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The mixture of TiO2-Al-C with stoichiometric ratio was prepared then ball milling process was done in a planetary ball mill in different times. The evidence of a chemical reaction was not detected in the 1 h milled sample however, the sign of an exothermic peak was detected at ~690ºC in the DTA results for this mixture. The XRD results of the as-milled samples indicated that the chemical reaction progresses as MSR model in the mixture with stoichiometric ratio. The decreasing of the particles size and the traces of amorphization were observed after increasing the milling time to 7 hours. The products of rection (i.e., Al2O3 and TiC) were well crystallized after isothermal heating of the 5 h milled sample at 1000 ºC for 1 h under argon atmosphere. The signs of these phases were also observed in the XRD patterns of the solid residues after DTA analysis. The evolution of the microstructures indicated the decreasing in the particle size due to ball milling and the change of morphology of the microstructure due to occurrence of chemical reaction. The assessments of the lattice parameter of the TiC in the final products indicated that the lattice parameter changes and reaches to amount of the stoichiometric composition due to isothermal heating. Thermodynamics assessments were done for the mixture of TiO2-Al-C and the feasibility of the reactions was studied using HSC thermodynamics software. The XRD results of the milled and the isothermally heated samples were accordance with the thermodynamics assessments.

The bauxite samples were prepared from the resources of Kohgiluyeh and Boyer-Ahmad province, Iran. The chemical and mineralogical compositions were determined after crushing of the specimens. The ball milling of the bauxite samples was done via a planetary ball mill in both steel and zirconia cups.  The isothermal heating was performed in the temperature range of 600-1000˚C for one hour under the air atmosphere. The boehmite phase was observed as the major mineral in the XRD patterns of the bauxite sample. The calcination (dehydration) temperature of the bauxite sample containing boehmite mineral was determined at ~540˚C using STA analysis. The boehmite phase of the bauxite sample was decomposed into aluminum oxide after heating, and the weight loss of the heated products caused by this phase transition was in the range of L.O.I in the chemical analysis. After heating of the milled bauxite samples at 800˚C, the traces of aluminum oxide were detected in the XRD patterns. The overlapping of the major peaks of aluminum oxide and magnetite phase in the XRD patterns was the reason to perform the VSM analysis. The VSM results confirmed the signs of a magnetic phase in the as-milled bauxite samples. The results of this research indicated that either the presence of iron impurities due to the abrasion of the chamber wall and the balls during the milling of the bauxite sample in the steel cup or the presence of the ferrous iron in the bauxite sample could be the origin of the magnetic sings. These items are also the main reasons for appearance of the magnetite phase.

In this research, barium carbonate was synthesized via mechanochemical method from the mixture of barite concentrate-sodium carbonate. The producing of barium carbonate form barite concentrate and the evaluation of the phases/products were the goal of this research.

After crushing the barite concentrate, the acid washing process was done with 1 N of HCl. The mixtures of barite concentrate-sodium carbonate with different molar ratios (BaSO4:Na2CO3=1:1, 1:2, 1:2.5) were prepared and milled in a planetary mill for different times (2 and 5 hours). The as-milled samples and the heated products were dissolved in distilled water and then the solid residues were dried in an oven. The isothermal heating of the samples was done into the alumina and zirconia crucibles. The unmilled mixture of barite concentrate-sodium carbonate was also prepared. The findings of this research were evaluated using XRF, XRD and STA methods and the microstructures of the samples were studied by SEM method.

The2 and 5 h-milled mixtures showed the sign of chemical reaction between the starting materials (barite concentrate-sodium carbonate) at 720⁰C in STA results. This sign however was observed at 735 ͦC in the unmilled mixture. According to XRD patterns, the chemical reaction between barite concentrates and sodium carbonate was not completed in the milled mixtures. The signs of orthorhombic phase of barium carbonate were observed in the products after isothermal heating at700⁰C for 1 h. The results indicated that the isothermal heating of the milled mixture of barite concentrate-sodium carbonate with a molar ratio of 1:2.5 at 750⁰C for 2 h was the suitable conditions for synthesizing of barium carbonate. Additionally, the weak signs of an intermediate phase (Ca4Ba2Si6O18) were observed in the XRD patterns of the barite concentrate-sodium carbonate mixture. For comparison, the experiments were performed with pure barium sulfate sample (Barex). In the product of isothermal heating (750⁰C, 2 h) for the mixture of barium sulfate (Barex)-sodium carbonate (molar ratio :1:2.5), barium carbonate phase was produced and no trace of the intermediate phase was observed. The results of this research showed that it is possible to synthesis barium carbonate phase from the mixture of barite concentrate-sodium carbonate using ball milling process and isothermal heating.

