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Laser based chemical vapour deposition of corrosion and wear resistant layers

Research has been carried out in order to develop industrially, applicable laser chemical vapour deposition (LCVD) processes for the local deposition of corrosion and wear resistant layers on high duty parts of industrial products and cutting or forming tools to enhance lifetime and reliability.

The applicability of photolytic LCVD to the deposition of boron, carbon, titanium carbide and titanium nitride coatings has been shown to be cumbersome mainly because of low deposition rates and in the case of boron, carbon and titanium carbide the bad adherence of the coatings. With titanium nitride relatively high (0.1 um min {-1} deposition rates and good adhering coatings could be obtained. However, layers grown at these high rates were too rough to be useful for wear applications.

On the other hand titanium carbide, titanium nitride, chromium oxide and Cr2OC layers with good properties (hardness, composition, adhesion) can be deposited locally on flat substrates using pyrolytic carbon dioxide; neodymium yttrium aluminium garnet LCVD. High growth rates are achieved (um min {-1} up to um S {-1}). Only very thin (50 nm) and therefore practically not usable layers of titanium nitride could be deposited using an argon (+) ion laser in the direct writing mode.

Titanium carbide coatings have also been prepared by twin beam processing (excimer laser assisted carbon dioxide laser deposition). The pyrolytic deposition rate can probably be increased by the use of an excimer laser. To assess industrial applicability of twin beam processing further investigations are requested.

Pyrolytic LCVD of titanium nitride using a neodymium yttrium aluminium garnet laser is of particular interest because it can be carried out at atmospheric pressure. Development of an industrial inline technique is feasible.
The laser induced temperature distribution is a parameter of prime importance in growing homogeneous layers using pyrolytic LCVD. Inline evaluation of the surface temperature by infrared pyrometry has been shown to be an indispensable process control tool.

Pyrolytic LCVD of titanium carbide, titanium nitride and Cr2OC layers locally on 3-dimensional tools has been demonstrated. Functional tests have been carried out on titanium nitride and the Cr2OC coated tools titanium nitride coated tools showed etch resistance and improved wear and corrosion
resistance. The Cr2OC coated tools showed improved corrosion resistance.

Spin off products from this research include a laser pyrometer and a pressure sensor.
Areas to which the technologies may be applied include textile machinery and the automotive industry.

Reported by

Philips Centre for Manufacturing Technology
Building SAQ 1314 PO Box 218
5600 MD Eindhoven
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