ة مجلة إبن الھیثم للعلوم الصرفة و التطبیقی 2012 السنة 25 المجلد 1 العدد Ibn A l-Haitham Journal f or Pure and Applied Science No. 1 Vol. 25 Year 2012 Using Gamma Ray Transmission for Determination of Porosity in Doped Alumina Samples A. J. Al- Saadiand A. K. Saadon College of Dentistry, Unive rsity of Karbala Departme nt of Physics, College of Education I bn Al-Haitham, Unive rsity of Baghdad Received in: 27April 2011,Accepted in: 18October2011 Abstract In t his study, gamma ray t ran smission met ho d have been used to determ ine t he t otal porosity in four samples: pure Alumina ( Al2O3 ), Al2O3 + (0.2wt %)MgO , Al2O3 + (0.6wt % )Y2O3 and Al2O3+ (8 wt % ) ZrO2 . T he ex periment al set up for t he gamma ray t ran smission co nsist of 13 7 Cs gamma source ( 662 KeV ), a NaI (T l) scint illat ion detect or measured t he at t enuat ion of stro ngly collimat ed gamma beam t hr ough alumina samples. T he p oro sity obt ained by t he gamm a ray t ran smission met hod were co mp ared wit h t he measurements by co nvent ion al (Archim edes) met hod. I t was observ ed that t he p oro sity measurem ent by gamma ray t ran smission met ho d has t he advant age of being accurat e, non dest ruct ive an d fast an alysis. Ke ywords: Gamma ray, Att enuat ion coefficient s, P oro sit y, Doped alumin a Introduction P oro sity is an impor t ant paramet er comm on ly used to describe t he behav ior of prose material, that is of great int erest in many areas such as medicine, pet ro leum, engineerin g, met allurgy , nuclear react or t echnolo gy an d ot her applicat ion s [1, 2 ]. T he p oro sity of a medium can be expr essed as a rat io of vo lume of t he vo id space to the bulk volume, t hat is a dimen sionless quant it y usually ex pr essed in percent age. Measurement of mat erial's por osity are usually perfor med by convent ion al met hods like Archimedes por osimet ry and mercury inject ion po ro simet ry [3 , 4] . However t he gamma ray t ran smission t echnique is allows determ inat ion of t he poro sity wit hout int erferin g in t he p hy sical int egrit y of t he sample [5]. T he met hod of gamma ray t ran smission was applied in the measurement of reservo ir ro cks por osity by P hogat and Aylmo re [6 ]. Oliveira et al. uses x ray in poro sity measurem ent s of t it anium sint ered foams [7]. Dem ir et al. uses gamma ray t ran smission in por osity measurem ent s of soil[8] . Alumina exhibit low volume dilatat ion an d high t herm al co nduct ivit y co efficient , ano t her application of this material is to cover recipients exp osed to thermal shocks and high temp eratures (up to 1700 °C) It is very imp ortant t o determine the p orosity of sintered materials because this p arameter has a large influence the efficiency of there app lications. In the p resent work, gamma ray att enuation coefficient and p orosity of p ure Alumina ( Al2O3 ), Al2O3 + (0.2wt %)M gO, Al2O3 + (0.6wt %) Y2O3 and Al2O3+ (8wt % )ZrO2 are determined by using gamma ray transmission method. The gamma ray att enuation measurements have carried out , using 137 Cs radioactive source. ة مجلة إبن الھیثم للعلوم الصرفة و التطبیقی 2012 السنة 25 المجلد 1 العدد Ibn A l-Haitham Journal f or Pure and Applied Science No. 1 Vol. 25 Year 2012 Experimentation 1. S amples preparation High p urity α-Alumina was used as t he starting p owder. The p owder characterist ic was 0.3µm average p article size. Samp les of alumina containin g weight p ercentages of M gO ( 0.2wt% ), Y2O3 ( 0.6wt% ) and ZrO2 (8wt%.) were prep ared by mixing for (20 hrs). After that, the mixture was p ressed to p ellets with 20mm diameter and ap p roximately 2mm thickness. T hese pellets were heated at 1550°C in air for 14hrs. Sintered densities were measured by using the Archimedes m ethod with mercury as the immersion medium. 2. Experime ntal se tup The gamma ray transmission sy st em consisted of radioactive source 137 Cs ( 662 KeV ) with an activity 100 µci . The radioactive source was shielded by the pin-hole lead collimator to obtain a narrow beam ( 3mm diameter ). The intensities of gamma p hotons were measured by using NaI(Tl) scintillation detector (Saint- Gobain Cry st als Bicron model 1.5in.