Fabrication of dense ZrB2/B4C composites using pulsed electric current pressure sintering and evaluation of their high-temperature bending strength. Issue 11 (1st August 2020)

• Record Type: Journal Article
• Authors: Le, Tung Duy; Hirota, Ken; Kato, Masaki; Miyamoto, Hiroyuki; Yuasa, Motohiro; Nishimura, Toshiyuki
• Is Part Of: Ceramics international. Volume 46:Issue 11(2020)Part B
• Page Start: 18478
• Page End: 18486
• Publication Date: 2020-08-01
• Subjects: Sintering -- Composites -- Mechanical properties -- Transition metal oxides; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2020.04.153
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: ZrB2 / x ·vol%B4 C ( x = 30–90) composites were fabricated from ZrB2 and amorphous B/C powders using pulsed electric current pressure sintering (PECPS) from 1600 °C to 1900 °C for 6.0 × 10 2 s (10 min) under 50 MPa in a vacuum, accompanied by self-propagating high-temperature synthesis (SHS). Since the B4 C phase was formed at 1600 °C, the relative density ( D r ) was evaluated; the composites sintered at 1900 °C attained the highest D r . Their D r values increased gradually from 99.35% to 99.99% with increasing B4 C contents up to 60 vol% and showed a constant value above 60 vol%. At room temperature, the mechanical properties of Vickers hardness ( H v ), fracture toughness ( K IC ) and three-point bending strength (σb ) were measured. H v exhibited a monotonous increase from 20.3 to 32.7 GPa. On the other hand, K IC and σb revealed the same behavior for each of the compositions; both exhibited the highest values, i.e., 10.2 MPa m 1/2 for K IC and 870 MPa for σb, in the 60 vol%B4 C sample, and then the K IC decreased gradually to 9.73 MPa m 1/2, and σb dropped suddenly from 850 MPa (70 vol%) to 340 MPa (80 vol%) and stayed as low σb in the 90 vol% B4 C sample. Next, the high-temperature σb values of the composites (40–70 vol%) were measured in Ar. The composites (40–60 vol%) revealed high σb (≥640 MPa) from R.T.~1600 °C; the maximum value of 803.5 MPa was observed for the 60 vol%B4 C composites at 1600 °C, and then the σb of all composites dropped to around 340 MPa at 1800 °C. From their stress-strain curves, elastic and plastic deformations were observed at 1600 °C and 1800 °C, respectively.