Scholarly

Study on the Production of Chromite Refractory Brick from Local Chromite Ore

Year: 2008 Volume: 2 Issue: 10 250 - 255 Pages

Abstract: Chromite is one of the principal ore of chromium in which the metal exists as a complex oxide (FeO.Cr2O3).The prepared chromite can be widely used as refractory in high temperature applications. This study describes the use of local chromite ore as refractory material. To study the feasibility of local chromite, chemical analysis and refractoriness are firstly measured. To produce chromite refractory brick, it is pressed under a press of 400 tons, dried and fired at 1580°C for fifty two hours. Then, the standard properties such as cold crushing strength, apparent porosity, apparent specific gravity, bulk density and water absorption that the chromite brick should possess were measured. According to the results obtained, the brick made by local chromite ore was suitable for use as refractory brick.

Investigation of Tool Temperature and Surface Quality in Hot Machining of Hard-to-Cut Materials

Year: 2008 Volume: 2 Issue: 10 245 - 249 Pages

Abstract: Production of hard-to-cut materials with uncoated carbide cutting tools in turning, not only cause tool life reduction but also, impairs the product surface roughness. In this paper, influence of hot machining method were studied and presented in two cases. Case1-Workpiece surface roughness quality with constant cutting parameter and 300 ºC initial workpiece surface temperature. Case 2- Tool temperature variation when cutting with two speeds 78.5 (m/min) and 51 (m/min). The workpiece material and tool used in this study were AISI 1060 steel (45HRC) and uncoated carbide TNNM 120408-SP10(SANDVIK Coromant) respectively. A gas flam heating source was used to preheating of the workpiece surface up to 300 ºC, causing reduction of yield stress about 15%. Results obtained experimentally, show that the method used can considerably improved surface quality of the workpiece.

The Effect of Ageing Treatment of Aluminum Alloys for Fuselage Structure-Light Aircraft

Year: 2008 Volume: 2 Issue: 10 241 - 244 Pages

Abstract: As the material used for fuselage structure must possess low density, high strength to weight ratio, the selection of appropriate materials for fuselage structure is one of the most important tasks. Aluminum metal itself is soft and low in strength. It can be made stronger by giving proper combination of suitable alloy addition, mechanical treatment and thermal treatment. The usual thermal treatment given to aluminum alloys is called age-hardening or precipitation hardening. In this paper, the studies are carried out on 7075 aluminum alloy which is how to improve strength level for fuselage structure. The marked effect of the strength on the ternary alloy is clearly demonstrated at several ageing times and temperatures. It is concluded that aluminum-zinc-magnesium alloy can get the highest strength level in natural ageing.

Study on Extraction of Niobium Oxide from Columbite–Tantalite Concentrate

Year: 2008 Volume: 2 Issue: 10 238 - 240 Pages

Abstract: The principal objective of this study is to be able to extract niobium oxide from columbite-tantalite concentrate of Thayet Kon Area in Nay Phi Taw. It is recovered from columbite-tantalite concentrate which contains 19.29 % Nb2O5.The recovery of niobium oxide from columbite-tantalite concentrate can be divided into three main sections, namely, digestion of the concentrate, recovery from the leached solution and precipitation and calcinations. The concentrate was digested with hydrofluoric acid and sulfuric acid. Of the various parameters that effect acidity and time were studied. In the recovery section solvent extraction process using methyl isobutyl ketone was investigated. Ammonium hydroxide was used as a precipitating agent and the precipitate was later calcined. The percentage of niobium oxide is 74%.

Affine Radial Basis Function Neural Networks for the Robust Control of Hyperbolic Distributed Parameter Systems

Year: 2008 Volume: 2 Issue: 10 231 - 237 Pages

Abstract: In this work, a radial basis function (RBF) neural network is developed for the identification of hyperbolic distributed parameter systems (DPSs). This empirical model is based only on process input-output data and used for the estimation of the controlled variables at specific locations, without the need of online solution of partial differential equations (PDEs). The nonlinear model that is obtained is suitably transformed to a nonlinear state space formulation that also takes into account the model mismatch. A stable robust control law is implemented for the attenuation of external disturbances. The proposed identification and control methodology is applied on a long duct, a common component of thermal systems, for a flow based control of temperature distribution. The closed loop performance is significantly improved in comparison to existing control methodologies.

Numerical Study of Microscale Gas Flow-Separation Using Explicit Finite Volume Method

Year: 2008 Volume: 2 Issue: 10 227 - 230 Pages

Abstract: Pressure driven microscale gas flow-separation has been investigated by solving the compressible Navier-Stokes (NS) system of equations. A two dimensional explicit finite volume (FV) compressible flow solver has been developed using modified advection upwind splitting methods (AUSM+) with no-slip/first order Maxwell-s velocity slip conditions to predict the flowseparation behavior in microdimensions. The effects of scale-factor of the flow geometry and gas species on the microscale gas flowseparation have been studied in this work. The intensity of flowseparation gets reduced with the decrease in scale of the flow geometry. In reduced dimension, flow-separation may not at all be present under similar flow conditions compared to the larger flow geometry. The flow-separation patterns greatly depend on the properties of the medium under similar flow conditions.

Study on Extraction of Lanthanum Oxide from Monazite Concentrate

Year: 2008 Volume: 2 Issue: 10 223 - 226 Pages

Abstract: Lanthanum oxide is to be recovered from monazite, which contains about 13.44% lanthanum oxide. The principal objective of this study is to be able to extract lanthanum oxide from monazite of Moemeik Myitsone Area. The treatment of monazite in this study involves three main steps; extraction of lanthanum hydroxide from monazite by using caustic soda, digestion with nitric acid and precipitation with ammonium hydroxide and calcination of lanthanum oxalate to lanthanum oxide.

International Journal of Chemical, Materials and Biomolecular Sciences

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