The metals industry makes use of a number of specialized analytical tools to determine the composition of samples. While arc/spark optical emission spectroscopy is probably the technique that is most associated with metals analysis, dedicated inorganic combustion analyzers are also heavily in demand. These instruments typically measure a small number of individual elements. Some metal combustion analyzers are designed to measure a single element. Others systems, such as carbon-sulfur analyzers and oxygen-nitrogen-hydrogen analyzers, measure common combinations of elements. This specialized nature is what most distinguishes the applications of these instruments from arc/spark, which is generally capable of measuring all of the elements in a sample.

The basic operation of a metal combustion analyzer is relatively simple. The sample is weighed and introduced into a high-temperature furnace. The furnace is usually an electrical induction furnace, which can be rapidly raised to temperatures well over 1000°C. At this temperature, the sample oxidizes in an oxygen-rich environment and the resultant gases are conducted to the detection system. For instance, carbon is detected in the form of carbon monoxide and carbon dioxide. Comparing the concentration of carbon in the evolved gases with the mass of the original sample allows a compositional analysis to be made.

The most common type of detection is infrared spectroscopy. In addition to infrared sensors, thermal conductivity sensors are also used, commonly for hydrogen and nitrogen determination. Depending on the system and element, combustion analyzers generally have the sensitivity to measure the target elements in concentrations ranging from a few percent down into the ppb range.

Obviously, metals analysis is the major application for these instruments. The properties of most industrial metals and alloys depend critically on the presence or absence of trace elements in their compositions. For instance, carbon content in steel affects hardness and differentiates between common low carbon steel and harder steels with carbon content in the 1%–2% range. At the same time, the presence of sulfur in steel can result in brittleness. Similarly, the presence of hydrogen causes problems in aluminum alloys, and needs to be carefully monitored. Beyond metals analysis, these instruments are used to analyze other inorganic and even some organic samples, including cement, rubber, glass, ceramics, soils, other environmental samples, and solid waste.

The 2009 market for combustion metals analyzers was about $100 million, including aftermarket and service revenues. The recent economic crisis had a particularly depressing effect on the metals market, but looking to the future, moderate growth in mid-single digits is expected. The largest market participant is LECO. Another significant participant, Juwe, was acquired by Bruker in 2008 (see IBO 1/15/08).

Metal Combustion Analyzers

at a Glance:

Leading Suppliers

• LECO

• Horiba

• Eltra

Largest Markets

• Metals and Mining

• Cement

• Environmental

Instrument Cost

• $35,000–$100,000