Advanced Materials Research Vols. 457-458

Abstract: GTD-111 superalloys are of the newest Ni-based superalloys which because of having good stability and strength in high temperatures are used in manufacturing of hot-gas-path parts of the gas turbines. Because of severe working conditions, application of these superalloys without coating isn't recommended. For this purpose, firstly the superalloy is coated and then is used. In this paper, the effect of Aluminide coating on rapture behavior of the GTD-111 superalloy is investigated. For this purpose, a number of samples made from GTD-111 superalloy have been coated by powder cementation method and have been subjected to rapture test and have been compared to uncoated samples. The results suggest that the presence of coating causes increase of Al content in the surface and contributes in stability of γ´ which is the most important factor of superalloy strength and also causes more life cycle of this superalloy with respect to similar uncoated samples.

Abstract: TWIP steels are high Mn (17-35%) austenitic steels having strength and ductility concurrently. This makes them suitable for applications that need high strength and ductility like gas tanks and oil platforms. To these applications corrosion resistance of these steel is also of paramount importance and needs to be noticed. This was achieved by two usual methods of weight loss and potentiodynamic polarization of the samples, after that they casted and hot rolled in experimental scale. The observed corrosion pits are related to the chemical composition. It is connected with the high dissolution rate of Mn and Fe atoms in NaCl solution. Fractographic analyses of samples revealed corrosion products on their surface in a form of pits with diversified size.

Abstract: Using •OH scavenging test, an efficient method had been developed to acquire protein hydrolysate (MMH) from Mytilus coruscus by an orthogonal L9(34) test. The optimal enzymolysis parameters were enzymolysis time 3 h, temperature 60°C, solid-liquid ratio 1:2 and enzyme dose 3%. Enzymolysis temperature and solid-liquid ratio showed significant effects (ANOVA p<0.05) on the hydrolysate preparation. Based on the molecular weight (MW), MMH-I (10

Abstract: Inspired by DPPH• scavenging assay, an efficient method had been developed to acquire muscle hydrolysate (AMH) from Mustelus greseus by an orthogonal L9(3)4 test. Under optimal enzymolysis parameters (enzymolysis time 4 h, enzyme dose 1%, enzymolysis temperature 55 °C and pH 6), the DPPH• scavenging rate of AMH reached to 27.92%. Enzymolysis time and enzyme dose showed significant effects on hydrolysate preparation (ANOVA p<0.05). Based on molecular weight (MW), AMH-I (10

Abstract: Abstract: Copper coated short carbon fiber reinforced aluminum alloy matrix composites have been prepared with 0.3-1.5 wt% Mg as alloying addition by stir casting. Effect of Mg on the microstructure and mechanical properties of the composites was investigated. The microstructure was observed by scanning electron microscopy and the results show that adding Mg can make the distribution of carbon fibers uniform in the composites, reduce laminated and agglomerated. Tensile test and hardness test were carried out, the results show that the tensile strength and the hardness of the composite is increased by 13% and 8% when Mg content is 0.9 wt%.

Abstract: Earthen buildings come in a vast variety of shapes and sizes, made from materials like fired clay, compressed dirt and a mixture of clay, sand, straw and water. People have been using various forms of earth to build structures for centuries. From underground green homes to other futuristic green houses. This paper is included 6 diverse examples of structures made from earthen materials in Iran that used Iranian architecture in their works. The buildings are included special mortar called Sarooj in their construction. The result has shown the earthen buildings create safer, more people-friendly buildings. The earthen buildings are very low in embodied energy, and extremely comfortable to live in. With captivating discussion, Earth Architecture showcases the beauty and simplicity of one of humankind's most evolved and sophisticated building technologies in Iran and the world.

Abstract: Passivation is a common means of material protection against corrosion applied in engineering. It is necessary to study the kinetics of the passive films forming to control the passivation process. A numerical analysis method is proposed and applied to study passivation kinetics of low carbon steel in sodium nitrate solution. Curve of passive film coverage against time is obtained and discussed. A maximum growth rate is found at initiating passive potential during the film forming process, and the film has already begun forming before the initiating passive potential arrived.

Abstract: In this paper the hydroxyapatite fibers reinforced chitosan nanocomposites with high hydroxyapatite dosage (70~90 wt%) were synthesized by in-situ hybridization. The semi-permeable membrane was used to control the process of hybridization and morphology of hydroxyapatite. The compositional and morphological properties of nanocomposites were investigated by FTIR spectroscopy, X-ray diffraction, and transmission electron microscopy. The results showed that the hydroxyapatite were carbonated nanometer crystalline fibers with high aspect ratio (about 25) and dispersed uniformly in the nanocomposites. The high-resolution image indicated that the growth of nano-hydroxyapatite crystallites in the chitosan matrix preferred in the c-axis. The mechanical properties of these nanocomposites were enhanced dramatically and the compressive strength increases almost to 170MPa when the hydroxyapatite content is 70 wt%. The in vitro tests indicated that the composites have high bioactivity and degradation. These properties illustrated the potential application of this kind of nanocomposites for bone tissue engineering.

Abstract: This paper presents a novel method for fabrication of carbon membranes for gas separation by mean of surface modification with a conventional 2B pencil on the low-cost macroporous Al2O3 substrate. The resulting membrane was characterized by SEM, which shows that the modified membrane is continuous and uniform without defects. Gas permeation experiments were conducted by single gas measurements (test gas: H2, CO2, O2 and N2) at 20–80 °C under 100–400 kPa. The results show that the pencil lead layer can effectively prevent deep infiltration of precursor solution into the pores of substrate, and that gas transport through carbon membrane follows the molecular sieving mechanism. Based on the modified substrate, the carbon membrane exhibits good permeability (up to the order magnitude of 10-9 mol/m2 s Pa) and separation capability such as H2/N2 of 37.3, CO2/N2 of 11.2, and O2/N2 of 8.3.

Abstract: Reversal symmetry is one kind of mechanical static structure symmetry, grouped by rotation symmetry and mirror symmetry, widely exists in structures of mechanical products. On the basis of research on the concept systems of rotation symmetry and mirror symmetry and based on analysis of a lot of instances, the concept system of reversal symmetry was established by taking the independence of symmetry components, the directivity of symmetry components, the rotary type of symmetry components and the dimensionality of symmetry components as standards. Accurate instances were particularized to explaining and verifying the concept system. The further research of the application laws of reversal symmetry can benefit from this research result.