In this study, effects of alumina nanoparticles and stirring pass in mechanical behavior of friction stir welded AM60 magnesium alloy were studied. Microscopic analysis showed occurrence of dynamic recrystallization during plastic deformation in weld area and mechanical tests revealed optimum condition for hardness and tensile strength could be produced in 1200 rpm rotational speed not only in absence of reinforcing alumina nanoparticles but also in presence of them. Opposing effects of higher temperatures in grain growth and greater strains in lowering grain size should be considered. In lacking of alumina nanoparticles, grain size diminished with increasing stirring pass but in being nanoparticles, predominant mechanism in depressing grain size came from nanoparticles and negligible effect of stirring pass in grain size was found. XRD results showed increasing solubility of γ-Mg phase as a result of stirring operation. Better toughness performance of weldment was produced via decreasing size of agglomerated alumina particles. Higher hardness and greater ultimate tensile strength were achieved in specimens with alumina nanoparticle with increasing rotational speed. In a constant rotational speed, higher hardness and greater ultimate tensile strength achieved in samples having alumina nanoparticles in contrast with free alumina nanoparticle samples

In this study mechanical properties of friction stir welded AM60 magnesium alloy in existence and lacking of alumina nanoparticles were examined. Microscopical analysis revealed peak condition could be made in 1200 rpm rotational speed, not only in the absence of reinforcing alumina nanoparticles but also in the presence of them. Adverse effects of higher strains in lowering grain size and higher temperatures in grain growth should be considered. In the existence of alumina nanoparticles in the matrix some areas of low content aluminum formed besides of high aluminum content of intermetallic compounds regions. Higher hardness and ultimate tensile strength achieved in optimum 1200 rpm rotational speed not only with alumina nanoparticles but also in the absence of alumina nanoparticles condition. Higher stresses and therefore lower agglomerated alumina nanoparticles resulted with increasing rotational speed. With alumina nanoparticles in matrix, lower grain size, higher hardness and higher ultimate tensile strength was attained.

The effect of metallic agents such as aluminium, magnesium and mixture of magnesium-zinc was studied on the carbothermic reduction of titanium dioxide in this research under mechanical milling. The mechanical milling runs were done in a planetary ball mill in different times. The stoichiometric mixtures of TiO2-Mg-C, TiO2-Mg-Zn-C and TiO2-Al-C were prepared based on stoichiometric ratios for each reaction. The acid washing process using 2 N HCl solution was done to remove the soluble phases after finishing mechanical milling of each sample. The isothermal heating was done at temperature of 1000 ºC for one hour for solid residues of acid washing under flowing of argon atmosphere. The analysis of products and phases was done using XRD and the microstructure of samples studied by SEM. The results showed the reaction between titanium dioxide and carbon would be exothermic after the adding metallic agent. The reaction progresses via MSR mode for the mixture of TiO2-Al-C in milling conditions and the products were titanium carbide and alumina in the 5 h milled sample. The reduction reaction however progressed via intermediate titanium dioxide in the milled samples for mixtures of TiO2-Mg-C and TiO2-Mg-Zn-C. The signs of titanium carbide and intermediate titanium oxide such as Ti2O3 were observed in the milled mixtures of TiO2-Mg-C and TiO2-Mg-Zn-C after isothermal heating under argon atmosphere. The signs of Ti2O3 phase reveal that the reduction reaction of titanium dioxide does not complete after 10 h milling when metallic agents such as magnesium and/or magnesium-zinc mixture are used.

Due to significant characters of metallic lithium, many research and studies have been done on the extraction and processing of lithium form brine sources and its pegmatite deposits. Lepidolite, spodumene, petalite and zinnwaldite are the most important lithium minerals however, spodumene is the most abundant lithium minerals containing pegmatite. Lithium production has substantially increased in the past few years due to demand for lithium electronic batteries. This article is a part of research project entitled “lithium ore processing” which was undertaken during sabbatical leave at Edith Cowan University (Australia). Different processes and routs for extraction of lithium form its minerals are studied in this article. Some results of sulfation roasting with sodium sulfate for spodumene concentrate are investigated in this article under ball milling conditions. The experimental results showed that roasting reactions at temperature of 1000 ºC results in formation of the water-soluble phase, i.e. lithium sodium sulfate (LiNaSO4), in the 5 h milled mixture of sodium sulfate-spodumene. The α to ß phase transition in the spodumene concentrate occurred at lower temperature in 5 h milled samples comparing to the un-milled sample. The results showed that ball milling plays significant role in the roasting reactions stage for spodumene-sodium sulfate mixture. The produced calcine from roasting of 5 h milled mixture of spodumene-sodium sulfate can dissolve in hot water during leaching stage and water has significant advantages as leachant agent. The dissolution of lithium reached to 93% for the 5 h milled samples after heating at 1000°C in this research.

