We review the fundamental properties and significant issues related to Cu/graphite composites. In particular, recent research on the interfacial modification of Cu/graphite composites is addressed, including the metal-modified layer, carbide-modified layer, and combined modified layer. Additionally, we propose the use of ternary layered carbide as an interface modification layer for Cu/graphite composites.
Microstructure and property of sulfur/carbon black composites prepared by ball milling were studied. Sulfur/carbon black composites were obtained by melting the mixture of sulfur and carbon black in 155 °C and dispersing evenly in carbon black after hydrothermal reaction. Thus, its conductive properties were improved. Moreover, microstructure and property of honeycomb sulfur/carbon black/ MoS2 prepared by hydrothermal method as a cathode material for lithium-sulfur batteries were studied. The initial discharge specific capacity of the material at 0.2 A/g current density is 838.495 mA·h/g, and the 55.14% after 100 weeks of cycling. It is indicated that MoS2 can not only combine with polysulfides through electrostatic action or the action of chemical bonds, but also honeycomb porous structure. MoS2 can fix polysulfides groups and prevent their shuttle. Therefore, the cycling performance of the battery is effectively improved.
Under illumination by 405, 520 and 655 nm monochromatic visible light (light intensity of 30 kW/m2), large photostriction (ΔL/L) of 0.19%, 0.13% and 0.26% for 67BiFeO3-33BaTiO3(67BF-33BT) lead-free ferroelectric ceramics are obtained, respectively. By studying the ferroelectric and photoelectric properties in conjunction with in situ Raman spectroscopy, it is found that the photostrictive effect of 67BF-33BT is not caused by the electrical strain induced by abnormal photovoltaic voltage, but related to the optical induced oxygen octahedral distortion. The 67BF-33BT lead-free ferroelectric material with excellent photostrictive response in the visible light region is expected to play an important role in the field of optical drive electromechanical devices.
We investigated the relationship between oxygen reduction reaction (ORR) activity and the pyrolysis temperature (650–850 °C) of CuPc in alkaline solution. The highly active sites were formed through the decomposition of CuPc or Cu-N4 structure after releasing 4-nitrophthalonitrile. Cu-N x incorporated with carbon were the main active sites. The XPS measurement results show that, at lower temperature, the contents of pyridinic-N and pyrrolic-N account for the most of the total N. As the temperature is higher than 750 °C, the content of graphitic N (26.11%) increases and pyridinic-N (58.81%) becomes the dominant specie. When the temperature is higher than 850 °C, the content of graphitic N increases remarkably and becomes the dominant species. Moreover, the specific surface areas decrease with increased pyrolysis temperature. Benefiting from the synergistic effect, the pyrolysis temperature at 750 °C of CuPc displays superior electrocatalytic properties. The obtained results reveal that the fabricated non-noble metal catalysts can be used as low-cost, efficient catalyst for water splitting ORR in metal-air batteries and fuel cells.
A series of mixed alkali-zinc borosilicate glasses with various r values (r = molar ratio of [ZnO] / ([R2O]+[ZnO])) from 0.00 to 1.00 were fabricated to probe the mixed alkali-zinc effects on thermo-mechanical properties. The nonlinear evolution of glass transition temperature (T g) with the addition of ZnO is ascribed to the competition of two converse factors, i e, the T g depression as one of the colligative properties for a solution, on the one hand, and the enhancement of T g due to the higher field strength of zinc cations compared to that of alkali ions. However, the nonlinear evolution of elastic moduli and coefficients of thermal expansion with r is attributed to the variance of intermediate-range clusters, which is confirmed by infrared and Raman scattering spectra. These findings are very helpful in tailoring the performance of borosilicate glasses.
A new composite separation membrane was developed by using organically modified montmorillonite (OMMT) as an additive. The effects of OMMT on the modification and properties of PVDF composite membranes were investigated. It is found that different kinds and amounts of OMMT into the casting solution can obviously change the pure water flux, separation performance and hydrophilicity of composite membrane in varying degrees. When the TA/PDA-MMT was 0.5 wt%, the pure water flux of the membrane reached the maximum, which was 584.7 L/(m2·h), about 6 times that of the original membrane. The OMMT/PVDF composite membrane had good hydrophilicity and stability in the treatment of oily wastewater. The development of novel OMMT/PVDF composite membrane will provide a new idea for solving the problem of oily wastewater treatment.
