Characterization and Analysis of Glass (Essay Sample)

CHARACTERIZATION AND ANALYSIS OF GLASS
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Characterization and analysis of glass
Introduction
Glass is a non-crystalline engineering design material formed by combining of inorganic materials like metallic oxides with carbonates. It has good thermal, optical, electrical, and mechanical properties. For this reason, engineers prefer to use it in situations where metals and plastics would fail. The analysis of glass allows a researcher to find the trace materials that make up the glass material. The analysis allows a designer to apply their knowledge in creating materials that meet optimum performance.
Properties of glass
Glass is resistant to most corrosive substances like solvents, and acids. However, forensic scientists have to collect information about the specific reactions of glass to different environmental conditions before they employ glass for construction and design. Glass is brittle due to its low ductility. They have low coefficients of thermal expansion and conductivity. They are good insulators of electric energy; hence, they do not conduct electricity. Their optical properties make them suitable for the manufacture of lenses and light transmitting materials for buildings to allow light into buildings. Glasses that have high amounts of silica have high thermal shock resistance (Shackelford, 2008).
However, the commercial use of glass is dependent on its strength for engineering application. The manipulation of glass to vary its refractive and reflective properties makes it suitable and adaptable to different engineering situations like manufacturing prisms, lenses, and optical fibers. Due to computer aided manufacturing and design, glass-processing techniques employ computer-managed processes to control the quality and quantity of glass by manipulating the thickness and refractive index of the glass. This allows the industry to have specific market targets (Shackelford, 2008).
Uses of glass
Soda lime glass is the most readily found type of glass used for manufacturing light transmission material into buildings. The fusion of glass with metal oxides creates different colors of glasses; this property makes it suitable for manufacturing art objects like tainted glass (Siegel, 2006). In technology, glass has shielding properties against harmful sound waves and radiation waves like x-rays, and gamma rays. Glass is a reinforcement material for making composite materials such as plastic laminates, filler plastics and laminated glass. These composite materials have superior properties than the individual materials that make up the composite (Siegel, 2006). Glass is resistant to corrosion; this property is applicable in the food industry to manufacture the inner linings of food tanks. This property makes the food tanks resistant to chemical corrosion. Building glasses have high compressive and tensile strengths hence they can endure high stress loads and varied environmental conditions in high and medium rise buildings. Glass melts at high temperatures, once melted they mold into different shapes and sizes for different technological and forensic needs (Siegel, 2006).
Composition of glass
Different formulas for manufacturing glass affect the mechanical, electrical, chemical, optical, and thermal integrity of the glass produced. An engineer requires three components to manufacture glass, they are, formers, fluxes and stabilizers (Bach, 2010). The formers make up for the largest percentage of the composition of glass. The most readily available former is silicon dioxide that makes up 75% of soda lime glass. Silicon dioxide comes in form of fine sand. Fluxes lower the temperatures of the mixture in the furnace because fine sand requires very high temperatures to melt. The former increases the efficiency of the furnace. The most common types of formers include sodium carbonates and potassium carbonate. Stabilizers in glass manufacture make the glass strong and resistant to corrosion from water. Stabilizers consist of calcium carbonates (Bach, 2010). Water makes glass weak and the amount of stabilizers applied in glass design determines the eventual type of glass produced. Different substances may be included in the melt to change the specific properties of the glass a scientist intends to achieve, for example, the addition of lead increases the luster and the mass of glass. Addition of barium changes the refractive index. Cerium regulates the ability of the glass to absorb infrared light. Metal oxides change the color, whereas manganese removes the color from the glass (Bach, 2010).
Elemental analysis of glass
The analysis of glass allows a researcher to evaluate trace elements that make up the glass material. The technique employed for evaluating glass samples depends on the sizes of the fragments and their shapes and the need for the examining the samples (Hornbostel, 1991). All samples require cleaning before analysis. An analyst should choose samples from different areas to increase the variability and scope of the research. The size and the number of samples chosen for evaluation depend on the technique employed, the criteria for interpreting the data collected, and the size of the glass fragments.
The aim of elemental analysis of glass is to help distinguish different types of glasses based on their chemical and physical properties. Elemental analysis caters to the minor and major components of glass. The major elements of glass consist silicon, sodium, calcium, magnesium, and potassium, whereas, the minor elements of glass consist aluminum, iron, Barium, manganese, titanium, strontium and they make up for less than 0.1 percent of the composition of glass (Hornbostel 1991). The refractive index shows different optical properties in glass to natural light. By obtaining the refractive index, an engineer distinguishes one type of glass from the other. The different refractive indices indicate the differences in the composition of major components of glass. The compositions of the major elements enable the analyst to distinguish between types of glasses while the minor elements help to categorize the types of glasses. A wide variety of techniques enables engineers to carry out elemental analysis. Such methods include the use of SEM-EDX method, x-ray method, fluorescence method and the neutron activation technique (Hornbostel, 1991).
Manufacturers give the end use products certain desirable properties deliberately by controlling the concentrations of some elements that constitute glass (Hills, 2007). The data that enables manufacturers make different glass types, helps analysts to identify the characteristics of a recovered glass sample or piece. The physical properties like the color and the thickness of the glass of glass help to determine the source of the sample piece. Elemental evaluation of glass enables an analyst compare minor variations in the elemental composition between common sources and within batches. This data helps determine an elemental profile of common sources and variations within batches of glasses samples, hence, the need for precise and exact techniques for glass evaluation.
The SEM/EDX technique of characterization of glass
In this technique, glass classification happens based on the elemental ratios of Magnesium and calcium. For example, the elemental composition for manufacturing glass containers requires the calcium/magnesium ratio be more than 15. This technique is non-destructive. Its weakness is that, it does not detect the levels of iron in a glass sample. It also is not sensitive while detecting trace elements. For this reasons, the XRF technique is much more superior (Houck, 2004).
The X-ray method
This method employs the use of a focused electron beam illuminated across the surface of glass samples, hence a discharge of X-rays from the sample. The wavelengths of the discharged rays distinguish the elements whereas; the intensity of the rays determines the quantities of each element present in a sample. This method of glass characterization requires the employment of either of two methods of detecting X-ray emissions from the glass samples. These techniques include the wavelength dispersive X-ray spectrometry (WDS) and the energy dispersive X-ray spectrometry (EDS) (Houck, 2004).
The WDS techniques employ a crystal monochromator that helps in determining the wavelengths of discharged radiation. This method gives an accurate spectral resolution of the glass samples hence giving precise ways of identifying the smallest elements that constitute a sample. However, the difficulty of operating the technique and the costs incurred while carrying out this research hinders its application in forensic science (Schmidt, 2013).
The EDS uses the intensity of radiation emitted from the glass samples to help differentiate glass samples. This method of spectrometry gives the fast and rapid results. The cost for operating this technique are relatively lower that WDS technique hence its popularity. The calcium/magnesium technique from the X-ray fluorescence combined with the data obtained from scanning E.D.S technique provides a systematic format for placing the glass into sheet or container categories. To acquire accurate results from the spectrometry, the samples have to be small, clean, and dried (Schmidt, 2013).
The X-ray Fluorescence technique
The X-ray fluorescence technique is a method of analyzing glass involving the emission of gamma rays to bombard with the glass samples hence causing the process of ionization. The fluorescence chamber captures the emissions from the glass samples. The spectrometer gives the data of the glass samples pieces.
The X-ray fluorescence method of evaluating glass samples is a non-destructive technique for analyzing small samples. It acquires faster results when compared to the SEM/EDX technique. I...