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Directional lamellar porous titanium scaffolds are widely used as bone implant bearing materials because of their anisotropic pore structure. Their mechanical properties can be effectively improved by enhancing the strength of pore walls through the introduction of ceramics. In this work, porous titanium implants were prepared by freeze casting combined with TiH2 decomposition. The graphene was introduced into the pore walls of porous titanium, which could transform into titanium carbide (TiC) in situ upon sintering. TiC was evenly distributed in the lamellar pore walls, and the interface was well bonded. The compression strength of the fabricated implants was up to 389.94 MPa when the graphene content was 3 wt%, which was 377.8% times as high as the porous titanium. The crack propagation was resisted by TiC because of the “pinning” effect on the pore wall. Some of TiC were pulled out from the matrix, and others were fractured. The strength of the fabricated implants was improved significantly by the large consumption of fracture energy. Also, fabricated porous titanium implants with TiC are suitable for bone implantation.

Porous ceramics with porosity up to 92.5 % have been successfully fabricated by freeze casting of polycarbosilane (PCS) solution. The effect of PCS concentration and thermal oxidation curing on the pore structure and compressive properties was investigated. Curing mechanism and thermodynamics were illuminated through analyzing the molecular structure, curing activation energy, and curing degree. Porous ceramics, mainly composed of SiC and a small amount of SiO2, have dendritic pore structure which well replicates the solidification morphology of camphene solvent. Results of FT-IR and Gaussian computation of PCS electron density show that Si–H and Si–CH3 bonds play a dominant role in thermal oxidation curing reaction. Both curing degree and ceramic yield increase with the increase in curing temperature and time. The curing degree of Si–H bond is close to 52 % and the corresponding ceramic yield is about 83 % when the porous PCS was cured at 200 °C for 90 min. Both polymer concentration and curing time have influences on the compressive strength of porous ceramics.

Being in the strategic direction of next-generation absorbers, multifunctional microwave absorbing materials possess great application value in military and commercial fields. However, the stringent requirements for performance necessitate the combination of multiple functions in such type of composites, which is still a challenge. This work aims to develop a foam-type absorber composed of multi-dimensional organic and inorganic materials, in which reduced graphene oxide sheets and polyvinyl alcohol membranes serve as the framework and crosslinker to form a three-dimensional skeleton. Meanwhile, SiC nanofibers as a reinforcing component can effectively suppress the over-stacking of reduced graphene oxide and enhance the conductivity and mechanical strength of cell walls. Among the remarkable microwave absorbing properties of the obtained foam, there are the ultra-light (9.85 mg cm-3), broadband (7.04 GHz), and strong absorption (reflection loss of -61.02 dB), all combined in the ultra-thin (2.5 mm). In addition, the foam possesses superelastic and excellent heat-insulating characteristics that ensure shock resistance, heat preservation, and infrared stealth. The remarkable versatility benefits from the porous structure, as well as from the synergistic effect of multi-dimensional organic and inorganic constituents of the foam. Therefore this study lays the foundation for the design of new-generation microwave absorbers with broad application potential.

As the representative MAX phase, Ti3SiC2 exhibits excellent mechanical strength and good temperature oxidation resistance, thus can be used to replace conventional ceramic matrix for the preparation of CMC composite. In this work, a new starting mixture containing different proportions of TiC and Si is proposed for in-situ synthesis of Ti3SiC2, in order to increase the yield while reducing costs and energy consumption. The results reveal that, as the sintering temperature increases, Si atoms gradually diffuse into the TiC crystal and replacing C atoms to form a Ti–Si eutectic (i.e. the Ti5Si3 phase), which then converts TiSi2 from sufficient Si source. Subsequently, either of these intermediates react with TiC and Si to form a Ti3SiC2 compound with SiC as a by-product. Mechanical analysis shows that, both flexural strength (312 ± 25 MPa) and fracture toughness (11.6 ± 1.1 MPa m1/2) have been significantly improved, by comparing with the Cf/SiC composite prepared by the same method. The toughening mechanism mainly derives from inherent merit of carbon fibers, and is assisted by the Ti3SiC2 grain, indicating the presence of this second phase, which is highly dispersed in the SiC matrix, effectively improves the toughness of the composite.

In this work, ZrB2–ZrC–SiC composite nanofibers were prepared by electrospinning combined with the carbothermal reduction method. The morphology, phase composition, and oxidation resistance of the composite nanofibers were investigated. The results showed that ZrB2–ZrC–SiC composite nanofibers with good crystallinity were obtained after calcination at 1550 °C. The obtained fibers distributed uniformly, and the average diameter was about 375 nm. ZrB2–ZrC–SiC nanofibers were oxidized at 587 °C, which was higher than that of the ZrB2–ZrC nanofibers. It revealed that the addition of SiC could improve the oxidation resistance of ZrB2–ZrC composite nanofibers.

