Nanoparticles ceramic materials

Askay, I. Nanostructured ceramics through self-assembly, in Seigel, R. W., Hu, E. and Roco, M. C. (eds) R D Status and Trends in Nanoparticles, Nanostructured Materials and Nanodevices in the United States, International Technology Research Institute, Baltimore, MD, USA, 1998. 

The above mentioned scaffolds were made completely of the ceramic materials. Other potential materials which could be used to fabricate a novel construct for the repair of ciitical-sized bone defects is a novel material made of biodegradable polymer reinforced with ceramics particles. The properties of such a composite depend on 1) properties of the polymer used for the matrix and properties of the ceramics used for the reinforcement, 2) composition of the composite (i.e. content of ceramic particles) and 3) size, shape and arrangement of the particles in the matrix. Several polymer-composite composites have been used for scaffolds fabrication including polylactide (PLA) and polycaprolacton (PCL) reinforced with calcium phosphate (CaP) micro and nanoparticles. Authors proposed a novel composite material by blending copolymer -Poly(L-lactide-co-D,E-lactide) (PLDLLA) a copolymer with a ceramic - Tri-Calcium Phosphate... 

The chemical methods have been used for the synthesis of bismuth nanoparticles by vapor flow condensation [6] and microemulsion process [7]. It is generally accepted that the microwave synthesis and sintering (MS) processes [8-10] can concentrate ceramic materials at a very rapid rate and at a substantially lower temperature than the conventional sintering (CS) process. 

Nanofillers have actually been around for decades (the oldest for over a century) carbon blacks, pigments, precipitated silicic acid (Ultrasil, Degussa-Hiils), pyrogenic silicic acids (Aerosile, Degussa-Hiils), phyllosilicates, nucleation agents, reactive silicone nanoparticles for epoxy resins, ceramic materials and inorganic-organic hybrid particles from sol-gel transformations, for example synthetic, dispersible aluminate (boehmite) powder. 

In-situ formation of CNTs in alumina matrices produced by spray pyrolysis might be considered an alternative to the CVD method, which involves spraying a slurry of ferrocene (metal catalysts) and alumina nanoparticles in xylene (hydrocarbon source) at 1000"C under Ar atmosphere [31]. However, the technique produced flake-like mixtures, which showed heterogeneous distribution of CNTs in the matrix material in through-thickness direction. The same spray pyrolysis method was used to fabricate C-SiC-carbon nanotube composite flakes [32]. Other ceramic materials including SiC [33], TiN [34], Fe2N [34], and BaTiOs [35] have also been demonstrated as matrices for incorporation of CNTs by the CVD method. 

One merit of special attention in this chapter is the fact that sol-gel synthesis offers a convenient method for hosting chemical reactions, a process which is not possible using other synthesis techniques. Typically, in sol-gel encapsulation, silica nanoparticles surround the captive molecules during gel formation. In principle, the sol-gel process can be considered as a phase separation by sol-reactions, sol-gelation and finally, removal of the solvent resulting in a ceramic material Depending on the preparation, dense oxide particles or polymeric clusters will be obtained [16]. 

Russo L, Colangelo F, Cioffi R, Rea I, De Stefano L (2011) A mechano-chemical approach to porous silicon nanoparticles fabrication. Materials 4 1023-1033 Stephen RG, Riley FL (1989) Oxidation of silicon by water. J Eur Ceram Soc 5 219-222 Stevulova N, Suzuki T, Senna M, Balintova M, Sepelak V, Tkacova K (1997) Mechanochemical oxidation of silicon and selectivity of oxide superficial layer dissolution in aqueous solutions of HF and KOH. Solid State Ion 101103(2) 681-686 Verdoni LP, Fink MJ, Mitchell BS (2011) A fractionation process of mechanochemically synthesized blue-green luminescent alkyl-passivated silicon nanoparticles. Chem Eng J 172 591-600... 

Another noteworthy effort at nanocomposite fabrication applied ceramic nanoparticles to a ceramic material to enhance osteoconductivity and mechanical performance. Nawa et al. [49] developed a ceria-stabiHzed tetragonal zirconia polycrystal (Ce-TZP) ceramic and incorporated alumina (AI2O3) nanocrystals into it via wet chemistry methods for load-bearing bone applications. Further studies of this material investigated its ability to induce apatite formation [50], in vivo biocompatibility, and resistance to wear [10] with favorable results. 

One very promising solution to overcome these drawbacks with ceramic materials as fuel electrodes is the infiltration of nanoparticles of ceria-based materials into the porous structures of the fabricated ceramic backbones. The infiltration of various materials has recently been used in SOFC electrodes (see e.g. the works ° and references therein for inspiration). Infiltration into composite fuel electrode backbones is illustrated in Fig. 12.22. 

The morphology of the particles in ceramic materials is a consequence of the preparation method, and wet chemical methods favor obtaining porous nanoparticles, because the reactions produce homogeneous materials composed of small and uniform particles. 

Composite nanofibers have been made by electrospinning solutions that contain nanoparticles, such as silica, titania, carbon black, silver, and iron oxides. The nanofiber matrices can be polymer, carbon, or ceramic. For carbon and ceramic matrices, post-electrospinning treatments are needed to convert their precirrsors into carbon and ceramic materials. 

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