Advanced Materials Research Vols. 557-559

Abstract: plasma arc sufacing； magnetic field style ；Ni-based alloy；microstructure and properties Abstract. The Ni60 alloy was overlaid on low carbon steel by plasma arc surfacing with Longitudinal magnetic field or transverse magnetic field. The magnetic field current and surfacing current could been changed during surfacing. After plasma arc surfacing with magnetic field, the XRD, wear loss tes, micro-hardness test were used to analyze the effect of magnetic field style on properties of overlay deposit. The acting mechanism of magnetic field style and parameters on properties and microstructure of overlay deposit was researched. The results indicate that longitudinal magnetic field and transverse magnetic field all can improve the properties of overlay deposit, but give little effectives intervention to the process parameters. The active effect of transverse magnetic field is better than longitudinal magnetic field because of transverse magnetic field can make the microstructure finer, component more uniform.

Abstract: The StelliteNo6 alloy was surfaced on low carbon steel by plasma arc surfacing with LMF or TMF. The magnetic field current could been changed during surfacing. After plasma arc surfacing with magnetic field, the OM, XRD, wear loss test, micro-hardness test were used to analyze the effect of magnetic field style on microstructure and properties of overlay deposit. The acting mechanisms of magnetic field style and parameters on properties and microstructure of overlay deposit were researched. The results indicate that LMF and TMF all can improve the properties of overlay deposit. The active effect of TMF is better than LMF because of TMF can make the matrix metal γ-Co finer, second phase (CoCx、Cr₇C₃、Cr23C and FeNi) dispersion.

Abstract: In order to systematically study the morphology and distribution of M₇C₃ and TiC which in situ synthesized by plasma arc in the surfacing layer, plasma arc was used to clad the Fe-Cr-Ti-C wear-resistant alloy on low-carbon steel. And high corrosion experiment was applied to the surfacing layer. The hardness, microstructure and phase constitution of the surfacing layer were investigated through the tests of hardness, OM, EDS, SEM and XRD analysis. The results shows that irregular hexagonal (Cross-section) and strip (Side) M₇C₃ and petal-like, granular TiC were in situ synthesized in the surfacing layer. The M₇C₃ and TiC was combined closely. The M₇C₃ grains which closed to the fusion line of the base metal and surfacing layer are fine, but the ones that away from the fusion line are larger caused by the large temperature gradient. Smooth metallurgical bonding layer was formed between the surfacing layer and the base metal, it has a good metallurgical bonding. The phenomenon that carbon diffusion into the base material was clearly, the hardness near the fusion zone was improved effectively.

Abstract: Small-scale experiments were conducted to evaluate the corrosion on buried pipeline by AC interference. The results showed that stray current, pH and conductivity are significantly influenced the pipeline corrosion rate according to the response surface methodology (RSM) . The corrosion rate of buried pipeline greatly increased with the increase of stray current. The corrosion rate of most specimens first decreased and then increased slightly with the rise of pH. The corrosion rate of most specimens first decreased and then increased with the rise of conductivity in acid soils, but contrary in neutral and alkaline soils. Most of the specimen surface was covered with different sizes of reddish-brown bumps corrosion products in the acidic solution and reddish-brown, black corrosion products in the alkaline solution, but the specimen surface was smooth in the neutral solution. Because of economic and environmental factors, the AC interference is not always achievable. Therefore, comprehensive approaches should be taken for AC interference protection.

Abstract: The effect of substrate conditions, including material type, thickness and radius on thermal shocking properties of plasma sprayed Sm₂Zr₂O₇/NiCoCrAlY functional graded thermal barrier coatings were analyzed by ANSYS—a finite element method software. Results show that thermal stresse in coatings increase with increasing of thermal expansion coefficients of substrates. The effect of substrate thickness can be ignored when it is greater than 20mm. Thermal stresses increase with radius increasing, however, they are almost not effected when substrate radius is over 18mm.

Abstract: Fe-based amorphous coating was prepared on stainless steel substrates by atmospheric plasma spraying (APS) using Fe-based amorphous powder as feedstock. Microstructures of the coating were investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM). The corrosion behavior of coating and stainless steel were evaluated respectively in 3.5% NaCl, 10% NaOH and 1 mol/L H2SO4 aqueous solutions by electrochemical workstation. The results indicated that the coating was composed of most amorphous phase and some Fe-Cr crystalline phase. The coating exhibited the better corrosion resistance in H2SO4 solution, while the worse in NaOH.

Abstract: A new basic solution for eletroless Ni-B alloy plating from DMF was studied. The effects of composition and operating conditions on the rate of deposition of Ni-B alloy have also been discussed. The alloy component was analyzed by EDS and Inductively Coupled Plasma (ICP). The plating rate is determined by electronic balance. And structures of the plating coatings were investigated by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD).The optimum composition and operating conditions for abstaining satisfied Ni-B alloy coating are provided.

Abstract: Superhydrophobic copper wafer was prepared using a sol-gel deposition method in the paper. The best superhydrophobic film was prepared with vinyltrimethoxysilane (VTES), ethanol (EtOH), water (H2O) and ammonium hydroxide (NH4OH) at a molar ratio of 1:62.79:8.58:1.49 respectively. The morphologies, chemical compositions and hydrophobicity of the substrates were analyzed by scanning electron microscopy (SEM), energy dispersive X-ray detector (EDX) and water contact angle measurement (CA). The surface morphological study showed that “lotus like structure” silica particles distributed on the copper substrate. The coatings showed the CA as high as 157.8°. The durability properties revealed that the coatings had a good superhydrophobicity deposited in 3.5 wt % sodium chloride solution for up to 14 days.

Abstract: Al/Ti multilayer films with bilayer thicknesses of 50nm, 100nm and 200nm were prepared by RF magnetron sputtering alternate Al and Ti layers. The relative thickness of Al and Ti layers was maintained at a 1:1 ratio in order to obtain a 1:1 atomic ratio. XRD measurements show that the compound of AlTi is the final product of the exothermic reactions. DSC curves show that the values of heat release in Al/Ti multilayer films with bilayer thicknesses of 50nm, 100nm and 200nm are 457.99 J∙g^-1, 493.42 J∙g^-1 and 696.81 J∙g^-1, respectively. The exothermic reaction in Al/Ti multilayer films lead to more intense electric explosion. Al/Ti multilayer bridge films with modulation period of 50nm explode more rapidly and intensely than other bridge films because decreasing the bilayer thickness results in an increased reaction velocity.

Abstract: C/FePt/Ti nano-thin films were prepared by DC facing-target magnetron sputtering system onto glass substrates at room temperature and subsequently in situ annealed for 500 °C 30 min in vacuum. The influence of C capping layer on microstructural and magnetic properties of the FePt films were investigated in detail. Atomic force microscopy (AFM) images indicate that C can effectively isolate the particles, refine particle, and distribute; however, the particle size distribution is uneven for too much C. The easy magnetic axial orientation is changed with the C layer thickness.