The stability, mechanical properties, and electronic structure of transition metal (TM, TM=Ti, V, Cr, Y, Zr, and Hf) elements doped tantalum nitride (Ta₇TMN₈) were investigated by first-principles calculations. According to the calculation results of structure and stability, all the doped compounds are stable, and Ta₇TiN₈ is energetically more favorable than others. The doping of Y, Zr, and Hf can cause lattice and volume expansion of TaN, while Ti, V, and Cr play an opposite role. The calculated mechanical properties reveal that the addition of Ti and V can significantly improve the shear modulus, elastic modulus, and theoretical hardness of TaN, while doping Cr can only increase the volume modulus but significantly decrease the theoretical hardness. Based on the calculation results of the total and partial density of states of Ta₇TMN₈, the density of states at the Fermi level indicates that all compounds exhibit metallic nature. The contribution of Ti-3d, V-3d, and Cr-3d orbitals at the Fermi level is quite more than other TM atoms, leading to a more metallic character of Ta₇TiN₈, Ta₇VN₈, and Ta₇CrN₈.

Phase field simulations combined with sintering experiments were used to study the grain growth behavior and the kinetics of nano alumina under the influence of solute element grain boundary segregation. By introducing the solute dragging effect into the phase field model of alumina polycrystalline grain growth, and relating the solute dragging intensity to the intracrystalline solute atom concentration and atomic equilibrium bias ratio, under various solute atoms equilibrium bias ratios at grain boundaries and initial intracrystalline solute atom concentrations, the growth behavior of alumina grains were investigated, furthermore, the anomalous growth phenomenon of alumina grains with different solute dragging intensity was quantitatively analyzed. By comparing the average size and morphological evolution of the grains, the results of the phase field simulations are consistent with the experimental growth behavior of lanthanum oxide doped nano alumina grains. The results show that the growth of alumina grains is significantly inhibited by the very strong solute dragging effect, leading to a slow growth. While the low solute dragging effect has no significant inhibitory effect on grain growth. From the simulated microstructure evolution results, grain boundary segregation may also trigger the abnormal growth of a few alumina grains, and the specific grains may grow rapidly with overcoming the solute drag effect during the growing process, resulting in the loss of material properties.

Two kinds of Al-Zn-Mg-Cu alloys adding Zr, Cr elements and Zr, Cr and Yb clements were prepared by the melting and casting method, respectively. Optical microscopy, transmission electron microscopy, and scanning electron microscopy were used to observe the microstructure of these alloys, and mechanical and corrosion properties were also tested. The results show that AlZnMgCu-Zr-Cr-Yb alloy maintains a fibrous structure dominated by small angular grain boundaries after solid solution treatment, which is attributed to the precipitation of a large number of fine and diffuse (Al,Cr)₃(Zr,Yb) phases of 10-20 nm, which can hinder dislocation and grain boundary migration and thus significantly inhibit matrix recrystallisation. The addition of Yb can increase the hardness, strength, elongation, and fracture toughness of the alloy, with the fracture toughness increases from 24.2 MPa·m^1/2 to 32.4 MPa·m^1/2. The resistances to stress corrosion, intergranular corrosion, and exfoliation corrosion all increase at the same time, with the threshold stress intensity factor for stress corrosion cracking (K_ISCC) increases from 10.6 MPa·m^1/2 to 17.0 MPa·m^1/2. The intergranular corrosion depth decreases, the exfoliation susceptibility reduces and the exfoliation grade lowers from EB+ to EA.