× 2 in. made in U.S.A.). The detector was coupled to p re-amplifier, amp lifier, p ower sup p ly and comp uter analyzer with LD Didactic GmbH sensor-cassy for data acquisition and analy sis t he obtain areas. The detector was also housed in a thick lead jacket with a 10 mm diameter holed collimator. Fig.1 shows schematic arrangement of t he exp erimental setup used in the p resent study . Samp les were used in the form of a tablets p lates with app roximately 20mm diameter and 2mm thickness. Each sp ectrum was recorded for a p eriod of 1000 sec, to reduce the st atist ical error. Background sp ectra were recorded for the same time p eriod and subt racted from each sp ectrum. 3. Porosi ty determination For determination of the total p orosity by gamma ray transmission method, it is necessary to determine the linear att enuation coefficient for the materials. The attenuation of a narrow collimated beam of gamma ray s for a given energy can be obtained by the relationship [ 8,9 ]: )1(...................0 xeII  Where I0 is the initial intensity of gamma rays , I is the intensity of gamma rays after att enuation through a media of thickness x and µ is the linear att enuation coefficient of the material. Equation (1) may also be written as: )2(...................ln 1 0 I I x  Total p orosity ( Pt ) of a medium can be d escribed as[10,11 ]: ة مجلة إبن الھیثم للعلوم الصرفة و التطبیقی 2012 السنة 25 المجلد 1 العدد Ibn A l-Haitham Journal f or Pure and Applied Science No. 1 Vol. 25 Year 2012 )3(................. p ap Pt     Where µp ( cm -1 ) is the linear att enuation coefficient of t he samp le at t he particle density and µa ( cm -1 ) is the linear attenuation coefficient of t he samp le crossed gamma ray beam. The linear att enuation coefficient of the sample (µa ) was exp erimentally determined by measuring the gamma att enuation through a known thickness of samp le for 662 KeV p hotons. The linear att enuation coefficient of the samp le at t he particle density (µp ) was accomplished by the app lication of the software XCOM [12], taking into account the chemical comp osition and bulk density of the samp le. For determination of the total p orosity by conventional method ( Archimedes ), using the following relation [10, 11 ]: )4(............... sss ds ww ww Pt    Where Ws is the weight in the air of the samp le saturated with water, Wd is the dry sample weight in the air and Wss is the weight saturated of water susp ended in water. Results and Discussion M easurement of material bulk density involves the determination of the mass and the volume of a given amount of alumina samples. Table 1 shows the measured bulk density , average values obtained for linear att enuation coefficients of the samples(µa ) and linear att enuation coefficients of the samp les at p article density (µp ). Table 2 shows the average total p orosity for the alumina samples by gamma-ray transmission method (calculated by eq.3 ) and by Archimedes method (calculated by eq.4 ). The values obtained by gamma ray method are larger than that obtained by Archimedes method, because the gamma ray transmission method characterizes total p orosity while the Archimedes method characterizes only connected p ores that rep resents app ortion of the total p orosity . Conclusions The total p orosity ( % ) of alumina samples were determined by gamma ray transmission method and Archimedes method. The results obtained for the total p orosity ( % ) by gamma ray method shown deceasing behavior with increasing the linear att enuation coefficient of t he sample (µa ) crossed gamma ray beam. The gamma ray transmission method gives characterizes total p orosity while the Archimedes method characterizes only effective p orosity or connected p ores that represents app ortion of the total p orosity . The comp arison between exp erimental results gives the gamma ray transmission method app ears to offer advantages such as inexp ensive, non destructive and fast analysis according to conventional Archimedes method. ة مجلة إبن الھیثم للعلوم الصرفة و التطبیقی 2012 السنة 25 المجلد 1 العدد Ibn A l-Haitham Journal f or Pure and Applied Science No. 1 Vol. 25 Year 2012 Re ferences 1. Ouellet, S.; Bussièr e, B.; Aubertin, M . and Benzaazoua, M .