Applied Mechanics and Materials Vol. 575

Abstract: The inhibition effect of synthesized fatty amides mixture, pyridine and pyrrole as corrosion inhibitors on carbon steels in saline water had been compared using Linear Polarization Resistance Method (LPRM). It is still unknown which of these organics performed best than another. The experimental results showed that the inhibition effect of the synthesized fatty amides mixture is found to be better than pyridine and pyrrole, indicating the presence of various chain lengths of fatty amides molecules. These molecules provide a better surface on carbon steels than pyrrole and pyridine.

Abstract: Aluminium alloy 6061 T6 circular specimens were joined using TIG welding method. AlMg5 was used as filler. The corrosion behavior of welded and un-welded AA 6061 T6 was investigated using potentiodynamic and open circuit potential (OCP) measurements. Specimens were immersed in 3.5 (wt %) NaCl solution. Different zones with different corrosion properties were created as a result of the welding process. Results reveals that sever pitting corrosion has taken place on the heat affected zone (HAZ); the corrosion current of HAZ was increased. The measured potential of HAZ was more negative and largely fluctuated comparing to base metal (BM).

Abstract: The aim of this study is to develop a novel maskless-curing slurry stereolithograhy and sintering process which can fabricate high strength ceramic parts. Three dimension printing of additive manufacturing method was used. High performance stereolithography slurry, which was composed of zirconia powder as structure material and methanol as a solvent and a dispersant, could be prepared with colloidal processing. During layer casting, the diaphanous slurry can penetrate into pores of the subjacent layers. After drying, the binder in the penetrated liquid could connect the fresh layer and subjacent layers. Eventually, a gel-like green block could be built layer by layer. In the exposed region, the resin contained in the green block was cured to connect the zirconia powders to be a part of the rigid green part. The obtained rigid green part was then heated up to 300°C for binder burnout, and then sintered at 1350°C to obtain a high dense zirconia ceramic part. The proposed method of maskless-curing slurry was briefly described and it was proved that the good capacity of solidifying thin layer.

Abstract: Titania nanofiber (TiO₂ NFs) arrays were fabricated in situ on a Ti-6Al-4V substrate by an oxidation process. Their surface morphology, crystallographic structure, surface roughness and wettability were characterized, as well as their in vitro interaction with bovine articular chondrocytes at different time points. Results showed that TiO₂ NFs possessed greater surface roughness, hydrophilicity and degree of crystallinity. The in vitro cell studies revealed that TiO₂ NFs substrate triggers enhanced cell adhesion, proliferation and extracellular matrix (ECM) formation compared to the untreated control sample. These results showed that chondrocytes have an affinity to the nanofibrous substrate surface and thus we suggest that such surfaces are suited to be used as an implant designed for cartilage growth.

Abstract: In this study, the physical properties of thermoplastic composites manufactured from linear medium density polyethylene (LMDPE), rice husk (RH) and maleic anhydride polyethylene (MAPE) were evaluated. Composites were manufactured with RH loadings of 15 wt%, 30 wt% and 50 wt% with 1 wt% of MAPE to investigate the effect of RH loading on the physical properties (water absorption and thickness swelling) of the composites. The results show that the water absorption and the corresponding thickness swelling increased with an increase in RH loading. Further manufacturing was carried out with 50 wt% of RH and 1wt%, 3.5 wt% and 6 wt% of MAPE to evaluate the effects of interfacial modification on the physical properties of the composites. The results show that the composites with 3.5 wt% of MAPE had least water absorption and the corresponding thickness swelling, whereas the composites having 1 wt% of MAPE had maximum water absorption and the thickness swelling. It can be concluded from these experiments that fibre loading as well as interfacial modification play a significant role in determining the physical properties of the composites.

Abstract: This paper used molecular dynamics (MD) simulations to investigate thermal stability of an axial compressed open-tip carbon nanocone, which have an apex angle of 19.2°. To study the thermal stability, the carbon nanocone was first compressed axially up to the compression strain near its critical strain for buckling. Temperature of carbon nanocone was then increased gradually and the corresponding axial force in the carbon nanocone was monitored to examine the thermal stability of the carbon nanocone. It was found that the critical temperature for thermal instability grows with the decrease of the initial compressed strain. Comparing with the buckling mode of the carbon nanocone, the thermal instability mode displayed a swelling configuration rather than a deflective configuration of the buckling mode. The interesting finding would be helpful for applications of open-tip carbon nanocones.

Abstract: Owing to its high dielectric constant, barium titanate is a material commonly employed in fabrication of high energy density capacitors. Dielectric properties required for practical applications can be attained in barium titanate with desired chemical composition and microstructure. This study, therefore, aims at examining effects of additive contents on formation of secondary phases, microstructure and dielectric properties of BaTiO3 and BaTiO3 with 20-40 at% Ca. Chemical composition analysis revealed that single-phase BaTiO3 powder could be attained by the solution combustion technique. However, the powder with high Ca content exhibited large quantities of secondary phases. Dielectric property measurements of the uniaxially pressed powders indicated that dielectric constants could be enhanced with low Ca content. On the contrary, dielectric constant significantly degraded with high Ca content. This was attributed to formation of large quantities of secondary phases, coarse grain size and low density. Values of dielectric loss of all materials were lower than 1%.

Abstract: About more than 90% highway have adopted asphalt concrete pavement in China. A lot of quality problems appeared in the highway pavement due to freezing-thawing circulations under the condition of low temperature. The scanning electron microscope (SEM) was utilized to observe the microstructure of styrene-butadiene-styrene (SBS) modified asphalt and rubber powder modified asphalt before and after the salt freezing. Also three routine indicators (penetration, softening point and ductility) for the two kinds of asphalt were tested before and after the salt freezing. The analysis results showed that the temperature susceptibility of SBS modified asphalt and rubber powder modified asphalt were all increased and the high temperature performance and low temperature performance of both asphalt were reduced after the salt freezing cycles as the same time the performance of rubber modified asphalt after salt freezing cycle was superior to SBS modified asphalt by comparing the basic indicators of them.

Abstract: With the development of some severely corrosive oil and gas fields, the phenomenon of material corrosion is increasingly serious. Through a large number of literature investigation, comparing with the advantages and disadvantages of anti-corrosion materials in CO₂, H₂S and Cl^- concomitant environment. In the development of oil and gas filed use some new anti-corrosion materias. CRAs under highly corrosive conditions remains the most effective and relatively economical choice in downhole and wellhead. At special pipe sections usually use super high-density polyethylene and nylon. Process piping usually use CRAs and CLASs. In water treatment systems use non-metallic pipes (HDPE, FRP). Oil and gas output pipelines and rubber seals use CLASs, try to slow down the corrosion.

Abstract: Linear and angular displacement is an important criteria for incompressible materials. Natural rubber is a one of the incompressible material because it has a potential to make uniform displacement when apply the quantum of force. This paper represents the linear and angular displacement of natural rubber engine isolator, respectively. The identity formulation is developed and trivial solution is faced. To doing so, the identity formulation is derived and finally the equation of relationship between linear and angular displacement is derived. Finally, the result has shown the transformation of these two displacements with quantum of frequency.