Deuterium trapping in and release from tungsten carbide

Tungsten carbide coating, W60C40 and W85C15 prepared by chemical vapor deposition and consisting of different carbide phases, are implanted with 0.8, 1.5 and 3 keV deuterium ions at room temperature and elevated temperatures. The trapping and release of deuterium are investigated by means of re-emission and thermal desorption spectroscopy. The results have been compared with previous data from graphite and from tungsten prepared by various methods. It is found that a few percent of carbon impurities strongly increases the deuterium inventory in tungsten. The thermal desorption of deuterium from tungsten carbide occurs at temperatures much lower than for graphite and the spectral form shows much more complicated features. The peak temperatures, in this case, mainly depends on the carbon concentration in different phases of the samples. Chemical erosion is only detected for sample W60C40. In this case all carbon atoms are eroded as volatile hydrocarbons while the physical sputtering of tungsten atoms limits the total erosion. Both fluence and temperature dependence of the chemical erosion are very similar to the results from the interaction of TiC with keV hydrogen ions.