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Surface contamination analysis is crucial in engineering and materials science industries as it helps researchers study a material’s surface layer composition. Using secondary ion mass spectrometry (SIMS), the composition of a surface layer can be identified and characterized and this information is then used to investigate contamination, defects, and trace elements on a substrate’s surface. SIMS is used for surface contamination analysis because it offers high-resolution imaging and is extremely surface sensitive, capable of monitoring the top layer of atoms on a surface. In this blog post, we will present a case study of how SIMS is used in surface contamination analysis and the importance of SIMS as an analytical technique.

SIMS and Surface Contamination Case Study

To demonstrate how effective SIMS is for identifying and characterising contamination on a material’s surface, a case study was conducted on characterising damaging biodiesel deposits on an engine component.

Biodiesel is now frequently used to reduce harmful emissions, as it is a renewable resource that could one day replace petroleum diesel.1 Unfortunately, however, biodiesel can be contaminated in several ways during storage, which leads to detrimental effects on the mechanical performance of equipment and process efficiency and safety. Dirt, dust, and water are three common contaminants, as well as biodiesel compounds, sand, rust from equipment and other particles than may infiltrate biodiesel tanks. Typically, storage tanks have fuel filters to prevent these contaminants entering the system, but water contamination can cause bigger problems and allow water soluble minerals to remain in the fuel.2

Case Study

A diesel injector was run in a test engine for 48 hours in order to observe effects of contamination.  When removed, the sealing surface displayed a very light staining and this was initially analysed Energy Dispersive X-ray in an electron microscope.  However, the very thin nature of the stain prevented a useful x-ray signal from the layer, instead it just showed the composition of the metal substrate. 

The component was then subjected to imaging SIMS analysis. In this case, the high surface specificity of SIMS was able to detect calcium in the stained area.  In fact, the underlying metal was not seen in the SIMS because it was masked by the calcium containing layer.

Hiden Analytical and SIMS Surface Analysis

Hiden Analytical is a UK-based company with over 40 years experience in the design, development and manufacturing of quadrupole mass spectrometers for advanced research applications. We offer several SIMS products for a wide range of applications, including surface analysis for contamination, depth profiling and other investigations.

  • AutoSIMS
  • Compact SIMS
  • SIMS Workstation
  • ToF-qSIMS Workstation

Contact a member of Hiden Analytical today to learn more about how SIMS can support surface contamination analysis and many other applications. 

References and Further Reading

  1. https://afdc.energy.gov/fuels/biodiesel_benefits.html#:~:text=Biodiesel%20Benefits%20and%20Considerations,environment%2C%20and%20provides%20safety%20benefits
  2. Contamination in BioDiesel   https://www.ipu.co.uk/diesel-contamination/