In the preparation of a series of Ce0.8Zr0.2O y catalysts catalyzing the removal of formaldehyde, BET, H2-TPR, IR, SEM, XPS, and XRD were used to characterize the catalyst, and the influence of humidity on the catalyst activity was studied by adjusting the humidity during the process. The experimental results showed that the formaldehyde removal rate increased with the increase of humidity. When the humidity was higher than 50%, the formaldehyde removal rate decreased by 3% over that when the humidity was 50%.The characterization results showed that humidity facilitated the activation of oxygen and the formation of hydroxyl groups, which both promoted the formation and oxidative decomposition of intermediates and prevented the deposition of intermediates that clogged the pores, allowing more formaldehyde to be adsorbed and oxidized, which increased the activity of the catalyst. This provides new mechanistic evidence for the oxidation of formaldehyde and helps in the development of relatively low-cost materials for formaldehyde purification.
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The wetting behavior of molten Cu on the B4C-xTiB2 ceramic composites was investigated in this work. The results show that the contact angle of molten Cu alloy on B4C-TiB2 ceramic composites is linear with the composition rate of TiB2 or B4C while the temperature is in the range of 1 300 to 1 350 °C, consistent with the expectation of the commonly used theoretical method. However, a nonlinear relationship between the contact angle and the composition rate unexpectedly occurred at temperatures ranging from 1 400 to 1 500 °C. The big difference of the contact angles between the molten metal and the components in the composites was found to be the key point. This result identifies that the commonly used theoretical method only works at a limited difference of the contact angle of the liquid on the different phases in the composites, and fails at a big difference.
The full-potential linearized augmented plane wave plus local orbital method is utilized for exploring the electronic, magnetic, and magneto-optical properties of the NiX2 (X=Cl, Br, and I) single layer. The first-principles calculation demonstrates that these compounds are ferromagnetic indirect semiconductors, and the energy band gaps of NiX2 for X=Cl, Br, and I are 3.888, 3.134, and 2.157 eV, respectively. The magnetic moments of Ni atoms in NiX2 monolayer are 1.656, 1.588, 1.449 µB, and their magneto-crystalline anisotropy energies are 0.167, 0.029, 0.090 meV, respectively. Based on the macro-linear response theory, we systematically studied the influences of the external magnetic field and out-of-plane strain on the magneto-optical Kerr effect (MOKE) spectrum of the NiX2 single layer. It is found that, when the external magnetic field is perpendicular to the sample plane, the value of the Kerr rotation angle reaches the maximum, and the single-layer NiI2 material has a Kerr rotation angle of 1.89° at the photon energy of 1.986 eV. Besides, the Kerr rotation spectrum of NiCl2 and NiBr2 monolayers redshift as the out-of-plane strain increases, while NiI2 monolayer blueshifts. Accurate computation of the MOKE spectrum of NiX2 materials provides an opportunity for applications of 2D magnetic material ranging from sensing to data storing.
We focused on the efflorescence induced microstructural evolution of ettringite-rich systems prepared with calcium aluminate cement (CAC) and anhydrite. The effects of anhydrite on the visible efflorescence, and the corresponding capillary absorption of CAC-anhydrite mortars were revealed. The composition and microstructure of efflorescence-causing substances were investigated by optical microscope, in-situ Raman spectroscopy, scanning electron microscope, energy dispersive spectrometer, thermogravimetric analysis, and differential scanning calorimetry, at multi-scales. Results indicate that, besides the calcium carbonate, ettringite is another main component of efflorescence-causing substances. Compared with the neat CAC mortars, the addition of anhydrite has a significant effect on the degree of efflorescence by acting on the composition of hydration products and pore structure. In addition, methods are proposed for the prevention of efflorescence of CAC-anhydrite binary system.