In this paper, Ti_xZr_1-xMnFe (x=0, 0.25, mole fraction) inspiratory alloy with a single C14 Laves phase structure was prepared by arc melting method. CO₂ gas adsorption reaction for ZrMnFe was tested by a self-made simple Sieverts constant volume equipment between 660-700 ℃, to study the adsorption performance as well as the adsorption behavior to CO₂ gas. The results show that with the increase of temperature, the adsorption capacity of CO₂ increases first and then decreases, and the maximum adsorption capacity is 3.869 mmol/g at 680 ℃, showing the best adsorption performance. After obtaining Ti_xZr_1-xMnFe alloy by Ti doping, the adsorption capacity increases by 19.2% compared with that before doping, but the adsorption rate decreases from 0.301 mmol/(g·h) to 0.119 mmol/(g·h) in the first 8 h. The adsorption mechanism was studied based on the first principles, by comparing the adsorption energies, we obtained the optimal adsorption position which is the horizontal orientation vacancy on the surface of ZrMnFe (110), and the adsorption energy is 5.531 eV. Under the study to density of state, it was found that the interaction between the surface of ZrMnFe (110) and CO₂ gas molecules is mainly because of the hybridization of 2s orbitals of O and 4p and 4d orbitals of Zr atom.

Based on the Gaussian heat source model, thermal conductivity model, and Flow-3D software, a powder particle model of coal gangue and polyethersulfone (PES) powder, as well as a three-dimensional model of coal gangue/PES (CPES) composite material powder bed, were established to numerically simulate the temperature field during the selected laser sintering process of CPES composites. The influences of laser power, scanning speed, and scanning space on the formation of single and double pass sintered layers were studed, the values of sintering process parameters was predicted and verified through experiments. The results show that when the laser power is 15 W, the average temperature of the melten pool is 596 K, the impact strength of the sintered part is 179.4 MPa, the melt path is relatively straight, the spheroidization phenomenon disappears, and the bonding with the powder is good, forming a high-quality melt path; When the scanning speed is 1 800 mm/s, the average depth of the molten pool is 99 um, the average width is 200 μm, and the impact strength of the sintered part is 173.5 MPa, the melting area is almost circular, the length of the melten pool is the shortest, the heat accumulation in the melt path is significant, and no deflection phenomenon is found; When the scanning space is 100 μm, the overlap rate of the melt path is 60.8%, and the impact strength of the sintered part is 176.2 MPa, the surface transition of the overlap area between two melt paths is smooth and continuous, without any holes or spheroidization phenomenon.

Using electrolytic dendritic copper powder with an average particle size of 55-112 μm as raw material and urea as pore forming agent, adding organic component binder, solvent and other organic matter to prepare slurry, using printing process to prepare capillary wick green, and then degreasing and sintering to prepare capillary wick with thickness of (0.2±0.02) mm. The effects of copper powder particle size, urea addition and slurry organic components on the pore structure and capillary performance of the capillary wick were studied. The results show that the addition of poreforming agent urea can increase the porosity, average pore size and permeability of the capillary wick structure, and reduce the capillary force and fractal dimension. As the particle size of copper powder decreases from 112 μm to 55 μm, the porosity, average pore size, average area, average perimeter, fractal dimension, permeability and capillary performanca parameters of the capillary wick all decrease, while the capillary force increases, its fractal dimension decreases from 1.39 to 1.20. The fractal dimension is related to the permeability, and as the permeability decreases, the fractal dimension decreases gradually. Its capillary performanca parameters are directly proportional to permeability and inversely proportional to capillary force. The capillary wick prepared by 112 μm copper powder has the best performance, the permeability is 2.02×10^-10 m², the capillary force (ΔP_c) is 1.29 kPa, and the capillary performanca parameter (ΔP_c·K) reaches 2.61×10^-7 N.

To develop efficient and stable hydrogen evolution electrocatalysts, Ni-Sn-B hydrogen evolution electrode were prepared on Ni mesh substrate by galvanostatic electrodeposition method. The morphology, structure, elemental composition, and electrocatalytic hydrogen evolution properties of the electrode were characterized and tested by scanning electron microscopy, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and electrochemical workstation. The results show that the surface of Ni-Sn-B electrode is composed of rough cellular particles, which are closely packed and have amorphous characteristic structure. Ni-Sn-B electrode has excellent catalytic performance and stability for hydrogen evolution in alkaline solution. The overpotential is only 63 mV at current density of 10 mA/cm², which is 38.2% and 59.1% lower than that of Ni-Sn and Ni-B electrodes. The charge transfer resistance of electrode is 1.56 Ω, and the excellent hydrogen evolution activity is still maintained after 5 000 cycles of voltammetry and 72 h electrolysis. The abundant surface morphology and amorphous characteristic structure can significantly increase the electrochemical active surface area and catalytic active site. The regulation of B and Sn on the electronic structure of Ni effectively decreases the charge transfer resistance and improves the properties of electrocatalytic hydrogen evolution reaction.

