Advanced Materials Research Vols. 189-193

Abstract: WC-12 %Co powders were sprayed by high velocity oxygen fuel (HVOF) to prepare coatings on carbon steel substrate, which was pretreated by electrospark and grit blast before spraying. The surface coating of WC-Co and the intermediate layer structure were studied by scanning electron microscopy and X-ray diffraction. The adhesion strength of the coating was measured by a scratching tester. Results show that the roughness value of the grit blasting and electrospark strengthened surface were 60~70 μm and 40~50 μm, respectively. The coating pretreated by grit blast and electrospark was dense and was bonded well with the substrate. The heat affected zone of the grit blasted specimen was larger than that of the electrospark pretreated one. The average adhesion strength of the coating pretreated with grit blasting and that with eletrospark were 35.00 N and 12.48 N, respectively. The reasion of the high adhesion strength of the grit blasting coating is discussed.

Abstract: To understand the structure and performance of Ni base coatings on 18Cr2Ni4WA steel, the key techniques of plasma arc cladding method are introduced. Microstructure and microhardness of the coating clad were analyzed by using Vickers hardness tester,scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS).Results show that the phase of the coating is composed of γ-Ni solid solution， nickel boride Ni3B，carbide Cr₂₇C₆ and Cr₂B₃ type chromium boride. The coating has no cracks and does not exhibit porosity, the bonding between layers is compact and the boundaries are not observed. The coating is featured by a homogenized microstructure; small grain and no evident heat-affected zone.

Abstract: Nowadays, remarkable immolations and charges are taking place deeply and continuously in the marketing area the enterprise brand operation is a strategic problem of operation which relates to the enterprise’s life. This article elaborated the creative meaning of the running of the business enterprise, and it emphasizes from establishing the brand operating, erecting the key of the brand operation, enhancing the key of the brand operation to carrying on the analysis of the brand value accurately and so on, in which it has a discuss about the problem of the design and the practice of the enterprise brand operation.

Abstract: In this paper, the Mo-Si-Ni-Al metal-ceramic composite cladding layer on the surface of the 304 stainless steel was applied by using tungsten inert gas (TIG) method. The phase composition and microstructure of the cladding layer were characterized by XRD, SEM and EDS. With the high temperature erosion experiment in the range of 873-1073 K, the erosion behavior of the Mo-Si-Ni-Al cladding layer was studied. The maximum total mass loss was observed in the specimen, which was tested at 923 K and 45°erosion angle. The high temperature erosion mechanism of the Mo-Si-Ni-Al cladding layer was discussed.

Abstract: Based on the normal H-K rheology model, a new rheological model containing fracture elements for concrete or rock cracked body is introduced. The method to ascertain rheology state is put forward. The new rheological model can change to Maxwell or Kelvin model to express the instantaneous failure, delayed failure state and the accelerating segment. The researching failure element method was used to study the crack propagation. Then the cracking elements were studied using rheology mechanics to solve the cracking time. At last a case study was given to validate the method is feasible.

Abstract: In this paper, the effect of different concentrations of complexing agent on the surface of aluminum alloy plating Ni-P alloys is studied. Study the influence of malic acid complexing agents on the electroless Ni-P alloy deposition rate, morphology, corrosion resistance, and determine the optimal complexing agent concentration. The results show that when the malic acid concentration is 24g /L, the deposition rate gets to maximum, and coating uniformity, structure compact and corrosion resistance is best.

Abstract: Hybrid inorganic/organic polymers have been prepared by copolymerizing a silanol terminated polydimethylsiloxane (PDMS) with an Octa(aminophenyl) -silsesquioxane (POSS). The AO resistance of these POSS/PDMS hybrid films was tested in the ground-based AO simulation facility. Exposed and unexposed surfaces have been characterized by X-ray photoelectron spectroscopy. The XPS data indicate that the carbon content of the near-surface region is decreased from 65.3 to 18.9 at% after AO exposure. The oxygen and silicon concentrations in the near-surface region increase after AO exposure. The data reveal the formation of a passive inorganic SiO₂ layer on the POSS/PDMS hybrid films during the AO exposure, which serves as a protective barrier preventing further degradation of the underlying polymer with increased exposure to the AO flux. The erosion yield of the POSS/PDMS (20 wt%) hybrid film was 1.7×10^-26 cm³/atom, decreased by two orders of magnitude compared with the value of 3.0×10^-24 cm³/atom of the polyimide film.

Abstract: In order to acquire evolution law of temperature field of laser remelting plasma sprayed Ni-based gradient coating on Ti6Al4V alloy surface，the effects such as heat conduction, heat radiation, heat convection ,phase change and materials highly non-linearity on coatings and substrate are taken into account comprehensively, and a 3D finite element model(FEM) of multi-tracks laser remelting temperature field is established. The analysis results show that mechanical bonding between coatings and substrate change into metallurgical bonding on present processing parameter，the depth of alloy belt vary in each scanning track and the average depth of alloy belt become deeper gradually with the increment of scanning lines. Temperature changing regular of different points on scanning tracks along scanning direction is similar. Temperature become higher and higher in succeeding scanning tracks due to the heat accumulation effect in laser remelting process. The cooling rate on the mid-points of each scanning track reaches 1200 /s above. The thermal gradient from coatings to substrate along Z direction is absolutely predominant compared with that along X,Y direction, so heat dissipates mainly along the direction normal to substrate which help to crystal grain grown preferentially.

Abstract: In this paper, the effect of different concentrations of sodium hydroxide on the surface of magnesium alloy plating Ni-B alloys is studied. Focuse on the influence of different NaOH concentrations on electroless plating Ni-B alloy plating rate, coating morphology, and composition. Ascertain the optimal concentration of NaOH. The results showed that when the sodium hydroxide concentration is 50g / L, the deposition rate is the maximum, coating uniformity, structure compact, and boron content in the coating is the maximum.

Abstract: This study is of aluminum alloy electroplating process temperature alloy electroplating Ni-SiC properties. Research shows that the results show that, when the bath temperature for 50, plating coating uniform structure, compact, the best performance, coating and maximum SiC content.