Microstructure and Mechanical Properties of ZrB₂⁻HfC Ceramics Influenced by HfC Addition

• Published in: Materials Vol. 11; no. 10; p. 2046
• Main Authors: Jing, Yi, Yuan, Hongbing, Lian, Zisheng
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 20.10.2018; MDPI
• Subjects: Additives; Alcohol; Bonding strength; Ceramics; Composite materials; Density; Diamond pyramid hardness; Flexural strength; Fracture toughness; Grain boundaries; Hafnium carbide; Hot pressing; Hydrofluorocarbons; Liquid phase sintering; Liquid phases; Mechanical properties; Microstructure; Nickel; Particle size; Plasma sintering; Powder metallurgy; Refractory materials; sintering aid; Solid solutions; Test methods; Zirconium compounds; ZrB2–HfC ceramics; Beijing China; China; Ceram; ZrB2–HfC ceramics; microstructure; sintering aid; hot pressing; mechanical properties
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma11102046

ZrB₂⁻HfC ceramics have been fabricated using the liquid phase sintering technique at a sintering temperature as low as 1750 °C through the addition of Ni. The effects of HfC addition on the microstructure and mechanical properties of ZrB₂⁻based ceramics have been investigated. These ceramics were composed of ZrB₂, HfC, Ni, and a small amount of possible (Zr, Hf)B₂ solid solution. Small HfC grains were distributed among ZrB₂ grain boundaries. These small grains could improve the density of ZrB₂⁻based ceramics and play a pinning role. With HfC content increasing from 10 wt % to 30 wt %, more HfC grains were distributed among ZrB₂ grain boundaries, leading to weaker interface bonding among HfC grains; the relative density and Vickers hardness increased, and flexural strength and fracture toughness decreased. The weak interface bonding for 20 and 30 wt % HfC contents was the main cause of the decrease in both flexural strength and fracture toughness.