title: Effect of sintering temperature on flexural properties of alumina fiber-reinforced, alumina-based ceramics prepared by tape casting technique.
abstract: OBJECTIVE
  The purpose of this study was to investigate the effect of sintering temperature on flexural properties of an alumina fiber-reinforced, alumina-based ceramic (alumina-fiber/alumina composite) prepared by a tape casting technique.
  
  
  METHODS
  The alumina-based ceramic used a matrix consisting of 60 wt% Al(2)O(3) powder and 40 wt% SiO(2)-B(2)O(3) glass powder with the following composition in terms of wt%: 33 SiO(2), 32 B(2)O(3), 20 CaO, and 15 MgO. Prepreg sheets of alumina-fiber/alumina composite in which uniaxial aligned alumina fibers were infiltrated with the alumina-based matrix were fabricated continuously using a tape casting technique employing a doctor blade system. Four sintering temperatures were investigated: 900 degrees C, 1000 degrees C, 1100 degrees C, and 1200 degrees C, all for 4 hours under atmospheric pressure in a furnace. The surface of the alumina-fiber/alumina composite after sintering was observed with a field-emission scanning electron microscope (FE-SEM). A three-point bending test was carried out to measure the flexural strength and modulus of alumina-fiber/alumina composite specimens. In addition, sintered alumina fiber was characterized by X-ray diffraction (XRD).
  
  
  RESULTS
  FE-SEM observation showed that alumina-fiber/alumina composite was confirmed to be densely sintered for all sintering temperatures. Three-point bending measurement revealed that alumina-fiber/alumina composite produced at sintering temperatures of 1100 degrees C and 1200 degrees C exhibit flexural strengths lower than those of alumina-fiber/alumina composite produced at sintering temperatures of 900 degrees C and 1000 degrees C; alumina-fiber/alumina composite produced at sintering temperatures of 1100 degrees C and 1200 degrees C exhibit flexural moduli lower than that of alumina-fiber/alumina composite produced at a sintering temperature of 1000 degrees C. Additional XRD pattern of alumina fiber indicated that with increasing sintering temperature, the crystallographic structure of gamma-alumina transformed to mullite.
  
  
  CONCLUSIONS
  There were significant differences in the flexural properties between the alumina-fiber/alumina composite sintered at the four temperatures. This indicates that the choice of optimum sintering temperature is an important factor for successful dental applications of alumina-fiber/alumina composite developed by the tape casting system.
authors.affiliation: Department of Dental Biomaterials, Research Institute of Oral Science, Nihon University School of Dentistry at Matsudo, Chiba, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Tanimoto
authors.forename: Kimiya
authors.initials: K
authors.lastname: Nemoto
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry*; D002516:Ceramics / Q000737:chemistry*; D003735:Dental Casting Technique; D006358:Hot Temperature / Q000009:adverse effects*; D019016:Mineral Fibers; D018583:Pliability
chemical_list: D019016:Mineral Fibers; D000537:Aluminum Oxide