Architectural design and cryogenic synthesis of Si₃N₄@(TiN–Si₃N₄) for high conductivity

Abstract

Si 3 N 4 @(TiN-Si 3 N 4 ) composites with heteroshelled structure were designed for enhanced conductivity and successfully synthesized through the simultaneous reduction and in-situ cocoating process in liquid ammonia at around À40°C. The heteroshells were composed of nanosized TiN and Si 3 N 4 particles, which were amorphous with the size ranging from 10 to 40 nm. Using spark plasma sintering, dense bulk composite with >98.1% relative density of theoretical value were obtained and their electrical conductivity were increased to an adequate value (6.62 9 10 2 SÁcm À1 ) for electrical discharge machining by compositing 15 vol% TiN to Si 3 N 4 , which is superior to the previous reports. The excellent electric performance could be attributed to the heteroshelled structure which guarantees the conductive network can be formed and kept with minimal TiN content. The nanosized Si 3 N 4 powders in the shells reduce the content of conductive powders and limit the growth of TiN particles.

Electrical Discharge Machining of Al2O3 and Si3N4 Ceramics; A Research

“…Si 3 N 4 -Tin it finds its usage in reinforced environment like convoluted moulds and heat exchanges which is in the metal forming, wear opposing components etc., it's composition is 55% tin, 40% si 3 n 4 , and 5% of additives like al 2 o 3 and y 2 o 3 . It has a very high material removal rate 100uj to 110uj because of the addition of tin which is a catalyst in EDM process [7], [25]- [27].…”

Highly electro-conductive B 4C–TiB 2 composites with three-dimensional interconnected intergranular TiB 2 network

“…Generally, there are two ways to improve the electrical conductivities of composite ceramics with low conductive phase contents. The first approach is to introduce uniformly dispersed conductive nanoparticles into a insulating matrix [9], and the second is to fabricate conductive coatings on the surface of matrix particles [16][17][18]. However, both methods require a process involving liquid phases before sintering, which is complicated (multi-step) and costly.…”