Al-Si coatings with different Si content were deposited on the surface of Ti-alloy Ti-6Al-4V by multi-arc ion plating, then which were subjected to vacuum heat treatment at 900^oC for 1 h and thereby Si-modified aluminide coatings with gradually decreasing Al-content along the normal of coating inwards were acquired The aluminide coatings exhibited layered structure and were mainly composed of Ti-Al intermetallics including TiAl₃, TiAl₂, TiAl and precipitates including Ti₅Si₃ and Ti₅Si₄, and certain amount of Si atoms were dissolved in the TiAl₃ as substitutes and formed Ti(Al, Si)₃. The Si modified aluminide coatings showed excellent cyclic oxidation resistance at 650^oC. It is worthy to note that at 750^oC, the cyclic oxidation resistance of the aluminide coatings increased with the increasing of Si content.

A new type of boron-doped carbon nanotube (B-CNT) film was successfully grown on the surface of paper- sintered stainless steel fiber (PSSF) carrier via chemical vapor deposition (CVD) method with phenylboronic acid as precursor, constituting a metal-free composite catalyst of boron-doped carbon nanotube membrane with gradient porous structure on PSSF (B-CNTs/PSSF). The B-CNTs/PSSF was characterized by means of FE-SEM, TEM, Raman, TG and XPS, and then applied to the degradation of phenol. The results showed that the prepared B-CNTs/PSSF had a better phenol degradation performance than CNTs/PSSF without B doping, with a phenol conversion rate of 100%, a total organic carbon conversion rate of 68%. Based on the density functional theory (DFT), it was found that the difference in catalytic performance comes from the stronger adsorption and mutual electron transfer of H₂O₂ by B-CNT than CNT.

The corrosion behavior of austenitic stainless steel S31655 in a simulated industrial wet process phosphoric acid solution at 25^oC, 40^oC, 60^oC and 80^oC was investigated by means of electrochemical test and XPS technique. The results show that: with the increasing temperature, the corrosion resistance of S31655 decreases and the is a critical point at 60^oC, while the corrosion resistance decreased significantly at 80^oC, meanwhile, the defects concentration N_D of the formed passivation film increased, its thickness W_sc decreased, and thestability deteriorated, meanwhile, the semi-conductivity of the passivation film transforms from n-type semiconductor to p-type semiconductor by potential above 0.7 V. Results of XPS spectra show that Cr₂O₃and Fe(Ⅲ) etc. could improve the corrosion resistance by stabilizing the passivation film, and ligands $\mathrm{NH}_{4}^{+}$ and NH₃ could inhibit the corrosion process by acting as retardant to acidic solutions. The presence of a critical temperature is associated with an increase in the solubility of N and $\mathrm{NH}_{4}^{+}$ in the passivation film at 80^oC. The increase in temperature simultaneously promotes the generation of soluble Fe(H₂PO₄)₂ and porous films, and the significant enrichment of Ni and N in S31655 leads to a decrease in the precipitation rate of Cr₂O₃, but also promotes the full crystallization and structural stability of Cr₂O₃, thereby improving its corrosion resistance.

The precipitation behavior of TiN particles during the solidification process of Ti-microalloyed steels with varying N contents was investigated by experimental observations and theoretical analysis. The results indicate that reducing the N content leads to decrease in the number of coarse TiN inclusions precipitated from the liquid phase and changes in the morphology of TiN inclusions, as well as alterations in the driving force for the precipitation and the size of TiN particles precipitated from the solid phase during solidification. Simultaneously, the decrease in N content contributes to the decrease of the volume fraction of TiN particles precipitated from both the liquid and solid phase. It is concluded that the morphology, size and volume fraction of TiN inclusions and precipitated TiN particles within the steel may be controlled by adjusting the N content of Ti-microalloyed steels with a set Ti content.

The chloride-based molten salt is expected to be the next generation of heat storage medium for concentrated solar power technology. However, the chloride-based molten salts have severer corrosive effect to the relevant metallic structural parts at elevated temperatures. In this paper, Ni-Al coatings were prepared on Ni-based alloy IN 625 by magnetron sputtering technique. Then the coated alloys were pre-oxidized in air at different temperatures. Next, the corrosion behavior of the pre-oxidized coatings in the mixed chloride molten salts at 800^oC was assessed via immersion test. Meanwhile, the formed oxide scales due to pre-oxidation treatment, and the variation of the pre-oxidized scales after immersion test were also characterized. The results show that a continuous and dense oxide scale can form when the pre-oxidation at 1000^oC. When the pre-oxidation at 800 and 900^oC, a complete and continuous dense oxide scale cannot form, and when the pre-oxidation at 1100^oC, although an oxide scale will form, but a large number of nodular oxides generate on the top surface of the pre-formed oxide scale due to the rapid outwards diffusion of alloying elements from the substrate during pre-oxidation, which is not conducive to the corrosion resistance of the coating. After corrosion in molten chloride salts at 800^oC for 100 h, the Ni-Al coated IN 625 alloy pre-oxidized at 1000^oC presented only little mass change, indicating that the coating has good high-temperature corrosion resistance, this may mainly be due to the formation of a complete and continuous oxide scale of α-Al₂O₃, which plays role in anti-corrosion protection for the substrate. With the progress of high temperature corrosion, the Cr content in the coating increases obviously, indicating that high temperature promotes the outward diffusion of Cr atoms from the substrate.