WC-10Co cemented carbides with finer WC and narrower grain size distributions are produced by using (Cr, V)2(C, N) as grain growth inhibitors. As a result, with the increase of (Cr0.9, V0.1)2(C, N) and (V0.9, Cr0.1)2(C, N), the grains size of WC and mean free path of Co phase decrease, and adjacency of WC increases. Refinement and homogenization of grains enhance the transverse rupture strength (TRS) and the hardness. Meanwhile, the deflection and bridging of cracks keep the fracture toughness at a respectable level. The WC-10Co-0.6(Cr0.9, V0.1)2(C, N)-0.025(V0.9, Cr0.1)2(C, N) cemented carbides exhibit excellent comprehensive mechanical properties with the TRS of 4 602.6 MPa, hardness of 1 835 kg/mm2, and fracture toughness of 10.39 MPa·m1/2, respectively. However, the large pores are caused by excess N larger than 0.03 wt% and deteriorates the mechanical properties. We provide a new approach to WC-Co cemented carbides preparation with a narrow grain size distribution by adding novel grain growth inhibitors.
To promote the recycling of reclaimed asphalt pavement (RAP), epoxy resin was used to prepare the epoxy-recycled asphalt mixtures. The effect of epoxy resin on the properties of aged asphalt binder was investigated based on the tensile test, flexural creep test, and laser scanning confocal microscopy. The curing characteristics and the mechanical performance of recycled asphalt with different epoxy contents were explored. The results show that the low-temperature performance, ductility, and strength of the aged asphalt binder were significantly improved when the epoxy content reached 40%. The curing time of epoxy-recycled asphalt should be at least 4 d to ensure the formation of good internal spatial network structure.
Monte Carlo simulations were carried out to generate a mesoscale model of concrete with randomly packed aggregates with different shapes and sizes. The mechanical properties of concrete specimens under uniaxial tensile loads were studied using statistical results. The results indicated that the entire process of damage and failure of specimens exhibited mainly two failure types: fracture patterns I and II. Furthermore, the influences of the aggregate content ratio, aggregate shape, aggregate size, interfacial transition zone (ITZ) strength, and porosity ratio on the concrete specimens were analyzed. The numerical simulation results showed that the elastic modulus of the concrete specimens increased approximately linearly with the aggregate volume ratio but decreased linearly with the porosity and was not affected by the ITZ strength. The tensile strength decreased with the increases in the aggregate content and porosity of the sample, but increased linearly with the ITZ strength. In addition, the aggregate shape led to a difference in the tensile strength of the concrete.
A ternary system comprising Ca20Al26Mg3Si3O68 (Q-phase), limestone, and metakaolin is proposed, and its hydration behavior, hydration product phases, microstructure, and mechanical properties are investigated and compared with pure Q-phase cement. The results indicate that the ternary system exhibits exceptional and sustained compressive strength even under a 40 °C environment, significantly outperforming pure Q-phase. The mechanism lies in that metakaolin effectively inhibits the transformation of metastable phase. Meanwhile, the interactions among Q-phase, limestone, and metakaolin further enhance the cementitious performance. The ternary system effectively addresses potential issues of strength loss in Q-phase cement application, and as a low-carbon cementitious material system, it holds promising potential applications.
