Associate Professor Isabel Lloyd
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
Phone: (301) 405-5221
- High elastic modulus dental composites
- All-ceramic dental restorations
- Ceramics for sensor systems
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)
Wang, Y.J. & Lloyd, I.K., Time-dependent nanoindentation behavior of high elastic modulus dental resin composites. Journal of Materials Research 25 (3), 529-536 (2010).
Lee, J.J.W. et al., Veneer vs. core failure in adhesively bonded all-ceramic crown layers. Journal of Dental Research 87 (4), 363-366 (2008).
Wang, Y.J. et al., High modulus nanopowder reinforced dimethacrylate matrix composites for dental cement applications. Journal of Biomedical Materials Research Part A 82A (3), 651-657 (2007).
Lee, J.J.W., Wang, Y., Lloyd, I.K., & Lawn, B.R., Joining veneers to ceramic cores and dentition with adhesive interlayers. Journal of Dental Research 86 (8), 745-748 (2007).
Lee, J.J.W., Lloyd, I.K., Chai, H., Jung, Y.G., & Lawn, B.R., Arrest, deflection, penetration and reinitiation of cracks in brittle layers across adhesive interlayers. Acta Materialia 55 (17), 5859-5866 (2007).
Lee, J.J.W., Chai, H., Lloyd, I.K., & Lawn, B.R., Crack propagation across an adhesive interlayer in flexural loading. Scripta Materialia 57 (12), 1077-1080 (2007).
Donahoe, D.N., Pecht, M., Lloyd, I.K., & Ganesan, S., Moisture induced degradation of multilayer ceramic capacitors. Microelectronics Reliability 46 (2-4), 400-408 (2006).
Lawn, B.R. et al., Materials design in the performance of all-ceramic crowns. Biomaterials 25 (14), 2885-2892 (2004).
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 (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 (2003).
Quinn, J.B. et al., 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 (2003).
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 (2003).
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 (2002).
Quinn, J.B., Yen, J., Katz, R.N., & Lloyd, I.K., Subjective ceramic machinability and material properties. Machining Science and Technology 6 (2), 291-299 (2002).
Olorunyolemi, T. et al., Thermal conductivity of zinc oxide: From green to sintered state. Journal of the American Ceramic Society 85 (5), 1249-1253 (2002).
Lawn, B.R. et al., Materials design of ceramic-based layer structures for crowns. Journal of Dental Research 81 (6), 433-438 (2002).
Deng, 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 (2002).
Deng, Y., Lawn, B.R., & Lloyd, I.K., Damage characterization of dental materials in ceramic-based crown-like layer structures. High-Performance Ceramics 2001, Proceedings 224-2, 453-457 (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 (2001).
Pert, E. et al., Temperature measurements during microwave processing: The significance of thermocouple effects. Journal of the American Ceramic Society 84 (9), 1981-1986 (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 (2000).
Nguyen, V.Q., Sanghera, J.S., Lloyd, I.K., Aggarwal, I.D., & Gershon, D., Room temperature dielectric properties of the As40S((60-x))Se-x glass system. Journal of Non-Crystalline Solids 276 (1-3), 151-158 (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 (2000).
Nguyen, V.Q., Sanghera, J.S., Kung, F.H., Aggarwal, I.D., & Lloyd, I.K., Effect of temperature on the absorption loss of chalcogenide glass fibers. Applied Optics 38 (15), 3206-3213 (1999).
Nguyen, V.Q., Sanghera, J.S., Freitas, J.A., Aggarwal, I.D., & Lloyd, I.K., Structural investigation of chalcogenide and chalcohalide glasses using Raman spectroscopy. Journal of Non-Crystalline Solids 248 (2-3), 103-114 (1999).
Wilson, O.C., Quinn, J., Peng, T., Lloyd, I.K., & Thompson, V.P., Environmental effects on material removal and damage in dental ceramics. Journal of Dental Research 76, 3091-3091 (1997).
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 (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 (1995).
Brower, D.T. & Lloyd, I.K., Investigation of the Effect of Host Composition on the Photoluminescent Properties of Srxba1-Xs Doped with Eu and Sm. Journal of Materials Research 10 (1), 211-213 (1995).
Benedetto, J.M., Roush, M.L., Lloyd, I.K., Ramesh, R., & Rychlik, B., The temperature dependence of ferroelectric imprint. Integrated Ferroelectrics 10 (1-4), 279-288 (1995).
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 (1994).
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 Composites. Journal of the American Ceramic Society 77 (7), 1889-1896 (1994).
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.
- American Ceramic Society
- American Association of Dental Research
- International Association of Dental Research