Papers by Author: Oana Gîngu

Abstract: This research focuses on Ag-Cu powder particles processing by mechanical alloying (MA) route. The powder mixture is representative for the eutectic composition, respectively 72%wt. Ag + 28% wt. Cu. The milling process is developed in high energy ball mill Pulverisette 6, using different size for the milling balls, in wet conditions for 80 hours. One of the most important parameter studied in this research is the particle size distribution of the processed powder mixture. Thus, it changes along the milling time, from 10…75 µm at the beginning of MA process up to (60 – 80) nm at 80 h. The milling parameters will be optimized in future research depending on the particle size distribution related with thermophysical and thermodynamic properties focused on electrical and optical properties improvement.

Abstract: The objective of this research is the development of a detailed structural analysis of biocomposites with ceramic matrix of hydroxyapatite (Hap) reinforced by titanium (Ti), elaborated by powder metallurgy technology. Nanometric Hap powders (<200nm) 75% wt and micrometric Ti powders (<150μm) are homogenized in a high energy ball mill Pulverisette 6. Spark plasma sintering (SPS) is the sintering route able to lead to nanostructured sintered samples when nanopowders are used as raw material. The SPS parameters are: the sintering temperature, T=(1000-1100)°C and the maintaining time, t=(10-20) minutes in vacuum. The influence of the sintering parameters on the composites structures is monitored using the optical microscopy (OM), electronic microscopy (SEM) and the X-Ray diffraction (XRD).

Abstract: The paper presents the experimental results regarding the influence of the reinforcing elements on the wear behavior of Al-matrix composites discontinuously reinforced by SiC and Graphite. This antifriction composite material is processed by Reactive Mechanically Alloyed and then by Spark Plasma Sintering technology. In order to optimize the processing technology, especially the sintering parameters, the Spark Plasma Sintering process was applied because of its advantageous aspects: lower sintering temperatures, shorter sintering time and higher properties values of the sintered material vs. the corresponding ones obtained by the classical sintering route. The authors realized a comparative analysis on the wear behavior of the researched composite materials.