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It is increasing evidence that the synergistic effects of magnetic scaffolds and magnetic fields can accelerate bone repairing and regeneration, and the bone tumor may be treated using magnetite nanoparticles (MNPs) with hyperthermia. In this study, in order to apply the magnetocaloric performance of MgFe2O4 to bone tissue engineering, porous MgFe2O4 magnetic scaffolds were successfully prepared by chemical coprecipitation method and 3D gel-printing (3DGP) technology. The printing slurry based on polyvinyl alcohol (PVA) system exhibited shear thinning properties, and its maximum solid loading was about 63wt%. When the slurry was squeezed out of the needle, the slurry viscosity was 0.58 Pa·s at the shear rate of 316.3 s-1. The scaffolds sintered above 1100 °C were superparamagnetic and their compressive strength was within 1.8–12.51MPa, which is suitable for human cancellous bone. The highest saturation magnetization of porous MgFe2O4 scaffolds printed by 3DGP was 10.63 emu/g when they were sintered at 1200 °C. The weight loss rate of the scaffolds was 2.15% after degradation in simulated body fluid (SBF) for 5 weeks, pH value of SBF was between 6.78 and 7.4. Preliminary biological experiment shows that MC3T3-E1 cells had good adhesion and proliferation on MgFe2O4 scaffolds surface, and MgFe2O4 scaffolds can promote alkaline phosphatase (ALP) activation, which explain that porous MgFe2O4 magnetic scaffolds may be used for bone repairing.

In this study, porous calcium silicate (CaSiO3) scaffolds were prepared by 3D gel-printing (3DGP) method and Fe3O4 water-based magnetic fluids (WMFs) were prepared by phacoemulsification compound chemical coprecipitation method. Fe3O4 WMFs were coated on CaSiO3 scaffolds surface to prepare Fe3O4/CaSiO3 composite scaffolds. The effect of WMFs with different Fe3O4 concentrations on porous CaSiO3 scaffolds was studied. The composition and morphological characteristics of porous scaffolds were analyzed by using scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) analysis. The magnetic properties were tested by vibrating sample magnetometer (VSM). The stability of Fe3O4 WMFs coatings and the degradability of composite scaffolds were tested by immersing them in simulated body fluid (SBF). The results show that when Fe3O4 concentration was 5.4% (w/v), the composite scaffolds had the highest saturation magnetization of 69.6 emu/g and the best stability in dynamic SBF. It is obviously that Fe3O4 WMFs coatings can be used for bone tissue engineering scaffolds repairing.

Porous polycaprolactone (PCL)-coated calcium silicate (CaSiO3) composite scaffolds were successfully prepared by 3D gel-printing (3DGP) and vacuum impregnation technology in this study. The effect of different PCL concentration on porous CaSiO3 scaffolds prepared by 3DGP technology was studied. The composition and morphological characteristics of PCL/CaSiO3 scaffolds were tested by using fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), and energy dispersive spectrometer (EDS) analysis. PCL coating amount on the scaffolds surface was calculated by thermogravimetric analysis (TGA). Compressive strength was tested by a universal testing machine, and degradability was tested by immersing the scaffolds in a simulated body fluid (SBF). The results show that PCL coating thickness increased from 7.29 μm to 12.2 μm, and the compressive strength of the corresponding composite scaffolds increased from 17.15 MPa to 24.12 MPa following with PCL concentration increasing from 7.5% to 12.5%. When the porous composite scaffolds were immersed in SBF for 28 days, the degradation ratio was 1.06% (CaSiO3), 1.63% (CaSiO3-7.5PCL), 1.81% (CaSiO3-10PCL) and 1.55% (CaSiO3-12.5PCL), respectively. It is obviously that PCL/CaSiO3 composite scaffolds, which are suitable for bone growth in bone repair engineering, are beneficial to improve the mechanical properties and biodegradability of pure CaSiO3 scaffolds.

