scholarly journals The Morphology Analysis of Plasma-Sprayed Cast Iron Splats at Different Substrate Temperatures via Fractal Dimension and Circularity Methods

2019 ◽  
Vol 38 (2019) ◽  
pp. 692-698
Author(s):  
Qiulan Wei ◽  
Li He ◽  
Zhang Liu ◽  
Xiao Feng ◽  
Ya-Zhe Xing
Keyword(s):  
Fractal Dimension ◽  
Cast Iron ◽  
Substrate Temperature ◽  
Solidification Rate ◽  
Molten Droplet ◽  
Characterization Methods ◽  
Different Temperatures ◽  
Molten Droplets ◽  
The Difference ◽  
Plasma Sprayed

AbstractPlasma-sprayed cast iron splats were deposited onto polished aluminum substrates preheated to different temperatures ranging from 25°C to 250°C. The morphology of single splat was observed by a field emission scanning electron microscope. Quantitative characterization methods, including fractal dimension (FD) and circularity analyses of the splat profile, were employed to identify the difference in morphology of the splats with the change of the substrate temperature. The results showed that the substrate temperature has a significant effect on the spreading of molten droplets and the morphology of resultant splats through changing the solidification rate of the droplets. With the increment of substrate temperature, the homogeneous and sufficient spreading of the droplets resulted from low solidification rate reduces the splashing of the droplets. In addition, the evaporation of adsorbed moisture on the substrate improves the wettability between the spreading droplet and the substrate, then benefits the homogeneous spreading of the molten droplet. As a result, a distinct decline in the FD value was observed. It was also suggested that the FD analysis could be used to characterize the morphology of the splat more effectively while the circularity method was heavily dependent on the area of the splat.

Formation of the Cast Iron Coatings Plasma-Sprayed at Different Substrate Temperatures

2010 ◽  
Vol 44-47 ◽  
pp. 2144-2147
Author(s):  
Ya Zhe Xing ◽  
Chao Ping Jiang ◽  
Hong Chen ◽  
Jian Min Hao
Keyword(s):  
Cast Iron ◽  
Substrate Temperature ◽  
Phase Structure ◽  
Processing Parameters ◽  
Optical Microscope ◽  
Atmospheric Plasma ◽  
Cross Sectional ◽  
The Cross ◽  
Plasma Sprayed ◽  
Iron Coatings

In this work, three cast iron coatings were produced by atmospheric plasma spraying. During spraying, the surface temperature of three coatings (substrate temperature) was controlled to be averagely 50oC, 180oC and 240oC by changing the processing parameters. X-ray diffraction (XRD) was employed to analyze the phase structure of the starting powder and the coatings. The results showed that the powder was mainly composed of (Fe,Cr)7C3 and martensite and both the spraying processing and the substrate temperature exerted no influence on coating phase structure. An optical microscope (OM) was used to characterize the microstructure of the cross-section and surface of the coatings. It was found that the cross sectional hardness increased with the increase of the substrate temperature due to the improvement in interlamellar bonding.

Influence of Substrate Temperature on Microcracks Formation in Plasma-Sprayed Yttria-Stabilized Zirconia Splats

2008 ◽  
Vol 373-374 ◽  
pp. 69-72 ◽  
Author(s):  
Ya Zhe Xing ◽  
Yong Li ◽  
Chang Jiu Li ◽  
Cheng Xin Li ◽  
Guan Jun Yang
Keyword(s):  
Substrate Temperature ◽  
Thermal Stresses ◽  
Initial Temperature ◽  
Crack Density ◽  
Crack Spacing ◽  
Stabilized Zirconia ◽  
Substrate Adhesion ◽  
Molten Droplets ◽  
Influence Of Substrate ◽  
Plasma Sprayed

YSZ molten droplets created by plasma spraying were deposited on the YSZ substrate preheated to different temperature from 75oC to 1000oC. The results showed that there is little change in crack spacing when substrate temperature is less than about 740oC, and a significant increase in crack spacing from 3.54 μm at 740oC to 10.91 μm at 1000oC was observed. A simple qualitative model was proposed on the basis of the origin of thermal stresses to explain the influence of substrate initial temperature on crack density characterized by crack spacing. The analysis indicates that the results can be ascribed to the changes in tensile stress and splat/substrate adhesion resulting from changes of substrate initial temperature.