In this research perovskite phase of strontium titanate was produced from celestite concentrate (strontium sulphate). At first stage, the precursor of strontium carbonate was prepared from celestite-sodium carbonate mixture using mechanochemical process. Strontium titanate was synthesized using strontium carbonate-TiO2 mixture in the second stage. The results indicated that high energy ball milling plays a significant role in the chemical reaction and results in decreasing the temperature of post-heat treatment for producing of strontium titanate. Although some traces of rutile phase were overlapped with strontium carbonate, however no sign of chemical reaction observed in the10 hours milled mixtures of strontium carbonate-TiO2. TGA results showed that milling results in decreasing the formation temperature of perovskite strontium titanate phase in the milled mixtures. Although the traces of strontium titanate phase were revealed in the 5 hours milled mixture after isothermal heating at temperature of 600℃, the signs of un-reacted raw materials (TiO2 and SrCO3) were observed in un-milled mixture at this temperature. The traces of SrTiO3 were observed in un-milled and milled mixtures after heating at temperature of 900℃. XRD and FT-IR results indicated that strontium titanate can be synthesized form celestite concentrate (SrSO4) at lower temperatures using mechanochemical process. SEM micrographs showed that the ultrafine particles of strontium titanate (SrTiO3) can be formed in the milled samples.

Mixtures of nickel oxide and activated carbon (99% carbon) with stiochiometric ratio were milled for different times in a planetary ball mill. The stiochiometric ratio of mixture was prepared in an un-milled condition. The unmilled mixture and milled samples were subjected to thermogravimetric analysis (TGA) under an argon atmosphere and their solid products of the reduction reaction were studied using XRD experiments. TGA showed that the reduction of NiO started at ~800℃ and ~720℃ in un-milled and one-hour milled samples respectively whilst after 25 h milling it decreased to about 430℃. Increasing the amount of carbon more than stiochiometric ratio did not affect on the kinetics of carbothermic reduction. Thermodynamics assessments for NiO-C system were done using HSC software. Thermodynamics assessment and the experimental results indicated that Boudouard reaction plays a significant role in the carbothermic reduction reaction of nickel oxide. The results revealed that formation and increasing of monoxide carbon gas (COg) can change the kinetic reaction mechanism into solid-gas mechanism which has the major effect on increasing the rate of reaction. The decrease in the particle size/crystallite size of the nickel oxide in the milled samples not only resulted in decreasing in the reaction temperature, but also resulted in formation of fine particles of metallic nickel. Therefore, it is possible to achieve the metallic nickel particle in the range of submicron or nanometer via carbothermic reduction reaction of NiO using mechanical activation of NiO-C mixture.

Mixtures of zinc sulfide and aluminum (ZnS-Al) with different stoichiometric molar ratios were prepared. Then the mixtures were milled in a planetary ball mill with different times. The results indicated that aluminothermic reduction of zinc sulfide progress gradually during ball milling and the reaction does not complete after 10 hours milling. The traces of mechanically induced self - sustaining reaction (MSR) did not observe in the zinc sulfide-aluminum mixtures induced ball milling. The 3 hours milled mixtures of ZnS-Al were heated isothermally under flow of argon atmosphere for one hour. The XRD analysis of the isothermal heated samples indicated that hexagonal zinc aluminum sulfide, (ZnAl2S4), is the major product. The spinel phase (ZnAl2S4) was well crystallized after isothermal heating of 3 hours milled sample in the zinc sulfide-aluminum mixtures with molar ratio of 4:2. However, no traces of aluminum sulfide phase observed in the XRD patterns of milled mixture ZnS-Al with molar ratio of 3:2. The possibility formation of product phases was explained using HSC software of thermodynamic assessments and phase diagram of ZnS-Al2S3 system. The results showed that addition of aluminum more than of stoichiometric ratio has negative effect on the crystallization of ZnAl2S4 spinel phase. Finally, the results of isothermal heated samples showed that Al/Zn ratio and molar ratio of zinc sulfide-aluminum in the initial mixtures have significant effect on the formation of zinc aluminum sulfide (ZnAl2S4) phase.