Cermet Development for High Temperature and High Pressure Applications

Many traditionally used low cost alloys are easily corroded in steam or supercritical CO2. An effective solution is to utilize ceramic heat exchangers that are often integrated with metallic components which result in a significant thermal expansion mismatch. The goal of this project is to develop a sealing method to create a hermetic joint between the ceramic and metal alloy. Proposed is a seal ring containing a cermet powder with a coefficient of thermal expansion (CTE) higher than the ceramic and metal to produce a high temperature compressive seal. Cermets of Ag and MgO have been selected to withstand pressures of 3000 psi and temperatures above 700 °C. Three preliminary tests were conducted to study the behavior of the cermet: 1. Static heat on cermet filled stainless steel tubes; 2. Radial compression test on cermet filled stainless steel tubes; 3. Compression tests on open cermet filled cavities. Tests 2 and 3 suggest that powder flowability and densification regions decrease with increased ceramic concentrations