Papers by Author: Marin Gavrila

Abstract: In this paper are presented the experimental results regarding the elaboration of electrical contacts using W-Cu composite powders obtained by mechanical alloying (MA) process. For the research commercial powders with a particle size between [10-80] µm were used. Three types of mixtures with different concentrations as follow: 90W-10Cu; 80W-20Cu; 70W-30Cu were mechanically alloyed for 2 up to 6 hours using a planetary ball mill. The mixtures obtained after MA process were pressed in a cylindrical die at 400 respective 600 MPa. The evolution of green densities function the compaction pressure and Cu content was studied. The green billets were sintered in an electrical furnace at 1180 oC and maintained 60 minutes at the sintering temperature in argon atmosphere. The evolution of densities, microstructures and electrical properties of the sintered samples function the Cu content and compaction pressure were studied.

Abstract: This paper presents a study about the influence of some alloying elements like Ni and Co on the elaboration of W-Cu electrical contacts. For the experimental work four types of mixture were prepared using mechanical alloying (MA) technique for six hours. All the samples had the same Ni and Co content (2%) varying the W content as following: 88W-10Cu-Ni, 78W-20Cu-Ni, 68W-30Cu-Ni, 88W-10Cu-Co, 78W-20Cu-Co and 68W-30Cu-Co. The mixtures were pressed in a cylindrical die with 10 mm diameter at two pressures: 400MPa and 600 MPa. The sintering process was carried out in an electrical furnace at the 1180 OC and maintained at this temperature for three hours. For all the samples the electrical properties: resistivity, conductivity, resistance were measured and were made correlation between electrical contacts with Ni and the other with Co. It is observed that, the compaction pressure influence the electrical properties and better properties are obtained for the samples compacted at 600 MPa.