Advanced Materials Research Vols. 391-392

Abstract: Thin organic layer-by-layer self-assembly films with negatively charged surface were prepared, which used as templates for the deposition of TiO₂ on Si substrate by hydrolysis of titanate solution in acid environment. The as-deposited thin films were fully amorphous from the result of XRD, also were homogeneous and continuous produced at 80 °C for 2 h as presented in SEM images. The thickness of thin films grew with deposition time gradually and reached 300 nm after 12 h immersion.

Abstract: Effects of technological parameters of thermo mechanical control process (TMCP) on microstructure and mechanical properties of the API X60 pipeline steels have been investigated. The parameters of TMCP for obtaining better mechanical properties are given. The experimental results show that the mixed microstructure mostly composed of polygonal ferrite, pearlite/bainite and martensite-austenite constituent (M-A) has the optimum strength and ductility.

Abstract: CAS₂-Al₂O₃ (Anorthite-alumina) refractory materials were prepared with magnesium slag, kaolin from Shanxi province of China and alumina as raw materials. The effects of sintering temperature, holding time and the rate of heating on the microscopic structures were investigated. The results showed that the sintering temperature and holding time are more important to CAS₂-Al₂O₃ refractory materials than the rate of heating in a certain extent. According to XRD and SEM analysis results, it indicates that CAS₂ and Al₂O₃ are the main phases which occurs in the temperature ranges of 1350-1400°C. The higher the sintering temperature is, the greater the grains grow. At the same time, while the temperature rising, it tends to precipitate the alumina particles. It is appropriate to keep 2h in 4°C/min heating rate at sintering temperature. CAS₂-Al₂O₃ refractory materials have porous mesh structure.

Abstract: The hydration resistance of gehlenite-forsterite refractory material has been studied. The results show that the sample hydrated for 72h have no obvious cracks or deformation and gets a maximum weight increasing ratio of 0.073%. It suggests that it has excellent hydration resistance property. Before being hydrated, the main phases are C₂AS and M₂S; after being hydrated for 72h, the main phases is not changed, while the diffraction peaks slightly shift to left. With the increase of the hydration time, surface morphology change greatly. During the course of hydration, firstly, the surface attachments are sheded from the surface, the matrix is exposed; secondly, the stick big grains are generated; thirdly, the mesh grains are formed; finally, hydration products fell off or dissolved, and a new course starts.

Abstract: The phase transformation and microstructure in solution-treated Ni₅₀Ti₄₅Ta₅ shape memory alloy have been investigated. Two different second-phase particles, (Ti,Ta)2Ni and a tantalum-rich solid solution (β-Ta) mostly located at grain boundaries are observed. The results indicate that the Ta atoms are suggested to replace Ti atoms, instead of Ni atoms in these alloys. Ni50Ti45Ta5 alloy is similar to equiatomic NiTi alloy with near equal transformation temperatures and having one stage transformation. The main lattice twin is type II twin. compound twin also observed because of 5at% Ta addition.

Abstract: o make full use of magnesium slags, the C₂AS-CAS₂ composite pavement bricks were sintered by using magnesium slags, kaolin and Al₂O₃ at normal pressure. The phases, microscopy, size deviation, compressive strength and anti-hydration property of samples were analyzed using XRD, FE-SEM, EDS, mechanical testing and others techniques. The results show that the main phases of the samples are C₂AS and CAS₂; the transverse contraction is 3.5%, while the longitudinal shrinkage is 4.2%; the compressive strength is up to 65.3Mpa; the samples have well anti-hydration property. The C₂AS-CAS₂ composite pavement bricks have excellent properties.

Abstract: The thermal shock and hydration resistance property of the light heat-insulation refractory materials is studied, which were prepared using high calcium magnesia slag as main raw materials. The phases and microscopy were characterized by means of X-Ray diffraction (XRD), field emission scanning electron microscope (FE-SEM). The results show that the main crystalline phase is CAS₂, and it is with low volume density, excellent thermal shock and hydration resistance property.

Abstract: In order to reduce the vibration load transmitted from the launch vehicle to the spacecraft during the launching stage, a whole-spacecraft vibration isolating method is advanced by modifying ordinary payload attach fitting (PAF). The core component of the PAF is a kind of damping rod produced by composite material encapsulating metal rubber (MR). In this paper, nonlinear equivalent damping model of the damping rod is built up. By using the model, the stiffness, damping and the transmissibility of the damping rod is studied attentively. Simulation results demonstrate that there exist nonlinear relationships between vibration parameters and the stiffness and damping characteristics of the damping rod. The damping rod can isolate high-frequency vibration as well as restrain the resonant peak effectively.

Abstract: The composite coating with 3%Cu/ Fe-based alloy was fabricated on Q235A steel by laser cladding. The effect of aging treatment on the microstructure and properties of laser-cladded coating was investigated. The results show that there is α-Fe phase accompanied by the M₇C₃ with an orthorhombic crystal structure and M₂₃C₆ in the cladded coating. The preferred direction at (110) crystal plane exist in the α-Fe. The TEM observation shows that the high density dislocations exist in the martensite. When the cladded coatings are aged at 550 for 20 h and 30 h respectively, the ε-Cu particles precipitate dispersedly from the supersaturated α-Fe solid solution along the M₇C₃. The ε-Cu particles play the role of anchoring dislocation. The microhardness and the wear resistance of coatings are increased greatly after the aging treatment. The coating aged for 20 h at 550 presents the best wear resistance in the tested coatings. With aging time, the microhardness and the wear resistance of cladding coating are decreased.

Abstract: Nd-YAG laser welding characteristics of Inconel 718, microstructures,tensile properties,and hardness of welding joint were researched. Nd-YAG laser welding was carried out on super thin Inconel 718 sheet(0.2 mm thick) with 6 specimens. The welding parameters of these specimens are varied expect for the welding speed(0.3mm/s), gas-flow rate (5L/min) and clearance between focal point and (plate) surface(0).In this research,the tensile strength of welding joint was found to be inferior to base metal and the ductility of welds was considerably lower than base material,the microhardness in weld zone is higher than the base material hardness and the hardness is highest in center zone of welding joint. These conclusions will be in favour of the manufacture with super thin Inconel 718.