Nanotube coatings on titanium surfaces have favorable biocompatibility and structures and are widely used in local drug delivery. However, when a drug freely diffuses out of a nanotube, it leads to an explosive release, making the duration of action extremely short. In this study, a high concentration of vancomycin hydrochloride region similar to a dam was formed on a nanotube coating surface by exploiting the attraction of the electric charge generated by the energy conversion of the piezoelectric effect to vancomycin hydrochloride. The “dam” not only reduces the diffusion rate of vancomycin hydrochloride inside the nanotube into the dam and the diffusion rate of the dam to the outside but also forms a high concentration of vancomycin hydrochloride action region. The free diffusion rate of vancomycin hydrochloride loaded on the TiO2 @ BaTiO3 coaxial nanotubes was reduced by the piezoelectric effect, and the cumulative release of vancomycin hydrochloride for 7 days is reduced by 54.8%. The polarized vancomycin-containing coaxial nanotube coating has a long-lasting antibacterial effect on Staphylococcus aureus. The TiO2 @ BaTiO3 coaxial nanotubes loaded with vancomycin hydrochloride coating with piezoelectric properties has potential application value in controlled drug delivery.

High-porosity dendritic porous alumina was fabricated by using tertiary butanol (TBA) hydrate crystals combined with directional freeze casting. The porosity of this porous alumina approximated 80 %, and its high porosity resulted in high water flux. Dendritic pores improved the physical interception capability of porous ceramics due to the intrinsic moving paths and intercepts from the pore structure. Changes in the TBA content (from 70 vol.% to 85 vol.%) caused a change in pore size from 36.58 μm to 11.54 μm and pore structure (change order: snowflake, dendritic, rod-like, and needle-like), which are important factors affecting water flux and interception capability. The interception and removal of Escherichia coli by 7 mm-height porous ceramics with dendritic structure and an average pore size of 27.90 μm reached 100 % at pH 7.2. This study provides a simple and low-cost method for the effective removal of bacteria.

Piezo-photocatalysis materials that can effectively utilize mechanical energy of water flow have become one of the research focuses in the field of water pollutant treatment. Herein, the unique thorn-like BaTiO3–TiO2 composite nanofibers were prepared in one step by coaxial electrospinning. The surface TiO2 nanorods and the core BaTiO3 nanofiber presented a certain angle when the advancing speed ratio of the shell and core solution was 2:1. The TiO2 nanorods were tightly bonded to the nanofiber and the thorn-like protrusions on the fiber surface were sensitive to water flow. The BaTiO3–TiO2 composite nanofibers exhibited excellent photocatalytic performance and recyclability with the bandgap value of 3.12 eV. The photocatalytic degradation rate of BaTiO3–TiO2 composite nanofibers was 99.8% under the vibration of tiny water current, while the degradation rate was just 56.1% without vibration. Scavenger study result indicated that superoxide radicals and hydroxyl radicals were the main factors to improve the photodegradation activity of the samples. After five cycles, the degradation rate still reached 98.6%. The obtained thorn-like BaTiO3–TiO2 composite nanofibers can effectively utilize the tiny water vibration energy and have broad application prospects in the field of water treatment. Most importantly, the method of synthesizing a unique thorn-like structure is universal.

The 3D highly elastic sponge constructed by BN fiber balls was fabricated through low-temperature treatment, freeze-drying and high-temperature treatment. Results indicated that the composition unit of fiber ball had highly elasticity. When the temperature difference was Δ115 °C, the Young's modulus reached 120 kPa and the energy loss coefficient reached 85% during the first compression. After 10 loading-unloading cycles, the energy loss coefficient was still larger than 51%. The obtained 3D highly elastic BN sponge composed of small-sized fiber balls has potential applications in the fields of energy absorption, catalyst support and environmental restoration.

Addition of oxygen in the interface between Cu and Al2O3 can significantly improve the wettability. In the present work, Cu/Al2O3 laminated composites were fabricated by bonding Cu foils with CuO-coated Al2O3 plates. Before bonding, the coated Al2O3 plates were pretreated at different temperature in the air. The effect of pretreated temperature on the interfacial microstructure, wettability and bending property were investigated. Phase composition in the interface after wetting test was characterized according to the thermodynamics of Cu–O system. The wetting mechanism and bending failure mode of Cu/Al2O3 laminated composites were also analyzed. Pretreated temperature significantly influences the wettability and bending strength of the composites. The contact angle decreased to about 22° when the pretreated temperature equal to 1100 °C. Continuous CuAlO2 in the interlayer is beneficial to the wettability between Cu melt and Al2O3, while other phases such as Cu2O and CuAl2O4 would increase the contact angle. Crack formation and propagation are the main failure mode of Cu/Al2O3 laminated composites during bending test. Different from the wettability, Cu/Al2O3 laminated composites fabricated with pretreated temperature at 1050 °C show the highest bending strength, although the contact angle is not the lowest on this condition. The reason is illustrated through analyzing the bending failure mode.

