
Pulse Duration ◽  
Short Pulse ◽  
Pulse Repetition Frequency ◽  
Microarc Oxidation ◽  
Pulse Mode ◽  
Electrical Parameters ◽  
Wide Range ◽  
Micro Arc Oxidation ◽  
Electric Parameters ◽  
The Moment

In the course of the work it was shown that in the process of short-pulse microarc oxidation, it is possible to control electric parameters – pulse duration and pulse repetition frequency – in a wide range of 12–200 μs and 100–500 Hz, by controlling the porosity and the nature of the surface melting of the MAO coating. As a result, it becomes possible to obtain coating with the required roughness. At the maximum values of the pulse duration and frequency (200 μs and 500 Hz) at the moment of the microplasma discharge, the maximum amount of energy is released, which allows uniformly, with the smallest amount of first irregularities, to melt the coating surface, to obtain round pores of stable size. All that factors favour a decrease in the surface roughness of the MAO coating

scholarly journals Mind the gap – Part 1: Accurately locating warm marine boundary layer clouds and precipitation using spaceborne radars

2020 ◽  
Vol 13 (5) ◽  
pp. 2363-2379 ◽  
Author(s):  
Katia Lamer ◽  
Pavlos Kollias ◽  
Alessandro Battaglia ◽  
Simon Preval
Keyword(s):  
Boundary Layer ◽  
Cloud Cover ◽  
Marine Boundary Layer ◽  
Short Pulse ◽  
Pulse Mode ◽  
Cloud Base ◽  
Boundary Layer Clouds ◽  
Highly Sensitive ◽  
Eastern North Atlantic ◽  
Long Pulse

Abstract. Ground-based radar observations show that, over the eastern North Atlantic, 50 % of warm marine boundary layer (WMBL) hydrometeors occur below 1.2 km and have reflectivities of < −17 dBZ, thus making their detection from space susceptible to the extent of surface clutter and radar sensitivity. Surface clutter limits the ability of the CloudSat cloud profiling radar (CPR) to observe the true cloud base in ∼52 % of the cloudy columns it detects and true virga base in ∼80 %, meaning the CloudSat CPR often provides an incomplete view of even the clouds it does detect. Using forward simulations, we determine that a 250 m resolution radar would most accurately capture the boundaries of WMBL clouds and precipitation; that being said, because of sensitivity limitations, such a radar would suffer from cloud cover biases similar to those of the CloudSat CPR. Observations and forward simulations indicate that the CloudSat CPR fails to detect 29 %–43 % of the cloudy columns detected by ground-based sensors. Out of all configurations tested, the 7 dB more sensitive EarthCARE CPR performs best (only missing 9.0 % of cloudy columns) indicating that improving radar sensitivity is more important than decreasing the vertical extent of surface clutter for measuring cloud cover. However, because 50 % of WMBL systems are thinner than 400 m, they tend to be artificially stretched by long sensitive radar pulses, hence the EarthCARE CPR overestimation of cloud top height and hydrometeor fraction. Thus, it is recommended that the next generation of space-borne radars targeting WMBL science should operate interlaced pulse modes including both a highly sensitive long-pulse mode and a less sensitive but clutter-limiting short-pulse mode.

scholarly journals Effects of Er:YAG Laser on Mineral Content of Sound Dentin in Primary Teeth

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Cigdem Guler ◽  
Meral Arslan Malkoc ◽  
Veli Alper Gorgen ◽  
Erhan Dilber ◽  
Mehmet Bulbul
Keyword(s):  
Surface Roughness ◽  
Mineral Content ◽  
Primary Teeth ◽  
Er:Yag Laser ◽  
Short Pulse ◽  
Pulse Mode ◽  
Emission Spectrometry ◽  
Control Group ◽  
Group A ◽  
Group B

The aim of the present study was to evaluate the mineral content of sound dentin in primary teeth prepared using an Er:YAG laser at two different power settings. Thirty-six primary second molars were used in this study. Three dentin slabs were obtained from each tooth, and the slabs were randomly divided into three groups: Group A, control; Group B, Er:YAG laser at 3.5 W, 175 mJ, and 20 Hz, short pulse mode; and Group C, Er:YAG laser at 4 W, 200 mJ, and 20 Hz, medium-short pulse mode. One dentin slab per group was used to evaluate the dentinal morphology and surface roughness values using SEM and profilometer, respectively. Mineral content in the dentin slabs were calculated by inductively coupled plasma-atomic emission spectrometry (ICP-AES). The data were analyzed by one-way analysis of variance and Tukey’s HSD tests. No significant differences in Ca, K, Mg, Na, and P levels or Ca/P ratio were found among the groups(P>0.05). SEM micrographs showed that surface irregularities increased with a higher power setting. The surface roughness after laser treatment in Group B and Group C was found to be similar, unlike Group A.

