CC BY 3.0 UnportedPuth, A.Kusýn, L.Pipa, A.V.Burlacov, I.Dalke, A.Hamann, S.van Helden, J.H.Biermann, H.Röpke, J.2021-12-102021-12-102020https://oa.tib.eu/renate/handle/123456789/7673https://doi.org/10.34657/6720The active screen plasma nitrocarburizing technology is an improvement of conventional plasma nitrocarburizing by providing a homogeneous temperature distribution within the workload and reducing soot formation. In this study, an industrial-scale active screen (AS) made of carbon-fibre-reinforced carbon serves as the cathode as well as the carbon source for the plasma-chemical processes taking place. The pulsed dc discharge was maintained at a few mbar of pressure while simultaneously being fed with a mixed gas flow of hydrogen and nitrogen ranging from 10 to 100 slh. Using in situ infrared laser absorption spectroscopy with lead salt tuneable diode lasers and external-cavity quantum cascade lasers, the temperatures and concentrations of HCN, NH3, CH4, C2H2, and CO have been monitored as a function of pressure and total gas flow. To simulate industrial treatment conditions the temperature of the sample workload in the centre of the reactor volume was kept at 773 K by varying the plasma power at the AS between 6 and 8.5 kW. The resulting spectroscopically measured temperatures in the plasma agreed well with this value. Concentrations of the various species ranged from 6 × 1013 to 1 × 1016 cm−3 with HCN being the most abundant species.enghttps://creativecommons.org/licenses/by/3.0/530infrared absorption spectroscopyplasma chemistryplasma diagnosticspulsed dc dischargeArticle