(2007), Research ,M icro st ructural evolution of cemented paste backfill: mercury intrusion porosimetry test results, Cement and Concrete Rese arch , 37,1654-1665. 2. M edvedovski, E. (2006) Ceramics Int ernational ,Alumina–mullite ceramics for st ructural applications, 32 ,369–375. 3 . Innocentini, M . D.; Pardo, A. R. and Salvini, V. R. (2002), Cerâmica ,Prediction of p ermeability constants t hrough p hysical prop erties of refractory cast ables, Issn 0366-6913, 48(305): 05-10 . 4. M oreira, A.C. and App oloni, C. R.( 2009), International Nuclear At lantic Conference - INAC. Porosity determination of alumin a and boron carbide ceramic samples by gamma r ay transmission, ISBN: 978-85-99141-03-8. 5. Bodwakar, S. V.and Reis, J.C.( 1994 ). Porosity measurements of core samples using gamma-ray att enuation Nucl. Geop hy s 8 (1):61–78. 6 . Phogat, V.K. and Ay lmore, L.A. (1989), . Evaluation of soil st ructure by using comp uter assisted tomography Soil Phys. Hy drol 27,313–323. 7. Oliveira, M . V.; M oreira, A. C., App oloni C. R, Lopes R. T., Pereira L. C. and Cairo C. A., (2006) , Porosity study of sintered titanium foams ,M aterials Science Forum 530-531,.22-28 8. Demir D.; Oz gul, A. and Sahin, Y.(2008). Determination of p hoton attenuation coefficient, p orosity and field cap acity of soil by gamma r ay transmission for 60,356 and 662KeVgamma ray ,App l. Radiat. and Isot 66,1834-1837. 9.Raje, D.V. and Chaudhari, L.M .( 2010), M ass attenuation of soil samp les in M aharashtra (India ) by using gamma en ergy at 0.662 M eV Bulg. J. Phy s. 37,158-164. 10 . Pottker, W.E. and App oloni, C.R.( 2001),M easurement of amorp hous materials p orosity by gamma-r ay transmission methodology , Radiation Phy sics and Chemist ry 61,535–536. 11. App oloni, C. R. and Pottker ,W. E.( 2004),Non-Destructive p orosity p rofile measure ment of amorp hous materials by gamma-ray transmission, App lied Radiation and Isot op es 61, 1133-1138. 12. Hubbel, J.H.and Berger, M .J.(1987), NBSIR ,p hoton cross sections on a p ersonal comp uter ,3597-3598. Table (1): Experime ntal values of bulk density , linear attenuation coefficients of the sample s at particle densi ty (µp ) and linear attenuation coefficients of the samples crossed gamma ray beam. (µa ) Material Bul k De nsi ty (g.cm -3 ) µp (cm -1 ) µa (cm -1 ) Al2O3 2.40±0.013 0.18211 0.1349±0.0004 Al2O3 + 0.2wt%M gO 2.65±0.015 0.20108 0.1537±0.0009 Al2O3 + 0.6wt% Y2O3 2.75±0.016 0.20864 0.1714±0.0010 Al2O3+ 8wt%Z rO2 2.89±0.015 0.21891 0.1855±0.0005 ة مجلة إبن الھیثم للعلوم الصرفة و التطبیقی 2012 السنة 25 المجلد 1 العدد Ibn A l-Haitham Journal f or Pure and Applied Science No. 1 Vol. 25 Year 2012 Table (2): Average value s of total porosity for the alumina samples obtained by gamma-ray transmission method and by conventi onal method ( Archi medes) Tot al porosi ty (%) Mate ri al gamma transmission Archime des Al2O3 25.9198±0.2196 22 .10 ±1.00 Al2O3 + 0.2wt%MgO 23.5323±0.4477 20 .67 ±1.30 Al2O3 + 0.6wt % Y2O3 17.8733±0.5195 16 .64 ±1.50 Al2O3+ 8wt% ZrO2 15.2619±0.2283 13 .78 ±1.12 Fig.(1): Experime ntal se tup for the measuring of line ar attenuati on coefficie nts ة مجلة إبن الھیثم للعلوم الصرفة و التطبیقی 2012 السنة 25 المجلد 1 العدد Ibn A l-Haitham Journal f or Pure and Applied Science No. 1 Vol. 25 Year 2012 استخدام نفاذیة أشعة كاما لتعیین المسامیة في عینات األلومینا المشوبة عباس كریم سعدون ، دي عباس جواد السع كربالءكلیة طب األسنان ، جامعة بغدادقسم الفیزیاء ، كلیة التربیة ابن الهیثم، جامعة 2011 تشرین االول 18: في ث بل البح ق،2011 نیسان27: استلم البحث في الخالصة ِتم في هذه الدراسة استخدام تقنیة نفاذیة أشعة كاما لتعیین المسامیة الكلیة ألربع عینات ِ األلومینا النقیة: ِّ (Al2O3) ، Al2O3 +(0.6wt%) Y2O3 ، Al2O3 +( 0.2wt%)MgO و Al2O3+ (8wt% )ZrO2. 662ذو الطاقـة ) فوتـون ( الباعـث ألشـعة كامـا 137 –الـسیزیوم تـضمنت منظومـة القیـاس كـل مـن مـصدر أشـعة كامـا لقیـاس تـوهین حزمـة أشـعة كامـا فــي NaI(Tl( الومیـضي یـود یـد الـصودیوم المنـشط بالثـالیوم كاشـف فولـت والإلكتـرون كیلـو .عینات األلومینا َلـوحظ ). طریقـة أرخمیـدس (ِول علیها بطریقة نفاذیة أشعة كامـا مـع الطریقـة التقلیدیـةُ قورنت المسامیة التي تم الحص . ِإعطاء نتائج دقیقة وغیر اتالفیة للنماذج وسریعة: منها عدیدة طریقة نفاذیة أشعة كاما تمتلك فوائدان األلومینا المشوبة،المسامیة، معامالت التوهین،أشعة كاما : الكلمات المفتاحیة