Precision Forming and Machining Technologies for Ceramic-Based Components

Abstract

Structural ceramics components for industrial use are classified under two categories: one that is originally designed for ceramics (Ceramic Origin), and the other that is originally designed for metals and subsequently replaced with ceramics because of their improved hardness and resistance to both heat and corrosion (Metal Origin). Ceramic insulators for power lines and catalytic substrates used to control automotive emissions in gasoline engines are “Ceramic Origin” components. As ceramics are difficult to machine, a precision mold has been used in the forming process to minimize the machining volume in the case of “Ceramic Origin” components. Meanwhile, ceramic turbo charger rotors and valves for automotive engines are “Metal Origin” components, which not only require durability under severe operating conditions but also severe dimensional accuracy, similar to metal parts. These components have been derived from extensive R&D efforts in materials and process technologies for ceramic gas turbines, which have been implemented in the majority of advanced countries since the 1970s. This paper includes some examples of precision forming and machining technologies for both types of ceramic components developed by NGK Insulators, Ltd., and highlight their issues. Finally, the possibility of new types of ceramic-based components will be introduced.