A sintering-free magnesium phosphate cement (MPC) with an arbitrary shape is potentially used as a bone implant material, especially with complex shapes. However, the high degradation rate of MPC may lead to the degradation of mechanical properties. In this study, graphene (G)/barium titanate (BT)/MPC composites were fabricated by introducing the piezoelectric phase BT and conductive phase G into MPC, which exhibited the piezoelectric effect after polarisation. The negative surface of the composite may attract Ca2+ and Mg2+ to mineralise rapidly, thereby reducing and improving its degradation rate and mechanical properties, respectively. The contents of additional G and BT were optimised. When BT and G contents were 50 mol% and 0.5 wt%, respectively, the piezoelectric coefficient of the composites increased to 6.31 pC/N, which is an increase of 421% without the addition of G. The results of in vitro degradation and mineralisation in simulated body fluids (SBF) showed that introducing BT and G could effectively slow down the degradation rate, promote mineralisation on the composite surface, and enhance the impact on bone integration.

In this paper, ZrB2–ZrC composite nanofibers were prepared by electrospinning method followed by carbothermal reduction process. Nanofibers with ZrC content of 15, 35 and 50 wt%, respectively, were obtained by varying the n(B)/n(Zr) molar ratio. The oxidation resistance of fabricated nanofibers was investigated by the non-isothermal thermogravimetric method. The effect of ZrC content on the oxidation resistance of ZrB2–ZrC composite nanofibers was analyzed systematically. The Kissinger method was used to calculate the oxidative activation energy (E) of the fibers with different ZrC content. The results show that the E values of fiber with n(B)/n(Zr) equal to 2.5, 3.5 and 4 are 219, 362 and 275 kJ/mol. Among the prepared fibers, the fiber with n(B)/n(Zr) of 3.5 has the highest oxidative activation energy and the best oxidation resistance.

The introduction of BaTiO3 (BT) particles into biomaterials, such as polymethyl methacrylate (PMMA) bone cement, is among the effective ways to improve their osteoinductivity. However, excessive addition leads to mechanical degradation. An important problem to solve is the manner by which piezoelectric properties matching human bones can be obtained under the premise of sufficient mechanical properties. The piezoelectric effect is obtained by adding BT particles into PMMA bone cement. The piezoelectric coefficient close to the human bone is obtained at a relatively low BT addition amount by adding graphene on this basis. High mechanical properties can also be obtained. Graphene increases the piezoelectric coefficient by increasing the conductivity, dielectric constant, and effective polarization voltage of graphene (G)/BT(BaTiO3)/PMMA bio-piezoelectric composites. The compression strength of the aforementioned composites increases from 83.5 MPa to 89.5 MPa after the addition of 0.5 vol% graphene, and the requirements of bone implant materials were met. G/BT/PMMA bio-piezoelectric composites have no cytotoxicity, and graphene can also promote cell adhesion and proliferation on the composite's surface. The polarized bio-piezoelectric composites can improve cell morphology and promote cell proliferation. The number of cells increases with increasing piezoelectric coefficient. The composite has potential application prospects in various fields, such as oral cavity and bone implant.

The application of piezoelectric materials in bone repair is a hot topic because both positive and negative charge can promote the cells growth. However, the deposition process of apatite induced by piezoelectric materials with periodic loading is still not clear. In this work, TiO2–BaTiO3 coatings were prepared on medical titanium alloys by microarc oxidation and hydrothermal reactions. The TiO2 layer obtained by micro-arc oxidation participated in hydrothermal reaction to generate BaTiO3 on the surface of TiO2 layer. After electric field polarization, the coating was endowed with bioelectric activity similar to that of natural bone. Periodic mechanical loading was applied to the coatings using a cyclic stress loading device. It was found that the negative charge could attract Ca2+ to be gathered on the coating surface, thus obtaining a high deposition of apatite, increasing the Ca/P ratio and promoting the crystallinity of the apatite. In addition, the negative charge also changed the type of apatite growth units near the coating, resulting in the deposition of apatite in hexagonal flake shapes perpendicular to the coating.