TiO₂, MgO and CaCO₃ were selected as mineralizing agents for porous alumina ceramics, which were prepared by atmospheric sintering under air atmosphere. The effects of different contents of MgO, CaCO₃ and holding time on the bending strength at room temperature, sintering shrinkage rate, apparent porosity and dissolving efficiency were studied. The results show that the addition of mineralizing agents MgO and CaCO₃ can decrease the shrinkage rate, bending strength at room temperature and density, and increase the apparent porosity and the dissolving efficiency. The shrinkage rate of the samples containing MgO decreases from 1.75% to 0.21% after 1 320 ℃/3 h sintering, and the apparent porosity increases from 33.49% to 36.86%. The shrinkage of the samples containing MaO decreases from 1.88% to 0.38% after 1 320 ℃/6 h sintering, and the apparent porosity increases from 32.94% to 35.46%. The shrinkage rate of the samples containing CaCO₃ decreases from 0.55% to -0.50% after 1 320 ℃/3 h sintering, and the porosity increases from 35.47% to 41.26%. The shrinkage of the samples containing CaCo₃ decreases from 1.16% to -0.21% after 1 320 ℃/6 h sintering, and the apparent porosity increases from 35.96% to 42.44%. When the holding time of heating treatment is extended from 3 h to 6 h, the shrinkage rate of the samples containing mineralizing agent MgO and CaCO₃ increases, while the bending strength at room temperature do not change significantly. The apparent porosity of the samples containing MgO decreases and that of the sample containing CaCO₃ increases. MgO and CaCO₃ can significantly improve the dissolving efficiency. The quality of the samples containing only mineralizing agent TiO₂ is almost unchanged after 72 h of boiling in alkaline liquid (adding cosolvent LiF), the samples containing MgO can be completely dissolved after 24 h of boiling in alkaline liquid (no cosolvent added), and the samples containing CaCO₃ can be completely dissolved after 72 h of boiling in alkaline liquid (adding cosolvent).

Hot deformation behavior of Ti-55511 titanium alloy was studied at deformation temperatures of 700-850 ℃, strain rates of 0.01-10 s^-1 and true strain of 0.6. The results indicate that the flow behavior of Ti-55511 titanium alloy is significantly affected by deformation temperature and strain rate. With the decrease of temperature and the increase of strain rate, the peak stress increases. In order to eliminate the deformation temperature rise effect in the process of hot compression and improve the accuracy of the model, a new temperature correction method was adopted in this paper. The temperature correction of the experimental flow stress curve was carried out through the Arrhenius constitutive equation derivation and combined with the mathematical extrapolation method. The results show that with the decrease of deformation temperature and the increase of strain rate, temperature rise and flow stress increment increase. The Arrhenius constitutive equation of strain-compensated is established, and the value of correlation coefficient (R²) and average absolute relative error (AARE) between experimental and predicted stress are 0.991 and 6.65%, respectively. This indicates that the established constitutive equation can accurately predict the flow stress under different thermal deformation conditions.

Diamond grinding wheels with intermetallic compound as binder are widely used in grinding sapphire, silicon carbide and other fields. The binding state between binder and diamond directly affects the mechanical and grinding properties of the diamond grinding wheels. In order to study the interface binding of binder and diamond, Ti-Al intermetallic-bonded diamond grinding blocks were prepared by hot pressing, and the binding state and the grinding property of grinding blocks were studied by various material characterization methods and friction wear tests. The results show that Ti-Al intermetallic compound is generated in the binder after hot pressing, and Al will be enriched on the diamond surface to improve the holding force of the binder on the diamond particles. When the sintering temperature is 900 ℃, the binder has the highest holding force on diamond particles, and the mechanical and grinding properties of the grinding block are the best, the maximum strength and hardness (HRB) are 160.48 MPa and 114.4, respectively, and the abrasion radio of grinding sapphire is 22.3 and the surface roughness of sapphire is 1.37 µm. However, the excessive oxidation of the binder will reduce the grinding property of the grinding block with the further increase of the temperature.

