title: Preparation of mica-based glass-ceramics with needle-like fluorapatite.
abstract: OBJECTIVE
  The aim of this study was to prepare mica-based glass-ceramics containing needle-like fluorapatites, and to understand the relationship between the composition, the microstructure and mechanical properties.
  
  
  METHODS
  The specimens were prepared by casting and subsequent heat treatment. The crystalline phases in the specimens were determined by X-ray diffraction (XRD). The microstructures of the fractured surface were examined by using a scanning electron microscope with an energy dispersive spectrometer (SEM/EDS). The Vickers hardness and fracture toughness were determined by the indentation method. Statistical analysis of the results was performed by one-way analysis of variance (ANOVA) and Tukey's test. The bioactivity of the glass-ceramics was evaluated by soaking the polished specimens in the simulated body fluid (SBF).
  
  
  RESULTS
  Needle-like fluorapatite crystals were successfully obtained in mica-based glass-ceramics by controlling the heat treatment process. The formation of needle-like fluorapatite crystals, instead of particle-like crystals reported in previous studies, can be attributed to the one-dimensional rapid growth of fluorapatite along the c-axis. The mechanical properties of the glass-ceramics are related to the fluorapatite content. The higher the fluorapatite content, the higher the Vickers hardness and the fracture toughness (p<0.01). The bioactivity test showed that the needle-like fluorapatite-containing glass-ceramics possess very good bioactivity.
  
  
  CONCLUSIONS
  As the needle-like fluorapatite crystal has the same morphology as human bones, it endows the mica-based glass-ceramics with good bioactivity. Moreover, the needle-like fluorapatite crystal toughens the base glass-ceramics. Therefore, the mica-based glass-ceramics with needle-like fluorapatite have the potential for the restoration of bone defects and implants.
authors.affiliation: State Key Laboratory for Powder Metallurgy, Central South University, Changsha, 410083 Hunan, PR China.
authors.forename: Qijun
authors.initials: Q
authors.lastname: Xiang
authors.forename: Yong
authors.initials: Y
authors.lastname: Liu
authors.forename: Xiaoxian
authors.initials: X
authors.lastname: Sheng
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Dan
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry*; D001031:Apatites / Q000737:chemistry*; D001672:Biocompatible Materials / Q000737:chemistry; D001826:Body Fluids / Q000737:chemistry; D002516:Ceramics / Q000737:chemistry*; D003461:Crystallography; D003764:Dental Materials / Q000138:chemical synthesis / Q000737:chemistry*; D004577:Electron Probe Microanalysis; D005898:Glass / Q000737:chemistry*; D006244:Hardness; D006358:Hot Temperature; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D013314:Stress, Mechanical; D013329:Structure-Activity Relationship; D013499:Surface Properties; D014961:X-Ray Diffraction
chemical_list: D000538:Aluminum Silicates; D001031:Apatites; D001672:Biocompatible Materials; D003764:Dental Materials; C025105:fluorapatite; C011934:mica