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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.

TiC-reinforced CrMo steel was successfully fabricated by 3D gel-printing in this study. The rheological behaviour and polymerisation of slurries with different TiC content were researched. The appr...

TiC–316L metal matrix composites were successfully printed with an epoxy resin–absolute ethanol system by direct ink writing (DIW) process in this study. Microstructure and fracture morphology of the samples were observed by a scanning electron microscope (SEM). Also, the relative density, hardness and transverse rupture strength (TRS) of the sintered samples were tested. The results show that the samples prepared with a new epoxy resin–absolute ethanol system by the DIW process have high solid content of printing slurry, good surface roughness, high relative density and high strength. The solid content of the slurry suitable for DIW was 60 vol%, and the internal diameter of the nozzle was set to 0.4 mm, the printing speed was set to 30 mm·s−1, and the layer height was set to 0.36 mm. For the sample with 35 wt% TiC–316L, the relative density, hardness and TRS of the sintered sample can reach 99.3%, HRA 79.5 and 1438 MPa, respectively.

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.

A new process, staggered stacking method of printing wires and printing wire deformation by 3D gel-printing, to prepare ZrO2 dense parts was used in this study. In order to reduce the gap between adjacent printing wires, a new type of stacking method-staggered stacking is proposed. The density of sintered parts prepared by staggered stacking method is about 88%. In order to eliminate the gap between the adjacent cylindrical printing lines, according to printing wire deformation and then adjusting the parameters, the printing head was used as a scraper to fill the gaps. The relative density of sintered body prepared by staggered stacking method of printing wires and printing wire deformation in this study is 98.86%, and the three-point bending strength of the parts is 496 ± 20 MPa.

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.

Porous hydroxyapatite (HA) scaffolds for bone tissue engineering were successfully prepared using 3D gel-printing technology. The rheological properties of the HA ceramic slurry, the porosity and shrinkage of the scaffold, and the mechanical properties and degradability of the scaffold were studied. The influence of printing speed on the formation of the scaffold was also investigated. HA ceramic slurry with a solid volume fraction of 55 vol% was used to prepare the scaffolds with an interconnected pore structure that can provide a channel for the adhesion, proliferation, and substance transportation of bone cells. The sintered scaffold had a pore size of about 350 µm × 350 µm. The porosity, and shrinkage in height and width were 52.26%, 16.2 ± 0.2%, and 17.8 ± 0.23%, respectively. The maximum compressive strength and compressive modulus of the sintered scaffolds were 16.77 ± 0.38 and 492 ± 11 MPa, respectively. The weight loss rate of the scaffold was 10.38% after degradation in Tris-HCl solution for 5 wk.

Fe3O4/γ-Fe2O3@SiO2 composite magnetic fluids were prepared successfully by microemulsion method in this study. Fe3O4 magnetic nanoparticles (Nps) were successfully converted to Fe3O4/γ-Fe2O3 magnetic Nps by low-temperature low-vacuum oxidation method (LTLV oxidation method), and then coated with silica by the modified Stober method. The core-shell structure composite magnetic Nps were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM), and transmission electron microscopy (TEM). The results show that the size of Fe3O4/γ-Fe2O3 particles was about 13 nm and that of SiO2 coating was about 3 nm, and the saturation magnetization of Fe3O4/γ-Fe2O3 and Fe3O4/γ-Fe2O3@SiO2 Nps was 59.12 A m2/kg and 35.84 A m2/kg, respectively. And the saturation magnetization of Fe3O4/γ-Fe2O3@SiO2 magnetic fluid was 22.91 A m2/kg.

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.

Fe 3 O 4 @SiO 2 @nimodipine(NMDP) core-shell structure nanoparticles were prepared successfully by sonochemical method. The composite magnetic nanoparticles with SiO 2 coating are effective and accurate for completing the delivery of NMDP in vitro . The samples are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR). Drug release was detected by high performance liquid chromatography (HPLC). The result shows the release rate of NMDP reach to 61.3% in a short time of 40 min in the PBS, and to 100% in a time of 60 min. The Fe 3 O 4 @SiO 2 @NMDP NPs prepared show a super-paramagnetic property with a saturation magnetization value of 21.4 emu/g. The accordingly composite magnetic fluid with a saturation magnetization value of 14.8 emu/g shows the spicules in external magnet field. It indicates that SiO 2 coating plays an important role and has a great potential application in treatment of high blood pressure and cerebrovascular disease by using magnetic drug delivery technology.

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.

