Effect of SiC on Interfacial Reaction and Sintering Mechanism of TiB₂

Abstract

Compacts of TiB, with densities approaching 100% are difficult to obtain using pressureless sintering. The addition of S i c was very effective in improving the sinterability of TiB,. The oxygen content of the raw TiB, powder used in this research was 1.5 wt%. X-ray photoelectron spectroscopy showed that the powder surface consisted mainly of TiO, and B,O,. Using vacuum sintering at 1700°C under 13-0.013 Pa, TiB, samples containing 2.5 wt% S i c achieved 96% of their theoretical density, and a density of 99% was achieved by HIPing. TEM observations revealed that S i c reacts to form an amorphous phase. TEM-EELS analysis indicated that the amorphous phase includes Si, 0, and Ti, and X-ray diffraction showed the reaction to be TiO, + S i c + SiO, + TIC. Therefore, the improved sinterability of TiB, resulted from the SiO, liquid phase that was formed during sintering when the raw TiB, powder had 1.5 wt% oxygen.

Fabrication and characterization of Ti-TiB2 functionally graded material system

“…They explained that the sintering aids could eliminate the oxide layer present on the surface of the starting powders. Other reports [20,21,22] have also proposed that when SiC is added, amorphous SiO 2 can form from the reaction between SiC and TiO 2 , which would further promote the sintering forces by introducing liquid-phase sintering.…”

Microstructural development and mechanical properties of hot pressed SiC reinforced TiB2 based composite

“…The remaining volatile B 2 O 3 was evaporated between 1400 to 1600 °C and excess TiO 2 was generated. Consequently, the residual TiO 2 was allowed to react with SiC to form TiC according to the following reaction [43][44][45][46][47][48]:…”

Oxidation Behavior of Titanium Boride at Elevated Temperatures

“…In addition, a thin oxygen-rich layer existing on the surface of TiB 2 powder is known to be very detrimental to densification. [3][4][5][6] The addition of carbon or SiC was found to be effective in enhancing the densification of TiB 2 through elimination of the oxide layer existing on the surface of the starting powder. 4 -6 Recently, we improved the flexural strength of TiB 2 markedly by adding a small amount of Si 3 N 4 as a sintering aid.…”