To explore the methods to improve the oxidation resistance at high temperature and the physical and mechanical properties simultaneously. Thus, this research designed WC-6Co-6Ni, WC-6Co-6Ni-1Cr₃C₂, WC-6Co- 6Ni-1CeO₂ and WC-12Co-1CeO₂ WC-based cemented carbides, corresponding to alloys 1^#-4^#, respectively. The microstructure, physical and mechanical properties and oxidation behavior of the alloys at 700 ℃ for 16 h were investigated by comparison. The results show that the presence of rare earth-containing oxide dispersion phase in the alloy does not lead to the decrease of alloy strength, and the alloy hardness follows the coupling law of hardness, grain size and volume fraction of the phase components. The hardness of alloy 4^# is the highest, followed by alloy 2^#. The influence of Co and Ni binder metals on the hardness of cemented carbides is significant. Both Cr₃C₂ and CeO₂ can significantly improve the oxidation resistance of the alloys at 700 ℃, but the improvement effect of Cr₃C₂ is better than that of CeO₂. The high temperature oxidation resistance and physical and mechanical properties of WC-based cemented carbide can be improved synchronously by adding appropriate amount of Cr₃C₂ and CeO₂, and using Ni to partially replace Co.

K doped O3-type Na_0.9-xK_xCu_0.22Fe_0.30Mn_0.48O₂ (x=0, 0.05, 0.1) cathode materials were prepared by simple solid phase method. The structural stabilities and electrochemical properties of the materials were analyzed and studied by X-ray diffractometer, scanning electron microscope, transmission electron microscope, and electrochemical experiment. The results show that K doping can enhance the structural stability, the Na⁺ diffusion rate and electrochemical reversibility are also significantly improved. The O3→P3 phase transition occurs earlier and faster, which has a positive effect on improving the energy efficiency of O3-type cathode materials. The O3-type Na_0.85K_0.05Cu_0.22Fe_0.30Mn_0.48O₂ cathode material possesses excellent cycle stability, which can deliver a capacity retention of 88.6% after 150 cycles at 0.5 C. K doping is low-cost and simple to operate, which can help to promote the industrialization of stable high-performance sodium ion batteries.

For the reuse of crucibles used to smelt nuclear metals and the recovery of spent fuel, a series of double-layer gradient composite Yttria-coatings were prepared on the surface of Niobium 521 alloy by slurry sintering process. Trace amounts of Si and Mo were added as reinforcing agents in the coating, the surface of the coating was pure Y₂O₃. With the help of finite element simulation, X-ray diffractometer, scanning electron microscopy, energy spectrometer and other means, the microstructure and thermal shock resistance of the coating were studied. The results show that the Nb/Y₂O₃ coating has a typical layered structure, which is composed of irregular powder particles stacked on top of each other, and the matrix area, diffusion area, transition layer and Y₂O₃ layer have distinct structures. The finite element simulation calculation and experimental results both prove that the double-layer gradient coating can change the stress distribution and effectively reduce the stress generated inside the material during thermal shock. Among them, the maximum principal stress of the 70%Y₂O₃+22% Nb+6%Si+2%Mo (7022) coating is 163.2 MPa, which decreases by 47.93% compared to the single-layer Y₂O₃ coating (313.4 MPa). After 60 thermal cycles, the microstructure of the 7022-Y₂O₃ coating is dense without obvious defects, and the morphology is the least damaged.

