Thermoluminescence study of Mn doped lithium tetraborate powder and pellet samples synthesized by solution combustion synthesis

In this paper, the thermoluminescence (TL) dosimetric characteristics under beta-ray, x-ray and gamma-ray excitations of powder and pellet Mn-doped lithium tetraborates (LTB) which were produced by solution combustion synthesis technique were investigated, and the results were compared with that of TLD-100 chips. The chemical composition and morphologies of the obtained LTB and Mn-doped LTB (LTB:Mn) were confirmed by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) and scanning electron microscopy (SEM) with EDX. LTB:Mn was studied using luminescence spectroscopy. In addition, the effects of sintering and annealing temperatures and times on the thermoluminescence (TL) properties of LTB:Mn were investigated. The glow curves of powder samples as well as pellet samples exposed to different beta doses exhibited a low temperature peak at about 100 °C followed by an intense principal high temperature peak at about 260 °C. The kinetic parameters (E, b, s) associated with the prominent glow peaks were estimated using Tm-Tstop, initial rise (IR) and computerized glow curve deconvolution (CGCD) methods. The TL response of integral TL output increased linearly with increasing the dose in the range of 0.1-10 Gy and was followed by a superlinearity up to 100 Gy both for powder and pellet samples using beta-rays. Powder and pellet LTB:Mn were irradiated to a known dose by a linear accelerator with 6 and 18 MV photon beams, 6-15 MeV electron beams and a traceable 137Cs beam to investigate energy response. Further, TL sensitivity, fading properties and recycling effects related with beta exposure of LTB:Mn phosphor were evaluated and its relative energy response was also compared with that of TLD-100 chips. The comparison of the results showed that the obtained phosphors have good TL dose response with adequate sensitivity and linearity for the measurement of medical doses

Chemical Additives for Corrosion Control in Desalination Plants

The addition of chemical additives has been considered as a standard operation in water treatment systems. This chapter discusses the chemical additives used for the control of corrosion in desalination systems. Specifically, corrosion inhibitors for various metallurgies, biocides, and oxygen scavengers are covered. The pros and cons of the additive chemicals have been highlighted. The need to utilize green corrosion inhibitors based on plants and ionic liquids materials have been emphasized. This class of materials are environmentally friendly, cheap, and readily available

Zinc deposited polymer coatings for copper protection

Polypyrrole (PPy) and polyaniline (PAni) coatings were electrosynthesized on copper, by using cyclic voltammetry technique. Then, these coatings were modified with the deposition of zinc particles from aqueous zinc sulphate solution. The electrodeposition of zinc was achieved at a constant potential value of -1.20 V, in the amount of ~0.75 mg/cm2. The corrosion performance of zinc modified polymer coatings were investigated in 3.5% NaCl solution; by using the electrochemical impedance spectroscopy (EIS), and anodic polarization curves. The zinc particles improved the barrier property of polymer films, thanks to formation of voluminous zinc corrosion products within the pores of polymer coating. Also, the zinc particles provided cathodic protection to the substrate, where the polymer film played the role of conductance between zinc particles and copper. © 2005 Elsevier B.V. All rights reserved

Polypyrrole films on stainless steel

Polypyrrole (PPy) films have been deposited on stainless steel substrates from two different solutions; 0.15 M LiClO4 in acetonitrile (ACN-LiClO4) and 0.3 M oxalic acid in water. For this aim cyclic voltammetry technique was used and approximately 1.7 µm thick PPy coating was obtained, applying the same potential range for the film growth in both solutions. The corrosion behaviour of coated and uncoated samples was investigated in 3.5% NaCl solution, using ac impedance spectroscopy and anodic polarisation curves. It was shown that the film obtained from ACN-LiClO4 had less porous structure and higher stability than that obtained from aqueous oxalic acid solution. The ac impedance results showed that both coatings exhibited important anodic protection behaviour and enhanced the self passivation of steel with protective oxide film. © 2005 Elsevier B.V. All rights reserved

Zinc modified polypyrrole coating on mild steel

Polypyrrole (PPy) films (~ 1.7 µm thick) have been electrodeposited on mild steel (MS) substrates from 0.1 M pyrrole containing aqueous oxalic acid solution, by using cyclic voltammetry technique. Then, the polymer coatings were modified with deposition of zinc particles (~ 1 mg/cm2), at a constant potential value of - 1.20 V in 0.2 M ZnSO4 solution. The corrosion performance of zinc modified PPy coating has been investigated in 3.5% NaCl solution, by using electrochemical impedance spectroscopy and anodic polarisation curves. Also, the corrosion behaviours of zinc modified PPy coated platinum and single PPy coated MS samples have been investigated, for comparison. It was shown that zinc modified coating exhibited very low permeability and provided important cathodic protection to MS for considerably long immersion period. The voluminous zinc corrosion products are formed during exposure time in aggressive solution, giving rise to a blocking effect on the porous structure and led to effective barrier behaviour of zinc modified PPy coating, even after 96 h of exposure time to corrosive solution. © 2006 Elsevier B.V. All rights reserved