To investigate the corrosion degradation law and service life of reinforced concrete in various salt solution environments, reinforced concrete specimens were semi-immersed in 3% Na2CO3(N3-0-0), 3% Na2CO3+3% NaCl (N3-Cl3-0) and 3% Na2CO3+3% NaCl+3% Na2SO4(N3-Cl3-S3)salt solutions. The electrochemical workstation was used for regular non-destructive testing, and the polarization curve and related electrochemical parameters were used as the macroscopic durability evaluation indicators, while microscopic analysis of steel bar corrosion products was performed in combination with SEM and EDS. In addition, the corrosion current density degradation model of GM (1,1) was established and compared with the modified GM (1,1)-Markov degradation model. The results showed that the prediction error of the GM (1,1)-Markov model was smaller and more accurate than that of GM (1,1). The reinforced concrete specimens in the N3-0-0, N3-Cl3-0 and N3-Cl3-S3 solutions reached the failure state in 3.08, 1.67, and 2.30 years, respectively, as predicted by the GM (1,1)-Markov model. According to ESM and EDS microscopic analysis of reinforcement, carbonate had no significant effect on reinforcement corrosion, chloride ions played a dominant role in reinforcement corrosion, and sulfate ion improved concrete’s resistance to chloride ion corrosion. Based on GM (1,1)-Markov model, the failure and damage of reinforced concrete in saline soil areas can be quantitatively evaluated in the whole life cycle, which provides a theoretical basis for the early maintenance or reinforcing of reinforced concrete.
This study explored the synergistic interaction of sewage sludge (SS) and distillation residue (DR) during co-pyrolysis for the optimized treatment of sewage sludge in cement kiln systems, utilizing thermogravimetric analysis (TGA) and thermogravimetric analysis with mass spectrometry (TGA-MS). The results reveal the coexisting synergistic and antagonistic effects in the co-pyrolysis of SS/DR. The synergistic effect arises from hydrogen free radicals in SS and catalytic components in ash fractions, while the antagonistic effect is mainly due to the melting of DR on the surface of SS particles during pyrolysis and the reaction of SS ash with alkali metals to form inert substances. SS/DR co-pyrolysis reduces the yielding of coke and gas while increasing tar production. This study will promote the reduction, recycling, and harmless treatment of hazardous solid waste.
This paper studied the effects of different retarders on the performance of the “one-step” alkali-activated composite cementitious material (ACCM) which is composed of ground granulated blast slag(GGBS) and fly ash(FA), and analyzed its mechanical properties, hydration mechanism, and retardation mechanism. The effects of retarders on the hydration products, mechanical properties, and hydration kinetics of ACCM were investigated using XRD, SEM, FTIR, EDS, and thermoactive microcalorimetry. The results showed that Na2B4O7·10H2O (B) delayed the exotherm during the alkali activation process and could effectively delay the setting time of ACCM, but the mechanical properties were slightly decreased. The setting time of ACCM increased with the increase in SG content, but the mechanical properties of ACCM decreased with the increase in SG content. C12H22O11 (CHO) could effectively delay the hydration reaction of ACCM and weakly enhanced the compressive strength. H3PO4 (HP) at a concentration of 0.05 mol/L had a certain effect on ACCM retardation, but HP at a concentration of 0.07 and 0.09 mol/L had an effect of promoting the setting and hardening time of ACCM.
Minerals in Portland cement including tricalcium silicate (C3S), β-dicalcium silicate (β-C2S), tricalcium aluminate (C3A), and tetracalcium ferroaluminate (C4AF), show a significantly different activity and product evolution for CO2 curing at various water-to-solid ratios. These pure minerals were synthesized and subject to CO2 curing in this study to make an in-depth understanding for the carbonation properties of cement-based materials. Results showed that the optimum water-to-solid ratios of C3S, β-C2S, C3A and C4AF were 0.25, 0.15, 0.30 and 0.40 for carbonation, corresponding to 2 h carbonation degree of 38.5%. 38.5%, 24.2%, and 21.9%, respectively. The produced calcite during β-C2S carbonation decreased as the water-to-solid ratio increased, with an increase in content of metastable CaCO3 of vaterite and aragonite. The thermodynamic stability of CaCO3 produced during carbonation was C3A>C4AF>β-C2S>C3S. The carbonation degree of Portland cement was predicted based on the results of pure minerals and the composition of cement, and the error of predicted production of CaCO3 was only 1.1%, which provides a potential method to predict carbonation properties of systems with a complex mineral composition.