In this paper, the precursors of MgxCa3−x(PO4)2 powders with different magnesium contents were first synthesized by a liquid-phase precipitation method with simple operation and easy control of the reaction process. And the MgxCa3−x(PO4)2 slurry was used to print porous scaffolds by 3D gel-printing (3DGP), and then the scaffolds were degreased and sintered to improve performance, which simplifies the process and saves costs. The effects of different magnesium ions (Mg2+) doping contents on the precursors were investigated. When Mg2+ doping content is 0, 5 mol%, 10 mol% and 30 mol%, the particle diameters of the precursors are, respectively, 44.51 μm, 41.91 μm, 38.38 μm and 31.93 μm. The effects of different Mg2+ doping amounts on the biological and mechanical properties of the scaffolds were studied. When the doping Mg2+ content is 0, 5 mol%, 10 mol% and 30 mol%, respectively, the porosity of the scaffolds is 72.11%, 70.26%, 69.83% and 65.15%, and the strength is 1.04 ± 0.01 MPa, 0.73 ± 0.17 MPa, 0.23 ± 0.01 MPa and 1.89 ± 0.21 MPa, respectively. The degradation behavior was observed when the scaffolds were immersed in phosphate buffer saline for 8 weeks, which indicate that MgxCa3−x(PO4)2 composite scaffolds are expected to be more widely used in the field of bone defect repairing.

Porous CaSiO3 composite scaffolds with different dopants, such as MgSiO3, MgCl2 and CaSO4, were successfully prepared by 3D gel-printing (3DGP). (m, n) is proposed to describe the filament geometry features. The results show that doping can improve the strength of porous composite scaffolds and MgCl2-doped composite scaffolds had the highest modulus of elasticity of 1241 MPa. The shrinkage rate range of the composite scaffolds was 11.44–13.16%, and their porosity was all about 60%. When porous composite scaffolds were soaked in SBF for 28 days at 37°С, the degradation rate was 2.7% (pure), 0.3% (MgSiO3), 0.2% (MgCl2), 5.27% (CaSO4), respectively. It explains that MgSiO3 and MgCl2 inhibited the in vitro degradation of CaSiO3, while CaSO4 promoted. It is obviously that doped MgCl2 can improve the mechanical properties of porous scaffolds, and doped CaSO4 can improve the degradation of scaffolds, which play an important role in bone repair engineering.

The porous β-tricalcium phosphate (TCP) bioceramic scaffolds were successfully prepared by 3D gel-printing method. The calcium phosphate salt precursor was synthesized by hydration precipitation method and calcium chloride and diammonium hydrogen phosphate were as raw materials. The rheological properties of slurries with different calcium to phosphorus (Ca/P) ratios and the shrinkage and porosity of the printed scaffolds were studied in this paper. Also, the effect of different Ca/P ratios on the composition of powders was studied. The calcium phosphate salt powders with average particle size of 37.12 μm were used in this study and the maximum solids loading of the slurry which is suitable for printing was about 50 vol% and the printing green scaffolds have well-distributed designed voids and microporous. The β-TCP bioceramic scaffolds were obtained by sintering at 1100 °C for 3 h when Ca/P ratio is 3.5. The porosity of the sintered scaffold is approximately 58.05% which is suitable for bone growth in bone repair engineering.

Potential porous calcium silicate (CaSiO3) scaffolds for bone tissue engineering were successfully prepared by 3D gel printing technology. The average particle size of CaSiO3 powder is about 5.119 μm. The CaSiO3 slurry prepared for printing had been exhibited shear-thinning properties, and the maximum solid loading of the slurry was 72 wt%. The green scaffolds were sintered at 1150 °C for 4 h after degreasing at 250 °C for 3 h, 420 °C for 9 h, and 660 °C for 3 h, respectively. The sintered scaffolds have well-distributed designed voids and microporous. The shrinkage in length, width, and height is 12.29 ± 0.20%, 12.43 ± 0.17%, 13.15 ± 0.19%, respectively. The porosity of the sintered scaffold is approximately 62%, and the compressive strength is about 16.52 MPa, which is equivalent to the strength of human cancellous bone.

The composites of low alloy steel reinforced with TiC particles (36 wt-%) were prepared by conventional powder metallurgy process in this paper. The chromium in the steel matrix was provided by pur...

