Sodalı camların elektromanyetik radyasyon karşısındaki davranışı

Abstract

Yaygın kullanımı olan cam türlerinden biri olan soda camlarının elektromanyetik radyasyon kaarşısındaki davranışı bu çalışmayla İncelenmeye çalışılmıştır. Burada soda camı olarak nitelenen ve Üzerinde çalışılan camların kimyasal bileşimi esas itibariyle SİO. Al O-, Fe O-, TİO. CaO. 2 2 3 2 3 2 MgO, Na O, K O ve SO içermektedir. Bu camlar Topkapı Sise 2 2 9 Cam Fabrikasın' dan kimyasal analizleri yapılmış, birbirinin aynı ve fakat farklı kalınlıklarda 5x3 cmZ ' lik camlar olarak özel şekilde temin edilmişlerdir. Elektromanyetik radyasyon karsısında soda camlarının davranışları, elektromanyetik radyasyonun tipine bağlı olarak farklı olabilmektedir. Burada elektromanyetik radyasyon olarak kızılötesi, görünür ışık, morötesi, X-ışınları gama ısınları ile çalışılmıştır. Bir başka deyişle, radyo dalgaları dışında tüm elektromanyetik radyasyon ailesine mensup ısınlara karsı soda camlarının bu ısınları geçirgenlikleri ve yansıtmaları ayrı ayrı tesbit edilmiş ve absorbsiyon oranları tayin edilmiştir. Ayrıca, yüksek dozda radyasyonun camlarda meydana getirdiği değişimler tesbit edilmeye çalışılmıştır. Bu amaçla, sodalı camlar, Co-60 radyoizotop kaynağı kullanılarak farklı dozlarda ışınlanmışlar ve görsel olarak da rahatlıkla gözlenebilen renklenme meydana geldiği tesbit edilmiştir. Söz konusu bu renklemdirilmiş camlar spektrofotometre yardımı ile incelenerek, farklılıklarının değerlendirilmesi yapılmıştır. Böylelikle, pencere camından, ayna ve sise camına kadar farklı amaçlarla, yaygın kullanımı olan ve ülkemiz mamulü soda camlarının elektromanyetik radyasyon karşısındaki davranışı rasyonel şekilde ve mukayeseli olarak incelenmiştir. xvi -

Glass is one of man's most valuable and versatile materials. Glass technology has advanced a great deal in the last fifty years. One of the earliest developments was air tempering to improve strength. Some standard tempered products are strong enough to withstand severe abuse. Glass formers are those elements such as silicin, boron, phosphorus, a nd arsenic that can be converted into glass when combiined with oxygen, sulfur, tellurium or selenium. In the liquid state, the silicon-oxygen bond is very strong so that a high activation energy is necessary to break the bond. The molecular arrangement is conductive to formation of an intricate three-dimensional network of oxyen tetrahedra with a silicon atom in the middle bonded to each oxygen atom. Common glasses contain about 70 % Sİ0. 2 About 700 different glass compositions are in commercial use, but theycan be classified in six main groups; Soda glasses Borosilicate glasses Lead glasses Wire glasses Special glasses - xvii -Most wide ver seti le glass is soda glasses that are used in different areas widespread. Sodium carbonate, or soda ash, decomposes to sodium oxide as the batch of raw material melts. Consequently, it acts as a flux. The carbon dioxide given off helps to stir the batch. The oxide lowers the melting point and the viscosity of the formed glass at any given temperature. This occurs as a result of the substitution of nondirectional silicon-oxygen bond in the molecular network. Limestone and dolomite act similar to soda ash, but ar used to make the glass more inert to water and to add other desirable properties. Other oxides, chiefly aluminium, lead and cadmium, act as stabilizers. They are used for increasing the strength of the glass and increasing resistance to chemical attack. Sodium or barium sulfate may be added to enhance the removal of fine particles of uncombined silica which may form a scum. Various iron compounds, chromium compounds, carbon and/or sulfur are used as coloring agents. Soda-lime-silica glass of ardinary composition containing a small concentration of reducing ions at least in surface layers thereof and having no visible coloratiion are given a yellow coloration by diffusing a substance into such surface layers from contacting medium. That are composed of a mixture of metal salts contaiiniing between 0.01 and 3 % by weight of a silver salt furnishing reducible silver metal ions capable of being reduced by the reducing ions in the glass in such a manner as to give the glass a yellow coloration. The process can be employed not only for coloriing initially colorless glass but also for mofifying the color of a glass body which has already been given some coloration. The modification of the coloration can result in a modification in the existing color, or tint, or can simply reinforce the existing color, or render the existing color, or tint, more intense, or darker. - xviii -Glass containing more than 0.0S % of nickel oxide, cobalt oxide, copper oxide, silver oxide or the like as a principal colorant is formed into flat glass by cooling it from a molten state while supporting it on molten metal in enclosed chamber containing sufficient oxygen to substantially prevent the formation of a visually observable metal-containing material on the surfaces of the glass being formed. The metal oxides employed as principle colorants are sufficiently reducible to form free metal. The metal oxides are primarily those which have favored monoxide forms. The colors range from light yellow through brownish grenn to chocolate and reddish brown. All these colors, in addition to being distinct, are ultraviolet absorbing colors. Glass melts were made where the hexavalent chrome levels ranged from O.OSS to 0.10 wt 3* and the manganese oxide levels extended from 0.10 to 0.1S wt %. The colors produced ranged from greenish brown to reddish brown. The fact that the spesific volume of glass is approximately an additive property of its constituent oxides has long been recognized within a narrow composition range. Calculation of density by means of additive factors often gave a fair approximation to the correct value. Today, there are different types of glass but in this study» investigation have been done on a common type soda glass that consists of Sİ0, Al 0_. Fe 0_, 2 2 3 2 3 TiO, CaO, MgO, Na O, K O and SO. Glasses have been 2 2 2 3 supplied from Topkapi Sise Cam Factory in different thickness but in the same chemical compound and they are cutting as square shape in S x S cm dimensions. - xix -In the other hand, electromagnetic radiation, of the same physical nature as visible light, radiowaves, etc., but which have a wavelength which allows them to penetrate all materials with partial absorption during transmission. They travel in straight lines outwards from a source. Energetic gamma rays can be effected on glass and caused changing the colors of it. In this study Co-60 radioisotope which has 1.17 MeV and 1.33 MeV gamma energy peaks, have been used for experiments as a exposing source. After the exposure with the different dose levels, the color of the glasses turn to brown according to doses. For all the glasses, transmission and reflection rates for visual and solar light have been measured by using spectrophotometer between 18S nm - 2500 nm and absorption rates can be determined. Some different measurements have been also done related to determination of transmission for ultraviolet rays, X-rays and gamma rays. In here, three different ultraviolet sources as black lamp, sun lamp and far lamp, and a spesial UV sensor are used for measurement of transmission. An X-ray tube is used as a source, and transmission is measured according to energy ranges between 18-70 KeV. After that absobant ratio is calculated for the soda glasses. Seven different gamma radioisotopes that are Co-S7, Co-60. Cs-137, Ba-133. Na-22. Cd-109 and Mn-34. are used as a source, and a scintillation detector with multichannel analyzer counting system used for measurements. - xx -In the result of the study; after high level gamma ray exposing which caused the change in the color of the glasses, are observed and differences according to each other are determined by measurements of transmission rate of electromagnetic radiation. - xxi -