An MMC is complementary to a cermet. In 1942, German scientists further developed carbide into cermet. A composite material of ceramic and metal is known as cermet. CerMet fuel consists of ceramic fuel particles (usually uranium oxide) embedded in a metal matrix. The mixture of zirconium carbide and tantalum carbide is an important cermet material. Today, cermet vacuum tube coatings have proved to be key to solar hot water systems. However tantalcarbide powders are used for tools, or cermet.