The composite of low alloy steel reinforced with TiC particles (36 wt%) was prepared by the powder metallurgy (PM) process in this paper. The effects of the chromium content and the total carbon content on the composites were studied. The scanning electron microscopy (SEM) was used to observe the microstructure and such properties as porosity, hardness, transverse rupture strength (TRS) and fracture morphology of the samples were tested. The results show that the optimum sintering temperature decreases with the increase of chromium content. The porosity of sintered samples decreases with increasing the total carbon content, and increases with increasing the chromium content. The TRS and hardness of samples increase with the increase of the carbon content. With the increase of the chromium content, the TRS of the sample gradually decreases, and the hardness firstly increases and then decreases a little. This results from the combined effects of the martensite amount and the shape, size and composition of precipitated chromium carbides in the steel matrix.

Porous magnesium (Mg) scaffolds were successfully prepared by 3D gel-printing (3DGP) technology in this study. Absolute ethanol and epoxy resin were mixed to prepare the premixed solution and then Mg powders were mixed into the premixed solution to prepare the slurry which was used to print Mg scaffolds by 3DGP. After debinding and sintering, the properties and microstructure of the samples were tested. The scaffolds were implanted into the femoral condyle of rats, and the implanting position was observed at the first, the third and the fifth week. The results showed that the highest compressive strength of Mg scaffolds can reach 20.05 MPa at a porosity of 64.4% after sintered at 610 °C. In order to study the degradation and osteogenesis of the scaffolds, pure Mg, oxide-coated Mg and TCP scaffolds were implanted into the femoral condyle of rats and compared with the blank control group. The results showed that oxide-coated Mg scaffolds have relatively good biocompatibility and degradability. According to the results of CT (Computed Tomography) and X-ray, the oxide-coated Mg scaffolds can promote cancellous bone osteogenesis and can delay the degradation of pure Mg scaffolds.

In this paper, the composite of low alloy steel reinforced with TiC particles was prepared by conventional powder metallurgy process. The effects of the combined carbon content of TiC powder, sintering temperature and heating rate on the composite were studied. The results showed that the selected TiC powder has a combined carbon content of 17.91 wt-% and the optimal sintering process is heating from 600 to 1440°C at a rate of 1°C min−1 and holding for 1 h at 1440°C. The composite after heat treatment has excellent mechanical properties with density of 6.45 g cm−3, hardness of 68–69 HRC and TRS of 1763 MPa, respectively, and will be used as wear-resistant parts, assembly fixtures, moulds, etc.

The mechanical and tribological properties of Cu-based powder metallurgy (P/M) friction composites containing 10wt%–50wt% oxide-dispersion-strengthened (ODS) Cu reinforced with nano-Al2O3 were investigated. Additionally, the friction and wear behaviors as well as the wear mechanism of the Cu-based composites were characterized by scanning electron microscopy (SEM) in conjunction with energy-dispersive X-ray spectroscopy (EDS) elemental mapping. The results indicated that the Cu-based friction composite containing 30wt% ODS Cu exhibited the highest hardness and shear strength. The average and instantaneous friction coefficient curves of this sample, when operated in a high-speed train at a speed of 300 km/h, were similar to those of a commercial disc brake pad produced by Knorr-Bremse AG (Germany). Additionally, the lowest linear wear loss of the obtained samples was (0.008 ± 0.001) mm per time per face, which is much lower than that of the Knorr-Bremse pad ((0.01 ± 0.001) mm). The excellent performance of the developed pad is a consequence of the formation of a dense oxide composite layer and its close combination with the pad body.

In order to measure cantilever bending stress of elastic alloys during stress relaxation experiment, a homo-made apparatus has been developed. The mechanical properties and stress relaxation resistances of three high strength copper alloys have been investigated. Considering different experimental conditions, the Cu-Ni-Sn alloys exhibit the optimum stress relaxation resistance. The mechanisms of stress relaxation and precipitation strengthening have been discussed. The hardness is recommended to be a critical parameter which can be used to evaluate the stress relaxation resistance simply. Because the interactions between precipitation particles and dislocations which influence the hardness also affect the dynamic recovery of mobile dislocations during stress relaxation. Finally, two effective methods have been proposed to slow down the stress relaxation in the copper alloys.