Q-switched all-fiber laser with short pulse duration based on tungsten diselenide

Laser Physics ◽  
2018 ◽  
Vol 28 (5) ◽  
pp. 055104 ◽  
Author(s):  
Wenyi Li ◽  
Yuyi OuYang ◽  
Guoli Ma ◽  
Mengli Liu ◽  
Wenjun Liu
Keyword(s):  
Fiber Laser ◽  
Pulse Duration ◽  
Short Pulse ◽  
Tungsten Diselenide ◽  
Short Pulse Duration

scholarly journals Q-Switch Nd:YAG Laser-Assisted Decontamination of Implant Surface

2019 ◽  
Vol 7 (4) ◽  
pp. 99 ◽  
Author(s):  
Namour ◽  
El Mobadder ◽  
Magnin ◽  
Peremans ◽  
Verspecht ◽  
...  
Keyword(s):  
Pulse Duration ◽  
Nd:Yag Laser ◽  
Yttrium Aluminum Garnet ◽  
Short Pulse ◽  
Sem Analysis ◽  
P Value ◽  
Implant Surface ◽  
Contact Mode ◽  
Short Pulse Duration ◽  
Clean Contaminated

Peri-implantitis (PI) is an inflammatory disease of peri-implant tissues, it represents the most frequent complication of dental implants. Evidence revealed that microorganisms play the chief role in causing PI. The purpose of our study is to evaluate the cleaning of contaminated dental implant surfaces by means of the Q-switch Nd:YAG (Neodymium-doped Yttrium Aluminum Garnet) laser and an increase in temperature at lased implant surfaces during the cleaning process. Seventy-eight implants (titanium grade 4) were used (Euroteknika, Sallanches, France). Thirty-six sterile implants and forty-two contaminated implants were collected from failed clinical implants for different reasons, independent from the study. Thirty-six contaminated implants were partially irradiated by Q-switch Nd:YAG laser (1064 nm). Six other contaminated implants were used for temperature rise evaluation. All laser irradiations were calibrated by means of a powermetter in order to evaluate the effective delivered energy. The irradiation conditions delivered per pulse on the target were effectively: energy density per pulse of 0.597 J/cm2, pick powers density of 56 mW/cm2, 270 mW per pulse with a spot diameter of 2.4 mm, and with repetition rate of 10 Hz for pulse duration of 6 ns. Irradiation was performed during a total time of 2 s in a non-contact mode at a distance of 0.5 mm from implant surfaces. The parameters were chosen according to the results of a theoretical modeling calculation of the Nd:YAG laser fluency on implant surface. Evaluation of contaminants removal showed that the cleaning of the irradiated implant surfaces was statistically similar to those of sterile implants (p-value ≤ 0.05). SEM analysis confirmed that our parameters did not alter the lased surfaces. The increase in temperature generated at lased implant surfaces during cleaning was below 1 °C. According to our findings, Q-switch Nd:YAG laser with short pulse duration in nanoseconds is able to significantly clean contaminated implant surfaces. Irradiation parameters used in our study can be considered safe for periodontal tissue.

EFFECT OF PULSE DURATION ON POLYTETRAFLUOROETHYLENE SHOCKED ABOVE THE CRYSTALLINE PHASE II–III TRANSITION

2008 ◽  
Author(s):  
E. N. Brown ◽  
G. T. Gray ◽  
P. J. Rae ◽  
C. P. Trujillo ◽  
N. K. Bourne ◽  
...  
Keyword(s):  
Pulse Duration ◽  
Phase Ii ◽  
Crystalline Phase

Point source of UV-radiation with a frequency of 1 khz and short pulse duration

2012 ◽  
Vol 54 (11) ◽  
pp. 1276-1279 ◽  
Author(s):  
E. Kh. Baksht ◽  
V. F. Tarasenko ◽  
Yu. V. Shut’ko ◽  
M. V. Erofeev
Keyword(s):  
Point Source ◽  
Pulse Duration ◽  
Uv Radiation ◽  
Short Pulse ◽  
Short Pulse Duration

Forming Fine V-Grooves on a Tungsten Carbide Workpiece with a PCD Electrode by EDM

2007 ◽  
Vol 329 ◽  
pp. 631-636 ◽  
Author(s):  
Sadao Sano ◽  
Kiyoshi Suzuki ◽  
Wei Li Pan ◽  
Manabu Iwai ◽  
Yoshihiko Murakami ◽  
...  
Keyword(s):  
Tungsten Carbide ◽  
Pulse Duration ◽  
Flat Surface ◽  
Short Pulse ◽  
Chemical Vapor ◽  
Polycrystalline Diamond ◽  
Chemical Vapor Deposition Diamond ◽  
Electrically Conductive ◽  
Short Pulse Duration ◽  
Low Wear

Polycrystalline diamond (PCD) exhibits a thermal conductivity similar to that of the electrically conductive chemical vapor deposition diamond (EC-CVD diamond) found to function as zero-wear electrodes at short pulse duration. In this study, PCD was used as electrodes applied to EDM on tungsten carbide. Two kinds of PCD (CTB-010 and CTH-025) with a flat surface were used. The wear of the PCD electrodes was about 1.5% for very short pulse duration such as te=1μs, but it was zero wear at te=30μs, though the wear of a Cu-W electrode was 10% even on the machine recommended conditions for the low wear. EDM experiment using a V-shaped PCD electrode with an included angle of 45° was also carried out and the performance was compared with the case using a V-shaped Cu-W electrode. Under the conditions of a no load voltage of 60V, a set peak current of 2A, and a medium pulse duration of te=15μs, there was no wear on PCD electrodes when observed under the SEM, whereas a 50μm-deep wear on the Cu-W electrodes even under the machine recommended condition for the low wear was observed.

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