1,940 research outputs found
Investigation into laser re-melting of inconel 625 HVOF coating blended with WC
Full text linkHigh velocity oxy-fuel (HVOF) spraying of Diamalloy 1005 powders mixed with WC particles onto steel (304) is considered and laser re-melting of the resulting coatings is examined. Laser re-melting process is modeled to determine the melt layer thickness while temperature increase is formulated using the Fourier heating law. The morphological and metallurgical analyses prior and post laser re-melting process are carried out using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). X-ray diffraction (XRD) technique is used to determine the residual stress developed in the coating while the analytical formulation is adopted to predict the residual stress levels at the coating base material interface. The indentation tests are carried out to determine the Young’s modulus and fracture toughness of the coating prior to laser re-melting. Corrosion resistance of coating is measured using potentiodynamic polarization technique prior and post laser treatment process. The predictions of the melt layer thickness are in good agreement with experimental results. The presence of WC particles modifies temperature rise and its gradient in the coating while affecting the Young’s modulus, residual stress levels, and fracture toughness of the coating. The differences in the thermal properties of Inconel 625 powders and WC particles result in formation of small size cellular structure through polyphase solidification. WC dissolution in the central region of the large polycrystalline cells is observed due to the loss of carbon through carbonic gas formation. The results of corrosion tests prevail that significant improvement of corrosion resistance can be achieved after laser treatment process
Highly-Aligned Electrospun Luminescent Nanofibers Prepared from Polyfluorene/PMMA Blends: Fabrication, Morphology, Photophysical Properties and Sensory Applications
No full textFabrication and characterization of high-T-c YBa2Cu3O7-x nanoSQUIDs made by focused ion beam milling
No full textQuality of sleep and its related factors in patients with breast cancer during chemotherapy
No full textThe Inhibitory Mechanism of YC-1, a benzyl indazole, on smooth muscle cell proliferation: an in vitro and in vivo study.
No full textNon-woven and aligned electrospun multicomponent luminescent polymer nanofibers: effects of aggregated morphology on the photophysical properties
No full textOSU-03012, a novel celecoxib derivative, induces reactive oxygen species-related autophagy in hepatocellular carcinoma.
No full textInvestigation of a ceramic metal matrix composite functional surface layer manufactured using gas tungsten arc welding
Full text linkWear resistant surfaces with high toughness and impact resistant properties are
to be created to improve the life cycle cost of brake discs for trains. A potential
solution to this industrial problem is to use an arc cladding process. This work
describes the application of gas tungsten arc welding (GTAW) for a structural
ceramic Metal Matrix Composite (MMC) on steel. The structure of the two
ceramics examined indicates the possibility of development of a wear resistant
surface, which would extend the life of the brake disc. Silicon Carbide (SiC)
and Tungsten Carbide (WC) ceramics were studied to embed them in a steel
matrix by an advanced GTAW method. WC particles penetrated the liquid weld
pool and also partially dissolved in the steel matrix, whereas, SiC because of
the physical properties never penetrated deeper into the weld pool but
segregated on the surface. Successful embedding and bonding of WC led to
the decision to exercise an in-depth analysis of the bonding between the WC
particles and the matrix. Chemical analysis of the matrix revealed more WC
dissolution as compared to particle form within the clad. It was observed that
WC reinforcement particles built a strong chemical bond with the steel matrix.
This was shown by electron backscatter diffraction (EBSD) analysis. The hard
clad layer composed of WC reinforced steel matrix gave an matching friction
coefficient to high-strength steel in cold wear conditions through Pin-on-Disc
wear and friction testing. A prototype railway brake disc was created with the
established GTAW parameters to find out the difficulties of producing industrial
scale components
Obtaining Crack-free WC-Co Alloys by Selective Laser Melting
No full textAbstractStandard hardmetals of WC-Co system are brittle and often crack at selective laser melting (SLM). The objective of this study is to estimate the range of WC/Co ratio where cracking can be avoided. Micron-sized Co powder was mixed with WC nanopowder in a ball mill to obtain uniform distribution of WC over the surface of Co particles. Continuous layers of remelted material on the surface of a hardmetal plate were obtained from this composite powder by SLM at 1.07μm wavelength. The layers have satisfactory porosity and are well bound to the substrate. The chemical composition of the layers matches the composition of the initial powder mixtures. The powder mixture with 25wt.%WC can be used for SLM to obtain materials without cracks. The powder mixture with 50wt.%WC cracks because of formation of brittle W3Co3C phase. Cracking can considerably reduce the mechanical strength, so that the use of this composition is not advised
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