Associate Professor Isabel Lloyd
Ph.D.,
M.I.T., 1980
Undergraduate Advisor, Sloan Scholars Advisor
Affiliate Professor, Graduate Program in Bioengineering and Institute for research in Electronics and Applied Physics (IREAP)
Room 2309 Chemical and Nuclear Engineering Building
E-mail: illoyd@umd.edu
Phone: (301) 405-5221
Research Interests
- High elastic modulus dental composites
- All-ceramic dental restorations
- Biomaterials
- Effects of processing on performance of ceramic materials
TopCurrent Research Projects
High Modulus Composites for Dental Applications
Dental ceramics are subject to high cycle point contact loading in the mouth. When a relatively thick (≥ 10 µm) compliant layer supports an all-ceramic crown, or the layers within a laminar ceramic crown, flexure and failure via radial crack initiation can occur. We have developed a new class of adhesive composites based on dental resins filled with nano-alumina and micro-diamond fillers to address this problem. We are working to understand the effects of surface interactions between fillers and resin on performance in oral environments and the balance between elastic modulus and toughness required for various dental applications.
Joined Laminar Composites for Dental Applications
Laminar restorations are typically the best approach to achieve the mechanical and aesthetic requirements of restorations. Current practice utilizes time consuming hand techniques to apply the aesthetic layers on the stronger underlayers. We are developing an approach similar to the sealing glasses used in lighting and fuel cells to produce a strong, variable thickness, dense bond between individually optimized layers. Our work focuses on development of glasses appropriate to an oral environment and characterization of resulting laminar composites under loading conditions typical of the mouth.
- Fellow, American Ceramic Society (1994)
- W.M. Keck Foundation, Engineering Excellence Teaching Award (1995)
Selected Publications
Lee J.J.-W., Chai H., Lloyd I.K., and Lawn B.R., "Crack propagation across an adhesive interlayer in flexural loading," in press, Scripta Materialia.
Lee J.J.-W., Lloyd I.K., Chai H. and Jung Y.-G. and Lawn B.R., "Arrest, deflection, penetration and reinitiation of cracks in brittle layers across adhesive interlayers," in press, Acta Materialia.
Wang Y.-J, Lee J.J., Lloyd I.K., Wilson O.C. Jr., Rosenblum M. and Thompson V., "High Modulus Nanopowder Reinforced Dimethylacrylate Matrix Composites for Adhesive Applications," JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART A 82A (3): 651-657 SEP 1 2007.
Lee J.J.-W., Wang Y., Lloyd I.K., and Lawn B.R., "Joining Veneers to Ceramic Cores and Dentition with Adhesive Interlayers," JOURNAL OF DENTAL RESEARCH 86 (8): 745-748 AUG 2007.
Donahoe D.N., Pecht M., Lloyd I.K., and Ganesan S., "Moisture induced degradation of multilayer ceramic capacitors," MICROELECTRONICS RELIABILITY 46 (2-4): 400-408 FEB-APR 2006.
Lawn B.R., Pajares A., Zhang Y., Zhang Y., Polack M.A., Lloyd I.K., Rekow E.D., Thompson V.P., "Materials design in the performance of all-ceramic crowns", BIOMATERIALS 25 (14): 2885-2892 JUN 2004.
Flanders L..A., Quinn J.B., Wilson O.C., Lloyd I.K., "Scratch hardness and chipping of dental ceramics under different environments", DENTAL MATERIALS 19 (8): 716-724 DEC 2003.
Quinn J.B., Sundar V., Lloyd I.K., "Influence of microstructure and chemistry on the fracture toughness of dental ceramics", DENTAL MATERIALS 19 (7): 603-611 NOV 2003.
Quinn J.B., Nguyen V.Q., Sanghera J.S., Lloyd I.K., Pureza P.C., Miklos R.E., Aggarwal I.D., "Strength and fractographic analysis of chalcogenide As-S-Se and Ge-As-Se-Te glass fibers", JOURNAL OF NON-CRYSTALLINE SOLIDS 325 (1-3): 150-157 SEP 15 2003.
Quinn J.B., Yen J., Katz R.N., et al., "Subjective ceramic machinability and material properties", MACHINING SCIENCE AND TECHNOLOGY 6 (2): 291-299 2002.
Xu G.F., Carmel Y., Olorunyolemi T., Lloyd I.K., Wilson O.C., "Microwave sintering and properties of AlN/TiB2 composites," JOURNAL OF MATERIALS RESEARCH 18 (1): 66-76 JAN 2003
Zhang Y., Lawn B.R., Lloyd I.K., "Damage characterization of dental materials in ceramic-based crown-like layer structures", KEY ENGINEERING MATERIALS 224-2: 453-457 2002.
Quinn G.D., Patel P.J., Lloyd I.K., "Effect of loading rate upon conventional ceramic microindentation hardness,"
JOURNAL OF RESEARCH OF THE NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY 107 (3): 299-306 MAY-JUN 2002.
Xu G.F., Olorunyolemi T., Wilson O.C., Lloyd I.K., Carmel Y., "Microwave sintering of high-density, high thermal conductivity AIN," JOURNAL OF MATERIALS RESEARCH 17 (11): 2837-2845 NOV 2002
Zhang Y., Lawn B.R., Lloyd I.K., "Damage characterization of dental materials in ceramic-based crown-like layer structures," KEY ENGINEERING MATERIALS 224-2: 453-457 2002.