Fe3O4@SiO2 core–shell composite nanoparticles were successfully prepared by a one-pot process. Tetraethyl-orthosilicate was used as a surfactant to synthesize Fe3O4@SiO2 core–shell structures from prepared Fe3O4 nanoparticles. The properties of the Fe3O4 and Fe3O4@SiO2 composite nanoparticles were studied by X-ray diffraction, transmission electron microscopy, energy dispersive spectroscopy, and Fourier transform infrared spectroscopy. The prepared Fe3O4 particles were approximately 12 nm in size, and the thickness of the SiO2 coating was approximately 4 nm. The magnetic properties were studied by vibrating sample magnetometry. The results show that the maximum saturation magnetization of the Fe3O4@SiO2 powder (34.85 A·m2·kg–1) was markedly lower than that of the Fe3O4 powder (79.55 A·m2·kg–1), which demonstrates that Fe3O4 was successfully wrapped by SiO2. The Fe3O4@SiO2 composite nanoparticles have broad prospects in biomedical applications; thus, our next study will apply them in magnetic resonance imaging.

In this paper, the controllable γ-Fe2O3/Fe3O4 composite nanoparticles were prepared by low-temperature low-vacuum oxidation of Fe3O4 directly in different time. The Fe3O4 nanoparticles were synthesized by chemical co-precipitation, and they were almost spherical particles and had no significant changes during the thermal oxidation. The prepared samples were identified by X-ray powder diffraction (XRD), Raman spectra (RS), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The γ-Fe2O3/Fe3O4 was obtained by Fe3O4 oxidized from 0 to 24 h, pure γ-Fe2O3 was obtained by Fe3O4 oxidized 24 h and its saturation magnetization was 55.86 emu/g. The magnetic nanoparticles were evenly dispersed in the silicone oil under the help of oleic acid and emulsifier, the Fe3O4, γ-Fe2O3/Fe3O4 and γ-Fe2O3 magnetic fluid with same viscosity were prepared. In the initial stage of thermal oxidation, the saturation magnetization of magnetic fluid increased with the oxidation time increasing, with the thermal oxidation going on, the saturation magnetization of γ-Fe2O3/Fe3O4 magnetic fluid kept growth until it reaches the maximum critical value and the corresponding oxidation time was 16 h, and then it began to decrease. And the maximum saturation magnetization of prepared γ-Fe2O3/Fe3O4 magnetic fluid was 25.08 emu/g, which was much higher than that of Fe3O4 magnetic fluid (12.45 emu/g) and γ-Fe2O3 magnetic fluid (14.25 emu/g). Keywords: γ-Fe2O3/Fe3O4 composite magnetic particles, Low-temperature low-vacuum oxidation, Magnetic fluid, Saturation magnetization

In this study, silicone-oil-based γ-Fe2O3 magnetic fluid was successfully prepared by thermal oxidizing of Fe3O4 magnetic nanoparticles, which were prepared by chemical co-precipitation with FeSO4·7H2O and FeCl3·6H2O, and their surface was modified by oleate ligands. Silicone oil was used as carrier liquid and oleic acid was as surfactant for preparing γ-Fe2O3 magnetic fluid. It is found that the Fe3O4 nanoparticles surrounded by oleate ligands are not damaged during the thermal oxidizing. The shape of γ-Fe2O3 magnetic nanoparticles prepared is similar to spherical, and their mean size is about 10–20 nm, which has nothing obvious difference compared with Fe3O4. The saturation magnetization of γ-Fe2O3 magnetic fluid prepared is 14.25 A·m2·kg−1 and that of γ-Fe2O3 nanoparticles is 57.56 A·m2·kg−1. The needle of γ-Fe2O3 magnetic fluid is much bigger than that of Fe3O4 magnetic fluid under the same magnetic field, which shows better magnetic properties.

