Metallized Ceramic Components for Emerging Applications

The Industrial Ceramics Division of Carborundum Universal Limited (CUMI), India offers a wide range of ceramic products for diverse industrial applications. CUMI’s capabilities also extend into metallized alumina ceramics for the manufacture of Vacuum Interrupters (VI) used in Vacuum Circuit Breakers. Equipped with state-of-the-art processing lines, CUMI is today one of the leading producers of metallized alumina cylinders, serving customers across the world. In addition, CUMI also manufactures a range of customized metallized alumina products for high vacuum, high voltage applications including applications like Night Vision equipment, which is covered in greater detail in this article.

Ceramics are chemically inert. Fully sintered alumina ceramics exhibit negligible wettability and porosity. They exhibit high dielectric strength making them suitable for various electrical applications for insulation.These ceramics when metallized, provide the best solution for bonding with metal, as well as maintaining its base properties. The metallization process is based on a proprietary molybdenum-manganese (Mo-Mn) refractory ink system and is matched to specific high-purity alumina ceramic bodies to ensure consistent high strength bonds.

The glass phases in the Mo-Mn metallization reacts with the glass phases in the ceramic to form the bond. A second layer of Nickel is deposited through a specialized plating process followed by sinteringto improve wettability for later brazing. The major challenge in developing metallized alumina ceramics lies in making complex contours and 1.00 mm in height, the manufacturing process posed several challenges. CUMI’s experience in metallized ceramics for over two decades and its exposure to several applications, close tolerances to satisfy the ever increasing and changing demand of customers.

The constant requirement of light weight and high dielectric strength materials in electrical applications has led to the usage of alumina ceramics in image intensifier tubes, amongst many others. Image intensification, the basis of night vision, is a complex conversion of energy particles that occurs within a vacuum tube. An image-intensifier system works by collecting photons through an objective lens, converting them to electrons via a photocathode, increasing the electrical energy with a Micro Channel plate (MCP), converting the electrical energy back to light using a phosphor screen and presenting the image for viewing through an eyepiece lens.

A refined miniaturized power supply is used to provide the voltages between the elements of the vacuum tube that allow for the energy conversion and amplification. All of the elements within the vacuum tube are closely spaced to avoid electron scatter. Maintaining this close packing and the vacuum inside the tube, called as "hermetic metal sealing" is provided by CUMI’s metallized ceramic rings. These rings require high dielectric strength, to avoid the Pico-amp leakage current, which would affect the quality of intensified image focusedon the eye piece lens.

Usually CUMI’s 975M formulation provides the necessary properties required for this application. Its pearly-white surface, high dielectric strength coupled with the metallization strength provided by CUMI’s propriety METZ paste, makes it the best option available for this application. With sharp edges and dimensions going as low as CUMI’s night vision rings (NVR) is one of CUMI’s regular product line-ups.For more information, please visit.. (…)

https://www.cumi-murugappa.com/ceramics/ic/products/metallised-ceramics-for-triodes/