Fuzhai Cui

Highly adhesive hydroxyapatite coatings on titanium alloy formed by ion beam assisted deposition.

A compact crystalline hydroxyapatite coating on Ti–6Al–4V substrate with an atomic intermixed coating/substrate interface about 27 nm in width was synthesized by ion beam assisted deposition (IBAD) and a following post-treatment. The coating after post-treatment was identified by X-ray diffraction as crystalline hydroxyapatite. The interface between coatings and substrates was studied by Auger electron spectroscopy. The adhesive strength between coatings and substrates was measured by scratch tester. The results showed that the adhesive strength of IBAD coatings is nearly twice that of ion beam sputtered coatings. The study also showed that coatings prepared by IBAD eliminated the interfacial deficiencies existing in plasma-sprayed coatings.

Oriented growth of hydroxyapatite on (0001) textured titanium with functionalized self-assembled silane monolayer as template

A highly (0001) textured hydroxyapatite [Ca 10 (PO 4 ) 6 (OH) 2 , HA] coating on polycrystalline titanium plate is successfully synthesized by a biomimetic process mimicking biomineralization. To simulate the first stage of biomineralization, that is, supramolecular preorganization, a template surface with highly organized arrangement of carboxyl (–COOH) and alcoholic hydroxyl (–1OH) groups is prepared through self-assembly of vinyltriethoxysilane [(C 2 H 5 O) 3 SiCH=CH 2 , VTS] on hydroxylated titanium with strong (0001) texture, followed by oxidation of the vinyl groups (–1CH=CH 2 ) with dilute KMnO 4 solution into alcoholic hydroxyl and then into carboxyl groups. The functionalized substrate can induce oriented nucleation and growth of HA with (0001) planes parallel to the substrate surface from supersaturated HA solution through interfacial molecular recognition. The mechanisms of molecular recognition are also discussed.

The functionalization of titanium with EDTA to induce biomimetic mineralization of hydroxyapatite

A new process is developed to functionalize an inorganic substrate with an organic polycarboxylic chelating agent to obtain a biomimetic template for mimicking biomineralization for the synthesis of films or coatings. A titanium plate is first placed in ethylenediaminetetracetic acid (EDTA) solution to effect chemisorption and self-assembly of EDTA molecules on the plate. The plate is then aged in supersaturated hydroxyapatite [(Ca 10 (PO 4 ) 6 (OH) 2 , HA] solution to mimic biomineralization. The functionalization process is found to be very effective in creating a surface with an organized arrangement of carboxylate ions (–COO – ) with the orientation of lone pairs of electrons on O perpendicular to or radiating from the substrate surface. The coating is formed through the plate-like outgrowth of HA grains along the [001] direction under the mediation of the functionalized surface, giving rise to the coexistence of two kinds of microstructural patterns in coating. One is a parallel arrangement of the plate-like HA grains with (001) planes preferably parallel to the substrate surface, the other is a radial arrangement of the plate-like HA grains with the [001] direction radiating from one surface core and the (111) planes preferably parallel to the surface. The mineralization mechanism is discussed on the basis of the conformation of the self-assembled EDTA molecules and the interfacial molecular recognition, analogous to the biomineralization, including electrostatic interactions, hydrogen bonding, stereochemical arrangement and geometrical correspondence.

Alterations in mineral properties of zebrafish skeletal bone induced by liliputdtc232 gene mutation

Abstract The alterations of mineral properties of bone by gene mutation in the zebrafish, which is associated with abnormal bone mineralization and bone diseases, were reported for the first time in this paper. Transmission electron microscope (TEM), Fourier transform infrared microspectroscopy (FTIRM) and thermogravimetric analysis (TGA) were used to investigate the changes in the mineral. Significant variations of the morphologies of the minerals and the mineral/matrix ratio after liliput dtc232 (lil) gene mutation have been observed. The morphologies of the minerals, examined by TEM, revealed that the mutated mineral was in bigger size and the shape was block shaped but not plate shaped. The results of FTIRM indicated that the lil mutant zebrafish skeleton exhibited a greater mineral/matrix ratio (phosphate/matrix=4.86±0.28) than that of wild-type zebrafish bone (phosphate/matrix=4.17±0.67), which was confirmed by TGA analysis. Furthermore, the mineral of lil bone became less mature and crystalline with more ion substitutions. And the selected areas electron diffraction (SAED) patterns showed that the main crystal phases of the two type fishes were both hydroxyapatite. In addition, we have discussed the relationship among the mineral properties, nanomechanical properties and biomineralization process.

Rectifying and photovoltaic effects observed in mesoporous MCM-41 silica film on silicon

Abstract Oriented mesoporous MCM-41 silica films have been synthesized on single-crystalline silicon (111) wafers by the self-assembly deposition in ammonia medium. For the first time, the I – V curves and surface photovoltaic spectra of the films has been investigated. The I – V curve of the as-synthesized film exhibits an excellent rectified ratio of σ + / σ − =3×10 3 (where σ + , σ − are the forward electrical conductivity and reverse electrical conductivity, respectively). The results of photovoltaic measurements indicate that the as-synthesized film possesses a significant surface photovoltaic increase.

Electrochemical synthesis and characterization of mesoporous Cu/Cu2O films

In summary, a new method for the electrochemical preparation of mesoporous alloy of Cu/Cu2O film was introduced. In terms of hierarchical order structure, the best results were achieved using low concentration of the anionic surfactant SDS (<10 wt.%). Through XRD, TEM, SEM and energy spectrum analysis, the film has been characterized as a mesoporous Cu/Cu2O film with hexagonal mesophase and high-quality atom-scale cubic crystalline framework. In combination with the results, this suggests that the growth of the film is accomplished through a deposition process of copper ions-coated rod-like micelles.

Preparation and characterization of TiO2/porous carbon multilayers☆

Abstract The hybrid film of TiO2/porous carbon multilayers was synthesized hydrothermally by self-assembly processing and then by sintering. Characterization of this film was performed by SEM, XRD, TGA, RAMAN and IR techniques. It is found that the film is micrometers thick and the period of TiO2/porous carbon multilayers is in 3.1 nm. This film is hopefully applicable for gas sensor and Li battery cathode materials.