Hexagonal boron nitride (h-BN) is widely used in the fields of pollutant adsorption and aerospace due to its low density, good electrical insulation, and excellent thermal conductivity. The precursor was prepared by using a liquid-phase method and then calcined in a flowing nitrogen atmosphere to achieve highly efficient preparation of high-purity h-BN and obtain h-BN short fibers. The chemical composition and generation rate of the precursor prepared at different BA(H3BO3):M(C3N6H6) ratios were characterized. The possible chemical synthesis reactions for converting raw materials into h-BN were discussed. The morphology and composition of h-BN short fibers were investigated, and the selective adsorption and reusability of h-BN short fibers was also analyzed. Results indicated that when the ratio of BA:M was 3:1, the generation rate of the precursor was the largest, reaching 85.424%. The maximum conversion rate of h-BN prepared from the precursor calcined in a flowing nitrogen atmosphere was 19.51%. When the BA:M ratio was 1:1 or 3:1, the obtained h-BN short fibers contained the least impurities, and the atomic content of O element was only 5.85%. The maximum specific surface area of h-BN fibers was 1144 m2/g and the main pore sizes were 1.72 nm and 3.78 nm. The maximum adsorption rate and adsorption capacity of h-BN short fibers to methylene blue (MB) reached 95.413% and 494.5 mg/g, respectively. The h-BN short fibers can rapidly adsorb MB from a mixed solution of MB and Cu2+, indicating that they have high adsorption selectivity for MB. After 5 times adsorption, the adsorption rate of the h-BN fibers to MB was still larger than 90%. This finding showed that the high-purity h-BN short fibers prepared in a flowing nitrogen atmosphere had the potential to selectively adsorb contaminants in the field of water treatment.

Solid solution ceramics of transition-metal carbides possess higher hardness and better oxidation resistance in comparison with monolithic transition-metal carbides. In this communication, (Ti, Zr)C solid solution nanofibers were successfully fabricated through electrospinning using polymeric precursors. The effect of n (Ti)/n (Zr) on the microstructure of nanofibers was investigated. Complete solid solutions of (Ti0·8Zr0.2)C and (Ti0·75Zr0.25)C were formed at 1600 °C when the value of n (Ti)/n (Zr) equal to 4 and 3, respectively. With a decrease in n (Ti)/n (Zr) to 2, Ti-rich and Zr-rich phases appear. The oxidation resistance of the fabricated nanofibers was tested by a non-isothermal method. The oxidation temperature of (Ti, Zr)C solid solution nanofibers is improved compared to TiC nanofibers.

ZrB2-ZrC composite nanofibers were fabricated by electrospinning and carbothermal reduction. The morphology, phase composition and interface were characterized. The fabricated ZrB2-ZrC composite nanofibers are uniform and the diameter is about 100 nm. The effects of heat-treatment temperature, n(B)/n(Zr) and n(C)/n(Zr) on the microstructure and phase composition of composite nanofibers were systematically investigated. The results shows heat-treatment temperature has influence on the phase composition and grain size of the ZrB2-ZrC composite nanofibers. The content of ZrC in the ZrB2-ZrC composite nanofibers can be adjusted by the value of n(B)/n(Zr) in the precursors. As n(B)/n(Zr) equal to 3.5, the mass ratio between ZrB2 and ZrC is about 48:52 which is very close to the eutectic composition of ZrB2-ZrC composites. The value of n(C)/n(Zr) also affects the phase composition of composite nanofibers. Reaction process and phase evolution during heat-treatment were studied based on analysis of reaction thermodynamics. The value of n(B)/n(Zr) influences the phase evolution during fabrication of ZrB2-ZrC composite nanofibers. The tensile mechanical properties were tested, indicating that the addition of ZrC has the ability to improve the plasticity of ZrB2.

Carbon-based nanomaterials are widely employed for microwave absorption. However, reasonable methods to enhance microwave absorption capacity remain worth exploring. Herein, carbon nanofibers (CNFs) modified by silicon carbide and metal silicide (SiC/Fe3Si/C) were fabricated through electrospinning and high-temperature pyrolysis processes, and their phase composition, micro-morphology, micro-structure, and magnetic characteristics evaluated. The composite nanofibers (SiC/Fe3Si/CNFs) exhibited excellent microwave absorption, with minimum reflection loss (RLmin) values of −41.6 dB at 12.8 GHz and a matching thickness of 4.5 mm. Further, the maximum effective absorption bandwidth (EAB, RL

The volume change difference between water and tert-butyl alcohol (TBA) hydrate was approximately 10.1% when ceramic slurry with water–TBA was frozen for fabrication of porous ceramics. Residual stress may be produced at the pore walls and led to low compressive strength of the ceramics. In this regard, sucrose was used in the ceramic slurry. Several water–TBA crystals were observed in the sucrose amorphous bodies after directional freezing. Water and TBA in the sucrose amorphous bodies were recrystallized during subsequent annealing. Sucrose was used as a protective agent and annealing additive in the TBA–water–sucrose system to eliminate residual stress and change the pore structure from snowflakes and dendrites into tiny cylinders. Adding sucrose and annealing process exerted minimal effect on the open porosity of porous ceramics but remarkably improved their compressive strength. When TBA and sucrose contents were 30 and 20 wt%, respectively, in the ceramic slurry with 20 vol% alumina content, the compressive strength of porous ceramics was 49.9 MPa after annealing at − 15 °C for 2 h. The value was 3.6-fold higher than that of the ceramic without annealing. Results provide a new method for improving the mechanical properties of porous ceramics prepared by freeze casting.