3D gel-printing (3DGP) is a new printing method, which is based on a 2-hydroxyethyl methacrylate (HEMA) gelation system to produce complex shape parts. In this study, the 3DGP process based on a water-based gelation system was used to prepare zirconia (ZrO 2 ) ceramic parts. The water-based ZrO 2 ceramic slurry with a solid volume fraction of 50 vol% was prepared and its rheological property was characterized. The surface roughness is Ra 8.90 µm on the printed green sample, and Ra 8.25 µm on the sample after sintered at 1520 °C for 2 h. The relative density, the Vickers hardness and the transverse rupture strength of the sintered sample are 97.6%, 14.4 GPa and 450 MPa, respectively.

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

The composite of 35CrMo high-strength steel matrix reinforced with TiC reinforcement (50 wt.%) has been produced by conventional powder metallurgy (PM). The sintering temperature and process for heating treatment were discussed. The scanning electron microscopy (SEM) revealed the morphology and distribution of the reinforcement phase. Density, hardness, and transverse rupture strength (TRS) of the samples were analyzed. The results showed that the optimal sintering process for the composite is sintering at 1430 °C for 1 h and heat treatment process is annealing at 850 °C/30 min, quenching at 880 °C/30 min and then tempering at 560 °C/60 min. The composite after heat treatment has excellent mechanical properties with a relative density of 99.7%, hardness of 65 HRC, TRS of 1850 ± 20 MPa, respectively, and will be used as refractory moulds, cold work moulds and some gaskets, etc.

A new 3D printing process, 3D gel-printing (3DGP) based on methaerylate-2-hydroxy ethyl (HEMA) gelation system, was proposed in this paper, and as an example, 316L stainless steel gear was prepared by 3DGP. The rheological behavior of metal slurry, the surface roughness and strength of green sample and sintered sample were researched. The results show that the metal slurry with a 316L particle content of 62.5 vol% can be prepared with a HEMA-based gelation system, whose rheological behavior is fit for printing. Catalyst can accelerate the gelation so that complex shape of parts could be setting in time during printing. The green sample has a strength of 16.1 ± 2.2 MPa and a roughness of 3.5 ± 0.5 μm on top surface. The sintered sample has a homogeneous microstructure and no interface between the printed layers and lines was observed. The sintered sample has a roughness of 3.8 ± 0.9 μm on top surface and a tensile strength of 488 ± 15 MPa. Generally, 3DGP based on HEMA gelation system is a promising method for producing complex shape parts.

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.

The vitrified bond diamond grinding wheel composites were successfully prepared by gel casting (GC) with 3D printing molds. The effects of different solid content on the properties of vitrified bond/diamond abrasive slurry were researched in this study. The results show that when the solid content was 54 vol%, the green sample had a better flexural strength of about 13 MPa. After the sample was sintered at 760 °C, the relative density and flexural strength of sintered samples was about 80.0% and 78 MPa, respectively. The grinding ratio of the vitrified bond diamond grinding wheel composites prepared by gel casting with 3D printing molds was 1:152, and the removal rate was 2.92 g/min, which means that the performance of the diamond grinding wheel reached the traditional cold pressed sample.

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.

Fe3O4@chitosan (CS)@Gefitinib (GFTN) core-shell structure composite magnetic nanoparticles (NPs) were prepared by chemical coprecipitation method in this study. In addition, protamine was doped in Fe3O4 cores to prepare Fe3O4@protamine@CS@GFTN core-shell structure composite NPs, in order to increase the loading of GFTN in composite NPs. They were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM) and spectrophotometer. The results show that the average size of Fe3O4@CS@GFTN and Fe3O4@protamine@CS@GFTN composite NPs is approximately 19 and 21[Formula: see text]nm, respectively. The saturation magnetizations of composite magnetic NPs and corresponding magnetic fluids are 57.20, 20.79, 59.58 and 19.75[Formula: see text]emu/g, respectively. The loading of GFTN in composite NPs was measured by a spectrophotometer to be about 13.5% and 27.6%, respectively. The addition of protamine increased the loading of GFTN two times, indicating that it will play an important role in the management of lung diseases.

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/

Owing to the absence of metal binder, binderless cemented carbides have higher wear, corrosion, and oxidation resistance. WC-0.3VC- 0.5Cr3C2 powders with an average particle size of 200 nm and a little amount of active element were consolidated by spark plasma sintering. The sintered microstructure revealed that the average WC grain size was 0.24 μm, which was almost consistent with the initial fine powder. The results of XRD showed that W2C phase was formed. Nearly complete densification of ultrafine binderless cemented carbide was achieved by sintering at 1400°C for 120 s under 50 MPa. The resulting hardness and the fracture toughness were 28.18 GPa and 6.05 MPa·m½, respectively.