Effect of Ni additives on pressureless sintering of SHS ZrB₂

Abstract

Pressureless sintering of ultrafine zirconium diboride ZrB₂ produced by self-propagating high temperature synthesis (SHS) was carried out over a temperature range of 1573 to 1873 K using a nickel additive. The additive improved densification behaviour and a maximum densification of 88% was achieved at 1873 K. The XRD pattern showed formation of Ni₃Zr phase during pressureless sintering. The microhardness of sintered ZrB₂ was found to increase with Ni content and a maximum hardness of 1150 kg mm⁻² was found at 40 wt-%Ni addition. The coefficient of thermal expansion of different sintered samples was also investigated.

Keywords:

• HARDNESS
• MICROSTRUCTURE
• SHS
• SINTERING
• THERMAL EXPANSION
• ZIRCONIUM DIBORIDE