Advanced Materials Research Vol. 1090

Abstract: The foamed polypropylene (PP) with excellent thermal insulating property was prepared by using the nanosilica (SiO₂) aerogels as nucleators, followed by mould pressing foam in cross-link. The weight ratio of SiO₂/ PP, which was at the range of 0~ 2%, significantly affected the morphology and thermal insulating properties of the foamed PP. The results showed that the foamed PP can get excellent properties when the weight contents of SiO₂ aerogels was 1 %. The foamed PP with low density as 0.43 g/cm³and thermal conductivities at the range of 0.046~0.507 W.(m.K^-1) was obtained by using this method.

Abstract: Objective: This study aimed to evaluate the effect of surface texture mold by stainless steel (SS) mesh on Invisalign material friction coefficient. Materials and methods: Ten kinds of SS mesh were used to mold surface texture on Invisalign material. Experiments were conducted using a zirconia ball that slid against Invisalign material plates with different surface textures. In the experiments, the coefficients of friction under normal loads of 100, 200, and 300 g under dry and artificial saliva conditions were recorded. Results: The coefficient of friction was relative to the pore size and wire diameter of SS mesh. Conclusions: The Invisalign material coefficient can be effectively managed by the surface texture mold by SS mesh.

Abstract: In this research work, the influence of jet velocities and different kind of metals during the quenching process with the use of array of jets was tested. Three different jet velocities i.e. 0.9m/s, 1.2m/s, and 1.8m/s were applied for the quenching of copper K12. Experiments with different kind of metals are using AA6082, Nickel, and Copper K12 samples. The influence of jet velocities and material properties was characterized by figuring out the trend of propagation of Leidenfrost Point (LFP) and maximum Heat Flux (maxHF) point over time. In addition, Leidenfrost Temperature (LFT), maxHF values with the corresponding DNB temperature as well as the width of wetting front over position were also presented. The results show that the jet velocities and the material properties significantly influence the boiling characteristics in a metal quenching process with array of jets.

Abstract: The corrosion inhibition activities of sorbitol on the corrosion of steel rebar were studied via potentialdynamic polarization, electrochemical impendence spectroscopy (EIS) techniques as well as the Fourier transform infrared spectroscopy (FTIR) in simulated concrete pore solution. In order to determine its corrosion inhibition effect in the concrete structure, concrete specimens with steel rebar inside were prepared and wet /dry cycles method was used to simulate the service environment of steel rebar in marine region as well as to accelerate rebar corrosion. The inhibition performances of sorbitol were investigated by half cell potential and corrosion current density measurements. The results indicate that sorbitol can effectively inhibit the corrosion of steel rebar both in simulated system and concrete structure. Its inhibition mechanism involves a chelating effect of the molecule with the iron ions and a protective film formed on the metal surface.

Abstract: Slow strain rate test (SSRT) applied with different potential was adopted to investigate the stress corrosion cracking (SCC) sensibility of stainless steel under marine environment. The fracture morphology of 321 stainless steel SCC specimens were analyzed with the aid of SEM. The strain-stress results showed that 321 stainless steel exhibited less SCC sensitivity when anodic potential or cathodic potential were applied on the specimen, both fracture elongation and fracture time ascended compared with that of corrosion potential. The fractography analysis results also proved this susceptibility clearly.

Abstract: In this paper, Pd ions doped cerium conversion coating (CeCC/Pd) was deposited on AA2219-T87 aluminum alloy by electroplating. The microstructure and composition of the coating were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS). Corrosion behavior of AA2219-T87 aluminum alloy with the coating was investigated in 3.5wt.% NaCl solution at the room temperature. XRD and XPS results indicate the existence of cerium-oxide and palladium-oxide in the CeCC/Pd. Polarization curves show that the CeCC/Pd exhibits excellent corrosion resistance. The corrosion current density of the CeCC/Pd decreases by two orders of magnitude compared with the CeCC. The improvement of corrosion resistance would be attributed to the small grain size, good compactness and adhesive strength of the composite coatings.

Abstract: The surface defects is an important factor affecting the quality of hot-rolled round steel, so the recognition of surface defects plays a very important role in the daily usage of the hot-rolled round steel. This paper aims to bring forward an appropriate method to find out the surface defects of the hot-rolled round steel under the help of Matlab software. First of all, the image edge of the round steel was detected, and the image was segmented. Secondly, the segmented image may appear bended, so it would be straightened to make the surface defects recognition easy. The third step is to eliminate image noise. Finally the processed image was analyzed and the appropriate recognition method was figured out. The results show that the method proposed in this paper is effective and accurate.

Abstract: Based on the existing empirical formula, applied binary regression model, Lytag, as an example, established a new style of regression equation for lightweight aggregate, and compared with Existing empirical formula, proved the availability of the new formula.

Abstract: The present world cannot be imagined without construction industry. On other hand we are not able to prevent impact of construction on the environment due to usage of its key component that is cement, which plays a greater role in the emission of greenhouse gases. Every tonne of Ordinary Portland Cement (OPC) that is produced releases on average a similar amount of CO₂ into the atmosphere, or in total roughly 6% of all man-made carbon emissions. One of the purposes of research should be to lower the amount of cement during construction without compromising the quality of building structure. Microbial metabolic activities often contribute to selective cementation by biomineralization. In the present study, a novel microbial based low energy green building material based on microbially induced calcium carbonate precipitation (MICP) has been reported that is known as “biocement”. Biocement has enormous potential and usage in building materials and structures with potential to partially replace the cement. The research demonstrates that production of biocement can enhance the durability of building structures in addition to have least impact on the environment.

Abstract: The back propagation artificial neural networks (BP-ANN) use a resilient back-propagation algorithm and early stopping technique. By inputing the properties of geometries and material, NNs can predict the strength of lightweight concrete. An BP-ANN model based on feed-forward neural network is built, trained and tested using the available test data of 148 mix records collected from the technical literature. And the test results are compared and analyzed with experimental data . It shows that the strength of lightweight concrete obtained by the simplified model based on NNs are in good agreement with test results, and they are close to the experimental values. The NNs model can be used in the shear strength prediction and design for the strength of lightweight concrete.