Advanced Materials Research Vols. 690-693

Abstract: The oxidation behavior of Pt modified aluminide coating on the CMSX-4 Ni-base alloy plays major role to the EB-PVD TBC failure. The thermally growth oxide (TGO) is one of the most important factors to affect TBC lifetime. Two different Pt-content NiPtAl coatings in EB-PVD TBC systems were studied at 1100°C in air. The results indicated that cross-sections of oxide layer on the NiPtAl coatings within TBC in air were similar for the both bondcoats. The cracks could be found on the TBC/TGO/BC interfaces for the two bondcoats. The TGO morphologies of the low and high-Pt bondcoats on the side without TBC showed great different due to small PtAl particles size within high-Pt bondcoats. The irregular alumina on the both bondcoats was also showed on the sides with TBC compared to ones without TBC due to absence of the TBC. The TGO growth on the high-Pt bondcoats was faster than the low-Pt coatings during initial oxidation time. With the time increasing, the high-Pt content could suppress the TGO growth rate. Thinner TGO thickness could be obeserved on the both NiPtAl coatings due to the stress in TGO accumulation and oxide spallation.

Abstract: In the present study, identify the fracture toughness and strength adhesion of borided layers in Steel AISI 8620 by boriding dehydrated paste. The formation of the borided at a temperature range of 1173, 1223 and 1273 K for 4, 6 and 8 h. X-ray diffraction analysis revealed peak of FeB, Fe2B, MoB and CrB and The distribution of alloying elements was detected by means of energy dispersive Spectroscopy (EDS), the Fracture toughness of the layers is estimated at 15 and 30 um from surface using different loads indentation Vickers, using Palmqvist crack model, the adherence of the layer/substrate was evaluate in qualitative form though the Rockwell C. The fracture toughness of the borides depends strongly on temperature and time boriding. Also, good adhesion is obtained around the Rockwell C indentation prints on the borided layer-substrate-interface.

Abstract: In the present study, identify the fracture toughness and strength adhesion of borided layers on grade tools steels by Boronizing, two commonly used steel AISI 4140 and AISI 9840 are considered, the steels contain 1.0 - 0.8 wt% Cr and 0.20 - 0.25 wt% Mo, respectively. The formation of the borided layers was carried out by the powder pack boriding process at a temperature range of 1273 K for 4, 6 and 8 h. X-ray diffraction analysis revealed peak of FeB, Fe2B and CrB, the Fracture toughness of the layers is estimated at 15 and 30 um from surface using four different Vickers indentation loads, using Palmqvist crack model, the adherence of the layer/substrate was evaluate in qualitative form though the Rockwell C. The fracture toughness of the borides depends strongly on temperature and time bronzing. Also, good adhesion is obtained around the Rockwell C indentation prints on the borided layer-substrate-interface.

Abstract: It is known that the micro-structure of coatings produced by low pressure plasma spraying (LPPS) is significantly different from the one produced by atmospheric plasma spraying (APS). Because of the different pressures between the inside and the outside of the plasma gun, the exiting plasma jet experiences unconventional behavior related to supersonic expansion at reduced pressure. In this work, the DPV 2000 system was used to measure in-flight particle velocity and temperature. Alumina powder was injected as sprayed particles under 150 mbar conditions. These preliminary researches are the starting points for development and optimization of this process.

Abstract: Micro arc oxidation (MAO) is a relatively new method of surface treatments which has been used to improve the mechanical and tribological behavior of light metals. Due to the ceramic coating generated by MAO, light metals can be used more widely. The fundamental of MAO and the influence factors of MAO process are discussed here. The surface characteristics of aluminum, titanium, magnesium, Zirconium and stainless steels have been improved by MAO. Scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDS) were used to study the surface morphology and the elemental composition of the MAO coating. The EDS analysis of the coating shows the elements in the electrolyte and oxygen have incorporated into the coating.

Abstract: A novel water-based paint stripper was prepared for white, metallic ink and varnish coated on the tinplate steel surface. The effect of accelerator and surfactant on stripping efficiency was investigated with the types and dosage of the accelerator and surfactant, the stripping temperature and stirring up condition. The highest stripping efficiency was achieved with the stripper composited by (mass fraction) 35% benzyl alcohol, 6% propanediol carbonate, 10% formic acid, 2% cetyl tri-methyl ammonium bromide (CTMAB) and 47% distilled water, respectively. This paint stripper had low volatility, and was not easy to burn. Scanning electron microscopy (SEM) test indicated that the paint stripper had little corrosive effect on tinplates.

Abstract: Cationic Gemini surfactant concentration, the inorganic salts added and the pH value of surface tension obtained cationic gemini surfactant critical micelle concentration is 0.4mmol / L;by adding three kinds of inorganic salts NaCl, MgCl2, and Na2SO4 ,which Na2SO4 has the greatest impact on surface tension, followed by MgCl2.The surface minimum tension of the pH ranged from 9 to 11 , indicating that the surface activity of cationic gemini surfactants achieved the highest.

Abstract: Titanium with surface nanostructure has superior mechanical and biological properties, which benefits titanium implants. To further improve the bioactivity of Ti surfaces, Ca/P-containing porous titania coatings were prepared on Ti with surface nanostructure by ultrasonic shot peening (USP) and micro-arc oxidation (MAO). The phase identification, composition, morphology and microstructure of the coatings of Ti with surface nanostructure during MAO were investigated subsequently. The amounts of Ca, P and the Ca/P ratio of the coatings formed on Ti with surface nanostructure were greater than those on coarse-grained Ti. Incubated in a simulated body fluid, bone-like apatite was completely formed on the surface of Ti, thus evidencing preferable bioactivity.

Abstract: We report a modification method for Gold target by intense pulsed ion beam (IPIB) irradiation. Based on the temporal and spatial distribution models of the ion beam density detected by Faraday cup in the chamber and the ions accelerating voltage, the energy deposition of the beam ions in Au is calculated by Monte Carlo method. Taking this time-dependent nonlinear deposited energy as the source term of two-dimensional thermal conduction equation, we obtain the temporal and spatial ablation process of metal Au during a pulse time. The top-layer Gold material in thickness of about 0.25μm is ablated by vaporization and the layer in thickness of 1.40μm is melted after one shot at the ion beam density of 300 A/cm2.

Abstract: FCC gasoline fraction (75~120°C) is feedstock, Ethyl silicate (TEOS) or γ-aminopropyl triethoxysilane were used as the silicon source respectively, aromatization were examined on the fixed-bed reactor. The catalyst activity and stability are improved when SiO2 depositions are 2% and 10%, respectively.