Numerical Study on Rapid Solidification of a Plasma-Sprayed Cast Iron Splat on a High-Temperature Substrate

2009 ◽  
Vol 79-82 ◽  
pp. 1129-1132 ◽  
Author(s):  
Ya Zhe Xing ◽  
Qiu Lan Wei ◽  
Jian Min Hao ◽  
Can Shang
Keyword(s):  
Cast Iron ◽  
Substrate Temperature ◽  
Rapid Solidification ◽  
Numerical Study ◽  
Substrate Surface ◽  
Melt Temperature ◽  
Metallurgical Bonding ◽  
Initial Substrate ◽  
Plasma Sprayed ◽  
Iron Coatings

In this work, an experiment was performed to demonstrate the possibility of the metallurgical bonding in plasma-sprayed cast iron coatings at high substrate temperature. A quantitative analysis of splat cooling and rapid solidification of cast iron splat is then presented. The effect of the substrate temperature on the development of melt undercooling within the splat is investigated in detail. The results indicated that the initial substrate temperature has a profound effect on the development of melt undercooling in a splat, the splat bottom melt temperature, and the substrate surface temperature. A high initial temperature of the substrate restrains the cooling of the splat and leads to a high melt temperature that may promote the grain growth directly on cast iron substrate surface to form the metallurgical bonding.

Substrate temperature dependence of splat morphology for plasma-sprayed cast iron on aluminum surface

2015 ◽  
Vol 283 ◽  
pp. 234-240 ◽  
Author(s):  
Ya-Zhe Xing ◽  
Xing-Hang Li ◽  
Qiang Wang ◽  
Yong Zhang ◽  
Xu-Ding Song
Keyword(s):  
Cast Iron ◽  
Substrate Temperature ◽  
Temperature Dependence ◽  
Aluminum Surface ◽  
Splat Morphology ◽  
Plasma Sprayed

scholarly journals The Respiration of some Planktonic copepods II. The Effect Of Temperature

1953 ◽  
Vol 31 (3) ◽  
pp. 447-460 ◽  
Author(s):  
D. T. Gauld ◽  
J. E. G. Raymont
Keyword(s):  
Respiratory Rate ◽  
The Body ◽  
The Other ◽  
Effect Of Temperature ◽  
Acartia Clausi ◽  
Temora Longicornis ◽  
Different Temperatures ◽  
Planktonic Copepods ◽  
The Difference ◽  
The Relationship

The respiratory rates of three species of planktonic copepods, Acartia clausi, Centropages hamatus and Temora longicornis, were measured at four different temperatures.The relationship between respiratory rate and temperature was found to be similar to that previously found for Calanus, although the slope of the curves differed in the different species.The observations on Centropages at 13 and 170 C. can be divided into two groups and it is suggested that the differences are due to the use of copepods from two different generations.The relationship between the respiratory rates and lengths of Acartia and Centropages agreed very well with that previously found for other species. That for Temora was rather different: the difference is probably due to the distinct difference in the shape of the body of Temora from those of the other species.The application of these measurements to estimates of the food requirements of the copepods is discussed.

scholarly journals Effect of tillage, slope, and rainfall on soil surface microtopography quantified by geostatistical and fractal indices during sheet erosion

2020 ◽  
Vol 12 (1) ◽  
pp. 232-241
Author(s):  
Na Ta ◽  
Chutian Zhang ◽  
Hongru Ding ◽  
Qingfeng Zhang
Keyword(s):  
Surface Roughness ◽  
Fractal Dimension ◽  
Soil Surface ◽  
Rainfall Events ◽  
Tillage Practices ◽  
Surface Microtopography ◽  
Artificial Rainfall ◽  
Soil Surface Roughness ◽  
The Difference ◽  
Sheet Erosion

AbstractTillage and slope will influence soil surface roughness that changes during rainfall events. This study tests this effect under controlled conditions quantified by geostatistical and fractal indices. When four commonly adopted tillage practices, namely, artificial backhoe (AB), artificial digging (AD), contour tillage (CT), and linear slope (CK), were prepared on soil surfaces at 2 × 1 × 0.5 m soil pans at 5°, 10°, or 20° slope gradients, artificial rainfall with an intensity of 60 or 90 mm h−1 was applied to it. Measurements of the difference in elevation points of the surface profiles were taken before rainfall and after rainfall events for sheet erosion. Tillage practices had a relationship with fractal indices that the surface treated with CT exhibited the biggest fractal dimension D value, followed by the surfaces AD, AB, and CK. Surfaces under a stronger rainfall tended to have a greater D value. Tillage treatments affected anisotropy differently and the surface CT had the strongest effect on anisotropy, followed by the surfaces AD, AB, and CK. A steeper surface would have less effect on anisotropy. Since the surface CT had the strongest effect on spatial variability or the weakest spatial autocorrelation, it had the smallest effect on runoff and sediment yield. Therefore, tillage CT could make a better tillage practice of conserving water and soil. Simultaneously, changes in semivariogram and fractal parameters for surface roughness were examined and evaluated. Fractal parameter – crossover length l – is more sensitive than fractal dimension D to rainfall action to describe vertical differences in soil surface roughness evolution.

