Key Engineering Materials Vol. 591

Abstract: CrN coatings were deposited by Closed Filed Unbalanced Magnetron Sputtering (CFUMS). The effect of N₂ flow rate on composition, phase components, morphologies and mechanical properties of CrN coatings were studied. The results show that the deposition rate of CrN coatings declined with the increase of nitrogen flow percentage in a Ar/N₂ mixture atmosphere. When the nitrogen flow percentage reached 50% or more, the Cr and N atomic ratio of CrN coatings is close to 1:1. The phase in coatings was the coexistence of Cr, Cr₂N and CrN, but the crystal preferred orientation changed significantly with the different N₂ flow rates. The columnar crystal CrN coating with low N₂ flow rate was denser. The hardness and adhension of CrN coatings have no direct relationship with N₂ flow rate.

Abstract: CrN coatings have been deposited successfully by Closed Filed Unbalanced Magnetron Sputter Ion Plating (CFUMSIP). The effect of substrate temperature (T_S) and bias voltage (V_B) together on microstructure, morphologies and mechanical properties of CrN coatings were studied. The results showed that the deposition rate of CrN coatings declines with the increase of V_B Under both room temperature (R.M.) and 300°C. The FCC-CrN disappeared gradually and orth-CrN arised with the increase of V_B, and the T_S promoted the transformation from FCC - CrN to orth - CrN. The surface morphology of CrN coatings with changed V_Bs was greatly different, and V_B could further improve the mechanical properties of coatings. In this paper, the CrN coating with the parameters (T_S =300°C, V_B =-30V) had relatively high deposition rate and mechanical properties.

Abstract: Pm-doped bismuth titanate (Pm_4-xLa_xTi₃O₁₂: BPT) and pure Bi₄Ti₃O₁₂ (BIT) thin films with random orientation were fabricated on Pt/Ti/SiO2/Si substrates by rf magnetron sputtering technique. These samples had polycrystalline Bi-layered perovskite structure without preferred orientation, and consisted of well developed rod-like grains with random orientation. For the samples with x=0.25, 1.0, and 1.25, the current-voltage characteristics exhibited negative differential resistance behaviors and their P-V hysteresis loops were characterized by large leakage current, whereas for the samples with x=0.5 and 0.75, the current-voltage characteristics showed simple ohmic behaviors and their P-V hysteresis loops were the saturated and undistorted hysteresis loops. The remanent polarization ( Pr ) and coercive field (Ec) of the BPT Fims with x=0.75 were above 40μC/cm2 and 60KV/cm , respectively.

Abstract: With the constant development of medical technology, biological materials become more and more important in surgical repair. Bioactive glass and glass ceramic, because of the good bioactivity and biocompatibility, are considered to be the most ideal material for bone repair and replacement. Thus in this paper the recent research progress in bioactive glasses and glass ceramics are summarized. The characteristics of component, structure and property of several kinds of bioactive glasses and glass ceramics are analyzed, the existent problems and some different solutions are also discussed, and their development foreground in surgical repair application is further forecast.

Abstract: Objective: To evaluate the colouration of zirconia ceramic by adding two kinds of rare earth oxides. Methods: Added different concentrations of Fe₂O₃ and CeO₂ in tetragonal zirconia poly crystals stabilized with 3Y-TZP powder compacted at 200MPa using cold isostatic pressure, and fully sinter. The chromaticity of sintered bodies was measured with spectrophotometer. Results: self-colored zirconia by two kinds of rare earth oxides: The lightness of zirconia by adding cerium oxides was about 85 and a* decreased slightly. The color shifted to more yellow-green color. The chroma of the ceramics became more intensity, the lightness decreased with the increasing of the content of ferrum oxides and the color change to red-yellow direction. Conclusion: Zirconia ceramic could be colorized by Fe₂O₃ and CeO₂.