ZrB₂-SiC-LaB₆ ultrafine multiphase powders were prepared by the way of sol-gel method and carbothermal/borothermal reduction process, using zirconium oxychloride (ZrOCl₂·8H₂O), boric acid (H₃BO₃), hydrated lanthanum chloride (LaCl₃·7H₂O), ethyl orthoate (TESO), and glucose (C₆H₁₂O₆) as the main raw materials, polyethylene glycol (PEG) as the dispersant. The effects of different temperatures and raw material ratios on the synthesis process of composite powders were studied and characterized by X-ray diffraction, SEM, infrared spectroscopy, and differential thermal scanning. The results show that when n(Zr)∶n(B)∶n(Si)∶n(La)∶n(C) =1∶3∶0.7∶0.16∶8 in the raw material, ZrB₂-SiC-LaB₆ superfine multiphase powders can be synthesized by holding at 1 500 ℃ for 2 h under argon atmosphere. The average particle size of multiphase powder is 300 nm, in which ZrB₂ phase is hexagonal crystal system, SiC and LaB₆ phase are cubic system, and the average size of ternary crystallite is 33.2 nm.

Ni₃Fe/Ni₃S₂ oxygen evolution catalysts were synthesized by two-step hydrothermal method using Fe(NO₃)₃·9H₂O and Na₂S·9H₂O as Fe source and S source, respectively, and nickel mesh (NM) as the Ni source and support substrate. The microstructure and morphology of the catalysts were analyzed by XRD, XPS, SEM, and TEM, and the electrochemical properties were tested by an electrochemical workstation. The results demonstrate that the Ni₃Fe/Ni₃S₂ catalyst synthesized by the two-step hydrothermal method has rich three-dimensional nanoflower morphology, which enhances the spatial utilization of the catalyst. Ni₃S₂ exposes a high refractive index $\{\bar{2}10\}$. crystalline surface, which contributes to the synergistic effect with the (111) crystalline surface of Ni₃Fe to enhance the catalytic activity. The oxygen evolution overpotential is 229 mV at a current density of 10 mA/cm² in 1 mol/L KOH (25 ℃), the overpotential is 335 mV for a current density of 600 mA/cm² in 5.35 mol/L KOH (80 ℃), and the decay rate of the overpotential is only 2.39% after 6 000 cyclic voltammetry cycles. It demonstrates that the catalyst has good oxygene evolution performance and stability.

Copper based brake pads have the problems of matrix softening and friction film breaking during high-speed cycle braking. Cu-based brake pads with boron carbide (B₄C) mass fraction of 0-6% were prepared using powder metallurgy (PM) method, and C/C-SiC brake discs were selected as dual components to study the effect of B₂O₃ friction film formed during the braking process on friction and wear performance, and to analyze the wear mechanism. The results show that the density of copper based friction materials can be reduced by modifying with B₄C. When the mass fraction of B₄C is 4% and 6%, the material density significantly decrease and the strength increase, and the most excellent thermal degradation resistance and the lowest wear rate are obtained, respectively. During the braking process, B₂O₃ formed by B₄C oxidation has a layered crystal structure similar to MoS₂ and graphite, which is easy to shear at the sliding interface, thereby improving the mean friction stability coefficient and reducing wear rate. B₂O₃ formed on the surface of B₄C combines well with the Cu matrix. When the mass fraction of B₄C exceeds 4%, the wear mechanism of Cu-based brake pads shifts from delamination wear to oxidation wear.

Resin-coated graphite/copper composites and copper-plated graphite/copper composites were prepared by cold pressing-pressure sintering process using phenolic resin powder, graphite powder, copper-plated graphite powder and electrolytic copper powder as raw materials, respectively, the friction and wear properties of two kinds of graphite/copper composites at room temperature, high temperature and current-carrying were studied, and compared with overseas Roland grounding brush; the effects of resin decomposition on the conductivity, mechanical and friction and wear properties of the composites were analyzed based on the crystal structure of copper matrix and the variation of composite conductivity and mechanical properties at high temperature (200-600 ℃). The results show that the mechanical properties of resin-coated graphite/copper composites at high temperature are better than that of copper-plated graphite/copper composites. When the ambient temperature reaches 600 ℃, the shear strength of resin-coated graphite/copper composites decreases by only 6%, while that of copper-plated graphite/copper composites decreases by 24%. The high temperature (250 ℃) wear resistance and friction stability of resin-coated graphite/copper composites are much better than those of copper-plated graphite/copper composites and Roland brush, the current-carrying friction factor of the resin-coated graphite/copper composites is lower than that of Roland brush. The resin coating of graphite can improve the friction and wear properties of copper matrix composites at high temperature and current-carrying, due to the protection of the resin layer, a continuous and stable graphite lubricating film can be formed even under the conditions of high temperature oxygen and current-carrying, thus reducing the friction contact micro-gap; the carbonized resin breaks into fine hard particles during the friction, which hinder the adhesion and wear between composite and disc; the Cu matrix softening at high temperature is not obvious, so the occurrence of arc decreases.

