Fabrication of BN-AlN-TiB₂ Compound Conductive Ceramics by Self-Propagating High Temperature Synthesis and Hot Isostatic Pressing

Abstract

BN-AlN-TiB2 compound conductive ceramics from powder mixtures of BN, Al, and TiB2 was fabricated by self-propagating high temperature synthesis (SHS) and hot isostatic pressing (HIP). The powder mixtures were shaped by isostatic cool pressing at 5-10MPa and the combustion reaction was carried at 100-200 MPa N2 by an ignitor. XRD experiments confirmed that the reaction was complete and only AlN, BN and TiB2 were detected. Optical microscopy as well as SEM with an electron probe microanalysis was used for microstructural analysis and revealed a relatively uniform distribution of particulates. The temperature-dependence and composition-dependence of the electrical resistivity of BN-AlN-TiB2 ceramics were studied. The results showed that the optimum composition was 5-10wt% BN, 30-55wt% Al and 60-40wt% TiB2, and the products had the density of 90% of the theoretical, resistivity of 80-1000 μ⋅cm and bending strength of 100-200 MPa.

Isothermal Oxidation Behavior of AlN-TiB₂ Ceramics Synthesized by SHS-HIP

“…The AlN-TiB 2 ceramic composites were prepared by self-propagating high-temperature synthesis and hot isostatic pressing [2], and the chemical equation of this reaction is as follows:…”

“…AlN has good thermal conductivity and is considered to use as substrate, while TiB 2 is the conductive phase. Many preparation methods, such as combustion synthesis (SHS) [1,2] and reactive synthesis [3], were introduced to prepare AlN-SiC-TiB 2 ceramic composites.The oxidation behavior of AlN-SiC-TiB 2 obtained by powder metallurgy methods was studied in air up to 1500 o C [4]. Research shows that TiO 2 , α-Al 2 O 3 and β-cristobalite were formed for short time and relatively low oxidation temperature (1200-1300 o C), while 3Al 2 O 3 •2SiO 2 and β-Al 2 TiO 5 were the main oxides for a longer oxidation times and higher oxidation temperatures (1350-1550 o C).…”