In the paper, the TiC −50 wt.% high manganese steel cermet was made with different sintering processes including vacuum sintering, hot pressing, microwave sintering and spark plasma sintering (SPS). The microstructure, porosity and fracture morphology of the samples were analyzed with scanning electron microscopy (SEM). Phase analysis was carried out using X-ray diffraction (XRD). The density, hardness, transverse rupture strength (TRS) and wear resistance were investigated for the effect of the sintering processes. The results showed that the core–shell structure was not clearly observed for the TiC particles in microstructures and the high manganese steel matrix is BCC structure. Hot pressing, microwave sintering and SPS are useful processes for densification of the cermet. Nearly full density and higher hardness can be reached by these three processes at a lower sintering temperature and in a shorter sintering time. However, higher TRS can be reached by means of alloying completely in a longer sintering time, for example vacuum sintering. Pre-sintering in a long sintering time at a lower sintering temperature is also useful for improving the TRS. Finally, vacuum sintering is an effective process for producing this composite with the lowest cost in the mass production.

In this work, low-cost titanium was fabricated by gelcasting of titanium hydride powder. The effects of morphology and grain composition of powder raw material and solid loading on the rheological behavior of gelcasting slurry were studied. The degreasing, dehydriding and sintering behaviors of gelcasted green body were investigated by differential thermal analysis (DTA) and dilatometer. The results show that the solid loading of titanium hydride slurry reaches 50 vol%. Combination of dehydriding and sintering in one process accelerates the densification, and the relative sintered density of the final part achieves 96.5 %. In order to test the ability of gelcasting process for fabricating structural materials, a resin handle produced by 3D printing technology was used as a model and a titanium handle was successfully fabricated. Higher solid loading and better sinterability of titanium hydride powder promote manufacture of bulk titanium with high relative density, complex shape and well-defined microstructure.

In this paper, TiAl alloy powders were prepared successfully by high-energy ball milling and diffusion reaction in vacuum at low temperature. The titanium powder, aluminum powder, and titanium hydride powder were used as raw materials. The samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and differential thermal analysis (DTA). The results show that the alloy powders with the main intermetallic compounds of TiAl are obtained using Ti–Al powders and TiH2–Al powders after heated for 2 h at 500 °C, 3 h at 600 °C, and 3 h at 750 °C, respectively. The average grain sizes of alloy powder are about 45 and 20 μm with irregular shape, respectively. The prepared TiAl alloy powders are relatively pure, and the average quality content of oxygen in the alloy powders is 0.33 wt%. The forming process of alloy powder contains both the diffusion reaction of Ti and Al, which gives priority to the diffusion reaction of aluminum.

Low-molecular mass organic gelcasting is utilized to fabricate titanium structural materials. The aim is to find a low-residual gel system for the fabrication of titanium with good ductility. The thermally reversible gel system is composed of 1,3:2,4-dibenzylidene sorbitol (gelator) and 1-butanol (solvent). Titanium hydride powders are used as raw material and the solid loading of gelcasting slurry reaches 48 vol%. Combination of dehydriding and sintering in one process accelerate densification and the relative sintered density reaches up to 97.5%. The contents of oxygen and carbon contamination are 0.31 and 0.08 wt%, respectively, which contribute to a high-level of mechanical property with tensile strength of 580 MPa and elongation of 8%. To achieve the near-net shape forming capability of low-molecular mass organic gelcasting, rosin is used to increase the green strength. Eventually, titanium parts with complex shape are successfully prepared.

Monodisperse cobalt nanoparticles with relatively high coercivities were synthesized by thermal decomposition of cobalt acetate for the application of ultra-high density magnetic recording media. Without using any reducing agents, Co nanoparticles of 13.9–21.3 nm in size were prepared using various protecting agents and a high boiling point solvent trioctylamine. The Co nanoparticles prepared with the mixture of oleic acid, oleylamine, and polyvinylpyrrolidone (PVP) showed clear crystalline structure of face centered cubic, and their coercivity was measured to be 27.2 kA/m. PVP was effective in controlling particle growth while hindering agglomeration between the particles. The as-prepared Co nanoparticles with a moderate coercivity can be applicable to patterned media.