Synthesis of Polyurethane Dendrimers and Transfer Properties of Dye

2013 ◽  
Vol 457-458 ◽  
pp. 65-71
Author(s):  
Jing Ru Jia
Keyword(s):  
Methyl Orange ◽  
Phase Transfer ◽  
Raw Materials ◽  
Toluene Diisocyanate ◽  
Polymerization Process ◽  
Process Conditions ◽  
Addition Polymerization ◽  
Different Temperatures ◽  
The Difference ◽  
Transfer Properties

The polyfunctional organic compounds 2- hydroxymethyl -1,4- butanediol (trihydric alcohol) and toluene diisocyanate -2, 4- diisocyanate (TDI) were taken as the raw materials in this study. A polyurethane dendrimer was synthesized by utilizing the difference in the reaction activity of two isocyanate groups of TDI at different temperatures. The polymerization process conditions were studied. The addition polymerization of para-position NCO groups occurred at 50 °C, and that of ortho NCO groups occurred at 90 °C. According to the structure of the dendrimer synthesized, methyl orange was used as the guest molecule. Consequently, the aqueous methyl orange showed a phase transfer. With the increase of dendrimer concentration, the transfer rate of methyl orange increased.

Simultaneous Independent Measurement of Splat Diameter and Cooling Time during Impact on a Substrate of Plasma Sprayed Molybdenum Particles

1997 ◽  
Author(s):  
P. Gougeon ◽  
C. Moreau
Keyword(s):  
High Speed ◽  
Thermal Emission ◽  
Particle Temperature ◽  
Cooling Time ◽  
Spray Parameters ◽  
Coating Structure ◽  
Molten Droplets ◽  
Plasma Sprayed ◽  
The Impact ◽  
Molybdenum Particles

Abstract In thermal spray processes, the coating structure is the result of flattening and cooling of molten droplets on the substrate. The study of the cooling time and evolution of the splat size during impact is then of the highest importance to understand the influence of the spray parameters and substrate characteristics on the coating structure. Measurement of particle temperature during impact requires the use of a high-speed 2-color pyrometer to collect the thermal emission of the particle during flattening. Simultaneous measurement of the splat size with this pyrometer is difficult since the size of the particle can change as it cools down. To measure the splat size independently, a new measurement technique has been developed. In this technique the splat size is measured from the attenuation of the radiation of a laser beam illuminating the particle during impact. Results are presented for plasma sprayed molybdenum particles impacting on a glass substrate at room temperature. It is shown that the molybdenum splat reaches its maximum extent about 2 microseconds after the impact. In this work, we show that this increase of the splat surface is followed by a phase during which the splat size decreases significantly during 2 to 3 microseconds.

scholarly journals V. Electrolytic conduction in solids.—First example. hot glass

1875 ◽  
Vol 23 (156-163) ◽  
pp. 463-464 ◽  
Keyword(s):  
Different Temperatures ◽  
The Difference ◽  
Voltaic Cell

Many years ago I projected an experiment to test the voltaic relations between different metals with glass substituted for the electrolytic liquid of an ordinary simple voltaic cell, and with so high a temperature that the glass would have conducting-power sufficient to allow induction through it to rule the difference of potentials between the two metals. Imperfect instrumental arrangements, and want of knowledge of the temperature at which glass would have sufficient conductivity to give satisfactory results, have hitherto prevented me from carrying out the proposed investigation. The quadrant electrometer has supplied the first of these deficiencies, and Mr. Perry’s recent experiments on the conductivity of glass at different temperatures the second. The investigation has now been resumed; and in a preliminary experiment I have already obtained a very decided result.

Formation of Grain Structures of Thermal Sprayed Nickel Coatings and the Coating Properties

2005 ◽  
Vol 502 ◽  
pp. 517-0
Author(s):  
Kenji Murakami
Keyword(s):  
Steel Substrate ◽  
Nickel Coatings ◽  
Grain Structures ◽  
Heat Treated ◽  
Columnar Grains ◽  
Different Temperatures ◽  
Plasma Sprayed ◽  
Equiaxed Grains ◽  
Sprayed Coatings ◽  
Lamellar Interfaces

Pure nickel powder was low pressure plasma sprayed onto a steel substrate held at different temperatures during spraying. The as-sprayed coatings consist of columnar grains whose axes are nearly perpendicular to the lamellae composing the coatings. As the coating temperature becomes higher, the length of the columnar grains increases and is longer than the thickness of the lamellae, indicating the growth of the grains across the lamellar interfaces during spraying. On the other hand, the coatings that were heat treated after spraying consist of coarse equiaxed grains. The coatings that experienced high temperatures during spraying or the heat treated coatings have large porosity and contain large globular pores. The hardness, apparent density and the tensile strength of the coating itself were the highest for the coating prepared at a low temperature and became low on heat treatment. The thermal conductivity in the direction perpendicular to the coating was the largest for the coating that consisted of long columnar grains.

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