Analysis of tungsten carbide coatings by UV laser ablation inductively coupled plasma atomic emission spectrometry

Tungsten carbide coatings (thickness 0.1-0.2 mm) containing 8.0, 12.2, 17.2 and 22.9% Co were studied with laser ablation inductively coupled plasma a tomic emission spectrometry (LA-ICP-AES). Composition of these plasma spray ed deposits on steel disks was determined using X-ray fluorescence spectrom etry and electron microprobe energy/wavelength dispersive X-ray spectrometr y. The coatings were ablated by means of a Q-switched Nd:YAG laser at 266 n m (10 Hz, 10 mJ per shot) coupled to an ICP echelle-based spectrometer equi pped with a segmented charge-coupled device detector. Non-linear dependence s of cobalt lines intensities on the Co percentage were observed both at a single spot ablation and at a sample translation. This behaviour could be a ttributed to a complex phase composition of the system W-C-Co. However, emp loying tungsten as internal standard the linear calibration was obtained fo r studied analytical lines Co II 228.616 nm, Co II 230.786 nm, Co II 236.37 9 nm and Co II 238.892 nm, (C) 2000 Elsevier Science B.V. All rights reserv ed.