Advanced Materials Research Vols. 15-17

Abstract: We have investigated the morphological changes with varying the substrate temperature in the range of 350-400°C, in synthesizing the indium oxide (In2O3) rod-like structures by using the metalorganic chemical vapor deposition method. The as-synthesized rod-like structures was aligned perpendicular to the Si substrate. X-ray diffraction (XRD) and selected area electron diffraction (SAED) analyses demonstrated that the rods had a cubic In2O3 structure. PL spectra of the In2O3 rod-like structures exhibited the visible light emission. We discussed the possible growth mechanisms.

Abstract: The influence of process parameters on shape stability and surface smoothness of cylindrical and rectangular castings produced by fused spinning deposition (FSD) method was investigated. The optimum conditions to control the shape and smoothness of side surface of the castings produced by the FSD method without water-cooling were limited to a narrow range of process parameters. The casting with a stable shape and a smooth side surface was obtained with the aid of water-cooling. The tensile strength of the castings produced by the FSD method was 1.4 times higher than those of the specimens cast into metal-mold and sand-mold, due to a finer equiaxed grain structure of the FSD castings. Employing the combination of the deposition patterns for tube and solid castings, some practical metallic components were fabricated by the FSD method.

Abstract: The interfacial reactions and bump shear properties of the electroplated Sn-37Pb (in wt.%) solder bumps with the Ni under bump metallization (UBM) were investigated as a function of the number of reflows. A continuous facetted Ni3Sn4 intermetallic compound (IMC) layer was formed at the interface between the solder bump and the Ni UBM during reflow. The thickness of the Ni3Sn4 IMC layer was 0.41 μm after 1 reflow, and then the thickness of the IMC layer increased with increasing the number of reflows. The shear properties of the bumps indicated the maximum values after 1 reflow, and then decreased with increasing the number of reflows. The fracture surfaces of the bumps showed ductile failure characteristics after 1 reflow, and then the fraction of the brittle fracture, induced by the IMC formed at the interface, increased with increasing the number of reflows.

Abstract: Expanded polytetrafluoroethylene (ePTFE) is a bioinert material. To improve the ePTFE film biocompatibility, the cold plasma technology was used with acetic acid as monomer to deposit onto ePTFE film and then (N-isopropylacrylamide) was grafted onto the surface by photo-grafting. The characteristics of the surface were evaluated with X-ray photoelectron spectroscopy (XPS), FTIR and water contact angle. It was found that the contact angle of water on the untreated ePTFE significantly decrease from125° to 72° after ePTFE film being treated with acetic acid plasma deposition treatment. Due to the hydrophilicity of poly(N-isopropylacrylamide), the contact angle of water on the ePTFE-g-NIPAAm approached to 0°.

Abstract: Investigations include alloying the X38CrMoV5-3 hot-work tool steel surface layer with the tungsten carbide, using the high power diode laser (HPDL). The tungsten carbide ceramic particles of the medium grain size according to FSSS = 50 /m were introduced using the rotor conveyer to improve the properties of the surface layer. The powder feed rate was set at the steady level of 8.64g/min. Remelting and alloying were carried out several times in the laser power range of 1.2 – 2.3 kW in the remelting/alloying, alloying/remelting sequences. The structural mechanism was determined of gradient layer development, effect was studied of alloying parameters, gas protection method, and powder feed rate on its mechanical properties, and especially on its hardness, abrasive wear resistance, and roughness. Structure changes were revealed consisting, in particular, in its refining, and also hardness and microhardness changes in comparizon to the nonremelted steel. Examination results obtained with the EDX microanalysis, surface and linear analysis of the chemical composition, as well as the X-ray qualitative phase analysis are presented.

Abstract: With the aim to obtain the high cavitation-erosion-resistance coating for the surface safeguard of fluid machinery, two kinds of hard coatings (WC-Cr-Co and Cr3C2-NiCr) were prepared on 1Cr18Ni9Ti substrate by high velocity oxy-fuel spraying (HVOF), which microstructure and performance were investigated respectively by optical microscope, X-ray diffraction, Vickers hardness, scanning electron microscope (SEM), and vibratory cavitation apparatus. The results indicated that these two coatings had the higher hardness and the finer structure than ZG06Cr13Ni5Mo, which is used actual in water conservancy. The results of cavitation erosion continued for 39 hours presented that the mass loss of WC-Cr-Co and Cr3C2 -NiCr coatings increased ceaselessly with time, and the cavitation erosion speeds varied with time. Compared with ZG06Cr13Ni5Mo, their cavitation erosion resistance performances were better due to their higher hardness and finer structure, and WC-Cr-Co coating was much better than Cr3C2-NiCr coating. Obviously, the higher hardness and finer structure could strengthen the cavitation erosion resistance of coating materials.

Abstract: In many applications such as catheters, artificial blood vessels and diagnostic sensors, blood compatibility or prevention of adhesion of platelet is required. The preferred way to control these purposes is to eliminate or drastically reduce the adsorption of proteins. Surface modification with Poly(ethylene glycol), PEG has long been known to reduce undesirable protein adsorption. No technique for the immobilization of PEG to base metal has been developed. In this study, PEG terminated at both terminals or one terminal with amine bases was immobilized onto titanium surface by immersion or electrodeposition. The bonding manners of PEG onto titanium, which involve directionality of terminated amines and chemical bonding states of interface between the deposited PEG layer and TiO2, were characterized using X-ray photoelectron spectroscopy, XPS. As a result, terminated amines locate inside of the PEG layer and combine mainly with TiO2 as stable NHO by electrodeposition, while amines randomly exist and show mainly unstable bonding with TiO2 by immersion. Moreover, the difference of amine termination leads to different bonding manners, U-shape in PEG terminated both terminals and brush in PEG terminated one terminal. This immobilization process is one-stage convenient technique and useful for all electroconductive and morphological materials.

Abstract: Carbonaceous fiber has high strength, high modulus and high thermal conductivity. Preforms were fabricated by suction filtration method. Regardless of fiber type, the buckling strength and elastic modulus of preforms increased with quantity of aluminum borate (AlBO) whisker addition. The carbon nano tube (CNT) preforms were not buckled but only elastically compressed. Carbonaceous fiber reinforced Al, Mg composites were fabricated by squeeze casting. CF+AlBO hybrid reinforced composites were fabricated with 5% or less deformation. On the other hand, 60% deformation was found in CNT+50AlBO hybrid reinforced composites.

Abstract: A Cu-TiB2 composite was successfully fabricated by in-situ liquid mixing process, and its microstructure, mechanical properties as well as electrical conductivity were evaluated. For Cu-2vol.%TiB2 composite, the hardness was as high as 5GPa and the Young’s modulus was 130GPa. And hardness and Young’s modulus of Cu-6vol.%TiB2 composite was 5.6Gpa and 138GPa, respectively. With the increase of the TiB2 content, hardness and Young’s modulus of Cu-10vol.%TiB2 composite were 20 and 12%, respectively, which was higher than that of Cu-2vol.%TiB2 composite. Young’s modulus of the Cu-TiB2 composite in this paper was in good agreement with the prediction by Hashin-Shtrikman (H-S) model. Furthermore, the electrical conductivity of the Cu-TiB2 composite showed its maximum value of about 78%IACS and decreased with the increase of the TiB2.