Solid-state reaction between tungsten and hydrogen-containing carbon film at elevated temperature

The solid-state reaction between hydrogen-containing carbon and tungsten was studied by means of infrared, Raman, X-ray photoelectron (XPS) and thermal desorption (TDS) spectroscopies. Infrared and Raman spectroscopies revealed that as-prepared hydrogen-containing films were composed of carbon atoms with sp2 and sp3 hybridized orbitals, where hydrogen was bound to carbon as –CH3 and >CH2. Vacuum heating of the carbon films deposited on tungsten caused thermal desorption peaks of hydrogen at about 723 and 1173 K in TDS. The former was accompanied by other desorption of CO, CO2 and hydrocarbons, whereas the latter was evolved with only a minor amount of CO. It was observed by XPS that the W4f peak began to appear at about 773 K, with an increasing surface composition corresponding to tungsten carbide at 1273 K. These observations indicate that a solid-state reaction between the carbon film and tungsten took place extensively above 973 K to yield an intermetallic compound of W2C at 1273 K.