Through exploring the effects of low pH on the composite system of desulfurization gypsum (DG) enhanced by melamine-formaldehyde resin (MF), it is found that the inducing of sulfate-ion, in contrast to chloride and oxalate ions, favors the longitudinal growth of the crystalline form of the hydration product, which was relatively simple and had the highest length to width (L/D) ratio. At the same time, MF can also improve L/D ratio of gypsum hydration products, which favors the formation of hydrated whiskers. Finally, in a composite system composed of hemihydrate gypsum, MF, and glass fibers, when dilute sulfuric acid was used to regulate pH=3–4, the tight binding formed among the components of the composite system compared to pH=5–6. The hydration product of gypsum adheres tightly to glass fiber surface and produces a good cross-linking and binding effect with MF. The flexural strength, compressive strength, elastic modulus, and water absorption of the desulphurized gypsum composite board is 22.7 MPa, 39.8 MPa, 5 608 MPa, and 1.8%, respectively.
Municipal solid waste incineration tailings were used as lightweight aggregate (MSWIT-LA) in the preparation of specified density concrete to study the effects on compressive strength, axial compressive strength, flexural strength, microhardness, total number of pores, pore area, and pore spacing. The results showed that the internal curing and morphological effects induced by an appropriate quantity of MSWIT-LA improved the compressive response of specified density concrete specimens, whereas an excessive quantity of MSWIT-LA significantly reduced their mechanical properties. An analysis of pore structure indicated that the addition of MSWIT-LA increased the total quantity of pores and promoted cement hydration, resulting in a denser microstructure than that of ordinary concrete. The results of a principal component analysis showed that the mechanical response of specified density concrete prepared with 25% MSWIT-LA was superior to that of an equivalent ordinary concrete. It was therefore concluded that MSWIT-LA can be feasibly applied to achieve excellent specified density concrete properties while utilising municipal solid waste incineration tailings to protect the environment and alleviate shortages of sand and gravel resources.
It was found that silica fume can reduce the maximum hydration heat release rate of cement by microcalorimetry, inhibit CAH10, promote the generation of C3AH6 and strätlingite C2ASH8, or promote the conversion of CAH10 to C3AH6. Sodium tripolyphosphate can retard the early hydration of cement, have a slight effect on 1 d hydration products of cement and inhibit the generation hydration products. Sodium tripolyphosphate and silica fume can promote the early hydration of cement, advance the formation of C2ASH8 or the conversion from CAH10 to C3AH6 at 1 d.
To improve the comprehensive mechanical properties of Al-Si-Cu alloy, it was treated by a high-pressure torsion process, and the effect of the deformation degree on the microstructure and properties of the Al-Si-Cu alloy was studied. The results show that the reinforcements (β-Si and θ-CuAl2 phases) of the Al-Si-Cu alloy are dispersed in the α-Al matrix phase with finer phase size after the treatment. The processed samples exhibit grain sizes in the submicron or even nanometer range, which effectively improves the mechanical properties of the material. The hardness and strength of the deformed alloy are both significantly raised to 268 HV and 390.04 MPa by 10 turns HPT process, and the fracture morphology shows that the material gradually transits from brittle to plastic before and after deformation. The elements interdiffusion at the interface between the phases has also been effectively enhanced. In addition, it is found that the severe plastic deformation at room temperature induces a ternary eutectic reaction, resulting in the formation of ternary Al+Si+CuAl2 eutectic.
In order to obtain the sharp cube texture, a new process, the intermediate annealing rolling technique, has been introduced to prepare the Ni7W substrate. In this paper, a cubic texture content up to 98.5% within 10° of the standard cubic orientation is obtained in the final substrate and the influence of this improved rolling technique on the cube texture formation has been discussed. The results show that the increased cube texture in the Ni7W substrate is caused by the optimized deformation texture and the increased nucleated fraction of the cube grains.
