Optical emission spectroscopy using arc and spark excitation (Arc Spark OES) is the preferred method for trace metal analysis to determine the chemical composition of metallic samples. This process is widely used in the metal making industries, including primary producers, foundries, die casters and manufacturing. Optical emission spectrometry involves applying electrical energy in the form of spark generated between an electrode and a metal sample, whereby the vaporized atoms are brought to a high energy state within a so-called "discharge plasma". These excited atoms and ions in the discharge plasma create a unique emission spectrum specific to each element, as shown at right. Thus, a single element generates numerous characteristic emission spectral lines.
Carbonitriding is a heat treatment process by which carbon and nitrogen (via ammonia gas) permeate the surface layer of steel components. The process involves temperatures of around 850°C followed by quenching in oil or gas solutions. Successful completion of this process will grant the steel components a variety of beneficial properties, most notably increased wear resistance Carbonitriding: the diffusion of carbon and nitrogen atoms into the surface of a metal to increase hardness; nitrogen is usually added to the endothermic atmosphere Heat Treatment: The temperature used for carbonitriding should be around 850°C (1550°F). This is lower than the temperature used for carburizing, and the time for which the part will be heat treated for is shorter as well. These lower temperatures used for carbonitriding compared to carburation also means there is less distortion of the part, especially during quenching. However, this is a higher temperature than what is used for standard nitriding