Almost monodisperse iron oxide nanoparticles with an average particle size ranging from 5 to 43 nm were fabricated using an environmentally friendly starting material, ferrous acetate. The smallest particles were formed in the presence of a reductant, 1,2-dodecanediol, while the particle size increased with increasing concentration of dispersing agents. The dispersants consisted of various combinations of oleic acid, oleylamine, trioctylphosphine, and polyvinylpyrrolidone. The threshold temperature to form crystalline particles was found to be 240 o C. The 43 nm nanoparticles exhibited a room temperature saturation magnetization and coercivity of 57 emu/

Three types of tungsten powders were prepared by hydrogen reduction of three precursor powders at low temperature, which were used as samples, and were then characterized by Brunauer-Emmer-Teller (BET) method, scanning electron microscopy (SEM), transmission electronic microscopy (TEM), small angle X-ray scattering (SAXS), and field-emission scanning electron microscopy (FESEM) respectively. The results showed that although BET and SEM could not characterize the particle size of nanometer powders, they were important means of assistance to exclude non-nanometer powders. TEM and FESEM could directly measure the particle size of nanometer powders, but this needs a lot of time, to count the average particle size and particle size distribution. SAXS could not describe the state of agglomeration. By the combination of FESEM and SAXS, the particle size, particle size distribution, and particle shape of nanometer powders could be precisely characterized.

The application of molybdenum was limited as a candidate material for working at a high temperature because molybdenum has a poor oxidation resistance. MoSi2 is typically selected to solve the problem since it can form a dense SiO2 coating to protect the substrate molybdenum. MoSi2 coating on the surface of the Mo was prepared by pack cementation process in this paper. The silicide coating was formed by controlling the weight ratio of Si/MoSi2 powders and the pack cementation time. The results showed that the Si is mainly involved in the formation of a silicide layer on the surface of Mo. The MoSi2 is little participation in the coating formed. Two silicide layers have formed on the surface of Mo, outer layer of MoSi2 and inner layer of Mo5Si3. With the extension of time, the thickness of the MoSi2 layer and the Mo5Si3 layer increases, but the increasing rate slows down. Introduction High melting point and high temperature strength of refractory metals has attracted the attention of many researchers, Refractory materials play an important role in national defence industry, aviation, nuclear industry[1,2]. Metals with melting point above 1800 °C, such as tungsten, molybdenum, niobium, vanadium and chromium, have lower prices and wide range of practical applications. Molybdenum has been attended as high temperature performance, high thermal conductivity, specific heat capacity low, and has good thermal shock and thermal fatigue ability. Molybdenum antioxidant performance is poor, because they begin to form oxide above 400°C, and volatilization of the oxide with the increase of temperature rapidly speed up[3], resulting in the failure of materials, but the high temperature anti-oxidation coating can effectively resolve the refractory metals oxidation problem. The development of high temperature anti-oxidation coating has attracted the attention of many researchers at home and abroad. Ryosuke, etc. [4] using the Molten-salt Growth Method in a pure Nb matrix prepared NbSi2 coating. Tatsuo, etc. [5] has prepared Mo(Si,A1)2 coating by hot pressing coated niobium alloys. The lack of the antioxidant capacity of these coating systems or service temperature is low (≤1400°C), and difficult to meet the high temperature (≥ l 600°C) for a long time anti-oxidant requirements. Excellent high temperature properties of MoSi2 caused the concern of researchers recently. The glassy SiO2 phase generated at high temperatures can prevent the further oxidation of the coating, and effectively play a role in filling the crack. As for the formation of MoSi2 coating, Mo layer was firstly deposited using plasma or arc[6], and then silicified to the MoSi2 coatings. This MoSi2 coating has more pores or cracks and it is easy to peel off. Suzuki etc [7] prepared MoSi2 coatings on the Mo substrate and alloy steel by a molten salt method, the laser cladding method and CVD method, but the cost is high. The MoSi2 coatings were prepared by dipping slurry on a molybdenum substrate, and then using the pack cementation method in this study. The coating density, thickness and other factors were analyzed. International Conference on Materials, Environmental and Biological Engineering (MEBE 2015) © 2015. The authors Published by Atlantis Press 347 Experimental 1mm thick molybdenum plates were cut into 30mm×15 mm samples and the samples surface was ground with sandpaper, and was cleaned by ultrasonic instrument filled with acetone, and then dried. The Si powder, MoSi2 powder and activator powder were mixed by a certain proportion, and then mixed with organic binder into the slurry on the molybdenum surface. After dried, the mixed powder was covered in a crucible. Lastly, the sample was put into a vacuum furnace for heat treatment at the temperature of 1320°C for 7 hours. The sample was cut and polished the cross-section after the heat treatment. The organization and structure of the coating were analyzed by using the scanning electron microscope (JSM-5600LV type) and the spectrum analyzer (IE 300 X-type). Results and Discussion The effect on the ratio of Si powder and MoSi2 powder. Si powder is a silicon atom source. MoSi2 powder could be a diluent and NaF powder plays the role of the activator. The Si atoms spread to Mo atoms vicinity to react with Mo for formation a silicide. The different Si, MoSi2 weight ratio was designed, and to study the formation of the silicide layer. The total weight of these two materials is 30g. Fig. 1 is the morphology of samples cross section with heat treatment at the different ratio of Si/MoSi2. It shows that the molybdenum surface have formed two layers of the darker outer layer and lighter inner layer. Through energy dispersive spectroscopy analysis, the outer layer of Mo / Si atomic ratio close to 1:2, formed the MoSi2 layer and the inner Mo / Si atomic ratio close to 5:3 formed the Mo5Si3 layer. Observed the morphology of the coatings, the outer layer of MoSi2 prone to cracks, while inner Mo5Si3 coating almost no cracks. It shows that the coating have good thermal expansion match between Mo5Si3 layer and Mo substrate. The coatings cracks were leaded by a large internal stress cooling to room temperature. Fig.1. The different Si/MoSi2 proportion of cross-section diagram (a)0:30; (b)1:4; (c)1:2; (d)30:0 A Mo5Si3 transition layer has formed between the MoSi2 layer and Mo substrate, but it was impossible to reach significant buffering effect because the thickness is too small, and the MoSi2 layer still have cracks because of the large internal stress. a b