The effects of the annealing methods and annealing temperatures on the pore structures and mechanical properties of porous alumina were investigated. The amorphisation behavior and solidification behavior of the sucrose solutions during annealing were discussed. The pore morphology of porous alumina changed noticeably after uniform annealing. As annealing temperature increased from −25 ℃ to −5 ℃, the pore morphology of porous alumina changed gradually from irregular lamellar channels to circular channels. After directional annealing, the pore morphology of porous alumina was similar to that after uniform annealing; however, the uniformity of pore channels and the density of pore walls were increased. During directional annealing at −15℃, the compressive strength of porous alumina reached 58.8 MPa, which was 35% higher than that of unannealed porous alumina.

Porous titanium scaffolds with aligned lamellar pore channels and smooth inner walls were fabricated by directional freeze casting using aqueous TiH2 slurries. The formation of dendrites was inhibited by increasing the TiH2 content in slurry. The pore structures and compression strengths of porous titanium scaffolds that were made with different solid contents were characterized. The formation mechanism of aligned lamellar pore channels and the reason for the improvement of compression strength were analyzed. With increasing TiH2 content in slurry, the open porosity reduced from 38.57 to 29.03% while lamellar spacing decreased. Young’s modulus was decreased with the increasing open porosity. Directional lamellar pore channels were obtained by controlling the TiH2 content in slurry, which can reduce the number of branches and prevent stress concentrations during compression. Also, the porous titanium scaffolds prepared by this process had a good biocompatibility with osteoblasts.

The development of methods to obtain ceramic pigments with fluorescence characteristics or hyper-domain performance has attracted research interest. In this study, Er-doped and Er/Yb-codoped CoAl2O4 pigments were synthesized by co-precipitation. The influence of Er doping, Er/Yb codoping, and the doping contents on the colour, composition, and luminescence properties of CoAl2O4 pigments were investigated. Er doping did not significantly affect the phase composition and colour performance of the CoAl2O4 pigment. The upconversion effect was induced by excitation with a 950 nm laser. Er doping could enhance the upconversion luminescence intensity of the CoAl2O4 pigment. At a 1 mol.% Er doping content, all luminous intensities reached maximum values. The downconversion effect was observed after excitation with a 350 nm laser. The luminescence was blue, and slight differences in the luminescence intensity with different Er doping contents were observed. Yb2O3 was formed after Er/Yb was codoped at > 6 mol.% Yb doping content, thereby affecting the phase composition and colour performance of the CoAl2O4 pigment. The luminous intensity of red light (739 nm) was the strongest in all cases. The luminous intensities of all of the colours decreased to the minimum value at 9 mol.% Yb doping content compared with those at other doping contents. At 3 mol.% Yb doping content, the luminous intensities of all colours decreased to very low values (close to 0), and the quenching effect of Yb3+ was achieved using a 350 nm laser. Er/Yb-codoped CoAl2O4 pigments exhibited the upconversion luminescence effect under an infrared laser and inhibited visible-light reflection under an UV laser. This ceramic pigment can be developed further to obtain ceramic pigments with anti-counterfeit function.

The in vitro cytotoxicity evaluation results of dental restorative materials do not correlate with the results of animal and clinical trials because they lack a dentin barrier between the cells and test materials. Porous bio-ceramics, which have a similar pore structure and permeability to dentin, are the key to solving this problem. In this report, hydroxyapatite (HA) gradient porous substrates were fabricated by multiple freeze-tape-casting. Influences of the slurry solid content and freezing temperature on the pore structures of HA porous substrates were investigated, and their permeability and biological properties were also determined. The total and open porosity of HA gradient porous substrates were decreased with the decrease in freezing temperature. When the freezing temperature was − 45 °C, the close porosity of the HA gradient porous substrate was the largest, reaching 22.8%. A low permeability value of 0.87 μL cm −2 ·min −1 can be obtained due to the partial penetration of the pore channels in each casting layer. The pore structure and permeability of the porous substrates were consistent with dentin, and furthermore, the biocompatibility of the cells in vitro was demonstrated. This indicates that the substrates can meet the requirement of in vitro dentin and can be used for in vitro cytotoxicity testing of dentin barriers.

