Protection of industrial sensors with ta-C

Tetrahedral amorphous carbon (ta-C) coatings are a very promising approach in order to develop chemically and mechanically resistant protective layers for industrial and medical applications. For this purpose our group has developed thick (50-200 mum), high-quality (sp(3)-fraction similar to80%) and hydrogen-free protective ta-C coatings deposited (5 mum/h/20cm(2)) with filtered pulsed arc discharge (FPAD) method. Earlier ta-C coatings have given excellent results in aluminium lathing. For this work ta-C films were tested on paper thickness, density and porosity probes, paper paste viscometer nozzles and support pieces of a water-jet cutter. Tests were performed both in laboratory and industrial environments. In the paper mill the paper sensors and the cutter support pieces were in constant contact with the high-speed (up to 100 km/h) travelling paper web. The ta-C coating reduced significantly the erosion of the sensors and the resin accumulation on the sensor contact surfaces. The viscometer nozzle pieces were tested under pressures that no other material has withstood. In particle erosion tests ta-C coating outperformed WC-Co hard metal, sintered SiC, sintered Al2O3, synthetic ruby and TiN coatings (Diamond Rel. Mater. 9 (2000) 1524). (C) 2002 Elsevier Science Ltd. All rights reserved.