MC_sf/Fe and C_fp/Fe powder metallurgy materials were prepared by pressing-vacuum sintering using reduced Fe powder as the matrix, micron short carbon fibers (MC_sf) with a length of about 20 μm and carbon fiber particles (C_fp) with a particle size of 1-4 μm as the dispersoid, respectively. Natural graphite (NG) with an average particle size of 10 μm as the raw material was used to prepare NG/Fe powder materials for comparison. The effects of micronshort carbon fibers and carbon fiber particles on the microstructure, physical properties, mechanical properties and dimensional changes were investigated. The results show that the activity of carbon fiber particles is much higher than that of graphite and degummed short carbon fibers (DC_sf), and the maximum mass loss rate at 800 ℃ in air atmosphere is 3.75 times that of graphite and 16.6 times that of degummed short carbon fibers. Compare with NG/Fe and MC_sf/Fe powder metallurgy materials, the dimensional stability of C_fp/Fe powder metallurgy materials during sintering is greatly improved, with the maximum radial expansion and shrinkage rates of 0.39% and 0.14%, respectively; the strength and toughness are the highest, with the density, flexural strength, shear strength and tensile strength of 6.91 g/cm³, 736.9 MPa, 205.7 MPa and 334.8 MPa, respectively. The elongation reach 10.5%, and the fracture mode of the materials change from a brittle along-crystal fracture to a completely severe nest fracture.

MoB, Al, Y and Si powders were used as raw materials to prepare MoAlB ceramics with trace Y and Si doping by dry milling and vacuum hot pressing methods. The phase composition and microstructure of the sample were characterized and analyzed by X-Ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The hardness, fracture toughness, bending strength and compressive strength of the ceramic were tested to study the effects of different doping elements on the microstructure and comprehensive mechanical properties of MoAlB ceramics. The results show that the MoAlB ceramics are mainly composed of MoAlB, Al₈Mo₃ and Al₂O₃ phases, and new phases are produced after doping with trace Si and Y. The doping of Si element can effectively refine the MoAlB grains, while the MoAlB grain size slightly increases after doping with Y element. MoAlB ceramics have good tolerance to damage. The hardness of MoAlB ceramics increases by doping Si and decrease by doping Y. The fracture toughness and bending strength of MoAlB ceramics increase by doping Si, while the bending strength and fracture toughness of ceramics decrease slightly by doping Y. Both Y and Si doping have a positive effect on improving the compressive strength of MoAlB ceramics, and Si doping has a better strengthening effect.

Tungsten skeleton with uniformly distributed pores is the key material for producing high-performance electronic cathodes and discharge lamps. This study systematically investigated the effects of pressing pressure on the pore structure, mechanical properties of the tungsten skeleton and the performance of discharge lamp. The results show that with the increase of pressing pressure, the porosity and average pore size of the tungsten skeleton decrease, the microhardness and compressive strength increase, and the uniformity index of pore distribution first increases and then decreases. When the pressing presure is 500 MPa, the pore structure and mechanical properties of the tungsten skeleton are the best, the porosity is 26.29%, the average pore size is 1.24 μm, the uniformity index of pore distribution is 4.17, the microhardness is 1 506 MPa, and the compressive strength is 810 MPa. The xenon lamp prepared by the tungsten skeleton as the cathode substrate do not show any flashovers after continuous flashing for 500 000 times, and its cathode emission performance is stable, and the tungsten cathode has not reach its lifespan limit yet, which shows a significant improvement in lifespan compared to existing cathodes.