[en] The oxidation behavior of γ-TiAl with Ta surface coating fabricated by double glow plasma surface alloying technology was investigated by thermogravimetric method. Oxidation experiments were carried out at 750 °C and 850 °C in air for 100 h. The modification layer was comprised of deposition layer and diffusion layer, which metallurgically adhered to the substrate. Tantalum element decreased with the case depth. The oxidation morphology was studied by a scanning electron microscope and X-ray diffraction. The results highlighted that in the oxidizing process of the oxidation, the phase containing Ta-richer may restrain diffusing outward of the element Al in the matrix. Ti diffused outward, and formed the TiO₂ scales, while the middle layer was rich in Al, and formed the continuous Al₂O₃ scales after oxidation, which was effective to prevent further infiltration of oxygen atoms, and as a result the oxidation resistance increased immensely. - Highlights: • A Ta modified coating was prepared on γ-TiAl using DGP surface alloying technology. • The modification layer metallurgically adhered to the substrate. • The bonding force is about 60 N, satisfying the demands of practical use. • The oxidation resistance increased immensely at 750 °C and 850 °C

[en] Objective: To explore the molecular mechanism of bone marrow injury caused by irradiation, gene expression of bone marrow cells in mice after whole body irradiation was studied. Methods: Total RNA extracted from bone marrow cells in mice at 4 h after whole body irradiation with 7 Gy γ-rays was taken as the tester and the total RNA from control mice as the driver cDNA subtraction was performed using the protocols described in the Clontech SMART PCR cDNA Sythesis Kit and PCR-select cDNA Subtraction Kit. The subtracted cDNA was then inserted into T vector to generate subtracted cDNA library. Clones of the subtracted cDNA library were screened by hybridization and the insert sequence of the positive clones was compared with the sequence in the GenBank. Results: A total of 800 clones selected from the subtracted cDNA library were PCR-amplified and about 86% had inserts. Fourteen differential cDNA fragments were acquired after two round hybridization screening, 7 of them showed high similarity to the expressed sequence tags (ESTs) in the mouse EST database and the other 7 cDNA fragments were possibly new ESTs. Conclusion: The successfully constructed subtracted cDNA library of bone marrow cells in mice after whole body high-dose irradiation and the validation of some differential ESTs establish the basis for further research of radiation-related genes

[en] The high-temperature oxidation behavior of Q235 steel coated with Fe–Al–Cr by using double glow plasma surface metallurgy method was studied in air at different temperatures of 500, 600 and 700 °C, respectively. The Q235 and the 304 stainless steels were produced as the control samples. Electron microscopy, energy dispersive spectroscopy and X-ray diffractometry were carried out to investigate the surface morphologies, microstructures and phases of alloyed layer before and after oxidation. It showed that the structure of the Fe–Al–Cr alloyed layer was compact without any microstructure defects. This alloyed layer connected with the substrate metal by metallurgical bonding. At the temperatures of 500 and 600 °C, the high temperature oxidation resistance of the Fe–Al–Cr alloyed layer was similar to that of the 304 steel, but 2–3 times higher than that of the Q235 steel. While at 700 °C, the Fe–Al–Cr alloyed layer exhibited much better oxidation resistance than that of the 304 steel (2.5 times) and the Q235 steel (5.5 times). And this was because the special Al distribution (approximate Gaussian distribution) in the Fe–Al–Cr alloyed layer, which displayed the self-healing ability for the oxidation film on the surface of the Fe–Al–Cr alloyed layer in the high temperature oxidation conditions.

[en] Highlights: ► A TiO₂ alloyed layer was formed by double-glow plasma surface alloying technology. ► The electrochemical corrosion behaviors were studied in Tyrode’s solution. ► The free corrosion potential increased and free corrosion current density decreased. ► The nano-hardness of the treated sample was also increased to 4.95 GPa. - Abstract: In this paper, the TiO₂ alloyed layer was successfully formed on pure titanium surface using the double glow plasma surface alloying technology. The microstructure and phase composition of the alloyed layer were analyzed by optical microscope (OM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and X-ray powder diffraction (XRD). The micro-hardness of the alloyed layer was investigated by nano-indentation test. The surface roughness was decreased after the treatment. Measuring the anodic polarization curves in Tyrode’s solution, the corrosion rates of the untreated and treated samples were compared. The results indicated that the uniform dense TiO₂ alloyed layer was obtained on the pure titanium surface. As compared with pure titanium, the free corrosion potential of TiO₂ alloyed layer increased and the free corrosion current density decreased, which corresponded to a decreased corrosion rate. It led to the improvement of corrosion resistance of the pure titanium surface

[en] Highlights: • A Ti–Nb alloyed layer was formed by double-glow plasma surface alloying technology. • The sliding wear behaviors of the alloyed layer were studied at room temperature. • The friction coefficient and the wear mass were reduced after the treatments. • The wear volume and the specific wear rate were also significantly reduced. - Abstract: In the present work, a Ti–Nb alloyed layer was successfully formed on the pure titanium surface by double-glow plasma surface alloying technology with Nb and the wear resistance has been investigated. The microstructure, phase identification and elements distribution were analyzed by optical microscope (OM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and X-ray powder diffraction (XRD). Specified tribological characterization was carried out by using a ball-on-disc tribometer and MicroXAM Surface Mapping Microscope at room temperature. The nano-hardness of the alloyed layer was also improved from 3.25 GPa to 5.25 GPa. As compared with pure titanium substrate, the friction coefficient of the alloyed layer was reduced from 0.57 to 0.27. The wear volume and relative wear rate at room temperature were reduced by 82% and 86%, which corresponded to an improvement of wear resistance. In the Haemolysis test, the treated sample exhibited better biocompatibility. Measuring the anodic polarization curves in Tyrode’s solution, the treated sample indicated a decreased corrosion rate