ABRASION RESISTANCE OF THE POLYMER-CERAMIC COATING OBTAINED IN THE SHORT-PULSE MODE OF MICROARC OXIDATION

2021 ◽  
pp. 67-72
Author(s):  
Pavel Butyagin
Keyword(s):  
Abrasion Resistance ◽  
Ceramic Coating ◽  
Short Pulse ◽  
Microarc Oxidation ◽  
Pulse Mode

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.

scholarly journals Effect of Anodic Current Density on Characteristics and Low Temperature IR Emissivity of Ceramic Coating on Aluminium 6061 Alloy Prepared by Microarc Oxidation

2013 ◽  
Vol 2013 ◽  
pp. 1-14 ◽  
Author(s):  
Mohannad M. S. Al Bosta ◽  
Keng-Jeng Ma ◽  
Hsi-Hsin Chien
Keyword(s):  
Surface Roughness ◽  
Current Density ◽  
Ceramic Coating ◽  
Microarc Oxidation ◽  
Ceramic Coatings ◽  
Anodic Current Density ◽  
Ceramic Surface ◽  
Anodic Current ◽  
Alumina Phase ◽  
Current Densities

High emitter MAO ceramic coatings were fabricated on the Al 6061 alloy, using different bipolar anodic current densities, in an alkali silicate electrolyte. We found that, as the current density increased from 10.94 A/dm2 to 43.75 A/dm2, the layer thickness was increased from 10.9 μm to 18.5 μm, the surface roughness was increased from 0.79 μm to 1.27 μm, the area ratio of volcano-like microstructure was increased from 55.6% to 59.6%, the volcano-like density was decreased from 2620 mm−2 to 1420 mm−2, and the γ-alumina phase was decreased from 66.6 wt.% to 26.2 wt.%, while the α-alumina phase was increased from 3.9 wt.% to 27.6 wt.%. The sillimanite and cristobalite phases were around 20 wt.% and 9 wt.%, respectively, for 10.94 A/dm2 and approximately constant around 40 wt.% and less than 5 wt.%, respectively, for the anodic current densities 14.58, 21.88, and 43.75 A/dm2. The ceramic surface roughness and thickness slightly enhanced the IR emissivity in the semitransparent region (4.0–7.8 μm), while the existing phases contributed together to raise the emissivity in the opaque region (8.6–16.0 μm) to higher but approximately the same emissivities.

An elevated temperature infrared emissivity ceramic coating formed on 2024 aluminium alloy by microarc oxidation

2013 ◽  
Vol 39 (3) ◽  
pp. 2869-2875 ◽  
Author(s):  
Y.M. Wang ◽  
H. Tian ◽  
X.E. Shen ◽  
L. Wen ◽  
J.H. Ouyang ◽  
...  
Keyword(s):  
Elevated Temperature ◽  
Aluminium Alloy ◽  
Ceramic Coating ◽  
Microarc Oxidation ◽  
Infrared Emissivity

Study On the Corrosion Resistance Properties of the Ceramic Coating Obtained Through Microarc Oxidation on the Aluminium Alloy Surface

2007 ◽  
Vol 353-358 ◽  
pp. 1733-1736 ◽  
Author(s):  
Fei Chen ◽  
Hai Zhou ◽  
Chen Chen ◽  
Fan Xiu Lu ◽  
Fan Xiu Lu
Keyword(s):  
Corrosion Resistance ◽  
Aluminium Alloy ◽  
Ceramic Coating ◽  
Microarc Oxidation ◽  
Electrochemical Corrosion ◽  
Nacl Solution ◽  
X Ray Diffraction ◽  
Micro Arc Oxidation ◽  
Coating Formation ◽  
Α Al2o3

Oxidation ceramic coating was directly synthesized on LY12 aluminium alloy by micro-arc oxidation (MAO) process in Na2SiO3 electrolyte solution with the Na2WO4-KOH-Na2EDTA addition. The corrosion resistance of the coating was tested using CS300P electrochemical corrosion workshop in 3.5% NaCl solution. Using the scanning electron microscopy (SEM) and X-ray diffraction (XRD), the cross-section microstructure, the surface morphology and the phase structure of the micro-arc oxidation ceramic coating were analyzed. The results showed that the corrosion resistance of the micro-arc oxidation ceramic coating in 3.5% NaCl solution was enhanced remarkably, the corrosion velocity was obviously slowed down. The thickness of micro-arc oxidation ceramic coating was about 11μm. The final phases in the coating were found to be α-Al2O3 and γ-Al2O3. The mechanism of the oxidation ceramic coating formation was investigated too.

Friction and Wear Behavior of Micro-Arc Oxidation Ceramic Coating on Pure Magnesium Surfaces

2011 ◽  
Vol 228-229 ◽  
pp. 661-665
Author(s):  
Fei Chen ◽  
Hai Zhou ◽  
Fan Xiu Lv
Keyword(s):  
Friction And Wear ◽  
Ceramic Coating ◽  
Wear Behavior ◽  
Microarc Oxidation ◽  
Pure Magnesium ◽  
Dry Sliding ◽  
Friction And Wear Behavior ◽  
Ceramic Oxide ◽  
Adhesion Wear ◽  
Micro Arc Oxidation

A relatively new process called microarc oxidation (MAO), also called plasma electrolytic oxidation (PEO), has emerged as a unique technique to produce hard, thick ceramic oxide coatings on different Mg or Al alloys. The magnesium offers various possibilities of application in industry, but its poor property in corrosion resistance, wear resistance, hardness and so on, limited its application. Through microarc oxidation, ceramic coating is directly formed on the surface of pure magnesium, by which its surface property is greatly improved. In this paper, a dense ceramic oxide ceramic coating was prepared on the magnesium by microarc oxidation in a Na2SiO3-Na2WO4-KOH-Na2EDTA electrolytic solution. The surface morphology of the coating was observed by the Scanning Electron Microscope (SEM). Using the X-ray diffraction (XRD), the phase structure of the coating was analyzed. The friction and wear behavior of the micro-arc oxidation ceramic coating under dry sliding against GCr15 steel was evaluated on a ball-on-disc test rig. The results showed that the magnesium was characterized by adhesion wear and scuffing under dry sliding against the steel, while the surface micro-arc oxidation ceramic coating experienced much abated adhesion wear and scuffing under the same testing condition. The micro-arc oxidation ceramic coating showed good friction-reducing and fair antiwear ability in dry sliding against the steel.

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