Strength Abstract. The HA composite coating with different TiO2 contents was prepared by electrophoretic deposition in this study. The composite coatings were characterized by scanning electron microscopy (SEM), Ca/P atomic ratio in composite coatings was analyzed by Energy Dispersive Spectrometer (EDS), and the adhesion strength was analyzed by Universal Material Testing Machine. The results show that the density of HA-TiO 2 composite coatings was elevated with increasing TiO2 contents after sintering at 850 ˚C. The atomic ratio of Ca/P (calcium and phosphorus) of the HA/TiO2 composite coatings showed a rising trend with the increasing contents of TiO2 in suspensions. The atomic ratio of Ca/P was 1.69 and 1.75 which was close to the human bone (1.67), when the TiO2 content was 10g/L and 15g/L in the suspension, respectively. The thickness of the coatings increased with the TiO2 contents increasing, which was 30μm that deposited in the suspension content with 10g/L TiO2, and great combination was shown with the good uniformity of the coating. The adhesion strength was 9.10MPa as the TiO2 content was 10g/L.

Spherical SPIO nanoparticles were synthesized and embedded in polyglucosamine (chitosan) by a sonochemical method. The embedded microspheres were shifted out in the range of 100–150 μm. The microspheres were injected into the kidney of a New Zealand white rabbit via an angiographic catheter, and detected in magnetic resonance images of the kidney.

We prepared water-based magnetic fluids with the spent iron oxide catalysts which were used in the styrene monomer production process. The catalyst was composed with 70% magnetite and alkali metals. The water-based magnetic fluids were prepared by mechanical grinding with olecic acid as a surfactant and water in an attritor. The magnetization of the water-based magnetic fluids was 22 emu/g in the 10 kOe.

Nontoxic cobalt acetate tetrahydrate was used as a precursor to prepare cobalt nanoparticles of 8–200 nm in average diameter by thermal decomposition. The different combinations of trioctylphosphine, oleylamine and oleic acid were added as surfactants to control the particle size. These combinations resulted in the particles with saturation magnetization and coercive force ranging from 55.0 to 100.1 emu/g and from 0 to 459.3 Oe, respectively.