The microstructure of the tissue has a very important determining effect on its performance. Herein, two calcium phosphate cement (CPC)/small intestinal submucosa(SIS) composites bionic bone scaffolds with different microstructures were fabricated by rolling or/ and assembling method. The microstructure, 3D morphology, the crystal phase and mechanical properties of the scaffolds were investigated by micro CT, XRD, FIIR, SEM and electronic universal testing machines respectively. The results showed that the pore size of all scaffolds are in the range of 100–400 µm, which are beneficial to cells growth, migration, and tissue vascularization. Their porosity and the specific surface area were 14.53 ± 0.76%, 8.74 ± 1.38 m 2 /m 3 and 32 ± 0.58%, 26.75 ± 2.69 m 2 /m 3 separately. The high porosity and the large specific surface area can provide a larger space and contact area for cells adhesion and proliferation. Meanwhile, compressive strength of the scaffolds soaked were 10 MPa and 27 MPa, about 1.2 folds and 3.2 folds of the original scaffolds, respectively. The results are derived from different microstructures of the scaffolds and chemical bonds between SIS and new phases (hydroxyapatite), and the scaffolds performance steadily increased at near the physiological conditions. Finally, biocompatibility of the scaffolds was evaluated by CCK8, bionic microstructure scaffolds are no cytotoxicity and their biocompatibility is favorable. Based on the microstructure, compressive strength and cytotoxicity of the scaffolds, bionic Harvarsin microstructure CPC/SIS composite scaffold is expected to turn into a scaffold with the excellent properties of real bone.

Lamellar porous alumina with graded structures was fabricated through a novel method of simultaneous centrifugal casting and directional freeze casting. Alumina particles in ceramic slurry moved outward from the center by centrifugal force and formed stable gradient distribution because of viscous resistance and electrostatic repulsion among particles. The porous and pore-size gradient structure were obtained after freeze drying. With increased rotational speed, the pore size of the lamellar pore channels also gradually increased. However, the sizes of the ice crystals and lamellar pores shrunk at 200 rpm due to the destabilization of laminar flow during ice-crystal growth. Compressive strength obviously improved with increased rotational speed, and that of the resulting porous ceramic was 2.3 times higher than that in the absence of centrifugation at 1000 rpm rotational speed.

CoAl 2 O 4 ceramic pigments produced by common methods have low chroma values, which limit their application in ceramic glazing, enamel glazing, and ceramic product printing. The colour stability of the ceramic pigments and changes upon high-temperature sintering are important factors, especially in 3D printing. In this study, CoAl 2 O 4 ceramic pigments were synthesized using a co-precipitation method and both the colouration mechanism and stability of CoAl 2 O 4 ceramic pigments were investigated. The Co content, Co ion valence, and coordination number were found to be important factors affecting the CoAl 2 O 4 ceramic pigments. When the Co content was excessively high, either Co 3+ was produced or Co 2+ entered the octahedron spaces of the spinel structure. The coordination field of the Co ions was consequently altered and the colour transitioned from blue to green. After sintering on substrates at 1300 °C, the brightness and chroma of obtained CoAl 2 O 4 coatings were superior to those of the pigment powders prior to sintering, and the colour of CoAl 2 O 4 with a relatively high Co/Al ratio changed from green to blue. The latter pigment may have formed a partially inverse spinel structure upon sintering at a high temperature. The probability of Co 2+ entering the octahedron spaces increased; concomitantly, the number of Co 2+ in the tetrahedron spaces decreased, resulting in an increase in the coordination number of Co. In addition, Co 3+ in the ceramic pigments was transformed into Co 2+ by deoxidation reactions during the coating sintering process, thereby increasing the chroma of blue CoAl 2 O 4 pigments.

Porous alumina with double-pore structure was fabricated by stepwise freeze casting using water/diphenyl methane (DPM) emulsion as freezing medium. The effects of DPM content in the alumina slurry on the pore structure, mechanical properties, and specific surface area of porous ceramics were investigated. The porosity of porous ceramics was not significantly affected by DPM content in the alumina slurry due to their same solid contents. The lamellar pore size decreased, and the spherical pore size increased in porous alumina with increasing DPM content in the slurry. Closed spherical pores were formed in lamellar pore walls when the DPM content was 10 vol%. The compressive strength slightly increased, and the specific surface area decreased in the samples with DPM compared with those in porous ceramics with pure water as freezing medium. The specific surface area of porous alumina was 0.566 m2/g, and the interception rate for titan yellow was 44.16% when the DPM content reached 25 vol% because the large spherical pore was connected to the outside. Hence, the fabricated porous alumina with DPM exhibited potential as adsorption and filtration materials.

