Metal matrix composites, high mechanical performance, usability at high temperatures, good wear resistance and low creep rate. This type of composite manufacturing method is very important. Among manufacturing processes, ARB process as a method of applying severe plastic deformation is used on the sheets. In this study 5Wt. % Al/alumina composites fabricated by accumulative roll bonding process up to eight steps using Al1060. Microstructure, mechanical properties and corrosion behavior of the composite were studied by scanning electron microscopy (SEM), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), measurement in 3. 5wt% NaCl solution. Corrosion behavior of the composite revealed a considerable improvement in the main electrochemical parameters, as a result of enhancing influence of cold rolling. Also, the electrochemical experiments showed that corrosion resistance of samples increasing with increasing the number of ARB cycles. After 8-cycle ARB have a low corrosion density in comparison with high corrosion density of annealed specimens.

The catalytic reduction of sulfur dioxide with methane to form elemental sulfur was studied. Al2O3, Cu-Al2O3, and Ni-Al2O3 were examined as catalysts whose performances were compared in terms of SO2 conversion and selectivity. Performance of the catalyst extremely improved when nickel and copper were added as promoters. The effects of temperature, SO2/CH4 molar ratio, and reaction time on SO2 reduction were studied. The operating temperature range was 550– 800 ° C, and it was observed that the reaction was strongly temperature dependent. At temperatures lower than 700 ° C, Al2O3-Cu (10 %) catalyst showed the best performance of all the catalysts. However, at 700 ° C and higher, performances of Al2O3-Cu (10 %) and Al2O3-Ni (10 %) catalysts were similar. Complete conversion and selectivity (more than 99. 5 %) was achieved by Al2O3-Cu (10 %) and Al2O3-Ni (10 %) catalyst, at 750 ° C. Effect of molar feed ratio of SO2/CH4= 1-3 was studied, and stoichiometric feed ratio showed the best performance. In addition, the investigation of reaction time for Al2O3-Cu (10 %) and Al2O3-Ni (10 %) catalysts showed good long-term stability for SO2 reduction with methane.

In the recent years, application of alumina-mullite composites in refractory industry has gained remarkable attention due to their high strength and life duration. In the present work, preparation of alumina-mullite composite was studied in optimal temperature and time condition using alumina nanopowder. Addition of alumina nanopowder in comparison with its micrometer-sized powder in alumina-mullite composites increased mechanical strength and thermal shock resistant. Also, addition of micrometer and nanometer-sized alumina powder to alumina-mullite composites increased and decreased the thermal expansion coefficient, respectively. SEM and EDS analyses showed that the addition of alumina nanopowder increased the amount of mullite phase which improved the strength and thermal shock resistant. Also, addition of micrometer-sized alumina in alumina-mullite composite increased porosity and water absorption and decreased the density. The addition of alumina nanopowder decreased the porosity while water absorption increased the density.

Jajarm bauxite mine as a largest known bauxite ore reserves with more than twenty million tons of diasporic bauxite, located in the north of Khorasan province, Iran. This bauxite mine cannot provide the suitable feed for at least twenty tears. Therefore, the possibility of using other bauxite deposits such as Shah-Bolaghi bauxite mine in Tehran province and Sorkh-cheshmeh mine in the north of Khorasan province was investigated. These studies were carried out based on the dissolution and sedimentation velocity of red mud. The results show that using these deposits separately is not applicable, because of low dissolution and/or low sedimentation velocity of red mud. The other parameters such as dissolution temperature, the amount of lime and Na2Oc must be carefully controlled to have the better results. Accordingly, a mixture of 50-50 Jajarm and Shah-Bolaghi bauxite ore has had the better performance with higher dissolution efficiency and also the lesser alumina amount in red mud.

Nano- size alumina particles have been synthesized by mechanical activation of a dry powder mixture of AlCl3 and CaO. Mechanical milling of the above raw materials with the conditions adopted in this study resulted in the formation of a mixture consisting of crystalline CaO and amorphous aluminum chlorides phases. There was no sign of chemical reaction occurring during milling stage as evidenced by x-ray diffraction studies. Subsequent heat treatment of the milled powder at 350°C resulted in the occurrence of displacement reaction and the formation of Al2O3 particles within a water soluble CaCl2 matrix. The effect of higher temperature calcinations on the phase development in this powder mixture was followed by X-ray diffraction (XRD) analysis and scanning electron microscope (SEM). Differential thermal analysis (DTA) was used to compare the thermal behavior between the milled and unmilled powders. Perhaps the most important result in this study was the observation of á-Al2O3 phase at a very low temperature of 500°C.

