Advanced Materials Research Vols. 189-193

Abstract: AISI 304 austenitic stainless steel was carburized at low temperature by means of the active screen plasma carburizing (ASPC). A layer of carbon supersaturated solid solution (i.e. the Sc phase) can be formed on the surface without precipitation of chromium carbide. The hardness of the carburized steel is greatly improved without degradation of its corrosion resistance. ASPC also solves some problems associated with the conventional DC plasma carburizing (DCPC), such as temperature uniformity, edge effect and so on. Particles sputtered from the active screen were collected and analyzed. XRD and SEM analysis indicated that the sputtered particles in sub-micron scale were neutral Fe₃C and Fe₂C₅. The particles play the role of the carbon carrier in ASPC. Therefore, ASPC is also a multi-stage process, involving sputtering, physical adsorption, desorption, diffusion and deposition, the same as active screen plasma nitriding.

Abstract: Red copper has been widely used in shaped charge liner because of its good ductility. Red copper penetrator is the Linear Explosively Formed Penetrator (LEFP) with some length and energy which has been produced when linear red copper shaped charge liner is overturned under the effect of detonation production. Compared with some ordinary jets sword, it has some characteristics such as the broad range of stand-off, big cratering and obvious rear effect and may meet with many operating requirements in different environment. It has been discovered that the bifurcate fracture phenomenon of red copper penetrator will occur with the increase of stand-off when it is initiated on edge midpoint in its property test experiment, and results in the separating cratering on the target which influences its effect. The Propagation characteristics of detonation wave in explosive and the effect of detonation wave on red copper shaped charge liner are analyzed, and then the velocity change obtained by each element and the velocity relationship between each element are studied. So it can be drawn a conclusion that the velocity gradient is the main factor which results in the bifurcate fracture phenomenon of red copper penetrator. In addition, the theoretic analysis model of the bifurcate fracture in red copper penetrator is built. On the basis of modeling analysis and calculation, the criterion of the occurring bifurcate fracture and the measures avoiding the bifurcate fracture are put forward. The results agree well with that of experiments.

Abstract: Electroless plating of Ni-Fe-B alloy on poly(ethylene terephthalate) (PET) fabrics with a novel activiting method was investigated. The activiting steps were immersion the samples to a methanol solution (10 mL) containing 2 g nickel acetate for 30 min, then immersed in an other methanol solution (10 mL) containing 1g potassium borohydride to adequate reaction. Low-cost activator was gained by potassium borohydride reduce nickel acetate on the PET fabric surface. Scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) were used to characterize morphology, structure, composition of the activated layer and Ni-Fe-B coating on the PET fabric. The results indicate that Ni-Fe-B alloy deposits by the electroless deposition were continuous and uniform.

Abstract: A medicinal titanium alloy hydroxyapatite coating was fabricated by microarc oxidation process, and a kind standard of simulated body fluid was configured, after that the biocompatibility experiment was carried out. The soaked coatings surface morphologies were observed and analysed by scanning electron microscopy,and the coating spectra were simultaneityly researched by X-ray diffraction. The instance of degradation and precipitate were investigated,and the transformation of Ca/P value were measured.

Abstract: : This topic has designed a kind of virtual oscilloscope based on the embedded technical. On the hardware the S3C2410+IDT7204 structure were used, on the software real-time operating system uC/OS-II were used in the design of embedded virtual oscilloscope. ARM9 microprocessor's high speed handling ability are fully used, as well as FIFO in the read-write control logic, the superiority in high speed data exchange aspect, realizes the double channel synchronization profile demonstration. the multi-task run and the real-time processing were realized by using on the uC/OS-II operating system's in ARM9 microprocessor transplant. This oscilloscope has the cost lowly, to be possible to as the common oscilloscope, also to be possible to as an intelligent module the merit which used in the embedded system.

Abstract: The influence of MoS₂ lubrication phase on the tribological properties of the Ni₆₀A/MoS₂ composite coating was conducted on UMT-2 micro-wear testing machine (USA), discussing the self-lubricating effect and mechanism. The result shows that with the increasing content of MoS₂, the friction coefficient of the coating which changed with the increasing content of the MoS₂ presents firstly decreases then increases, and the value reach the minimum when the quality percent of MoS₂ wrapped with Nickel is 35%. Low-friction property of the Ni₆₀A/MoS₂ composite coating is due to the forming of MoS₂ lubricating film in friction surface. The decreasing of the friction coefficient of the coating is in proportion to the coverage area of MoS₂ lubricating film.

Abstract: In the present work, warm tension tests for DP steel LTWB (B340/590DP) with 1.0mm/1.0mm thickness are performed on the CMT5205 universal tester, and its microstructure in the region adjacent to weld line is observed by the JSM-7001F scanning electron microscopy. Moreover, Imagetool software is applied to deal with the SEM photographs in order to study the influence of forming temperature on the martensite volume fraction, average length and thickness. By building the relationship of martensite structure volume fraction, feature size, configuration with macro-mechanical properties including stress peak, yield strength, elongation at failure and temperature, the mechanism of improving the formability of DP steel LTWB at the elevated temperature level is revealed, which is vital for optimizing the warm forming process parameters of DP steel LTWB and setting up the precise material constitutive model to enhance the FEM simulation accuracy.

Abstract: Metal Cutting based on cold air technology is a green manufacturing technology which has the potential of great application prospect. In order to study the influence of cold air technology on metal cutting characteristics, the experiment and FEM simulation of both 0Cr18Ni9 stainless steel and 45 steel were performed under three cutting conditions. The results are analyzed to reveal that with cold air technology the temperature of cutting area can be effectively reduced and the tool life, surface roughness and the shape of chip can be significantly improved. The study on metal cutting with cold air technology based on simulation has a relatively high reliability, which provides a novel approach for the research on metal cutting with cold air technology.

Abstract: The hybrid Kevlar/PTFE(polytetrafluroethylene) fabric composites filled with nano-additives at the content of 1wt% of the matrix resin were fabricated. To determine the influence of the load on the tribological properties, the filled and unfilled composites sliding against AISI-1045 steel were performed on the block-on-ring wear tester under varied load condition. Scanning electron microscopy(SEM) was utilized to examine the morphology of worn surfaces of the composites and the counterparts. The results show that: the addition of nano-titania and nano-alumina can enhance the wear resistance of the composite; at the low load, the influence of load on the friction coefficient of the composite is obvious, the main wear mechanism of the composite is microcutting; with the increase of the load, the influence of the load on the wear resistance of the fabric composite becomes significant, the main wear mechanisms of the composite are plastic deformation and matrix-fiber debonding.

Abstract: As a new environment-friendly waterproof material, polymer cement waterproof coating combines the rigidity of cement and the flexibility of polymer materials. The ratio of the liquid powder、the ratio of the C/P, the dosage of stuffing, the coating-forming additives, the defoamer were discussed to investigate their effect on the waterproof materials’ tensile performance and fracture elongation.