Papers by Keyword: Interface Reaction

Abstract: In this paper, BaZrO_3, which is successfully used to prepare the YBCO single crystal superconductor, is introduced into the melting of titanium alloys. The density of the home-made BaZrO₃ crucible reaches 97% of theoretical density, and TiNi alloy is melted using this crucible by the vacuum induction method. It is found that the home-made BaZrO₃ crucible possesses excellent thermal shock resistance. After melting, the surface of the ingot is smooth and it can be separated from the crucible easily, there is no reaction layer and elemental diffusion between the refractory and the melt is not observed, the oxygen content of the melt is about 600 ppm, and the increase of other impurity elements (i.e., Ba, Zr) is negligible. This implies that the BaZrO₃ is a promising candidate for refractories for melting the TiNi alloy.

Abstract: The interfacial reactions between ceramic moulds and DZ417G and DZ125 superalloys were investigated. The microstructure and composition of the interface region were observed by optical microscope, X-ray diffraction and scanning electron microscope with energy dispersive spectroscopy. The results showed that (Al_1-xCr_x)₂O₃ solid solution phase with pink color was formed from the dissolution of Cr₂O₃ and Al₂O₃ and vapour phase, which was transferred to the reaction surfaces. The reaction layer thicknesses of DZ417G and DZ125 alloys were about in the range of 40-50μm. The interface reaction product between DZ417G alloy and ceramic mould was TiO₂ and the product between DZ125 alloy and ceramic mould was HfO₂.

Abstract: The Present Work Investigated the Effects of Adsorbed Moisture in Substrates on the Growth of a Self-Forming Barrier Layer between Mn and SiO₂. In Order to Control the Adsorbed Moisture, the Substrates of TEOS-SiO₂/Si Were Pre-Annealed in Vacuum at Various Temperatures. Then, Mn Thin Films Were Deposited on the Substrate with or without Pre-Annealing. The Results of Interface Reaction after Additional Post-Annealing Indicated that an Interface Reaction Layer Becomes Thinner with Decreasing the Adsorbed Moisture in the SiO₂ Substrates.

Abstract: The Cu thin films were prepared at room temperature by radio frequency magnetron sputtering on p-type Si (111) substrates. The surface morphology and interface reaction of Cu thin films were studied at different deposition condition by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that the existence of the native silicon oxide layer suppresses the interdiffusion and interface reaction of Cu and Si. The formation of the copper-silicide phase is observed by XRD when the annealing temperature arrives at 450 °C.

Abstract: Based on experimental results and theoretical analysis at different temperatures and time of unit diffusion quantity，the mixing entropy in the reaction process between iron and molten tin, is investigated within the range of 260～350°C. The mixing entropy is plotted versus the dimensional time, which showed that the difference value of it at different time was an upward trend. At different temperatures, the mixing entropy of the system increased with the temperature, tin atoms diffusing into the matrix gradually becaming greater, so as to there has been a appreciable increase in the values of mixing entropy. In addition, the mixing entropy’s increase trend becomes smoothly with the temperature increasing, and the entropy change of the system is decreasing more obvious with the temperature increasing.

Abstract: The Cu films were deposited on P type Si (111) substrates by ionized cluster beam (ICB) technique. The interface reaction and atomic diffusion of Cu/Si (111) system were studied at different annealing temperatures by X-ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS). Some significant results were obtained: For the Cu/Si (111) samples prepared by ionized cluster beams at V_a=3 kV, the interdiffusion of Cu and Si atoms occurred in the as deposited samples. The RBS spectra features were changed with a very small extent with increasing the annealing temperature. There are no copper-silicide phases observed by XRD before and after being annealed at different temperatures. The reason may be that there is a thermally stable interface between Cu films and Si substrates formed.

Abstract: The Cu thin films have been deposited on Si(100) substrates by magnetron sputtering at room temperature. The samples were heat treated by conventional thermal annealing in different temperatures: 230°C, 350°C, 450°C and 500°C. The interface reaction and atomic diffusion of the Cu films and Si substrates between as-deposited and as-annealed at different temperatures are investigated by means of Rutherford backscattering spectrometry(RBS) and X-ray diffraction(XRD). Some significant results are obtained on the following aspects: (1) According to RBS, as-deposited Cu/Si(100) samples are not found interdiffusion, and the onset temperature of interdiffusion is 230°C. With the increase of temperature, the interdiffusion becomes more apparent. (2) After annealing at 230°C, the XRD results of the samples showed formation of Cu₃Si(300). As the annealing temperature increases, the other copper-silicide phases are formed. The main copper-silicide phase is Cu₃Si(300) after annealing at 500°C. It means that Cu₃Si is a reliable copper-silicide in a wide range for the Cu/Si(100) interface.

Abstract: In SiC whisker reinforced Al matrix composite, the interface reaction significantly influences the property of the composite. Si films have been deposited on SiC whiskers by quasi atomic layer deposition from gaseous SiH4 to protect the whiskers from being eroded by Al matrix. The structure and morphology of the coating were characterized by X-ray diffraction and transmission electron microscope. The coating deposited on SiC whiskers is cubic phase polycrystalline silicon and this ultrathin Si film is even and continuous, completely covering every individual SiC whisker. The effect of the Si coating on improving the whisker/matrix interaction was also studied in this work. The interface layer, Si coating, could effectively protect the SiC whisker from erosion caused by Al matrix during the high temperature manufacturing process and improve the adhesion between the SiC whisker and the Al matrix.

Abstract: The reactive diffusion between Ti and a bronze was experimentally examined using sandwich diffusion couples consisting of Ti and a Cu-9.3Sn-0.3Ti alloy. The diffusion couples were isothermally annealed at temperatures of T = 923-1023 K. During annealing, CuTi, (Cu, Sn)₄Ti₃ and (Sn, Cu)₅Ti₆ compounds are formed as layers at the interface in the diffusion couple. The overall growth of the compound layers is controlled by volume diffusion at T = 1023 K but by boundary and volume diffusion at T = 923-973 K. Hence, the interface reaction is not the bottleneck for the growth of the compound layers under the present experimental conditions.

Abstract: The influence of boron concentration on corrosion resistance of high boron white cast iron dipped into a pure liquid zinc bath at 460°C was investigated. The results reveal that high boron white cast iron containing 3.5 wt.%B exhibits excellent corrosion resistance due to the dense continuous netlike or parallel Fe2B phase which hinders the Fe/Zn interface reaction. The corrosion rate decreases significantly when the boron concentration increases, but the corrosion rate declines slightly when the boron concentration exceeds 3.5wt.%. EDS results indicate the coarse and compact δ phase generated near the matrix and a large amount of massive and blocky  phase occurred close to the liquid zinc. The corrosion process includes Fe/Zn interface reaction and the spalling and fracture of Fe2B. The failure of Fe2B is mainly caused by the microcrack of phase transformation.