Abstract
The effect of TiO2 and of Ti additions on the sintering behavior of B4C was studied in the 1800 °C to 2190 °C temperature range. According to thermodynamic predictions that were verified by the experimental results, TiB2 is formed in situ in both instances. Titanium oxide is reduced by carbon that originates in B4C and decreases its carbon content. The activity of carbon in the boron carbide phase is reduced significantly with decreasing carbon content. By sintering at 2160 °C for 1 hour, a mixture of fine-sized B4C with 40 wt pct TiO2 is transformed into a 95 pct dense two-phase composite that consists of substoichiometric boron carbide and TiB2 and displays a bending strength of 420 MPa. The significantly improved sintering behavior of this composite ceramic is attributed to the enhanced mass transport processes that takes place in substoichiometric B4C. The low carbon activity values in substoichiometric B4C ensure that no deleterious carbide phases are produced by reaction with molten metals.
| Original language | English |
|---|---|
| Pages (from-to) | 3201-3210 |
| Number of pages | 10 |
| Journal | Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science |
| Volume | 30 |
| Issue number | 12 |
| DOIs | |
| State | Published - 1 Jan 1999 |
ASJC Scopus subject areas
- Condensed Matter Physics
- Mechanics of Materials
- Metals and Alloys