Characterization of hot deformation behavior of Ti-6Al-4V-0.5Ni-0.5Nb titanium alloy was investigated through isothermal compression at various temperatures from 750 to 1 050 °C and strain rate from 0.01 to 10 s−1. The isothermal compression experiment results showed that the peak stress of Ti-6Al-4V-0.5Ni-0.5Nb titanium alloy decreased with the temperature increasing and the strain rate decreasing. The softening mechanism was dynamic recovery below T β and changed to dynamic recrystallization above T β. The arrhenius-type relationship was used to calculate the constitutive equation of Ti-6Al-4V-0.5Ni-0.5Nb alloy in two-phase regions. It was found that the apparent activation energies were 427.095 kJ·mol−1 in the α+β phase region and 205.451 kJ·mol−1 in the β phase region, respectively. On the basis of dynamic materials model, the processing map is generated, which shows that the highest peak efficiency of power dissipation of 56% occurs at about 1 050 °C/0.01 s−1. It can be found in the processing maps that the strain had significant effect on the peak region of power dissipation efficiency of Ti-6Al-4V-0.5Ni-0.5Nb alloy. Furthermore, optimized hot working regions were investigated and validated through microstructure observation. The optimum thermo mechanical process condition for hot working of Ti-6Al-4V-0.5Ni-0.5Nb titanium alloy was suggested to be in the temperature range of 950–1 000 °C with a strain rate of 0.01–0.1 s−1.
Modifying agents 2,2-Bis(4-glycidyloxyphenyl) propane (2BPE) and dibutyl phthalate (DBP) were selected to enhance the compatibility. By using molecular simulation software (Materials Studio, MS), nine systems were constructed, including molecular models of aged asphalt and WVO monomers with 2BPE and/or DBP. The solubility parameters, Flory-Huggins parameters, and interaction energies of these systems were calculated to determine the impact of 2BPE and DBP on the compatibility of WVO and aged asphalt. Results showed that the addition of 2BPE and DBP reduced the difference in the solubility parameters between WVO and aged asphalt, thus improving the compatibility between WVO and aged asphalt. Additionally, using a combination of 2BPE and DBP in both aged asphalt and rejuvenator was found to be more effective than using either 2BPE or DBP alone. Finally, it was determined that evaluating the compatibility of WVO and aged asphalt using Van der Waals potential and non-bonding energy as evaluation indicators was more accurate than using electrostatic potential energy.
A hierarchical reduced graphene oxide-MnO2@polypyrrole coaxial nanotube composite hydrogel was prepared via oxidative polymerization of pyrrole in the presence of MnO2 nanotubes, followed by the hydrothermal treatment of graphene oxide and MnO2@polypyrrole coaxial nanotubes. The stable composite hydrogel with a hierarchical network was composed of one-dimensional MnO2@polypyrrole coaxial nanotube and two-dimensional graphene nanosheet and characterized by scanning electron microscope, Fourier transform infrared spectroscopy, X-ray diffraction, Brunauer-Emmett-Teller surface, and X-ray photoelectron spectroscopy measurements. The composite hydrogel can be used as an efficient adsorbent for Cr(VI) removal due to the synergistic interaction between graphene and MnO2@polypyrrole and the hierarchical structure of the hydrogel. Moreover, the composite hydrogel is easily separated because of its stable monolith, and it is reusable (76.8% of removal ability remaining after five adsorption-desorption cycles). The simple fabrication and cost-effective separation process together with the excellent absorption performance endow the composite hydrogel with great potential for practical wastewater treatment.
Fluorographene (FG) with narrow lateral size and thickness distributions was prepared by a liquid-phase exfoliation method, based on liquid cascade centrifugation. The Rtec MFT-5000 tribo-meter was used to investigate the lubricating performance of bentonite grease enhanced by the as-prepared FG. The results showed that the coefficient of friction and the wear volume of bentonite grease with 0.3 wt% FG were decreased by 20.4% and 44.9%, respectively, as compared to those of the base grease. The main reason is that FG can promote the formation of the tribo-chemical reaction film consisting of complex carbon oxide, Fe2O3 and FeF3 on the friction surface, which can remarkably improve the performance of friction reduction and prevent the appearance of severe wear.
