Interstitial Gas Analysis

Interstitial gases include nitrogen, oxygen, carbon, sulfur, and hydrogen dissolved in a solid material and dispersed throughout its matrix. These gases can have significant effects on the physical properties of manufactured materials. Interstitial gas analysis at ChemTrace measures N, O, C, S, and H present in solid materials from sub-ppm levels to percentage levels.

Nitrogen, oxygen, and hydrogen are measured by inert gas fusion. In this process, the sample is placed in a graphite crucible and inserted into a DC electrode furnace. An inert gas, such as He or Ar, is purged through the furnace, and a high current is passed through the crucible. The current creates a temperature above 2500˚C, causing the sample to fuse. The interstitial gases within the sample are released into the inert gas stream, and are then detected by infrared or thermal conductivity measurements.

Carbon and sulfur are measured by utilizing an RF combustion tube furnace. The sample is placed in a ceramic crucible in a high frequency induction furnace set above 2000°C. An RF field is applied, resulting in the combustion of the sample. This releases various gases (such as SO₂, CO, and CO₂) from the sample, which are then measured by infrared detection. These measurements are used to calculate the concentration of C and S in the sample.