Ceramic-Metal Joining of Components Used at High-Temperature and High Pressure

Ceramic heat exchange components such as boiler tubes, heat exchangers, or recuperators are required to improve the performance of advanced fossil energy power generation systems based on steam or supercritical CO2, targeting temperatures in excess of 700°C. Some of these heat exchange environments contain very large pressure differentials (20-25 MPa), while others may contain periodic or occasional pressure fluctuations. However, current ceramic components perform poorly in tension requiring specialized engineering, in particular with respect to joining with adjacent components. In this Phase I project, Physical Optics Corporation will address joining technologies for ceramics to metallic components and fabrication methods to produce complex-shaped parts. The proposed joining technology is based on the addition of metallic particles to a ceramic gelcasting slurry, which can be molded into complex-shaped monolithic ceramic parts and can be joined to metallic parts. The non-aqueous gelcasting ceramic slurry technology is capable of being cast into accurate wax molds and sintered into shapes such as heat exchangers and microchannels. Metallic particles added to the slurry allow the ceramic parts to be joined to adjoining metal parts and directly address the requirement for low cost manufacturing. During Phase I, the material composition and fabrication method will be developed, and sub-scale tubes and panels will be fabricated and tested. Physical Optics Corporation will also demonstrate the joining technology’s ability to join to metal parts, and measure the mechanical strength of the joints and the bonding properties. Ceramics that can withstand high temperature and pressures and that can be joined to metallic components are needed for advanced fossil energy power generation systems. The proposed process will develop improved materials capable of being joined together and manufactured at lower cost compared to existing materials. Commercial Applications and Other Benefits: The proposed technology will result in a high-strength ceramic part able to be joined to metal parts and produced at low cost using low-cost wax molds. It will have commercial applications in areas such as structural components and advanced fossil energy power generation systems, as well as in the automotive, aerospace, and defense industries. A large commercial market is envisioned in aerospace rocket and engine components, which require high strength, high temperature, and lightweight materials.