Flower branch-like TiO2@SiC/C composite nanofibers that are lightweight and have high-efficiency microwave absorption (MA) in the 2–18 ​GHz frequency range were fabricated via electrospinning and hydrothermal approaches. Phase analysis results showed the presence of rutile TiO2, β-SiC, and amorphous carbon in the composite nanofibers. Nanowhiskers grew randomly on the surface of the nanofibers along the (101) plane of rutile TiO2 nanocrystalline and formed a flower branch-like structure. The bionic morphology generated a great deal of heterojunctions and porous structures, which enable interfacial polarization, dipole polarization, conductance loss, multirelaxation, and suitable impedance matching through synergistic effects. Therefore, excellent wave-absorbing performance was achieved in the X and Ku bands when the composite nanofibers' filler loading was changed. The minimum reflection loss (RL) value was less than −45.3 ​dB with the thickness of less than 3 ​mm when the composite nanofibers absorber content was 10 ​wt%. Also, the maximum effective absorption bandwidth (EAB) exceeded 5 ​GHz. This study developed a neoteric structure to construct composite fibers loaded with nanowhiskers, and the TiO2@SiC/C nanofibers could be a remarkable candidate for broadband and efficient microwave absorbers. Also, the tunable wave-absorbing performance indicates a wide range of applications is possible under various environmental conditions.

Since hydroxyapatite crystals are characteristically c-axis orientation on the surface of vertebrate long bone, c-axis orientation HAP biomimetic synthesized will find extensive applications in long bone growth, remodeling and fracture healing. In this paper, plate-like single-crystal HAP rods with c-axis orientation was successfully synthesized at bone mineralization conditions in vivo, with small intestinal submucosa membrane as biomineralization template. The samples were characterized by XRD, FIIR, SEM, TEM and EDS to unveil the phase structure, composition, morphology, and a plausible growth mechanism was proposed. The results showed that morphology of samples changed from flower-like to plate-like with extension reaction time from 1 day to 10 days. The plate-like HAp rods were single-crystal with c-axis orientation. A unit of plate-like HAP rods is about 70 µm and the width is 4 µm. Phase composition transformed from octocalcium phosphate and HAp biphase to HAp phase with very little octocalcium phosphate phase. Finally, biocompatibility of the samples was evaluated by CCK8. The samples without significant cytotoxicity conformed to the need for substitute materials of bone regeneration.

Amorphous Fe 2 O 3 loaded SiO 2 hollow particles were obtained via a one-pot two-step solution synthesis followed by calcination. With the help of citrate ions, the iron containing resorcinol formaldehyde resin nanoparticles (Fe-RF NPs) were first synthesized through the extended Stober method. Then silica coating is further conducted in a one-pot manner. It was found that the silica layer can effectively prevent the inner Fe 2 O 3 nanoparticles from becoming large during heat treatment, endowing them with small size and amorphous structure. The final product exhibits good catalytic performance in photo-Fenton degradation of methylene blue with visible light.

Barium titanate/hydroxyapatite (BT/HA) spherical nanocomposites were fabricated by hydrothermal process using HA nanopowders dispersed in BT precursor solution. The samples were characterized by XRD, SEM and TEM to obtain sizes and crystal structure. The results showed that the BT/HA spherical nanocomposites can be obtained at 120–180 °C for 12 h and the morphology is HA nanopowders of 20–30 nm growth on the surface of spherical structure BT nanoparticles with diameter of 100–150 nm. The BT/HA spherical nanocomposites obtained at 160 °C for 12 h has the e value and compressive strengths were 2.98 and 39.15 MPa, respectively. A growth mechanism was also proposed to account for BT/HA spherical nanocomposites. Moreover, the biotoxicity of nanocomposites show that the BT/HA materials is non-toxic to the MSCs cells.

It was proposed that the piezoelectric effect played an important physiological role in bone growth, remodeling and fracture healing. Barium titanate/hydroxyapatite (BT/HA) nanorods piezoelectric composite was fabricated by hydrothermal process using 30 nm HA dissolved in different solvents (H2O, DMF, ethanol and ethylene glycol), and then reacted in the BaCl2, C6H8O7, butyl titanate mixture solution, respectively. The samples were characterized by XRD, IR, SEM and TEM to obtain sizes and crystal structure. The results showed that the BT/HA rod-like particles can be obtained at ethanol solvent, and the average diameter is about 30 nm and length is 150 nm. Meanwhile, BT/HA nanorod composites obtained at different solvents exhibited both good dielectric constant e (18.45, 21.79, 27.40, 19.87), and piezoelectric coefficient d33 (2.74, 3.23, 6.88, 4.20), which were all higher than the piezoelectric coefficient of natural bone. The e and d33 were improved by increasing the BT in ethanol solvent.

