As a high-tech manufacturing company that produces precision components for critical applications in several industries, Elcon Precision (San Jose, Calif.) is always investing in new technologies and developing better processes to not only meet customer specifications but also satisfy scientific curiosity.

One puzzle that Elcon has encountered for many years is discoloration of some alumina compositions during ceramic metallization, a service that Elcon offers. In this process, a proprietary thick film moly-manganese paint is applied to bare ceramic substrates to prepare them for subsequent brazing into assemblies. After metallization, parts undergo wet hydrogen firing at around 1,400°C. For aluminas with high calcia concentrations (1–2%), greyish discoloration is often observed on the surface of the ceramic (Fig. 1). This phenomenon is often called nucleation.