Spark Plasma Joining of Ultra-High Temperature Ceramics without the Use of Filler Materials

This invention’s approach to solving this problem uses direct current heating to rapidly join two conductive ceramics with seamless joint microstructures. Conventional ceramic joining methods include brazing, transient liquid phase bonding, or mechanical fasteners. Although these methods are widely used and are reliable for most applications, they do have limitations form a production cost and application properties standpoint. These limitations are: 1) extended brazing time period (>4 hours) due to radiative heating methods, 2) inhomogeneous joint microstructures resulting form filler or braze materials reacting with the base material, and 3) low application temperature due to low melting point brazes or glass materials used with respect to the base ceramic. These issues are of particular concern for ceramic materials to be used in extreme heat (>1800 C) such as aerospace vehicles, which are intended for operation at speed greater than mach 4 while maintaining mechanical and thermal properties under extreme aero-thermal heating loads.
 

Background:

Ceramic materials have exceptional high temperature properties, which make them ideal materials for high temperature applications. However, costs associated with post processing machining and integrating ceramics with other materials for use in complex material systems limits their use in many engineering applications. Therefore, a joining method that is cost effective, reliable, and a rapid process would enable the integration of ceramics into metallic, ceramic, or composite systems.

Applications:

• This novel technology approaches to solve the issues of joining multiple ceramic materials or ceramic materials to different surfaces
• This invention can be applied to biomedical, electronics, aerospace, optical, automotive, and military technologies

Advantages:

• The invention, spark plasma joining without filters, is a more advantageous joining method compared to previously reported techniques because it rapidly produces a homogeneous joint microstructure, which exhibits identical properties to the baseline substrates. Other joining methods use brazes with compositions varied from the substrates, which in turn produces joints with microstructures significantly different than the substrates, resulting in dimensioned joint properties. 

Status: 

Stage of Development: Proof of Concept- Fully Developed