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Microstructural, electrical, thermal and tribological studies of copper-fly ash composites through powder metallurgy

Thanga_Kasi_Rajan S., Balaji A. N., Narayanasamy P., Vettivel S. C.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2018

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Vol. 66, nr 6

935--940

EN

This research work address the fabrication of copper (Cu) matrix composites, reinforced with fly ash (FA) particulates with 3, 6, 9 and 12 wt.% using the powder metallurgy route. The microstructural, physical, electrical, thermal, mechanical and tribological properties of thus fabricated Cu-FA composites have been studied. Optical microstructural characterization of the composites exposed persuasively uniform distribution of FA reinforcement with minimum porosity. The mixed powder SEM images revealed the homogeneous dispersion of fly ash particulates in the copper matrix. The hardness values showed improvement with increase in the weight percentage of FA in the Cu matrix. Electrical conductivity was measured using the four-point probe method at room temperature. Thermal conductivity was measured with a thermal diffusivity analyzer at room temperature. The fly ash addition leads to weakening the conductivity of Cu-FA composites. The tribological properties of Cu-FA composite specimens were investigated using a Pin-on-disc tribo testing machine against an EN81 steel contour disc. The specific wear rate of the composites tended first to decrease, which was attributed mainly to the formation of a mechanically mixed layer on the worn surface. Then it would increase as the FA content increased because of reduction in ductility and brittle oxide cracks associated with adding more FA particulates. It seems that composites with FA percentages below 9wt.% have optimum properties of microstructure, hardness and wear resistance, which is suitable for applications such as electrical sliding contacts, electrical discharge machining and spot welding electrodes.

2

Effect of B4C Reinforcement on the Dry Sliding Wear Behaviour of Ti-6Al-4V/B4C Sintered Composites Using Response Surface Methodology

Ramkumar T., Narayanasamy P., Selvakumar M., Balasundar P.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 3

1179--1200

EN

The present investigation has been made to assess the influence of B4C reinforced with Ti-6Al-4V matrix prepared by powder metallurgy route. High energy ball milling was used to prepare the composites. Cylindrical preforms were prepared using suitable die set assembly. The green preforms were sintered in the muffle furnace at 900°C for 1h. Further the preforms were cooled inside the furnace till the room temperature has attained. SEM with EDS mapping analysis was used to evaluate the morphology and elemental confirmation of the prepared composite. The density and hardness of the samples are determined using Archimedes principle and Rockwell hardness testing machine. The wear resistance of the samples was determined by employing a pin on disc apparatus. The hardness of the composites (Ti-6Al-4V /10B4C) was increased while comparing to the base material (Ti-6Al-4V) which is attributed to the presence of hard ceramic phase. Response Surface Methodology (RSM) five level central composite design approach was accustomed and it minimised the amount of experimental conditions and developed mathematical models among the key process parameters namely wt. % of B4C, applied load and sliding distances to forecast the abrasive response of Specific Wear Rate (SWR) and Coefficient of Friction (CoF). Analysis of variance was used to check the validity of the developed model. The optimum parameters of specific wear rate and coefficient of friction were identified.

3

Proactive network security event management using mobile agents

Narendran G., Vimal Jebaraj G.N., Sugesh Kumar R., ILayaraja R., Narayanasamy P.

Studia Informatica

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2003

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Vol. 24, nr 2B

107-116

EN

This paper introduces a novel implementation of an upcoming paradigm in network security. The Network Security Event Management paradigm aims at detecting events in the network and correlating them with attacks, so that the attacks can be prevented even from being successfully attempted. The use of mobile agent technology provides distinctive advantages over client-server architecture and the use of an expert system adds to the intelligent analysis and correlating capabilities of the system. The event management paradigm has been successfully implemented by integrating the modules of Network Monitor, Network Traffic Analyzer and an Expert System for intelligent decision making. This system provides with various advantages over traditional network security tools in manners that, this system detects and acts on pre-attack postures itself, reduces the network traffic by transporting the know-how to the client itself. Other advantages include intelligent analysis and correlation of events, flexible reporting, automated alerting and preventive action enabling.

PL

Artykuł przedstawia implementację nowej polityki bezpieczeństwa w sieci, polegającej na wykrywaniu zdarzeń w sieci i ustalaniu ich korelacji z występującymi atakami, co pomaga zapobieżeniu tych ataków. Wykorzystanie technologii ruchomych agentów przynosi znaczne korzyści w stosunku do architektury klient-serwer, a zastosowanie systemu eksperckiego wspiera inteligentną analizę zdarzeń i ustalanie korelacji. System zarządzania zdarzeniami jest realizowany poprzez integracje modułów Monitora Sieci, Analizatora Ruchu i Systemu Eksperckiego. Niektóre zalety opisywanego systemu w stosunku do tradycyjnych narzędzi zabezpieczających sieć to możliwość uprzedzania ataków, zmniejszenie natężenia ruchu w sieci poprzez przeniesienie niezbędnej wiedzy na poziom użytkownika, inteligentna analiza i korelacja zdarzeń, raportowanie dostosowane do indywidualnych potrzeb, automatyczne alarmowanie i podejmowanie akcji zapobiegawczych.