Study On Fabrication Of Titanium Diboride Porous Ceramics

Effective mechanical property prediction of multi-phase composites with co-continuous phase structures is attracting interest as new processing routes for these types of composites are developed. Co-continuous phase structures have been experimentally shown to enhance elastic properties, as compared with discontinuous reinforced phase structures. The basic step in the fabrication of this composite is to produce a ceramic body, which has a reticulated of continuous open porosity. Most research have focused on the techniques of porous ceramic performs.TiB₂ ceramics have excellent physical and chemical properties (high melting point, high hardness, good friction resistance). Moreover, TiB₂ ceramics have good wettability with liquid Al, Cu, Ni, et al, so there is a probability that the porous TiB₂ ceramics and liquid metal can have a good interface combine. According to these, this paper study the preparation of TiB₂ reticulated porous ceramics by Spark Plasma Sintering technique and polymeric sponge based method.In the fabrication of porous TiB₂ ceramics by the Spark Plasma Sintering technique, study the influents of sintering temperature, heat-holding time, pressure and heating rate to the porosity and flexural strength of the sample. It has been observed that the grains are well interconnected by the formation of thick and strong necksCommercial polyurethane sponges (Foshan Foam, China) with cell size approximately 30 pores per inch were chosen in this study. The main experimental material is titanium diboride powder (d50=4μm), which was synthesized by the self-propagating high-temperature synthesis (SHS), method. Ni, Mo (200, meshes) powders were added as sintering aids. A commercial silica sol (30.0-30.1%SiO2, PH=8.5-10) was used as a binder, and sodium carboxymethyl cellulose (CMC) was added into the slurry as a thickening agent. Tri-Ammonium Citrate (TCA) was added as a dispersant. Kaolin was added to improve the rheology of the slurry. Study the preparation and properties of the TiB₂ slurry; study the influences of impregnating and sintering processes on the TiB₂ ceramics. The best PH value is 9; the best dispersant amount is 0.3%; the solid content is 77%. The sample sintered at 1800°C has a porosity of 74.9%, and the flexural strength can reach 1.01MPa.By multi-immersing and sintering process, the strength of the porous ceramics increase obviously.