Abstract: In the present study, novel pyrocarbon samples were prepared by carbonization with phenolic resin as precursor and such as graphite nanosheets, carbon black, and TiO₂ with various ratios as additives. The microstructure, morphology, mechanical and anti-oxidation properties were investigated by X-ray diffraction, scanning electronic microscopy, electron universal testing machine, and oxidation weight loss method, respectively. The results show that the graphite nanosheets and carbon black can help to improve the mechanical properties and oxidation resistance of resin-based pyrocarbon because the structure of resin-based carbon will be effectively enhanced by these additives. TiO₂ will be restored in the coking process which led to destroy of the internal structure of pyrocarbon, thus the addition of TiO₂ will reduce the compressive strength and oxidation resistance of pyrocarbon. Mechanical property analysis indicate that the sample add graphite micro chip has the highest compressive strength of resin carbon, Numerical value for the sample is 17.3MPa, is 19 times of the sample which added graphite and boric acid, and 2 times of the sample which added TiO₂,graphite and boric. Oxidation experiment under 500 °C results show that add boric acid against oxidation resistance of resin carbon materials, without boric acid resin carbon the burning loss rate is only 40% of the sample. Oxidation experiment under 500 °C results show that added boric acid, TiO₂ and graphite sample of ignition loss rate is the lowest, the value of 71%, 25% lower compared to other samples.

Abstract: Extracting indium from water quenching slag, which contains poor indium, by two process of leaching, the effect of different oxidants and dosages on the leaching rate of indium in water quenching slag were studied. The leaching conditions: temperature 80 °C, leaching time 2 h, the liquid to solid ratio of neutral leaching 8︰1, the liquid to solid ratio of acid leaching 2︰1, initial concentration of sulfuric acid 500 g·L^-1, adding different oxidants, the concentration was detected by crystal violet spectrophotometry. Test results showed that the leaching rate of indium was significantly improved by adding hydrogen peroxide and potassium permanganate. Compared with the effect of different oxidants, the effect of potassium permanganate was significantly higher than that of hydrogen peroxide on the leaching rate of indium.

Abstract: Well-crystallised nanozeolite P has been synthesized from coal fly ash by combined method of alkaline-fusion and hydrothermal reactions. The influence of preparation parameters, such as the proportion of fly ash/NaOH, the hydrothermal reaction temperature and time on the reaction products were investigated by XRD and FESEM. Results indicated that, the optimum conditions for fabrication of a single phase of zeolite P were the mass ratio of fly ash/ NaOH =1/1, fusion temperature at 550°C and hydrothermal temperature at 100°C for 48h .The average crystallite sizes of the zeolite samples are 29.4nm. The obtained products show crystal morphology heterogeneity comprised by various euhedral forms.

Abstract: In this study, reference the method of preparing cement sand to produce geopolymer, using Electrolytic Manganese Residue(EMR), fly ash, magnesium slag (with boric acid), sodium silicate, sand, calcined kaolin as the main raw materials, focus on the study of using electrolytic manganese residue to produce Geopolymeric cement. Finally, through a series of comparison, we find out the best recipe of Geopolymer preparation, and the best ratio of each raw material is 80% EMR, 10% magnesium slag, 10% fly ash. In this way, the Geopolymer has the best mechanical properties.

Abstract: MCM-41 mesoporous silica was prepared by hydrothermal method. 2-carboxyethyl phenyl phosphinic acid (CEPPA) was loaded on MCM-41 by solution method. The structure of MCM-41 and its supported CEPPA was studied by X-ray diffraction (XRD), transmission electron microscope (TEM) and scanning electron microscopy (SEM) coupled with energy dispersive spectrometer (EDS). The results revealed that CEPPA was successfully loaded on MCM-41 with Si/P molar ratio of about 20:1. The XRD spectrum of MCM-41 supported CEPPA was different from MCM-41, indicating the structure of MCM-41 was changed after loading of CEPPA. CEPPA molecule moved into the mesoporous structure and filled in the mesopores, leading to the disappearance of characteristic diffraction peaks of MCM-41. The interaction between hydroxyl group of CEPPA and silanol of MCM-41 made it stable for CEPPA to be in the mesopores and on the surface of MCM-41. MCM-41 supported CEPPA also showed the similar mesoporous structure with long-range order to MCM-41 when observed by TEM. SEM provided further evidences of the similar particle size and different morphology.