The effect of Ce addition on the microstructure and Ce distribution characteristics of the as-cast T15 high speed steel (T15 HSS) was investigated by OM, SEM, XRD, EBSD and EPMA. The primary carbides and mechanical properties of the as-cast T15 micro-alloyed without and with Ce were also assessed comparatively by nanoindentation and tensile tests. The results show that the amount of alloyed Ce in T15 HSS enriches mainly in rare earth containing granular inclusions, but a few distributes uniformly in MC primary carbides. The addition of 0.021wt.%Ce does not change the as-cast microstructure types, but it obviously refines the primary carbides, remarkably enhances the plasticity and toughness of MC carbides, and significantly improves the mechanical properties of T15 HSS. Comparing the T15 HSS micro-alloyed with Ce to that without Ce, the average equivalent diameter and maximum size of primary carbides decreased from 4.70 μm and 120.25 μm to 2.91 μm and 105.39 μm, with decrement 38.08% and 12.35%, respectively. The amount of V in MC primary carbides decreased by 6.16 at.%, and the morphology of these carbides changed from thick branches into spots. Moreover, the plasticity factor and fracture toughness of MC primary carbides increase from 0.47 and 1.63 MPa·m^1/2 to 0.50 and 2.32 MPa·m^1/2, respectively. Thus, the hardness, bending strength and tensile strength of as-cast T15 HSS increased from 48.88 HRC, 1491.06 MPa and 1122.41 MPa to 51.72 HRC, 1621.58 MPa and 1181.83 MPa, respectively.

Al-based composite coatings with different Al₂O₃ contents (0%, 15%, 30%, 45%) were prepared on AZ91 Mg-alloy substrate by cold spraying technique, the deposition efficiency of Al₂O₃ and the porosity of the coatings were measured, and their reciprocating dry friction wear performance was examined in terms of wear gouge volume. Meanwhile, the effect of Al₂O₃ content, the applied load, and frequency on the friction and wear behavior of Al-based composite coatings were investigated. A finite element model of the Al-based composite coating was established, and the simulated values of the finite element wear volume were obtained by using the friction and wear subroutine (UMESHMOTION) embedded with the Archard model, which then were compared with those acquired from the friction and wear experiments. The results show that with the increasing Al₂O₃ content, the porosity of the composite coatings decreases, while the deposition efficiency of Al₂O₃ particles, and thereby the wear resistance of coatings increases. The simulated value of the finite element wear calculated by the model under this condition is 0.0249 mm³ for the coating with 15% Al₂O₃with a difference of 5.9574% compared to that acquired from the wear experiments, indicating the universality of the proposed model.

Herein, photocatalyst composite films of polyporphyrin/MXene were prepared via anodic oxidation method with octaethyl porphyrin zinc and 4,4-bipyridine as monomers, and multi-layered Ti₃C₂ as MXene self-supporting film, with the aim to prepare a novel material with high-photocatalysis efficiency for degradation of dyestuffs wastewaters. The prepared catalyst was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, electrochemical impedance spectroscopy, photoelectrochemical testing etc. The photocatalytic degradation effect of the synthesized self-supporting composite film photocatalyst on methylene blue was assessed through photocatalytic degradation testing. The results indicate that loading polyporphyrin onto MXene thin films can promote the separation of photo generated electron pairs, improve the efficiency of polyporphyrin photocatalysis, and achieve reusable recycling of materials. The increase in interlayer spacing of MXene was achieved by loading polyporphyrin onto the MXene through anodic oxidation, effectively solving the problem related with restacking and increasing the porosity of MXene. When the area of the polyporphyrin/MXene based composite film is 1 cm² and the initial concentration of methylene blue is 10 mg/L, the degradation rate of methylene blue by the composite material reaches 98% after 80 minutes of illumination. The capture experiment shows that the main free radical playing a role in the photocatalytic degradation of methylene blue is h⁺.