An investigation of the gas composition during plasma thermochemical treatments

As well as the temperature of the workpiece and the duration of a plasma th ermochemical process, the characteristics of the treatment atmosphere (pres sure, flow rates, gas composition) have a great influence on the structure and the quality of the surface layer imparted. The composition of the proce ssing atmosphere is usually controlled by the input flow rates but the actu al percentages of the partial pressures are very often different from the r atio of the flows. A high-performance gas analyser has been used to investi gate the partial pressures of the atmosphere constituents during plasma nit riding and nitrocarburising processes.