With the wide application of high-power LED, heat dissipation substrate not only demonstrates a high thermal performance but also requires a low thermal expansion coefficient that matches that of the chip. Metal/ceramic composite materials can combine the excellent heat dissipation performance of metals and low thermal expansion property of ceramics, satisfying the requirement for high-power LED. In this study, alumina/copper composite substrates were fabricated through freeze-tape casting and melt infiltration. Morphologies, infiltration rates, thermal properties, and heat dissipation properties of the fabricated composite substrates were investigated. This study found that copper was distributed in the lamellar pore channels of alumina substrates, and the infiltration rate of copper in alumina/copper composite substrates increased under increasing Ti content, infiltration temperature, and time. Furthermore, thermal conductivity and thermal expansion coefficient decreased as alumina content in the composite substrates decreases. The thermal resistance, junction temperature, and increase in junction temperature of the alumina/copper composite substrate when 57.33 vol% copper was used as heat dissipation substrates for 2W LED lamps are 22.5 K·W −1 , 80.5 °C, and 40.5 °C, respectively. The heat dissipation performance of the LED module with the copper/alumina composite substrate with copper infiltration rate of 57.33 vol% was significantly better than that of the commercial alumina substrate. Fabricated composite substrate (57.33 vol% infiltration rate of copper) has a junction temperature of 80.5 °C and thermal resistance of 24.6 K·W −1 , which are lower than the junction temperature (93.2 °C) and thermal resistance (32.1 K·W −1 ) of the commercial alumina substrate tested at same conditions. The reduction of junction temperature is important to improve the service life of the LED lamp.

Tert -butyl alcohol (TBA)–water (H 2 O) crystals are used as template to fabricate aligned porous alumina with special pore structures. Alumina slurries were prepared using TBA–H 2 O mixtures, which could undergo continuous crystallization by unidirectional freezing. The pore shape of porous alumina constantly changed from lamellar to snowflake, dendritic, needle-like, and hexagonal with the increase in the TBA content in alumina slurries. The hexagonal porous structure obtained by pure TBA slurry exhibited the best mechanical properties, whereas the mixture structure with irregular pore walls showed the worst, exhibiting inferior properties to lamellar pore structures.

A novel directional solidification method was used to fabricate lamellar porous alumina with an axisymmetrical structure by combining multiple cold sources, electrostatic field, and magnetic field during the freezing of aqueous alumina slurries. Multiple cold sources with mutually perpendicular directions formed by the bottom and parallel sides of rectangular copper molds induced a specific growth direction for ice crystals. The pore channels of porous ceramic are arranged parallel to the direction of electric field lines, and the axisymmetrical structure was obtained after applying the electrostatic field. The applied magnetic field can reduce pore channel size; however, the field has no effect on pore channel direction and distribution, and leads to cracking in the central region of porous ceramics. The compressive strength along the electrostatic field direction is higher than that achieved by conventional freeze casting.

Titanium dioxide nanotube coatings are prepared on the surface of titanium alloy to improve their biocompatibility, and the nanotube structure of the coating can be used for drug delivery. However, the titanium dioxide nanotube coating is an inert material, which still needs to be improved in terms of inducing bone growth. In this work, the TiO2 @ BaTiO3 coaxial nanotube coating on titanium surface was prepared by anodization combined with in-situ hydrothermal reaction. The nanotube structure was preserved in the TiO2 @ BaTiO3 coaxial nanotube coating, and the surface of the titanium dioxide nanotube was covered with polycrystalline barium titanate. Piezoelectric properties of the TiO2 @ BaTiO3 coaxial nanotube coating were clearly confirmed from the results of the amplitude and phase diagrams of the piezoelectric response which were tested by piezoelectric force microscopy. The TiO2 @ BaTiO3 coaxial nanotube coating on the surface of titanium alloy with piezoelectric properties and nanotube structure can be used for fast repair of bone defects and drug delivery.

To construct Z-scheme not only can effectively separate the excited electron-hole pairs, but also utilize the ample redox capability of each semiconductor component in this system for the surface photocatalytic reaction. In this work, a TiO2–Au–BiOBr ternary Z-scheme photocatalyst was constructed, in which Au NPs were used as the electron mediator to join BiOBr nanosheets and TiO2 nanofibers. The results showed that, under full spectrum irradiation, TiO2–Au–BiOBr nanofibers exhibited outstanding photocatalytic performance toward the degradation of Rhodamine B (RhB) with an excellent photodegradation efficiency of 99.91% within 30 min as well as good stability. The reaction mechanism of the TiO2–Au–BiOBr Z-scheme system was systemically studied by XPS, photoelectrochemical tests and free radical trapping experiments, etc. Moreover, the photocatalyst also exhibited excellent photocatalytic activity for degrading methyl orange and methylene blue.