Key Engineering Materials Vols. 330-332

Abstract: Amorphous carbon (a-C) and carbon nitrogen (a-CN) films were synthesized using plasma immersion ion implantation and deposition (PIII-D) under different N2 flow at room temperature (R.T.). Lifshitz-van der Waals/acid-base approach (LW-AB) was introduced in order to study films’ surface energy deeply. The results showed that the capability of the surface of the film on receive electron changed with N2 flow, which effected platelet adhesion of film strongly. Hall effects tests were employed to characterize the electrical properties of the films. The results showed that the as-deposited films exhibited n-type semiconductor characteristic, and carrier concentration of the films decreased with N2 flow increasing. Raman spectra with 514nm laser-source were employed to analyze the structural of the films.

Abstract: The goal of this paper is elaboration and characterization of chemical and electrochemical phosphate deposition on titanium. The behavior of the bioactive coating was evaluated using electrochemical methods (open circuit potential, cyclic voltametry) and spectroscopy (FTIR and atomic adsorbtion spectroscopy).

Abstract: In this study, bovine serum albumin protein (BSA) was introduced to investigate the co-precipitation process of calcium phosphate and BSA on bioactivated Ti. Commercially pure titanium were bioactivated firstly, and then immersed in a highly supersaturated stable calcium phosphate (Ca-P) solution at three different conditions. The samples designated as Ti-C, Ti-C-CB, and Ti-C-B for control. The samples were evaluated by SEM with EDX, XRD and XPS. The co-precipitation of BSA protein and Ca-P influenced the morphology of the crystals of Ti-C-CB significantly. In terms of the immersion in the Ca-P solution containing BSA, the co-precipitation of Ca-P with BSA on the surface of Ti-C-CB was a chemical process rather than simple physical adsorption, which was most possibly achieved by the linkage of –COO− groups to Ca-P. Such coprecipitated interaction led to the formation of a tight, dense and uniform Ca-P coating.

Abstract: In this study we explore the possibility of incorporating Sr into nano-apatite coatings prepared by a solution-derived biomimetic methodology for coating titanium based implants. The way this element is incorporated in the apatite structure and its effects on the stereochemistry and morphology of the resulting apatite layers were investigated, as well as the resulting mineralization kinetics. The presence of Sr in solution induced an inhibitory effect on mineralization, leading to a decrease in the thickness of the mineral layers. This ion was incorporated in the apatite structure through a substitution mechanism by replacing Ca in the crystal lattice. The obtained Sr-substituted biomimetic coatings are expected to enhance bone formation and osteointegration.

Abstract: Hydroxyapatite (HA) was widely used as coating on metals and alloys to enhance the interconnection between metal implants and bone. To improve the bonding strength and bioactivity, in this work, bioactive glass (G) was added and HA-G composite coating was prepared on Ti-6Al-4V at low temperature. The scanning electronic microscope (SEM) graphs showed that the surface of the coating was composed with needle-like crystals, and the X-ray diffractometer (XRD) and Fourier transform infra-red spectrometry (FTIR) results proved that the crystals was carbonate hydroxyapatite (CHA), no other crystal phase was detected. The SEM micrographs of the cross section showed that the coating was porous and bonded closely with the surface of the alloy. The energy diffraction spectra (EDS) result show that a Si-Ti-Al-V-O layer was formed at the interface and enhance the interconnection between the coating and alloy. The bonding strength of the coating was 34.8±6.8MPa, which was much higher than that of the pure HA coating on Ti-6Al-4V prepared by plasma spraying method. The HA-G composite coating on Ti-6Al-4V showed high bonding strength, porous structure, and bone like CHA composition, which has good potential to be used as bone substitutes.

Abstract: The composition of the electrolytes used in the process of anodic oxidation was modified to generate the novel anodic oxidation. The surface topography of the novel anodic oxidation showed that the pore/crater structures with the precipitants attached over the surface were observed in SEM. The physical properties and biocompatibility of the surface with the novel anodic oxidation were compared with that of anodic oxidation and machined surface of titanium. XRD, Bioactivity in a simulated body fluid, cell proliferation, and MTT test were performed to evaluate the differences among different surfaces.

Abstract: The aim of this study is to evaluate the effects of coating implants with hydroxyapatite (HA) by an ion beam-assisted deposition (IBAD) method and to compare them with implants prepared with machined and anodized surfaces. Twenty-four implants in this study were divided into three groups; machined, anodized, anodized plus IBAD surface implants. Implant stability and osseointegration were assessed by resonance frequency analysis (RFA) and histologic analysis. We can conclude that implants coated by HA by IBAD demonstrate characteristics of contact osteogenesis, but the research design does not permit conclusions regarding long-term treatment outcome with implants. Further studies are needed.

Abstract: Homogeneous coatings adhered strongly to titanium substrates were attained by electrochemical method in electrolytes containing Ca2+ and PO4 3- ions with Ca/P ratio being 1.67. SEM observation showed that the HAp crystals prepared with higher concentration electrolyte (4x10-2M Ca2+) are ribbon-like with thickness of nanometer size, a morphology seldom reported previously. In an electrolyte of lower concentration (6x10-4M Ca2+), the HAp crystals formed are rod-like with defined hexagonal cross section and diameter of about 70-80nm. The electrolyte of intermediary concentration (5x10-3M Ca2+) produced plate-like HAp crystals. XRD patterns and IR spectra confirmed that the coatings consist of HAp crystals.

Abstract: Rutile titanium oxide films were fabricated by reactive unbalanced magnetron sputtering. The blood compatibility is evaluated in vitro by clotting time and platelet adhesion measurement. The surface valence band electronic structure is gained by the XPS valence band spectra. The rutile titanium oxide films exhibit attractive hemocompatibility. The result of the valence band electronic structure of the films on the surface indicated that the rutile titanium oxide film represent an n-type semiconductor characteristics and the characters result in the prevention of the charge transfering between the blood and materials and overall excellent antithrombogenic properties.

Abstract: The objective of the present study was to define the optimal conditions and characterizations of hydroxyapatite (HA) coatings on titanium by electrophoretic deposition (EPD). The EPD processing parameters, such as deposition time, HA concentration level in the suspension, and applied voltage are experimentally determined. A good packing, crack-free and uniform HA coating on titanium was prepared. Then the coatings were sintered at 800 °C for 2 h. The sintered coatings presented a very homogeneous polycrystalline structure free of cracks. The results show that the application of EPD is an effective method in obtaining HA coatings with good properties.