Effect of Hot‐Pressing Temperature on Densification and Mechanical Properties of Titanium Diboride with Silicon Nitride as a Sintering Aid

Abstract

The effect of hot-pressing temperature on the densification behavior and mechanical properties of titanium diboride (TiB 2 ) was investigated. TiB 2 specimens were hot-pressed for 1 h at temperatures in the range of 1500°-1800°C, with an addition of 2.5 wt% of silicon nitride (Si 3 N 4 ) as a sintering aid. The density increased markedly at temperatures in the range of 1500°-1600°C and remained constant thereafter. The formation of a eutectic liquid at 1550°C was attributed to the steep increase in density. The hot-pressing temperature also improved the mechanical properties, such as the flexural strength, Vickers hardness, and fracture toughness of the specimens. Similar to the density, the mechanical properties improved remarkably at ϳ1550°C, so that optimum properties were obtainable at temperatures as low as 1600°C.

Influence of Sintering Temperature on the Microstructure of TiB₂ Sintered with Al₃Ti Additive

“…Then, powders of TiH x and Al were mixed, pulverized and heated at 973 K for 1 h in Ar environment. By this procedure, fine powders of Al 3 Ti of several microns in diameter could be obtained.…”

“…35) Such extreme processing conditions result in exaggerated grain growth of the sintered materials leading to degradation of mechanical properties. 57) In the previous work, we have reported that the addition of Al 3 Ti improves the sintering at 1273 K of TiB 2 powders. 8) It has been shown that TiB 2 and Al 3 Ti coexist stably at 1273 K and by the addition of Al 3 Ti up to 30 mass%, the Vickers hardness of the sintered materials increases up to as high as 2100 Hv.…”

“…57) In the previous work, we have reported that the addition of Al 3 Ti improves the sintering at 1273 K of TiB 2 powders. 8) It has been shown that TiB 2 and Al 3 Ti coexist stably at 1273 K and by the addition of Al 3 Ti up to 30 mass%, the Vickers hardness of the sintered materials increases up to as high as 2100 Hv. 8) In the present study, in order to investigate the sintering behavior of TiB 2 with the addition of Al 3 Ti, we have sintered TiB 2 Al 3 Ti mixed powders by using spark plasma sintering method at the temperature between 1273 and 1573 K and investigated the microstructure and mechanical properties.…”

Improving Hardness and Toughness of Boride Composites Based on AIMgB₁₄

“…Most research involving the wear resistance of TiB 2 has focused on TiB 2 with appreciable amounts of binder phase or with TiB 2 as a reinforcement phase for a softer ceramic or alloy [126][127][128][129][130][131][132]. The presence of only a few percent porosity in monolithic TiB 2 has been shown to have a significant impact on erosion resistance.…”

“…In order to obtain nearly fully dense material, sintering temperatures of 1800ºC or higher are usually needed unless large additions of sintering aids, especially metallic, are used [63][64][66][67][68][123][124][125]. Studies have shown that small additions of Si 3 N 4 or metallic elements such as Fe or Ni perform exceptionally well at reducing the temperatures and pressures required to sinter TiB 2 to near 100% density [102,126]. TiC and TiN additions are common in the sintering of TiB 2 , usually in high concentrations, because they aid in sintering while inhibiting grain growth due to their immiscibility in TiB 2 [63,65,85].…”