Technological Advanced Techniques for Joining Ceramics-Metals/Alloys

Ceramics and metals are two of the oldest established classes of technologically useful materials. While metals dominate engineering applications, ceramics have some attractive properties compared to metals, which make them useful for specific applications. The properties of individual ceramics and metals can vary widely; however, the characteristics of most materials in the two classes differ significantly. Joining of Ceramics with Metals/Alloys is difficult because of the difficulty of mismatching of Coefficient of Thermal Expansion of materials formed in weld pool with components to be joined. Difficulties arise if ceramics sublime rather than melt or the metal undergoes phase changes on cooling. Joints between a metal and ceramic are becoming increasingly important in the manufacturing of a wide variety of technological product. But joining ceramics to metallic materials often remains an unresolved or unsatisfactorily resolved problem. Technological advances are extending the applications for bonded Ceramic-Metal/Alloys components and demanding more rigorous performance characteristics..Successful application of ceramics in many devices and structures requires some type of ceramic metal joining. Ceramic-metal seals are used extensively in a wide variety of applications. Examples include vacuum tubes, high voltage feedthroughs, transistor packages, sapphire-metal windows, rocket ignitor bodies and many others. Newer joining applications include engine components, such as the Si3N4 turbocharger rotor joined to a metal shaft now being produced commercially, multilayer electronic devices that comprise both ceramics and electrodes, electroding and metallizing of hybrid microcircuit substrates, and ceramic-metal composites. All applications require a high-strength metal-ceramic bond. Many new techniques have been developed for successful joining of ceramics to metals; Metal-ceramic joining has slowly but steadily become an important manufacturing step. New joining methods and newer approaches to conventional methods have been developed aiming at joints characterized by improved reliability, and interfaces capable of withstanding high-temperature resistance with minimum residual stresses. Some of the Technological advanced Techniques for joining Ceramics to metals are Ultrasonic Joining, Transient Liquid Phase Bonding, Microwave Joining Infiltration Processes, Brazing.