Investigation of the Effect of Different Current Loads on the Arc-Erosion Performance of Electrical Contacts

Aydın

2017

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In this study, Ag-based SnO2-reinforced electrical contact materials were produced by powder metallurgy and mechanical alloying techniques. Elemental powder mixture containing 8 wt.% SnO2 was milled in a highenergy planetary-type ball mill, to achieve homogeneously mixed composite powder, and subsequently pressed in a closed die to obtain green compacts with a cylindrical shape and then sintered under vacuum to obtain composites. Composites were then subjected to electrical wear tests under inductive loads to investigate the arc-erosion performance of electrical contacts. Surface deterioration and mass losses of electrical contacts were also evaluated, as a function of increasing switching number. Characterization of the starting and composite powders, green compacts, composites and arc-originated surface deterioration was carried out using scanning electron microscopy and energy-dispersive X-ray spectroscopy. It was found that powder particle size had decreased with the increasing milling time. Density and hardness values of the composites had increased, whereas porosity had decreased with the increasing sintering temperature. Optimum sintering temperature was determined as 900The arc-affected zones became bigger with the increase of the number of switching operations. Furthermore, comparison between surface morphologies and mass losses of arc-eroded specimens had revealed that the stationary contacts exhibit higher rates of erosion than the movable contacts.

Section: Methodsmentioning

confidence: 99%

Fabrication and Arc-Erosion Behavior of Ag8SnO₂ Electrical Contact Materials under Inductive Loads

Aydın

2017

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“…PCAs are basically used to establish a balance between cold welding and fracturing events and the non-use of the PCAs leads excessive cold welding which inhibits further size reduction, especially in compositions containing a substantial fraction of ductile component. Much work has been done towards producing and evaluating the electrical performances of contact materials [6][7][8][9][10][11][12][13][14][15]. However, studies regarding the type of PCA on the characterization of composite powders containing noble metals, especially silver are very limited.…”

Section: Introductionmentioning

confidence: 99%

Influence of Type of Process Control Agent on the Synthesis of Ag8ZnO Composite Powder

2019

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In this study, the effect of different types of process control agents on the particle size and morphology of Ag8ZnO composite powder was investigated. For this purpose, commercial elemental silver and zinc oxide powders were initially mixed with different types of process control agents and then milled in a two stationary planetarytype ball mill with a ball-to-powder weight ratio of 10:1 and a milling speed of 300 rpm. The usage of process control agents is advantageous to eliminate or minimize agglomeration and to decrease the tendency of excessive cold welding among powder particles. However, contamination from the process control agent essentially leads to interstitial contamination, since the process control agents used are mostly organic compounds containing carbon, oxygen, and nitrogen. Hence, it is of importance to investigate the nature of PCA and milling duration that both influence the performance of electrical contacts. Characterization of starting and ball-milled powders was investigated using scanning electron microscopy and laser diffraction analysis. It was found that final powder particle sizes significantly affected by the nature of process control agent. Besides, morphology of powders and microstructural analyses prove that the type of process control agent is also crucial in obtaining homogeneous mixture of the constituent powder particles.

“…Electrical contacts have a major influence on the electrical performance and reliability of electromagnetic switches, such as relays and contactors [1]. The contact surfaces can deteriorate with increasing number of switching operations due to the arc-originated overheating and substantial material losses [2,3]. These situations may eventually result in failure of electrical contacts, and therefore they must be minimized by compositional arrangements and/or production methods [4].…”

Section: Introductionmentioning

confidence: 99%

Effect of Polyethylene Glycol on the Mechanical Alloying Behavior of Cu-W Electrical Contact Material

2018

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In this study, the effect of polyethylene glycol on the particle size and morphology of Cu25W composite powder was investigated. For this purpose, commercial elemental copper and tungsten powders were milled in a planetary-type ball mill. Milling conditions, namely ball-to-powder weight ratio and milling speed, were selected to be 10:1 and 300 rpm, respectively. In order to avoid agglomeration and to decrease the tendency of cold welding among powder particles, polyethylene glycol at the amount of 2 wt% was used as a process control agent. Morphological evolution of milled powders was investigated using scanning electron microscopy. In addition, the variation of particle size as a function of milling duration was examined using laser diffraction analysis. It was found that powder particle size gradually decreased with increasing milling duration. However, compared to the powder mixture without the process control agent, the powder mixture containing polyethylene glycol tends to lower the milling duration to achieve the same amount of particle size reduction. As a result of this effort, the usage of polyethylene glycol as a process control agent was found to be effective to obtain a composite powder with smaller particle sizes, especially in the earlier stages of milling process.