Depth profile analysis of various titanium based coatings on steel and tungsten carbide using laser ablation inductively coupled plasma - "time of flight" mass spectrometry

A homogenized 193 nm ArF* laser ablation system coupled to an inductively c oupled plasma-"Time of Flight"-mass spectrometer (LA-ICP-TOFMS) was tested for depth profiling analysis on different single-layer Ti based coatings on steel and W carbides. Laser parameters, such as repetition rate, pulse ene rgy and spatial resolution were tested to allow optimum depth related calib ration curves. The ablation process using a laser repetition rate of 3 Hz, 120 mu m crater diameter, and 100 mJ output energy, leads to linear calibra tion curves independent of the drill time or peak area used for calibrating the thickness of the layer. The best depth resolution obtained (without be am splitter) was 0.20 mu m per laser shot. The time resolution of the ICP-T OFMS of 102 ms integration time per isotope was sufficient for the determin ation of the drill time of the laser through the coatings into the matrix w ith better than 2.6% RSD (about 7 mu m coating thickness, n = 7). Variation of the volume of the ablation cell was not influencing the depth resolutio n, which suggests that the depth resolution is governed by the ablation pro cess. However, the application on the Ti(N,C) based single layer shows the potential of LA-ICP-TOFMS as a complementary technique for fast depth deter minations on various coatings in the low to medium mu m region.