scholarly journals Testing of Sinters Made of Copper Powders Coated with Carbon Structure Containing Graphene

2021 ◽  
Vol 12 (2) ◽  
pp. 75-90
Author(s):  
Kamil RAJKOWSKI ◽  
Tomasz MAJEWSKI
Keyword(s):  
Powder Mixture ◽  
Copper Powder ◽  
Brinell Hardness ◽  
Optical Microscope ◽  
Cold Isostatic Pressing ◽  
Powder Mixtures ◽  
Copper Powders ◽  
Tap Density ◽  
Process Measurements ◽  
Made In

This paper presents the results of preliminary tests on specimens made from mixtures of dendritic copper powder (CuE) with the graphene-coated copper powder (CuG) in a range from 20% to 100% (CuG). The properties of the powder mixtures, green compacts and sinters were determined. To study the properties of the powder mixtures, the following tests were carried out: a measurement of the CuG powder grain size after the grinding process, measurements of the bulk density and tap density of the prepared powder mixtures. The porosity of the produced green compacts and the sinters was calculated as well as the densification capabilities of the powder mixtures by die pressing, cold isostatic pressing and sintering in a reducing atmosphere were tested. Moreover, the nature of the porosity formation was analysed using an optical microscope and the Brinell hardness was determined. The measured Brinell hardness was in the range of 17 HB for sinters made from CuG to 34 HB for sinters made from a 20% CuG powder mixture. More than six hundred measurements that were made in this study show that the high CuG content in the powder mixture reduce the hardness of the sinters as well increase their porosity.

Experimental Study of High Velocity Oxygen Fuel Sprayed Cr3C2- Ni-Cr-B-Si Coatings on Inconel 718 Using Design of Experiments

2019 ◽  
Vol 969 ◽  
pp. 48-54 ◽  
Author(s):  
R. Shankar ◽  
K.R. Balasubramanian ◽  
S.P. Sivapirakasam
Keyword(s):  
Design Of Experiments ◽  
Powder Mixture ◽  
High Velocity ◽  
Inconel 718 ◽  
Optical Microscope ◽  
Mixture Design ◽  
High Velocity Oxygen Fuel ◽  
Powder Mixtures ◽  
Hardness Tester ◽  
Oxygen Fuel

In the present study, D-optimal based mixture design of experiments (DoE) is used to find the optimum powder mixture for High Velocity Oxygen Fuel (HVOF) coating. Twenty five experimental trials are performed by varying the powder mixtures based on mixture design. Cr3C2, Ni, Cr, B, Si powder mixtures are deposited on Inconel 718 substrate by HVOF process.The responses porosity and hardness are determined by the cross-sectioning the specimens.The effect of powder mixtures on coated samples are characterized by X-ray diffraction, optical microscope, Vickers hardness tester and Scanning electron microscope.The optimal powder mixture is determined to obtain minimum porosity and maximum hardness and the confirmatory experiment confirms with the predicted results. From the analysis it is observed that Cr3C2, Ni and Cr are the major factor which influences the porosity and hardness followed by B and Si respectively.

scholarly journals Малогазовая детонация в низкоплотных механоактивированных порошковых смесях

2019 ◽  
Vol 89 (6) ◽  
pp. 821
Author(s):  
С.А. Рашковский ◽  
А.Ю. Долгобородов
Keyword(s):  
Experimental Data ◽  
Shock Wave ◽  
Energy Release ◽  
Powder Mixture ◽  
Powder Compaction ◽  
Mutual Friction ◽  
Low Density ◽  
Powder Mixtures ◽  
Release Wave ◽  
Fuel Particles

Experimental data on supersonic self-sustaining propagation of the energy release wave in low-density mechanically activated powder mixtures are analyzed. Various mechanisms that may be responsible for this process are analyzed, and a mechanism for the detonation-like propagation of the reaction in powder mixtures is proposed. It is shown that under certain conditions this process has all the signs of detonation and should be recognized as one of the types of detonation. It is shown that this type of detonation is fundamentally different from the classical "ideal" detonation, for example, in gases: instead of a shock wave, a compaction wave propagates through the powder mixture, in which there is basically no compression of the particle material, but powder compaction occurs due to the mutual rearrangement of particles. In this case, the initiation of a chemical reaction occurs due to the mutual friction of the oxidizer and fuel particles in the powder compaction wave.

scholarly journals Physical modeling of representative particles of electrodeposited copper powders

2006 ◽  
Vol 71 (4) ◽  
pp. 397-400 ◽  
Author(s):  
Konstantin Popov ◽  
Nebojsa Nikolic ◽  
Snezana Krstic ◽  
Miomir Pavlovic
Keyword(s):  
Cross Sections ◽  
Copper Powder ◽  
Physical Modeling ◽  
Copper Powders

A method for the estimation of the size of the representative particle of a copper powder is given. Cross sections of representative particles of flowing and non-flowing powders estimated by this procedure are also presented.

