Jump to Nanostructured Materials, Bonded Abrasives, Educational
Most of my materials research interests focus on the effect of
on material properties.
Nanostructured materials are generally defined as materials having
structural elements with at least one dimension less than 100 nm. (A nm is
a billionth of a meter.) Such structural elements could include second
phase particles, the thickness of layers in a laminated material, the diameter of in-situ whiskers or fibers, or
the grain size in a single phase crystalline material. By comparison, most
conventional polycrystalline materials have grain sizes on the order of
microns to tens of microns. To put this size difference in perspective,
consider the width of a human hair; that dimension is the approximate
grain size of some conventional polycrystalline materials. A
nanocrystalline material could easily have 1000 grains across the diameter
of that human hair!
My research in nanostructured materials focuses on developing a better
understanding of several size-dependent phenomena: defect chemistry in
oxides and grain boundary segregation, in particular. A recently completed
Master's Thesis by Xinlan Shi demonstrated that nanocrystalline TiO2 has
an enhanced conductivity and a wide PO2-independent regime
relative to conventional TiO2. This behavior is likely due to either
enhanced ionic conductivity or conduction of protons; further work is
planned to distinguish between these mechanisms.
Another master's student
whether there is a grain size-dependence of the anatase-rutile phase
transformation in TiO2. Related research focuses on understanding the
thermal stability (or lack
thereof) in nanostructured ceramics. If fine grain sizes could
be stabilized at elevated temperatures, these materials could see more
Recent Publications and Presentations
My major refereed journal publications and presentations in the area of nanostructured materials are listed below, along with links to the abstracts. Send e-mail if you would like reprints of any of these papers.
- C. Demetry and X. Shi, "Grain size-dependent electrical properties of
rutile (TiO2)," Solid State Ionics 118[3-4]
- C.D. Terwilliger, "Size-Dependent Defect Phenomena in Ultrafine-grained Ceramics," (Invited Talk), Extremely Fine Scaled Ceramics Focused Session, Annual Meeting of the American Ceramic Society, Indianapolis, IN, April 14-18, 1996.
- "Size-Dependent Defect Phenomena in Ultrafine-grained Ceramics," Invited presentation, Institute of Materials Science, University of Connecticut, March 6, 1996.
- C.D. Terwilliger and Y.-M. Chiang, "Measurements of Excess Enthalpy in
Ultrafine-grained Titanium Dioxide," Journal of the American Ceramic
Society 78, 2045-55 (1995). Abstract
- C.D. Terwilliger and Y.-M. Chiang, "Size-Dependent Solute Segregation and Total Solubility in Ultrafine Polycrystals: Ca in TiO2," Acta Metallurgica et Materialia 43, 319-328 (1995). Abstract
- C.D. Terwilliger and Y.-M. Chiang, "The Effect of Calcium Segregation on Grain Growth in Nanocrystalline TiO2," NanoStructured Materials 4, 651-661 (1994). Abstract
- C.D. Terwilliger and Y.-M. Chiang, "Characterization of Chemically- and Physically-Derived Nanophase Titanium Dioxide," NanoStructured Materials 2, 37-45 (1993). Abstract
- Carey T. Williams, Chrysanthe Demetry, and Rounan Li, "Structure and
Strength of Interfaces in Titanium-Coated Diamond-Glass
Composites," pp. 697-704 in Ceramic Science and Engineering
Vol. 21, No. 3, 24th Annual Conference on Composites, Advanced Ceramics,
Materials and Structures: A (Eds. T. Jessen, E. Ustundag), American
Ceramic Society (2000).
- G.L. Kourtoukova, C. Demetry, S. Ramanath, R. Andrews,
D.S. Jacobs, and R.R. Biederman, "Design and Tailoring of Ni-Sn-W
Composites for Bonded
Applications," Materials Science and
Engineering A 276[1-2], 58-69 (2000). Abstract
the upper left is a scanning electron micrograph of a W
particulate-reinforced Ni-Sn composite that was hot pressed from
elemental powders. The accompanying x-ray dot maps
show the distribution of Ni, Sn, and W in the microstructure. Moving
clockwise from the upper right, the maps are for Ni, W, and Sn. Further
characterization by EDX showed that there are four phases in the
composite: W, a Ni-W intermetallic, Ni-W solid solution, and a Ni-Sn
intermetallic. The formation of the intermetallics gives the composite
a significantly enhanced elastic
modulus relative to a rule-of-mixtures prediction based on the moduli of
the unreacted constituents. The wear resistance of the composite,
however, is not significantly different than the Ni-Sn matrix. This
combination of higher stiffness without significantly greater wear
resistance is a desirable combination of properties for some
superabrasive grinding wheels that is not possible to achieve with a
The composite to the right has the same overall composition, but has
fiber reinforcement replacing half of the W particulate reinforcement.
