Microstructural Characterization of Shrouded Plasma-Sprayed Titanium Coatings

Titanium and its alloys are often used for corrosion protection because they are able to offer high chemical resistance against various corrosive media. In this paper, shrouded plasma spray technology was applied to produce titanium coatings. A solid shroud with an external shrouding gas was used to plasma spray titanium powder feedstock with aim of reducing the oxide content in the as-sprayed coatings. The titanium coatings were assessed by optical microscope, scanning electron microscopy, X-ray diffraction, LECO combustion method and Vickers microhardness testing. The results showed that the presence of the shroud and the external shrouding gas led to a dense microstructure with a low porosity in the plasma-sprayed titanium coatings. The oxygen and nitrogen contents in the titanium coating were kept at a low level due to the shielding effect of the shroud attachment and the external shrouding gas. The dominant phase in the shrouded titanium coatings was mainly composed of α-Ti phase, which was very similar to the titanium feedstock powders. The shrouded plasma-sprayed titanium coatings had a Vickers microhardness of 404.2 ± 103.2 HV

Data transfer of non-matching meshes in a common dimensionality reduction space for turbine blade

A data transfer method in dimensionality reduction space is proposed for the fluil-structure-interaction problems, which commonly have non-matching meshes at interface. The method provided in the article can reduce the dimensionality of the data transfer by means of projecting interface surface meshes into a dimensionality reduction space. The dimensionality reduction projection can be realized by defining local coordinates system for interface surface. Furthermore, the size of interface surface meshes has little influence on the data transfer. At last, the method is validated using a temperature transfer problem of turbine blade

Mode II Fracture of GFRP Laminates Bonded Interfaces under 4-ENF Test

This experiment studies the mode II fracture behavior of an adhesively bonded joint composed of GFRP laminates. A new beam model is presented to calculate the mode II ERR for GFRP bonded 4-ENF specimens. In this model, the deformation of 4-ENF specimens caused by the relative deflection angle between the upper and lower layers and by the bending deformation of the upper and lower layers, respectively, is introduced; the effect of the adhesive layer deformation is presented. The closed-form analytical solutions of compliance and energy release rate based on the crack compliance method are obtained. The high accuracy of present analytical solutions are verified by finite element analysis through bonded GFRP 4-ENF specimens and compared to the rigid joint model and the CBT model. The interfacial crack propagation is numerically simulated using shear fracture toughness determined in this experiment, from which the predicted critical load results are in good agreement with the experimental results. The conclusion indicates that the compliance and ERR can accurately be predicted using the new bonded 4-ENF beam model

Chemical composition of Dipsacus asper Wallich ex Candolle (Dipsacaceae) essential oil and its activity against mosquito larvae of Aedes aegypti and Culex pipiens pallens

Purpose: To evaluate the larvicidal activity of the essential oil of Dipsacus asper Wallich ex Candolle (Dipsacaceae) roots against the larvae of Aedes aegypti L. and Culex pipiens pallens Coquillett.Methods: Essential oil was extracted from D. asper roots by hydrodistillation and analyzed for its composition by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The oil was evaluated for larvicidal activity, using World Health Organization (WHO) procedures, against the fourth larvae of A. aegypti and C. pipiens pallens within 24 h, and activity was recorded for various concentrations of the oil ranging from 12.5 – 200.0 μg/mL.Results: A total of 34 components of the essential oil of D. asper were identified. The major compounds of the essential oil were caryophyllene oxide (13.29 %), caryophyllene (9.14 %), cubebene (7.87 %), β-gurjunene (6.43 %), carvone (5.38 %), 1,8-cineole (5.29 %), and calamenene (5.05 %). The oil exhibited larvicidal activity against A. aegypti and C. pipiens pallens at median lethal concentrations (LC50) of 56.29 μg/mL and 47.49 μg/mL, respectively.Conclusion: The essential oil of D. asper roots has potentials for use in the control of A. aegypti and C. pipiens pallens and may be useful in the search for new, safer and more effective natural larvicides.Keywords: Dipsacus asper, Aedes aegypti, Culex pipiens pallens, Essential oil, Larvicidal activity, Caryophyllene, Cubebene, β-Gurjunene, Carvon