Expansion Behavior of Iron-Copper Compact from (FeCu) Pre-Alloyed Powder

2007 ◽  
Vol 534-536 ◽  
pp. 517-520
Author(s):  
Youn Che Kim ◽  
Myung Jin Suk
Keyword(s):  
Copper Powder ◽  
Copper Content ◽  
Liquid Copper ◽  
Alloyed Powder ◽  
Maximum Expansion ◽  
Iron Copper ◽  
Expansion Behavior ◽  
Expansion Mechanism ◽  
Copper Powders ◽  
Powder Content

Dilatometric curves of iron-copper compact made from elemental or pre-alloyed powder were compared in order to study its expansion mechanism. The compacts from a mixture of elemental iron and copper powders showed the maximum expansion at the copper powder content of 7.44mass% and at the sintering temperatures above the copper melting-point. In the case of the compacts from a mixture of iron pre-alloyed powder of (Fe- 3.44mass%Cu) and copper powder, the maximum expansion which is lower than the former case was obtained at the additive copper powder content of 4.00mass%. But the compact from a mixture of iron pre-alloyed powder of (Fe-7.18mass%Cu) and copper powder showed only shrinkages at any additive copper powder content. The penetration of liquid copper into the interstices between solid grains was observed in all sintered compacts. The iron-copper compacts containing the same content of copper powder showed a very different expansion behavior depending on the amount of copper content in the starting iron raw powder.

scholarly journals Metallographical Aspects of the Application of Special Paint Layers for the Protection of Machine Part Sections against the Effect of lonitriding

2019 ◽  
Vol 290 ◽  
pp. 03002
Author(s):  
Marius Bibu ◽  
Florin Ciofu
Keyword(s):  
Copper Powder ◽  
Machine Part ◽  
Plasma Nitriding ◽  
Metallic Component ◽  
Copper Powders ◽  
Ionic Nitriding ◽  
Local Protection ◽  
Before And After ◽  
Gas Volume ◽  
Physical And Chemical

The paper presents aspects concerning the appreciation of the protection through special paints based on copper powders used against plasma nitriding. First of all the choice of copper is motivated as an important metallic component of protecting paints, with the characteristics that the copper presents in the context of the physical and chemical phenomena (from the cathode and from gas volume) specific for the ionic nitriding process. The paper contains comparatively some characteristics (the duration of drying on the coat, the compatibility of the components, the capacity of extension and of avoiding the leakage, the power of covering, the capacity of joining, and the emitting of gases, the resistance in friction before and after the ionic nitriding, the way of obtaining the copper powder and its quality, the capacity of removing after ionic nitriding etc.) of the mixtures, for the protection against ionic nitriding. Following the researches on making more efficient technologies of local protection of metal pieces on certain areas with isolated layers against plasma nitride, the authors realized 2 different kinds of special original paints noted V-1 and V-2 used for this purpose. These paints are made having a basis of copper powder combined with magnesium oxide and polystiren dissolved in carbon chloride.

Vacuum Repair Brazing of the Inconel 939 Superalloy

2008 ◽  
Vol 51 ◽  
pp. 71-78 ◽  
Author(s):  
D.K. Wang ◽  
H.C. Wu ◽  
R.K. Shiue ◽  
C. Chen
Keyword(s):  
Chemical Composition ◽  
Oxide Film ◽  
Oxidation Resistance ◽  
Powder Mixture ◽  
Eutectic Temperature ◽  
Early Stage ◽  
Isothermal Solidification ◽  
Catastrophic Failure ◽  
Powder Mixtures ◽  
Residual Melt

Vacuum repair brazing of Inconel 939 using various ratios of DF3 and Rene 80 powder mixtures has been performed in this study. The porosity of the brazed zone is decreased as the amount of DF3 is increased in the powder mixture. At least four phases are observed in the brazed zone including chromium borides, sparse carbides, Ni-rich matrix and eutectic phases. Primary chromium borides are widely observed at the early stage of repair brazing. Dissolution of the Ni from the Rene 80 powder into the molten braze results in isothermal solidification of the residual melt. The chemical composition of the residual melt subsequently moves towards the lowest eutectic temperature, and the eutectic is finally formed in brazing. The oxidation resistance test is performed at 1000oC. Extensive spalling of the oxide film begins at 144 h, and catastrophic failure of the oxide film is observed at 1272 h. The oxidation resistance of the brazed zone is significantly degraded due to the formation of chromium borides in the brazed zone.

Liquid-phase sintering of very fine tungsten-copper powder mixtures

1982 ◽  
Vol 21 (6) ◽  
pp. 447-450 ◽  
Author(s):  
V. V. Panichkina ◽  
M. M. Sirotyuk ◽  
V. V. Skorokhod
Keyword(s):  
Liquid Phase ◽  
Copper Powder ◽  
Liquid Phase Sintering ◽  
Powder Mixtures ◽  
Fine Tungsten

scholarly journals Experimental model of the morphological and morphometric aspects of tissue repair in skin wounds submitted to beta radiation emitted by Strontium -90 in rats

2004 ◽  
Vol 19 (suppl 1) ◽  
pp. 51-58
Author(s):  
Gerson Vilhena Pereira Filho ◽  
José Mario Camelo-Nunes ◽  
Fabrício Yui
Keyword(s):  
Experimental Model ◽  
Optical Microscope ◽  
Beta Radiation ◽  
Daily Group ◽  
Morphometrical Analysis ◽  
Strontium 90 ◽  
Group A ◽  
Group B ◽  
And Control ◽  
Made In

The purperose of this work is tell the use of the experimental model to investigation of the effects of Beta radiation of estroncium-90 for repairing the tissue of wounds made in rats. 48 animals of the lineage EPM-1 Wistar were used, distributed in two groups that received radiation in alternate days (group A) and daily (group B). Each group was divided in four groups of six rats to be analysed in the 3rd, 7th, 14th and 21st day after operation. Two incisions were made in the back of the animal and sutured immediately afterwards; the upper part was irradiated and the lower part used as control. On the dates established the irradiated and control wounds were macroscopically examined and withdrawn for preparation of the histological comparative study in the optical microscope. Following, an morphometrical analysis was performed to count leucocyts, fiberblast and colagen fibers which were submitted to statistical study.

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