Chemical Vapor Deposition (CVD) is a method for producing low stress coatings by means of thermally-induced chemical reactions. The material of the coating is supplied to the coating zone as vapor of the respective precursor. The vapor then either decomposes or reacts with additional precursors, thus producing a film on the substrate. The precursors are continuously fed into the reaction zone and by-products are removed. CVD processes can be carried out under vacuum or at atmospheric pressure.
The Bernex™ CVD process has been developed in the early 1970s. The deposition process uses metal halides as coating precursors, such as TiCl4 or AlCl3. Over the years, the technology has been continuously improved in order to respond to increasing market requirements to quality of the coatings, reliability and productivity of the process and equipment.
The CVD process is used to deposit 5 to 12, in special cases up to 20, µm thick coatings. Materials employed are TiC, TiCN, TiN and α or κ aluminum oxide (Al203). They are applied as single or multi-layers on inserts for cutting applications, forming and molding tools like punches, extrusion and trimming dies and various mechanical components subject to abrasive or corrosive environments.
The typical process temperatures for Bernex™ CVD coatings are between 900 and 1050 °C for the HT CVD and between 720 and 900 °C for the Bernex™ MT CVD process.
Substrate materials are tungsten carbides, tool steels, high temperature nickel alloys, ceramics and graphite. Tempered steel tools and components require heat treatment after coating to re-establish the required hardness.