Study on Microstructure and Nanomechanics Properties of Antibacterial Bone China

Fracture appearance, surface and nanomechanics properties of antibacterial ceramics contairing rare earth phosphate composite antibacterial materials were characterized and measured by SEM, AFM and Nanoindenter, respectively. Results show that grain of fracture surface of antibacterial ceramics grows uniform refinement topography of bubble break-up appears at the surface, which is flat and has liquid character, by adding the phosphate composite containing rare earth, nevertheless needle-like crystal and granular outgrowth form at fracture surface and surface of common ceramics, respectively. Young's modulus of antibacterial ceramic film is 74. 397 GPa and hardness is 8. 134 GPa, which increses by 4.4﹪ and 1.6﹪ comparing with common ceramics, respectively. Loading curves of two kind of ceramics have obvious nonlinear character under 700 nm and linear character between 700 ～ 1000 nm, and unloading curve have obvious linear character.

Nonlinear Constitutive Behavior Of Ferroelectric Materials

The ferroelectric specimen is considered as an aggregation of many randomly oriented domains. According to this mechanism, a multi-domain mechanical model is developed in this paper. Each domain is represented by one element. The applied stress and electric field are taken to be the stress and electric field in the formula of the driving force of domain switching for each element in the specimen. It means that the macroscopic switching criterion is used for calculating the volume fraction of domain switching for each element. By using the hardening relation between the driving force of domain switching and the volume fraction of domain switching calibrated, the volume fraction of domain switching for each element is calculated. Substituting the stress and electric field and the volume fraction of domain switching into the constitutive equation of ferroelectric material, one can easily get the strain and electric displacement for each element. The macroscopic behavior of the ferroelectric specimen is then directly calculated by volume averaging. Meanwhile, the nonlinear finite element analysis for the ferroelectric specimen is carried out. In the finite element simulation, the volume fraction of domain switching for each element is calculated by using the same method mentioned above. The interaction between different elements is taken into account in the finite element simulation and the local stress and electric field for each element is obtained. The macroscopic behavior of the specimen is then calculated by volume averaging. The computation results involve the electric butterfly shaped curves of axial strain versus the axial electric field and the hysteresis loops of electric displacement versus the electric field for ferroelectric specimens under the uniaxial coupled stress and electric field loading. The present theoretical prediction agrees reasonably with the experimental results.