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X-Ray Analysis of Ceramics
 

X-Ray Analysis of Ceramics

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A look into how x-ray technology is utilized in the ceramic industry. ...

A look into how x-ray technology is utilized in the ceramic industry.

As the complexity of ceramic materials evolves, techniques and technologies are required to study, identify and measure them. Non-destructive X-ray spectrometry is a technique that quickly addresses important questions such as:

Elemental composition
Arrangements of those elements
Quantity of elements and compounds

This information is needed from the mining of raw materials to the finishes applied to them as final products.

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    X-Ray Analysis of Ceramics X-Ray Analysis of Ceramics Presentation Transcript

    • X-Ray Analysis of Ceramics: A Look into How X-Ray Technology is Utilized in the Ceramic Industry Dan Davis and Robert H. Clifford, Ph.D February 2013
    • Introduction Ceramics are found in most aspects of daily life, as society continues to rely on their versatility. Ceramics are sought after for their strength, making them good structural materials, as well as insulators for heat and electricity. Glass-ceramics are also used to make optical equipment and fiber insulation. Other attributes:  Hardness  Abrasion resistance  Chemical resistance, especially to caustic applications 2
    • Introduction As the complexity of ceramic materials evolves, techniques and technologies are required to study, identify and measure them. Non-destructive X-ray spectrometry is a technique that quickly addresses important questions such as:  Elemental composition  Arrangements of those elements  Quantity of elements and compounds This information is needed from the mining of raw materials to the finishes applied to them as final products. 3
    • X-Ray Fluorescence vs. X-Ray Diffraction This presentation describes two aspects of X-ray spectroscopy:  X-ray  X-ray fluorescence (XRF) diffraction (XRD) These technologies are well-established and used in various industries to answer the same questions of elemental composition and how those elements are connected. 4
    • X-Ray Fluorescence vs. X-Ray Diffraction Example: Diamonds and Graphite Although they are made from the same element (carbon), they are two very different compounds with different physical properties. XRF — Identifies that both compounds are 100% carbon XRD — Reveals how carbons are connected to each other, which gives diamonds and graphite different properties and values XRF and XRD spectroscopy provide different information but 5 can complement each other.
    • How Does This Apply to Ceramics? All ceramics have one thing in common:  They did not start out as ceramics.  Raw materials were processed to make them. Consider historic ceramics:  They began as clay and were processed into ceramic materials and objects.  These starting materials need to be mined, identified and refined. 6
    • XRD Spectroscopy XRDs are well-suited for identifying types of clay Each clay has a specific elemental composition and arrangement of those elements. This gives each type of clay a unique diffraction pattern similar to a fingerprint. XRDs are used in mining industries to quantify the clays contained in the mines. Samples are taken and processed by different techniques to achieve a powder sample that can be analyzed. 7
    • Diffraction Pattern of Bentonite Bentonite: a clay consisting mostly of montmorillonite and other minerals. Industrial applications include:  Mud drilling component  Cement additive  Making green sand for sand casting  Protein absorber in wine making 8
    • Diffraction Pattern of Bentonite Figure 1 shows a diffraction pattern of a sample of bentonite. Figure 1: X-Ray Diffraction of Bentonite Clay (top) and spectral reference of the minerals identified, montmorillonite, quartz, calcite, and cristobalite Depending on the application, certain ratios or particular minerals are more favorable for different applications. Therefore, it is useful to be able to quantitate the different minerals contained in the bentonite sample. Quantitation can be achieved by a few different techniques that are applied to the spectra. 9
    • XRD Quantitation Empirical Calibration  Response for measureable signal is related to a concentration of that particular analyte  Quantitation of particular minerals is performed by identifying peaks for the minerals of interest and measuring the responses for those minerals at different concentrations.  This generates a calibration curve. 10
    • XRD Quantitation Refinement  This process models the identified minerals onto the spectra collected.  It uses ratios of the intensities of the minerals to calculate relative concentrations of each mineral to give a semi-quantitative determination. 11
    • XRF Spectroscopy XRFs have been applied as a tool for the formulations of ceramics and for impurity testing of raw materials used in manufacture of medical implants:  Good sensitivity  Wide elemental analysis range  Simple sample preparation techniques Systems can have elemental ranges for elements as light as beryllium and as heavy as uranium with sensitivity to the parts per million (ppm) level. 12
    • XRF Spectroscopy Analysis time for XRF measurements is based on desired level of sensitivity Range from tens of seconds to a few hundred seconds for trace-level determinations  For analysis of materials where light elements are of interest at lower concentrations, removal of atmosphere is required. Commonly practiced methods for this are:   Removal by vacuum system Displacement using a light element gas purge 13
    • XRF Analysis of Mixed Oxides Figure 2 shows the spectra from the analysis of a sample of mixed oxides used in the manufacturing of a medical implant composed mostly of zirconia oxide. Figure 2: XRF scan of ceramic medical implant material with iron impurity Analysis identified the expected oxides of zirconia, yttrium and hafnium. Iron was identified as the impurity in the material and quantitated to trace level of 0.16% 14
    • More XRF Characteristics  Variety of sample forms, ranging from bulk items to powder samples  Small samples (e.g., powders) are placed/packed in sample cups or pressed into discs or pellets for analysis. See Figure 3.  Packing and pressing help reduce scattered X-rays by increasing the density of the sample, which improves sensitivity. Figure 3: Powder Sample Prep 15
    • XRF Analysis of Heavy Metals X-ray spectroscopy can measure the finishes applied to products for performance purposes or safety reasons (e.g., metal leaching), particularly as it relates to heavy metals. XRF is well-suited for this analysis because finished products can be measured with little to no sample prep. Some XRF systems can accommodate fairly large samples, which increase their flexibility by enabling a wide variety of samples to be analyzed. 16
    • XRF Analysis of Heavy Metals Figure 4 shows a drinking  mug placed in the sample  compartment for analysis. Figure 4: Spectra of drinking mug where lead contamination is identified; the mug is placed directly in the sample compartment.   Analysis of the mug identified  that the mug contained lead. The XRF system determined  that the lead levels were in  2,352 ppm. Lead is a metal that can be  leached out of materials with  water. Elevating the  temperature of the water or  reducing its pH increases the  rate of leachability. 17
    • XRF Analysis of Heavy Metals Measurements were conducted on finished and non-finished surfaces of the mug. This technique determined that lead was contained in the glaze of the mug. That was of additional concern, as the likelihood of exposure is increased as the lead is contained in a contact surface. 18
    • XRF in Manufacturing XRF can be used in developing finishes and monitoring the  manufacturing and application of these finishes, which impart  particular attributes to products. By adding particular components to ceramic finishes, desired  functions can be imparted.  Example: Adding materials to glazes that make their surfaces anti-microbial.  These materials contain elements that can be measured by XRF. X-ray  spectroscopy also can be used to ensure appropriate levels of microbialinhibiting materials are added to the glazes, and that the application of the  glazes to the products achieves the desired effect. 19
    • Conclusion X-ray spectroscopy is used in the ceramics industry in many  ways, from identifying materials that begin in the mining of  raw materials to quantifying minerals and contaminants in  those materials. These techniques are rapid and nondestructive, and they give  information about elemental composition and the  arrangement of those elements. XRFs and XRDs answer different questions, but they can be  used together to get a more complete picture of the materials  used in the ceramics industry. 20