Subhash H. Risbud

SUBHASH H. RISBUD

Abstract

The Enduring Legacy of Mullite the Quintessential Engineering Ceramic

Ever since its discovery on the Island of Mull in Scotland, Mullite has enjoyed a rich reputation as an engineering ceramic with widespread applications ranging from high temperature refractories to space shuttle tiles. Research on the Silica-Alumina phase equilibrium diagram date back to the classic work of Bowen and Greig in 1924 followed by many re-evaluations over the past 6 to 7 decades by Aramaki and Roy, Davis and Pask, Aksay and Pask and other ceramic researchers worldwide. Standard melt quenching, diffusion couple heating and sol-gel techniques have been used among others for studying stable and metastable phase equilibria, liquidus-solidus curves, and liquid-liquid immiscibility domes. The time temperature processing parameters are at the heart of the formation of mullite both in the metastable condition as well as the lowest energy stable phase. Clearly, time-temperature-pressure all influence the morphology, structure and properties of mullite. Most phase diagrams of the mullite phase shown on the silica-alumina system are at one atmosphere pressure though high-pressure studies have been reported. While mullite is a dominant phase in modern aluminosilicate ceramics like refractories its presence has been observed in pottery dating back millennia. And in recent times mullite is finding applications in space, electronics and photonics. This talk will focus on the many interesting issues of phase stability, metastability, crystallography, and stoichiometry of the mullite phase. I will review the history and prior work and talk of the future possibilities for this “quintessential” ceramic that has enriched our profession.

Biography

Subhash Risbud is a widely respected materials scientist with a long history of distinguished achievements spanning a multidisciplinary range of academic and industrial research contributions that have notably advanced the field of nano and biomaterials. Following undergraduate studies in materials science and engineering at the Indian Institute of Technology in Mumbai, he obtained an M.S. degree at Berkeley in 1971 followed by three years of hands-on experience in crystal growth at the Stanford Center for Materials Research (1971-1973) and slurry making and tape casting at GTE Sylvania (1973-74). After returning to Berkeley, he completed his Ph.D. working on phase separation and metastable liquid immiscibility.  His academic career started in Fall 1976 and he rose rapidly through the ranks to achieve tenure at the University of Illinois-Urbana and full professorship at the University of Arizona in Tucson in 1985. A prolific author, Professor Risbud and his students have published over 300 publications and six U.S. patents. For over four decades he has been the Principal Investigator on government and industry funded projects and in 1994 The W.M. Keck Foundation awarded him a $ 600,000 grant to create a campus wide NMR facility, the first Keck award on the Davis campus.

Risbud and his group work on sol-gel processing of a variety of biological and amorphous materials and he has developed worldwide collaborations on projects ranging from biophotonics, nanotechnology and computer modeling to environmental effects on human health. Parallel with outstanding teaching and research, his administrative repertoire was enriched as he took on leadership roles in the College of Engineering (Department Chair) and the campus-wide Designated Emphasis on Biotechnology (DEB) graduate groups serving as a NIH Faculty Trainer and member of the advisory board of the Advanced Degree Program (ADP) for Corporate Employees. During his term as Chair he actively sought diversity by recruiting eight faculty (four of whom are women) and worked with Deans of other colleges to promote cross-college appointments. He encouraged faculty to form multidisciplinary teams from academia, industry, and national laboratories and led efforts to write proposals for centers of excellence. He was a founding member of the NSF MRSEC Center for Polymer Interfaces and Macromolecular Assemblies (CPIMA) involving investigators from the Stanford-UC Davis-IBM. From 2005 to 2014 he served as the Director of the Internship and Career Center (ICC) at UC -Davis. Beyond success with traditional research support from NSF, DOE, DARPA, and industry, he promoted fund-raising efforts by inspiring staff in the Internship and Career Center to write a successful NIH-STEER grant for training future engineers for the U.S. workforce.  By pioneering numerous research interactions on processing of materials, he has nurtured healthy working relationships with industries, universities and national laboratories. His worldwide reputation has led to several honors and awards including the 2020 Kingery Award from the American Ceramic Society, Distinguished Engineering Educator Award from the Engineers’ Council in 2019,  and election to the World Academy of Ceramics in 2014.