Addition of fibers gives
an additional stiffening effect, again without an increase in wear
These micrographs were taken by Galina Kourtoukova, who earned a M.S.
in Materials Science and Engineering in May 1998.
- C. Demetry, F. S. Souto, B. C. Ryden, and J. M. Roy, "Tactile sensing
of density uniformity in powder beds after die filling," Powder
Technology 99 (1998) 119-124. Abstract
Recent Publications, Presentations, and Workshops
- C. Demetry, "Outcomes Assessment of Educational Approaches: Examples
for Materials Science Educators," Journal of Materials Education
20 [1-2] 1-8 (1998). Abstract
- C. Demetry, "Alumni-Contributed Materials Selection Projects in an
Introductory Materials Science Course," Journal of Materials
Education 20 [1-2] 126-133 (1998). Abstract
Demetry, "The WPI-Norton Company Project Center: A University-Industry
Partnership in U.S. Undergraduate Education," Industry and Higher
Education (Invited Contribution), August 1997, pp. 218-223.Abstract
- C. Demetry and J.E. Groccia, "A Comparative Assessment of Students'
Experiences in Two Instructional Formats of an Introductory Materials
Science Course," Journal of Engineering Education 86,
203-210 (1997). Abstract
- C.D. Terwilliger, "The WPI-Norton Company Project Center: A
University-Industry Partnership in Undergraduate Education," pp. 88-92 in
Proceedings of the 22nd Annual Conference for Industry and Education
Collaboration, American Society for Engineering Education (1997).
- J.E. Miller, D. DiBiasio, C.D. Terwilliger, "Outcomes of the Use of
Undergraduate Peer Learning Assistants to Facilitate Cooperative Learning
in Introductory Science and Engineering Classes," presented at the Lilly
Conference on College Teaching, Miam
i University, Oxford, OH, November 21-24, 1996.
- J.E. Miller, D. DiBiasio, C.D. Terwilliger, "The Use of Undergraduate Peer Learning Assistants to Facilitate Cooperative Learning Classes," Workshop presented at the Lilly Conference on College Teaching, Miami University, Oxford, OH, November 21-24,
- K. O'Connor, N.M. Acuna, R.D. Sisson, Jr., and C.D. Terwilliger, "Engineering Education as Apprenticeship: A Guided Participation Model of Learning," Second Davis Educational Conference, Worcester Polytechnic Institute, May 30, 1996.
- C.D. Terwilliger, "Use of Active and Cooperative Learning in an Introductory Materials Science Course," presented at the Ceramics/Materials Curricula Session, Annual Meeting of the American Ceramic Society, Indianapolis, IN, April 14-18, 1996.
- J.E. Miller, D. DiBiasio, C.D. Terwilliger, "Task Design for Cooperative Learning," Workshop presented at the Lilly Conference on College Teaching, Miami University, Oxford, OH, November 16-19, 1995.
- C.D. Terwilliger, "A Comparative Assessment of Traditional and Active/Cooperative Instructional Formats in an Introductory Materials Science Course," Idea Swap Session, Lilly Conference on College Teaching, Miami University, Oxford, OH, November 16-19
- C.D. Terwilliger and J.E. Groccia, "A Comparative Assessment of Traditional Lecture and Active/Cooperative Instructional Formats in an Introductory Materials Science Course," presented in the Innovations in Materials Education session at the American
Society for Engineering Education Annual Meeting, Anaheim, CA, June 25-28, 1995.
- J.E. Miller, D. DiBiasio, W. Farr, C.D. Terwilliger, C. Wills, "Task Design for Cooperative Learning," Worcester Consortium Workshop presented at WPI, March 14, 1995.
Last modified: 28 January 1999