Lawn B.R., Zhang Y., Lloyd I.K., Janal MN, Rekow E.D., Thompson V.P., "Materials design of ceramic-based layer structures for crowns," JOURNAL OF DENTAL RESEARCH 81 (6): 433-438 JUN 2002.
Olorunyolemi T., Birnboim A., Carmel Y., Wilson O.C., Lloyd I.K., Smith S, Campbell R, "Thermal conductivity of zinc oxide: From green to sintered state," JOURNAL OF THE AMERICAN CERAMIC SOCIETY 85 (5): 1249-1253 MAY 2002.
Zhang Y., Lawn B.R., Lloyd I.K., "Characterization of damage modes in dental ceramic bilayer structures," JOURNAL OF BIOMEDICAL MATERIALS RESEARCH 63 (2): 137-145 APR 2002.
Xu G.F., Lloyd I.K., Carmel Y., Olorunyolemi T., Wilson O.C., "Microwave sintering of ZnO at ultra high heating rates," JOURNAL OF MATERIALS RESEARCH 16 (10): 2850-2858 OCT 2001.
Pert E., Carmel Y., Birnboim A., Olorunyolemi T., Gershon D., Calame J., Lloyd I.K., Wilson O.C., "Temperature measurements during microwave processing: The significance of thermocouple effects," JOURNAL OF THE AMERICAN CERAMIC SOCIETY 84 (9): 1981-1986 SEP 2001.
Quinn J.B., Lloyd I.K., "Comparison of methods to determine the fracture toughness of three glass-ceramics at elevated temperatures," JOURNAL OF THE AMERICAN CERAMIC SOCIETY 83 (12): 3070-3076 DEC 2000.
Quinn J.B., Su L., Flanders L., Lloyd I.K., "Edge toughness" and material properties related to the machining of dental ceramics," MACHINING SCIENCE AND TECHNOLOGY 4 (2): 291-304 2000.
Nguyen V.Q., Sanghera J.S., Aggarwal I.D., Lloyd I.K., "Physical properties of chalcogenide and chalcohalide glasses,"JOURNAL OF THE AMERICAN CERAMIC SOCIETY 83 (4): 855-859 APR 2000.
Hill M.D., White G.S., Hwang C.S., Lloyd I.K., "Cyclic damage in lead zirconate titanate," JOURNAL OF THE AMERICAN CERAMIC SOCIETY 79 (7): 1915-1920 JUL 1996.
Xu H.H.K., Braun L.M., Ostertag C.P., Krause R.F., Lloyd I.K., "Failure Modes of SiC-Fiber/Si3N4-Matrix Composites at Elevated Temperatures," JOURNAL OF THE AMERICAN CERAMIC SOCIETY 78 (2): 388-394 FEB 1995.
Xu H.H.K., Ostertag C.P., Braun L.M., Lloyd I.K., "Short-Crack Mechanical-Properties and Failure Mechanisms of SI3N4-MATRIX SIC-Fiber Composite," JOURNAL OF THE AMERICAN CERAMIC SOCIETY 77 (11): 3048-3048 NOV 1994.
Xu H.H.K., Ostertag C.P., Braun L.M., Lloyd I.K., "Effects of Fiber Volume Fraction on Mechanical-Properties of SiC-Fiber Si3N4-Matrix Composites,"JOURNAL OF THE AMERICAN CERAMIC SOCIETY 77 (7): 1897-1900 JUL 1994.
Invited Talks
I.K. Lloyd, Y Carmel, O.C. Wilson, Jr., and G.-F. Xu, "Microwave Processing of Ceramics," in press CIMTEC,11th International Ceramics Congress and 4th Forum on New Materials, Acireale, Italy, June 2006.
I.K. Lloyd, George Kimball Burgess Lecture: Microwave Processing: Difficult Materials and Tailored Microstructures ASM International Washington DC Chapt. March 2004.
Y. Carmel, A. Birnboim, T. Olorunyolemi, I.K. Lloyd, and O.C. Wilson, Jr., "Multi-Scale Dielectric and Thermal Properties of Composites Modeling and Experiments, 3rd World Congress on Microwave and Radiofrequency Applications," section M3C- Dielectric Properties, Sept 22-26, 2002, Sidney Australia
L.J. Martinez-Miranda, O.C. Wilson, Jr., I.K. Lloyd, J. Kidder and L. Salamanca-Riba, "Teaching Undergraduates Results from Recent Research as a Part of a Laboratory Class: An X-Ray Diffraction Experiment," Mat. Res. Soc. Symp. 634E, 2002.
Y. Carmel, I.K. Lloyd, O.C. Wilson, Jr., T. Olorunyolemi, A. Birnboim, D. Gershon, E. Pert, and G. Xu, "Dielectric and Thermal Properties and Their Importance in Microwave Sintering of Advanced Ceramics, 2nd International Congress on Microwave and Radio-Frequency Processing, solicted for April 2-6, 2000, Orlando, FL paper MWC-DP20.
Professional Affiliations
- American Ceramic Society
- American Association of Dental Research
- International Association of Dental Research
