Advanced Materials Research Vol. 1058

Abstract: The stability of the fluorine doped tin oxide (FTO) and the indium doped tin oxide (ITO) films, which are used as gene chip carrier, are detected in an acid solution. The change of relative resistivity (Δ R/R) with immersion time and average visible light transmittance of the films are contrasted before and after immersing in 1 mol/L (1M) H₂SO₄ solution. The results indicate that the Δ R/R of ITO film sample increases rapidly with increasing the immersion time, and Δ R/R is 111% after 12 h;However, the Δ R/R of FTO film sample increases smoothly and the Δ R/R is 2.9% after 100 h immersion. At the same time, the average visible light transmittance of FTO film decreased, but ITO film is completely corroded, and the average visible light transmittance is close to the glass transmittance. The potentiodynamic polarization curves show that the corrosion current of FTO film is 1.749 × 10⁻⁶A and less than ITO,so the corrosion resistance of FTO film is higher than ITO film in 1M H₂SO₄ solution. Moreover, the corrosion morphology validates this conclusion.

Abstract: By creatively using R.F Magnetic sputtering technique , we have successfully prepared ZnSe polycrystalline thin films on glass substrates..The effect of different sputtering powers on the structural, morphological and optical properties of the as-deposited films were studied. The films were characterized by using X-ray diffraction, UV-VIS spectrometer ,scanning electrical microscope ,etc. The results indicate that :Under the pressure of o.8pa,with the diverse sputtering power varying from 60w to 100w,the intensities of XRD peaks of ZnSe thin films varied apparently ,while the morphological properties were almost the same. It should be noted here that the crystallinity of the ZnSe film, which was deposited with the power of 90W, showed a face-centered cubic phase. Besides, it showed relatively better performance: with strong [111] orientation ,smooth surface without obvious defects, comparatively large band gap and high transmission rate.

Abstract: Mg₂Si thin film on Si(100) substrate was obtained by pulsed laser deposition. Effects of the annealing procedure on the growth of Mg₂Si film were discussed. X-ray, atomic force microscopy (AFM) and field-emission scanning electron microscopy (FESEM) were applied for the phase and microstructure of the obtained Mg₂Si film. The results revealed that the annealing procedure was very important for the crystallization of Mg₂Si thin film. The Ar partial pressure of 10Pa, temperature of 500°C and time of 30min for annealing were the optimal annealing parameters for Mg2Si thin film formation. Furthermore, electrical properties of the obtained Mg₂Si thin film were detected. The results showed that the maximal resistivity of Mg₂Si thin film was 7Ω·cm within the temperature range of 110~230°C. And the resistivity gradually decreased with the increase of temperature, which was the characteristic behaviour of a semiconductor. Carrier concentration of the film was negative in the temperature range of testing, showing Mg₂Si thin film as n-type semiconductor.

Abstract: TiO₂/ZnO composite thin film was prepared by sequentially spread TiO₂ and ZnO thin film on the ground layer by layer with sol-gel method respectively. Two different natural dyes (Hehuang safflower yellow pigment and Lycium ruthenicum Murr pigment) were used as sensitizer respectively to sensitize TiO₂/ZnO thin film photoanodes and be assembled into solar cells. Dipping time of photoanodes stayed in sensitizer was investigated systematically and the results show that higher photovoltaic conversion efficiency can be obtained with extension of immersing time. The phase structure, crystallinity, morphology and optical property of photoanode were characterized based on XRD, SEM and UV-vis measurements.

Abstract: C/C composites have excellent properties, but it will be rapidly oxidized when temperature is above 500 °C, which limits its applications in high temperature environment. In order to improve Anti-oxidation, using CVD method, a SiC coating is prepared on the surface of C/C composites. We have studied the microstructure of the SiC coating, oxidation resistance and high temperature mechanical properties. The results show that SiC coating has excellent oxidation resistance. When coated sample is oxidized at 1500 °C after 50 hours, its oxidation weight loss rate is only 1.45%, and coated samples can still maintain high mechanical properties at 1200 °C.

Abstract: C_f/SiC composite are widely used in aerospace, chemical industry, traffic, and many other fields because of good mechanical properties, heat resistance, thermal shock resistance and abrasion resistance, corrosion resistance, etc. But its oxidation resistance is poor in the application of high temperature environment. In this paper, high-temperature ceramic coating was prepared on C_f/SiC composites surface through brush painting method and the oxidation resistance of the coating were studied. The coating was tested by XRD, SEM, etc. The results showed that the coating and composite matrix is good combination, at the same time the coating has good oxidation resistance.

Abstract: . Zirconium diboride (ZrB₂) acts as an ultra-high-temperature ceramics, and are applied in over 2000°C environment. With the characterization of strong covalent bonding structure and high melting point, it is difficult to realize sintering. For achieving composites system densification, the transition metals with good wettability and other matching properties, or the second phases ceramics were added as sintering aids, but the bulk materials' application temperature limit and ablating rate resistance were reduced by sintering aids. Among the A1₂O₃-Y₂O₃ binary phase system, YAM(Y₄A1₂O₉) has the highest melting point, chemical and physical compatibility is matched with ZrB₂ composites. The YAM coating was prepared on bulk materials surface by co-precipitation routine, the effects of precursor volume fractions and calcining process on coating phases were investigated, and the coating morphology and interface bonding were observed. The aim is to obtain the best protective coating constituents and technology parameters.

Abstract: In the current work, low pressure plasma spray process (LPPS) was applied to deposit Ti-Ni intermetallic coatings with Ni-clad Ti powder as feedstock. The microstructure and phase transition of LPPS sprayed Ti-Ni coating were investigated. Cavitation erosion resistance was examined using a standard ultrasonic cavitation test. The coating mainly consisted of TiNi phase with a certain amount of Ti₂Ni, Ni₃Ti phase and a few Ti phase. A few pores concentrated on the boundaries of the sprayed splats. The TiNi coating exhibited excellent cavitation erosion resistance.

Abstract: In this paper we take advantage of the phosphate film which has a porous structure, by phosphate process on the surface of nickel plated copper conductor so as to improve the bonding force of wire and ceramic layer; Through the study of resistance voltage breakdown after phosphate , phosphate liquid was determined Manganese dihydrogen phosphate for 3g100^-1ml, Zinc Nitrate was 8g100^-1ml, Sodium Fluoride was 0.45g100^-1ml; Optimum temperature was 60°C and the appropriate time was 15min at the temperature of 60°C.

Abstract: Novel 4-phase ceramic abradable seal coatings have been prepared by plasma spray. The as-prepared coatings were characterized by SEM, EDS and XRD. The results showed that the 4-phase ceramic abradable coating exhibited porous structures and had good adhesion with the bond coat. The ZrO₂ and Al₂O₃ in the coating existed in the form of tetragonal-ZrO₂ and α-Al₂O₃, respectively. The result of thermal shock test revealed that compared with the 3-phase abradable coating, the thermal shock life of the 4-phase abradable coating had increased tenfold to 1900~2000 cycles from 100~200 cycles. The reason is owing to the reduction of oxygen partial pressure and thermal stresses at the top/bond coat interface due to the addition of the fourth nanoAl₂O₃ phase.