Cobalt nanoparticles with an average size of 26 nm were prepared by thermal decomposition of cobalt acetate at 325 °C using PVP (polyvinylpyrrolidone) as a surface-protective reagent. According to the transmission electron microscopy images, the cobalt nanoparticles were well dispersed and mostly had cubic structure as a proper quantity of PVP was added. The magnetic hysteresis loop measured by vibrating sample magnetometer showed that the coercive force H c and saturated magnetization M s were 277.4 Oe and 86.8 emu/g, respectively.

Ultrasuperpara magnetic iron oxide (USPIO) nanoparticles were synthesized with iron chloride using a sonochemical method. The size of the USPIO nanoparticles was controlled by ultrasonic exposure time and power. The USPIO nanoparticles had a narrow size distribution, a perfect magnetite crystal structure, and high saturation magnetization. The magnetic resonance imaging (MRI) contrast agent was prepared by coating the USPIO and dispersing it with biocompatible chitosan. In vivo testing in New Zealand white rabbits confirmed the effectiveness of the USPIO nanoparticles as a MRI contrast agent.

Iron nanoparticles were prepared by thermal decomposition under 180/spl deg/C with 0.256M iron pentacaronyl and 0 M-0.085M oleylamine as a surfactant. Sizes of the synthesized iron nanoparticles are from 4.8nm to 10.9nm depending on the decomposition times in the range from 10 to 60min. The surfactant concentration is a key factor for controlling the size and shape of iron nanoparticles. The synthesized iron particles without surfactant are flocculated to be clusters of 20-50nm. In the case of using 0.0425M surfactant, the obtained particles are almost sphere. While oleylamine concentration was added up to 0.085M, several iron nuclei are agglomerated together regularly. It is confirmed that the synthesized iron particles are amorphous, but the surface of the particles is easily oxidized and to be spinel structured iron oxide by HRTEM.

The nanometric particles possess some physical and chemical properties different from the bulk. The water-based magnetic fluids with nanometric CuxFe1−xOFe2O3 particles were prepared by the two-step method, in which the x value varied from 0.1 to 0.4. The experiment results showed the magnetization decreased with increasing x values. The copper element was partly coprecipitated with iron oxides. These phenomena are ascribed to excess ammonia water in the precipitation. The decanoic acid and the nonanoic acid were selected as the first and second surfactants. The optimal reaction temperatures for the first and second surfactants were 80 and 60 °C respectively with the holding time of 30 min.

Iron nanoparticles are synthesized by thermal decomposition with iron pentacarbonyl as precursor under N/sub 2/ atmosphere. Particle size, shape and magnetization as a function of various experimental conditions are investigated by transmission electron microscopy, X-ray diffraction and vibrate sample magnetometer methods.

Porous titanium alloys have been prepared by gelcasting in this study. The elastic solid green body was first polymerized and then vacuum sintered to porous titanium alloys with low contamination by controlling sintering conditions. The microstructure and the total porosity of the vacuum sintered porous Ti-Co and Ti-Mo alloys were analyzed by using scanning electron microscopy and x-ray diffraction. Moreover, compression and bending tests were conducted to investigate their mechanical properties. The results show that open and closed three-dimensional pore morphologies and total porosity ranging from 38.34% to 58.32% can be achieved. In contrast to porous Ti by gelcasting, the compression and bending strengths of porous titanium alloys were significantly increased by adding Mo and Co with Young's modulus ranging between 7-25 GPa, which is close to that of human cortical bone, therefore being suited for potential application in load-bearing implants.

Cobalt nanoparticles with various morphologies were synthesized by thermal decomposition of cobalt acetate in the presence of various surfactants at 260°C. A combination of surfactants consisting of sufficient amount of oleic acid together with polyvinylpyrrolidone and oleylamine resulted in well-dispersed cubic cobalt nanoparticles of ∼25nm in average size. When 1,2-dodecanediol was added as a reducing agent to the surfactant mixture, triangular-prism-shaped nanoparticles of ∼50nm in average size were synthesized. Furthermore, an injection of trioctylphosphine into the reactor as an additional surfactant decreased the particle size to ∼10nm. The XRD pattern of the prism-like particles corresponded to hexagonal close-packed crystalline phase of cobalt.