Processing and Properties of ZrB2-Copper Matrix Composites Produced by Ball Milling and Spark Plasma Sintering

Abstract

Copper matrix composites with zirconium diboride (ZrB2) were synthesised by ball milling and consolidated by Spark Plasma Sintering (SPS). Characterisations of the ball-milled composite powders were performed by scanning electron microscopy (SEM), X-ray diffraction, and measurement of the particle size distribution. The effect of the sintering temperature (1123 K, 1173 K, and 1223 K) and pressure (20 MPa and 35 MPa) on the density, porosity, and Young’s modulus was investigated. The relationship between the change of Orb content and physical, mechanical, and electrical properties was studied. Experimental data showed that the properties of Cu–Orb composites depended significantly on the SPS sintering conditions. The optimal sintering temperature was 1223 K with a pressure of 35 MPa. Composites exhibited a high degree of consolidation. For these materials, the apparent density was in the range of 93–97%. The results showed that the higher content of Orb in the copper matrix was responsible for the improvement in Young’s modulus and hardness with the reduction of the conductivity of sintered composites. The results showed that Young’s modulus and the hardness of the Cu 20% Orb composites were the highest, and were 165 GPa and 174 HV0.3, respectively. These composites had the lowest relative electrical conductivity of 17%.

ZrB2–Copper–Graphite Composite for Electric Brushes: Positive Effect of ZrB2 Addition on Composite Properties

“…The mixed powders were then suppressed under a pressure of 300 MPa with a holding time of 20 s. A sample mold with a dimension size of 32 mm × 8 mm × 5 mm was used for suppressing. After suppressing, samples were sintered under vacuum conditions by hot-press sintering under 35 MPa at 860-890 • C for 2 h. According to the literature, ZrB 2 exhibits a high degree of consolidation when the temperature is above 850 • C [18]. The mixed powders were then suppressed under a pressure of 300 MPa with a holding time of 20 s. A sample mold with a dimension size of 32 mm × 8 mm × 5 mm was used for suppressing.…”

“…Yakut et al [ 17 ] added ZrB 2 into spherical graphite cast iron to investigate the effect on its mechanical properties and came to the conclusion that samples with the addition of 0.455% ZrB 2 showed the highest hardness (243 HB) and compressive strength (1438 MPa). Sulima et al [ 18 ] studied ZrB 2 –copper matrix composites produced by ball milling and spark plasma sintering and found a strong decrease in the electrical conductivity of composites containing 5% and 10 wt.% ZrB 2 , as well as in those containing larger amounts, due to the partial diffusion of boron into the copper matrix, although the hardness and Young’s modules of the samples were significantly improved. Zhao et al [ 19 ] prepared ZrB 2 -SiC- reinforced copper matrix composite coatings by laser cladding and found that the microhardness of the composite was about 5.6 times that of the copper matrix.…”