Advanced Materials Research Vols. 239-242

Abstract: The inhibition effect of N,N-diethylammonium O,O'-dicyclohexyldithiophosphate(NOCP) against the corrosion of carbon steel in HCl solution was studied by weight loss measurement, potentiodynamic polarization and atomic force microscopy techniques. The studies of weight loss measurement show that the inhibition efficiency was up to 99.54 % at the inhibitor concentration of 2.717×10^-4 M in 1.0 M HCl solution at 25°C. The adsorption of NOCP on carbon steel surface obeys the Langmuir isotherm. Polarization curves indicate NOCP is a mixed-type inhibitor, and the obtained standard free energy of adsorption suggests that the chemisorption takes place spontaneously. The effects of temperature, acid concentration and immersion time were also studied.

Abstract: The effects of 2-12 wt.% Y addition on the microstructure and mechanical properties of as-cast Mg-Y binary alloys have been investigated. The results show that proper content of rare earth Y addition can obviously refine the grains and form high melting point Mg₂₄Y₅ phases in the matrix, and improve the microstructure and mechanical properties of the alloys. At room temperature, the optimum combination of ultimate tensile strength and elongation, 195MPa and 7.5%, is obtained in Mg-10 wt.% Y alloy.

Abstract: YVO₄ nanoparticles with various morphologies were tuned directly by hydrothermal treatment in different solutions, including pure water, potassium hydroxide solution, hydrazine hydrate, ethanolamine, triethylamine, and pyridine. X-ray diffraction (XRD), Raman, and transmission electron microscopy (TEM) were utilized to characterize the structure, morphology, and size of the products, which indicated that tetragonal phase YVO₄ crystallites displaying rod-like, square, and olivary shapes were obtained. It was found that the selected solvents play an important role in modulating the morphology and confining the size of the obtained products.

Abstract: The process of Vacuum Evaporation and characteristic of poly-Si thin film on different kinds of substrates (copper and glass) are studied in this thesis. The samples were characterized by TEM, AFM and metallographic microscope. The result indicates that the samples after annealing treatment are polycrystalline. Thin film on copper substrate shows better properties in degree of crystallization, grain smoothness, compact density and uniformity. The thickness of thin films on both copper and glass substrates is 1.2µm.The grain size ranges from 0.1~0.15µm.And the pressure-resisting value of the poly-Si thin film is 384.2V.

Abstract: Gd substrates were differently coated with Ti and 1Cr18Ni9Ti by means of DC magnetron sputtering technology. The characteristics of the films have been investigated by scanning electron microscopy(SEM), EDS,X-ray photoelectron spectroscopy(XPS),and the adhesion of films were tested by tension test. The results show that the surfaces of films are smooth and perfect, the interferences between Gd and films join together strongly, and the adhesion strengths are larger than 15MPa in these tests.

Abstract: A detection method for organophosphorus pesticides using electrochemical sensor based on enzyme inhibition has been developed. Acetylcholine esterase (AChE) was selected to quantify the pesticides concentration in water samples due to its activity was non-competitively inhibited in the presence of pesticides. To detect parathion and dichlorvos, optimized analytical conditions were that the substrate concentration was 3mmol/L, enzyme solution concentration was 18g/L and reaction time was 20min. Under the optimized detection conditons, a detection limit of 1.2ng/mL and 0.004ng/mL for parathion and dichlorvos was obtained, respectively. The approach was rapid, simple, accurate and of high sensitivity when compared with immunoassays or chromatographic methods.

Abstract: Ce-containing Layered Double Hydroxides (Ce-LDHs) were prepared by conventional and microwave-assisted crystallization method, which were denoted as Ce-LDHs-A and Ce-LDHs-B, respectively. The dispersibility of Ce-LDHs-B is much better than that of Ce-LDHs-A; the particles of Ce-LDHs-B with particle size ranging from 20 to 70 nm are smaller than that of Ce-LDHs-A with sizes around 50-300 nm. The effect of the cerium to aluminum molar ratios, microwave crystallization time and reaction temperature on the structure of Ce-LDHs was also investigated. The results show the excessive Ce into LDHs causes distortion of the samdwich, the damage of the LDHs structure becomes more and more serious with increasing the proportion of Ce/Al. The structure of Ce-LDHs becomes more and more perfect with the increasing of the microwave crystallization time and reaction temperature.

Abstract: The faults of the machines appeared suddenly usually cause to huge losing. So it’s important to monitor and analyze the condition of the machines. Now, more and more methods have been applied to condition monitoring and fault diagnoses. The spectral analysis technique has been widely used to detect the contents of abrasive metal in the lubricating oil. To mine the spectral data better, a method was put forward, which can be used to build the healthy record and reveal the important information about the operated conditions of the equipment. In the method, the similar information of the principal component in oil was obtained in the stable abrasion of the different friction pairs of equipment. The composition of mechanical and electrical equipment was also gained. The healthy record was created preliminarily according to all the information. In the malfunction detection of the equipment, cooperated with the data of the threshold of oil, the analysis results of spectra can be compared with the healthy record. So, the abnormal abrasion can be judged accurately.

Abstract: Aggregation structure and properties such as crystallinity, orientation, mechanical properties, boiling water shrinkage of high-shrinkage component, low-shrinkage component, and the bi-shrinkage yarns which are spun at different process conditions are characterized and tested. The high-shrinkage component and low-shrinkage component spin individually, the bi-shrinkage yarns spun by one-step spinning process. The research indicates that with the spinning speed increases, the degree of crystallinity and orientation of the high-shrinkage component increases, and its tensile strength increases, elongation at break decreases, boiling water shrinkage attain the highest value when the spinning speed is 3,000 m/min; With draft ratio decreased, the orientation, crystallinity, tensile strength, initial modulus of the low shrinkage component decrease, and its elongation at break, boiling water shrinkage increases; as the draft ratio decrease, BSY crystallinity decreased, orientation first increases, then decreases, strength, initial modulus decrease slightly, boiling water shrinkage increases; H1 increases from 80 °C to 95 °C, BSY crystallinity gradually increased; degree of orientation decrease, strength, initial modulus increases and elongation decreases, boiling water shrinkage increases firstly,and decreases slightly afterwards; with the H2 temperature increases, BSY crystallinity increase, orientation first increased and then decreased slightly,the tensile strength reduce a little, elongation at break increase, initial modulus decreased, boiling water shrinkage decreased.

Abstract: Ni brazing alloy coating on soft metal substrate has been made extensively with different hard-facing processes. Among various hard-facing processes, hot-dipping has rarely been investigated as an inexpensive technique. In this study, thick Ni-Cr-Si-B-Fe alloy coating (>3 mm) has been made successfully on the plain carbon steel substrate with hot-dipping process. Microstructure and phase identification have been made to the coating with SEM and XRD. It was found that the Ni brazing alloy coating has good binding steel substrate with defect free. Four regions across the thickness of Ni brazing alloy coating, due to solidification conditions upon hot-dipping, have been identified with distinguished microstructure. The main phases of the coating include hard phases of CrB, Fe₂B, and Cr₂₃C₆ dispersed in g(Fe,Ni) matrix.