Polyacrylic acid (PAA) hydrogel composites with different hexagonal boron nitride (h-BN) fillers were synthesized and successfully 3D-printed while their thermal conductivity was systematically studied. With the content of h-BN increasing from 0.1 wt% to 0.3 wt%, the thermal conductivity of the 3D-printed composites has been improved. Moreover, through the shear force given by the 3D printer, a complete thermal conductivity path is obtained inside the hydrogel, which significantly improves the thermal conductivity of the h-BN hydrogel composites. The maximum thermal conductivity is 0.880 8 W/(m·K), leading to a thermal conductive enhancement of 1 000%, compared with the thermal conductivity of pure PAA hydrogels. This study shows that using h-BN fillers can effectively and significantly improve the thermal conductivity of hydrogel-based materials while its 3D-printable ability has been maintained.
Calix[n]arenes was utilized to detect PABA, the primary sunscreen component. This study investigates the interaction of calix[4]arene (C4), calix[6]arene (C6), and PABA using the Langmuir method and first-principle density functional theory (DFT). Using the Langmuir-Schaefer (LS) technique, an ultrathin film composed of calix[n]arenes and their complexes with PABA was deposited on various substrates. Based on the Langmuir study, the PABA molecule was bonded to the lower rims of both C4 and C6 with the host-guest ratio of 1:1. All of the LS films formed were then characterized by ultraviolet-visible spectroscopy (UV-Vis), Fourier-transform infrared spectroscopy (FTIR) and carbon, hydrogen, nitrogen, sulfur elemental analyzer (CHNS). The band gap reduction obtained in the DFT study denotes the charge transfer interaction with promising reactivity between the calix[n]arenes and PABA. The sensing of PABA by C4 and C6 is successful based on the formation of bonding between them due to the hosts’ effective trapping capacity. The outcomes of this study could be applied to drug delivery systems for future pharmaceutical and medical applications.
Micrometer-sized diamonds were incorporated into silicon nitride (Si3N4) matrix to manufacture high-performance Si3N4-based composites using spark plasma sintering at 1 500 °C under 50 MPa. The effects of the diamond content on the phase composition, microstructure, mechanical properties and thermal conductivity of the composites were investigated. The results showed that the addition of diamond could effectively improve the hardness of the material. The thermal conductivity of Si3N4 increased to 52.97 W/m·k at the maximum with the addition of 15 wt% diamond, which was 27.5% higher than that of the monolithic Si3N4. At this point, the fracture toughness was 7.54 MPa·m1/2. Due to the addition of diamond, the composite material generated a new substance, MgSiN2, which effectively combined Si3N4 with diamond. MgSiN2 might improve the hardness and thermal conductivity of the materials.
The contents of waste glass powder (WGP) (0%, 10%, 15%, 20%, 25%) and water-binder ratio (W/C) (0.24, 0.26, 0.28) were used as influencing factors, and the quality loss rate (Δm) and compressive strength loss rate (Δfc) were used as characterization parameters. The Ca/Si ratio and main element contents of C-S-H gels with different WGP content were investigated by energy dispersive spectrometry (EDS). The pore structure evolution characteristics of WGP composite cementing materials were investigated by low field nuclear magnetic resonance (NMR). Using Δfc as the index of frost resistance degradation and Weibull function, the frost resistance degradation of glass doped pervious concrete (WGP-PC) was modeled. The results show that, with WGP, for the same number of cycles, Δm and Δfc decrease and increase with the increase of WGP. Under the same WGP content, Δm and Δfc decrease first and then increase with the increase of W/C. After 100 freeze-thaw cycles, the samples with WGP content of 20% and W/C of 0.26 have the best freeze-resistance. Microscopic tests show that with the increase of WGP content, the Ca/Si ratio of C-S-H gel decreases at first and then increases with the increase of WGP content. The extreme value of Ca/Si is 2.36 when WGP is added by 20%. The pore volume of hardened paste with 20% WGP content decreased by 18.6% compared with that of cement system without WGP. The overall compactness of the specimen was improved. On the basis of the test data, a life prediction model was established according to Weibull function. The experiment showed that Δfc could be used as a durability degradation index, and the slope of the reliability curve became gentle after WGP was added, which reduced the damage degradation rate of PC. W/C was 0.26. It’s about 5 000 hours.