Brick is the most widely used construction material. Demolition of buildings and production of construction waste, including clay brick, are dramatically increasing in an alarming rate. The production of traditional bricks such as clay bricks has hazardous impacts on the environment, such as pollution and extensive use of natural resources. This study addressed the application of the geo-polymerization process as an environmental and sustainable method to produce new bricks from clay brick waste and different types of fillers. Accordingly, the powder and grains of clay brick waste, dune sand, washed sand, industrial sodium hydroxide, and water glass were utilized to prepare cubic and brick-shaped geopolymer samples with different mix designs and then cured at 70 °C. The samples' compressive strength, water absorption and SEM analysis were examined. According to the results, the highest compressive strength for cubic mortar samples was obtained in the case without filler; for these samples, with mass ratios of water glass to sodium hydroxide solution equal to 1 and 2, compressive strength was 18.45 and 22.15 MPa, respectively. In the brick samples, the highest compressive strength was obtained in the 28-day and 8 M geopolymer samples, which was equal to 25.38 MPa. On the other hand, the geopolymer samples made by sand filler had higher compressive strength and lower water absorption in comparison to other samples. Therefore, sustainable production of geopolymer bricks from clay brick waste and inexpensive materials as the filler can be a step toward mitigating the environmental impact of construction and demolition waste.

Today, fabrication of complex-shaped ceramic parts in large quantities has been limited to the processes required extensive and expensive machining (i.e., injection moulding or pressure slip casting). These technologies for shaping ceramics, however, possess several shortcomings that limit their use as a complex-shape forming method. Because of these limitations “gel-casting” which was lacking in above deficiencies, has been proposed as a general and desired method for shaping any ceramic powder. In this work, gel-casting of ?-alumina is investigated based on in situ polymerization and gelation of acrylamide monomers as the setting mechanism for forming the green part. Special attention was paid to the preparation of fluid, castable slurries with a high loading of α-Al2O4 (>80 wt.%) and low viscosity (0.65 Pa.s) by using polyelectrolyte dispersants (i.e., poly(methacrylic acid salts), also gelation of acrylamide (effect of gelation factors on idle time), mould materials, drying of parts through the liquid desiccant drying method and its comparison with conventional drying technique, green machining, debinding and si

MgO/γ-alumina and CaO/γ-alumina heterogeneous base catalysts have been prepared by wet impregnation, using 10 wt.% of metal oxide precursors, and used in the transesterification reaction of castor oil (Riccinus communis) into biodiesel. Catalyst characterization includes X-Ray Diffraction (XRD), Fourie Transform InfraRed (FT-IR) spectroscopy, X-Ray Fluorescence (XRF), Surface Area Analyzer (SAA), average pore radius (BJH), and basicity. The catalyst performance was observed from the activity and selectivity of the catalyst in converting castor oil into methyl ester with the batch system at 60°C for 2 hours. The castor oil biodiesel was analyzed using GC-MS to determine the selectivity of the catalyst towards methyl ricinoleate. The results showed that the addition of MgO and CaO to γ-alumina increased the basicity and average pore radius but decreased the specific surface area of γ-alumina. The FAME yields of γ-alumina, MgO/γ-alumina, CaO/γ-alumina, MgO, CaO, and KOH catalysts with 3 wt.% ratio were 81.15%, 82.17%, 82.45%, 82.02%, 82.16%, and 84.57%. The selectivity to methyl ricinoleate was the highest for CaO/γ-alumina catalyst which was 87.57% area GC. The yield of FAME at various weight ratios of CaO/γ-alumina (1, 2, 3, 4, and 5 wt.%) were 81.81%, 82.13%, 82.45%, 83.57%, and 83.96% and the selectivity to methyl ricinoleate was the largest at 4 wt.% CaO/γ-alumina catalyst which was 90.20% GC area. Castor oil biodiesel was analyzed using the American Standard of Testing Materials (ASTM) method for biodiesel eligibility. ASTM test results for castor oil biodiesel showed a kinematic viscosity (40°C) of 15.76 mm2/s which is above the biodiesel standard because the kinematic viscosity of castor oil was also high. The flash point of 222.5°C, pour point <27°C, and cloud point of 15°C have fulfilled the requirements of the biodiesel standard.