Betonarme binaların deprem tasarımı için sayısal kriterlerin belirlenmesi

The amount of total and relative sway of a framed or a composite (frame-shear wall) building is of utmost importance in assessing the seismic resistance of the building. Therefore, the design engineer must calculate the sway profile of the building several times during the design process. However, it is not a simple task to calculate the sway of a three-dimensional structure. Of course, computer programs can do the job, but developing the three-dimensional model becomes necessary, which is obviously tedious and time consuming. An easy to apply analytical method is developed, which enables the determination of sway profiles of framed and composite buildings subject to seismic loading. Various framed and composite three-dimensional buildings subject to lateral seismic loads are solved by SAP2000 and the proposed analytical method. The sway profiles are compared and found to be in very good agreement. In most cases, the amount of error involved is less than 5 %. The analytical method is applied to determine sway magnitudes at any desired elevation of the building, the relative sway between two consecutive floors, the slope at any desired point along the height and the curvature distribution of the building from foundation to roof level. After sway and sway-related properties are known, the requirements of the Turkish Earthquake Code can be evaluated and / or checked. By using the analytical method, the amount of shear walls necessary to satisfy Turkish Earthquake Code requirements are determined. Thus, a vital design question has been answered, which up till present time, could only be met by rough empirical guidelines. A mathematical derivation is presented to satisfy the strength requirement of a three-dimensional composite building subject to seismic loading. Thus, the occurrence of shear failure before moment failure in the building is securely avoided. A designPh.D. - Doctoral Progra

Experimentally measuring the wear of the machining tool in the shaping material produced in Turkey and removal of tool life equation

Bu çalışmada,"Makina-Takım Endistrisi A.S."nin üret­tiği yüksek hız çeliği,kesici takımın talaşlı şekillendir­mede aşınmaları deneysel olarak ölçülmüş ve takım ömür denkleminde k sabiti tesbit edilmiştir. Deneyler,farklı iki yapıdaki malzeme üzerinde yapıl­mıştır . Takım ömrü ölçütü olarak, ana kesici kenar serbest yüzey aşınmasından "BOSLUK AŞINMASI" alınmış ve değeri VBB = 0,3 mm. seçilmiştir. Yumuşak malzeme olarak alınan, St 42 iş malzemesinin kimyasal kompozisyonu; % 0,167 C %0,038 S %0,40 Mn %0,15- 0,30 Si olarak saptanmıştır.Sertlik 125 Vickers 72 HRA değerindedir.Sert malzeme olarak alınan St 70 iş malzemesi­nin kimyasal kompozisyonu; % 0,45C %0,025S %0,78Mn %0,20Ni % 0,15-0,30Cr %0,30-0,40Si olarak saptanmıştır.Sertlik 205 Vickers 95,8HRA değerindedir. Deney'e alınan takım malzemesinin kimyasal kompozis­yonu % 1,15-1,30C %11W %4M %3,50V %11Co %4,50 Cr olarak sap­tanmıştır. Sertlik 300 HB değerindedir. İş malzemesi olarak St 42 kullanıldığında k= 4,8 iş malzemesi olarak St 70 kullanıldığında k= 6,93 bulunmuştur.In this study, in with chip shaping of wear of cutting group high speed Steel (HSS) that " Makina-Takım Endüstrisi AS." produces were experimantaly measured and constad k was proved in tool life equation. Test were done two different materials. As tool-life measurement, flank-wear was taken from major-flonk edge free surface wear and it's walve was chosen as VBB = 0,3 mm. Chemical composition of St 42 work piece mateirals. That is ta­ken as soft mateirals, was established as 0,167 C %, 0,038 S %, 0,40 Mn %, 0,15-0,30 Si %. Hardness is 125 vickers 72 HRA. Chemical composition of St 70 work piece mateirals. That is ta­ken as had material, was established as 0,45 C %, 0,025 S %, 0,78 Mn %, 0,20 Ni %, 0,15-0,30 Cr %, 0,30-0,40 Si %. Hardness is 205 vickers 95.8 HRA. Chemical composition of group-material is 1,15-1,30 C %,11 max W %, 4M%, 3.50 V %, 11 Co %, 4,50 Cr %. Hardness is 300 HB. When St 42 was used as work piece-material was found k= 4,8. when St 70 was used as work piece material was found k= 6,93

Elektrokimyasal olarak oluşturulacak polipirol kaplamanın demirli malzemelrin korozyon davranışları üzerine etkilerinin incelenmesi

TEZ5582Tez (Doktora) -- Çukurova Üniversitesi, Adana, 2005.Kaynakça (s. 148-154) var.ix, 154 s. ; 30 cm.