Chemical Analysis – XRF

X-Ray Fluorescence (XRF) offers a simple methodology for determining the elemental constituents within a material, as well as to measure the film thickness and composition.  This testing technique is based on the principle that individual atoms can emit X-ray photons of a characteristic energy or wavelength.  Either the energy or wavelengths corresponds to a specific element within the sample and allows it to be identified.  Based on the total counts of the characteristic energy or wavelength, the quantification of the element can also be determined, showing that XRF can be both a qualitative and quantitative measurement technique.

H&M offers multiple methodologies that use this technology in the form of wavelength dispersive XRF (WDXRF) and energy dispersive XRF (EDXRF).  Both techniques work well but offer subtle differences based on the application that is required.  WDXRF has improved energy resolution leading to fewer spectral overlaps and improved background intensities. It also permits for the separation of a complex emitted X-ray spectrum into characteristic wavelengths for each element present.  EDXRF has higher signal throughput which enables small area analysis or mapping.  These types of characterization are most commonly used with SEM and FESEM to analyze and map out small areas for both chemical analysis and topography.

Main Applications of X-Ray Fluorescence 

  • Chemical analyses of rocks, minerals, sediments and fluids
  • Cement production
  • Quality control for metallurgy
  • Trace level analysis of contaminants in solids
  • Measuring film thickness and composition from angstrom to µm range
  • Elemental mapping of the sample

Pros

  • Non-destructive test method (in some cases)
  • Sample multiplicity – solids, liquids, powders can be analyzed
  • Sampling depth ranges from µm to mm ranges based on the material
  • Analyze small areas of ~ 150 µm
  • Can test any solid material

Cons

  • Cannot detect light elements in WDXRF (< O, <C in ED)
  • High accuracy measurements need reference standards which are similar in composition and thickness to the sample

Detailed Analysis

Alloy Identification

Alloy identification is an important area to be able to determine the specifics of an unknown material.  This can be important in applications such as welding to determine the correct conditions based on the alloy, aerospace testing for the correct materials used in construction and even scrap sorting.  Metals such as Aluminum has multiple categories and is the most recycled metal.  Each of the different alloys corresponds to a specific Aluminum series and requires different processing.  Utilizing XRF characterization can easily identify the specific alloy’s in question.

This includes:

  • Titanium alloys
  • Carbon and low alloy steels
  • Nickel alloys
  • Copper alloys
  • Exotic and precious metals
  • Aluminum alloys
  • Stainless steels

Geological Materials

Geological sources are used as raw materials and even additives for a wide variety of industrial based applications.  Once the minerals and ores are mined they require analytic tools to determine the correct compositions so they can be correctly identified and sent to the appropriate industry.  Common minerals used are silica, limestone, gypsum, talc and barite.  XRF is the characterization tool of choice for determining the exact composition of these raw minerals and any impurities since it is fast and non-destructive.  This analysis provides added value since the quality of the raw material has been identified and characterized, and can be processed to the appropriate end use.

Minerals and Ores that undergo this process are used in the following fields:

  • Chemicals
  • Ceramics
  • Glass
  • Paints
  • Construction materials
  • Plastics

Concrete, Cement, Clinker Analysis

X-ray fluorescence is a common testing technique to perform for quality control in the manufacturing and production of cements and concrete.  It can begins at the raw materials stage by testing the quarry.  As it moves to an intermediate stage called the clinker, XRF can test the composition to ensure the process is stable before moving to the finished cement product.  At this point the cement can also be analyzed to ensure it meets the specific standards of the product and to ensure that production does not suffer delays if the composition is not correct.

 

 Technical Specifications of Equipment

  • Signal Detected: X-rays
  • Elements Detected: All elements heavier than Oxygen
  • Detection Limits: 1 ppm to 100 ppm for most elements
  • Imaging/Mapping: Yes (EDS)
  • Lateral Resolution/Probe Size: 1 µm (EDS)

Key Markets Served

  • Pharmaceuticals
  • Semiconductors
  • Mining & Metals
  • Ceramics
  • Aerospace
  • Solar and Lighting
  • Defense
  • Raw Chemicals
  • Personal Care
  • Packaging
  • Life Sciences
  • Law and Litigation