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Abstract:
This paper presents technological trials aimed at producing Ag-W, Ag-WC, Ag-W-C and Ag-WC-C composite contact materials and characterizing their properties. These materials were obtained using two methods, i.e. press-sinter-repress (PSR) at the refractory phase content of less than 30% by weight as well as press-sinter-infiltration (PSI) at the refractory phase content of ≥50% by weight). The results of research into both the physical and electrical properties of the outcome composites were shown. They include the analysis of the influence of the refractory phase content (W or WC) on arc erosion and contact resistance changes for the following current range: 6 kAmax in the case of composites with a low refractory phase content, 10 kAmax in the case of composites with the refractory phase content of ≥50% by weight.

Keywords:
composite materials, electrical contacts, arc erosion, contact resistance

Abstract:
This paper presents the manufacturing method of silver based composite materials containing 3 % vol. carbon forms (nanotubes and graphene). The most significant challenge was to obtain good dispersion of carbon in the metallic matrix. The applying of suitable dispersants allows to get uniform distribution of carbon reinforcement. Triton X-100 and ultrasonic support were used in the powder mixing process. Ag-nanotubes and Ag-graphene contact tips were made using Spark Plasma Sintering process (SPS). The results of research into both physical and electrical properties of these composites are presented. It has been demonstrated that the form of introduced carbon exerts influence on the electrical characteristics of contacts, and particularly on arc erosion. Performed electrical test indicated that Ag-nanotubes contacts showed higher resistance to arc erosion than Ag-graphene contacts. It can be explained by the better dispersion to individual carbon nanotubes their lower than for graphene edge defects density and due to this higher thermal and electrical conductivity.

Keywords:
composite materials, silver-nanotubes, silver-graphene, arc erosion, contact resistance

Abstract:
The main current of publication is focused around the issues and problems associated with the formation of composite materials with Cu matrix and reinforcing phases in the various carbon nanoforms. The core of the research has been focused on thermal conductivity of these composites types. This parameter globally reflects the state of the structure, quality of raw materials and the technology used during the formation of composite materials. Vanishingly low affinity of copper for carbon, multilayered forms of graphene, the existence of critical values of graphene volume in the composite are not conducive to the classic procedures of composites designing. As a result, the expected, significant increase in thermal conductivity of composites is not greater than for pure copper matrix. Present paper especially includes: (i) data of obtaining procedure of copper/graphene mixtures, (ii) data of sintering process, (iii) the results of structure investigations and of thermal properties. Structural analysis revealed the homogenous distribution of graphene in copper matrix, the thermal analysis indicate the existence of carbon phase critical concentration, where improvement of thermal diffusivity to pure copper can occur

Keywords:
metal matrix composite, sintering, copper, graphene, thermal diffusivity