Materials Science Forum Vols. 620-622

Abstract: In this paper, antibacterial silver-containing hydroxyapatite coating was prepared by vacuum plasma spraying method and osteoblasts were seeded onto the surface of the coating to evaluate its cytocompatibility. The results indicated that the cells proliferated well on the samples, and the proliferation rate on the silver-containing hydroxyapatite coating was a little bit higher than that on the silver-free hydroxyapatite coating. The contact angle of water drop on the coating was measured, and it was found that the contact angles of the silver-containing hydroxyapatite coatings were smaller than the hydroxyapatite coating. The improvement of hydrophilicity for the silver-containing hydroxyapatite coating could be beneficial to the cells proliferation on its surface. It can be concluded that the addition of silver in the hydroxyapatite coating endowed the coating with antibacterial property while maintaining its excellent cytocompatibility.

Abstract: The lignin was extracted and purified by organic acid from pulping black liquor, and the process and influencing factors of extraction and purification were studied. The results of single factor experiments showed that the citric acid which contains three -COOH was suitable to extract and purify lignin. The results of orthogonal experiment demonstrated that the optimal condition of extraction and purification was as follows: citric acid saturated solution, 80°C, pH value of acid evolution endpoint was 3.0. The analysis of FT-IR spectrum, GPC and DSC indicated that the type of lignin extracted by citric acid was G-S, and the lignin was characterized as complete structure, higher molecular weight and Tg. The study on extraction technology of high purity lignin by citric acid method is hopeful to overcome the disadvantages of exorbitant cost and secondary pollution caused by the residues from lignin separation. It could change waste into valuables and put resource utilization of pulping black liquor into practice.

Abstract: Glass-ceramics are especially useful for the dental restorations because of their good biocompatibility, chemical stability, aesthetic, mechanical strength and wear resistance. The aim of this work was to obtain one mica glass-ceramic, which can be easily used for rapid machining into all-ceramic tooth with computer assisted design/computer assisted manufacture (CAD/CAM) devices. In the study, on the base of low melting machinable fluorosilicic mica glass ceramics, the effects of CeO2 and Fe2O3 in SiO2-B2O3-K2O-Na2O-Li2O-Al2O3-MgO-F system on color were studied. By orthogonal experimental design, the effects of crystallized parameters on the color, three point flexural strength and machinability of the glass ceramics were obtained, and the samples were analyzed by differential thermal analysis(DTA), X-ray diffraction (XRD) and scanning electron microscopy(SEM), respectively. Experimental results showed that the glass-ceramics with color close to the tooth can be obtained by adjusting the percentage of CeO2 and Fe2O3, and the glass-ceramics crystallized at 680°C for 2h have excellent mechanical properties and machinability.

Abstract: In order to improve the biocompatibility of carbon/carbon(C/C) composites used for hip prosthesis, pyrolytic carbon coating was prepared on their surface by chemical vapor deposition. The microstructures of the samples were analyzed by scanning electron microscopy (SEM) and the biomedical response was assessed by the morphology and proliferation of MG63 osteoblast-like cells. The results show that the texture on the surface of C/C composites changes from chaotic structure to uniform state after the pyrolytic carbon coating is prepared. Osteoblasts cultured on pyrolytic carbon coating present flat shape with thin thickness, and display better proliferation in comparison with those on the uncoated C/C composites surface.

Abstract: In order to quantify the relationship between collapse-shrinkage properties and colorimetric parameters on plantation-grown eucalyptus as solid-wood furniture, measurements of the above-mentioned indices were carried out on five species of plantation-grown Eucalyptus (Eucalyptus urophylla, E.grandis, E.urophylla×grandis, E.grandis ×urophylla and E.cloeziana) under three kinds of heat-treat patterns(heat, steaming and combination of heat and steaming) and their correlations were investigated by means of regression analysis. Results showed that for the former four low-density prone-collapse eucalypt, collapse-shrinkage properties were strongly correlated with L* and △E*( R2 ≥0.85) under the above treated conditions, while weak linear correlation with a* and b*. For high-density E.cloeziana with extremely lower collapse, the four colorimetric indexes were lightly correlated with collapse-shrinkage properties. Thus, it can be concluded that L* and △Eab* may be regarded as the two primary and more reliable predictors of shrinkage-collapse parameters for low-density collapse-prone eucalypt wood.

Abstract: Acicular nano-hydroxyapatite (n-HA) was used to make a new biomaterial composite with polycarbonate by a novel technique. The physical and chemical characteristics of the composites were tested. It was found that the synthesized n-HA crystals were similar to bone apatite in size, phase composition and crystal structure. The TEM results indicated the biomimetic n-HA crystals were uniformly distributed in the polymer matrix. Chemical inter-action between inorganic n-HA and polycarbonate was investigated and discussed. These results indicate that the composite fulfills the basic requirement of bone substitute material, and has the potential for clinical applications.

Abstract: A new fabrication process of a stem for an artificial hip joint has been investigated to improve mechanical properties and to reduce both the fabrication cost and consumption of expensive Ti alloys by swaging and die-forging into near-net-shape at room temperature, followed by local heat treatment and precise machining. In this study metastable Ti-Nb-Sn alloys consisting of non-cytotoxic elements (biocompatible Ti alloys) were used for biomedical applications. It is found that swaging at both ends of a rod before die-forging saves material consumption by approximately 50% in comparison with turning, and enhances subsequent age-hardening. In addition the cold die-forging enables the fabrication costs to decrease. It is suggested that high strength of higher than 1100 MPa in the proximal part connected to a stem head and low Young’s modulus of less than 60 GPa in the distal part implanted in a femur can be obtained simultaneously in advanced Ti alloy stems.

Abstract: Functional poly(L-lactide) (PLLA-OH) containing vinyl groups as well as hydroxyl end groups was synthesized by ring-opening polymerization (ROP), using stannous octanoate as the catalyst and 2-hydroxyethyl methacrylate (HEMA) as the initiator. The structure of the obtained PLLA-OH was characterized using both Fourier Transform Infrared (FT-IR) spectroscopy and 1H nuclear magnetic resonance (1H-NMR) spectroscopy, while their crystallinities and thermo behavior were studied by differential scanning calorimetry (DSC), separately. The best condition for the ROP of the studied PLLA-OH was found with the polymerization temperature of T= 145 °C, the weight percent of the catalyst of 0.03 wt%, the ROP duration of 48 h and the L-lactide/initiator molar ratio of 100/1.

Abstract: Organic silane perfluorinated octyl sulfonic acid amide is synthesized by compounding aminosilane (N-(β-aminoethyl)-γ-aminopropyl trimethoxy silane) and perfluorinated octyl sulfonic acid fluoride. The results show that the product yield of 88% is achieved when the ratio of perfluorinated octyl sulfonic acid fluoride and aminosilane is maintained at 1:1.1 at 50°C for 2 hours.

Abstract: The EAF Dusts and pickling sludges generated in the stainless steel production contain a lot of valuable metals such as iron, nickel, chromium and manganese. Their compositions are similar to those of laterite nickel ore, and sometimes even better than that at the contents of nickel and chromium. But it is regret that these valuable resources were random piled up or landed fill disposal. In this paper, the typical EAF dusts and pickling sludges and reductant coke powder were mixed in appropriate ratio, and then smelted in a medium frequency induction furnace. In the smelting process, the lime powder and fluorite was added to fluxing, and the ferrosilicon powder was added to strengthen the reduction. The product nickel-chromium-iron can be used as the raw material for stainless steel or cast iron production. The technology has good social and economic benefits.