Application of intermediate or bonding coatings in machining inserts, by laser methods, for anchoring CVD diamond film

Abstract

The goal of this work is the deposition of CVD diamond films in ceramic carbide inserts (WC-Co) for the industrial application in the machining processes. The demand for better machining tools for aluminum-silicon and titanium alloys are increasing as they are widely employed in the aerospace industries. Diamond-coated tools (WC-Co) are ideal for machining these alloys because of their excellent wear resistance properties. Another important reason with CVD diamond deposition on the tool is the use of green machining. The cutting fluid has the purpose of avoiding excessive heat and in the aid of the removal of the machining chip, on the other hand, the fluid raises the production costs, makes the reuse of the machining chip impossible, besides causing damages to the environment and aggression to the operator health. The use of a protective film not only increases tool life but also achieves significant increases in machining speed and removes the use of cutting fluid. However, lack of adhesion leads to a shorter coated tool life than expected. The main reasons for this displacement are: the presences of the cobalt binder and the residual stresses at the interface between the diamond film and a tool. In this project, a powder layer will be deposited on the surface of the WC that will act in addition to a diffusional barrier (preventing the migration of the Cobalt to the surface), as a binder between the WC and the diamond. We will employ the carbon black powders and boron carbide. The technique for creating this intermediate barrier will be the laser cladding process. In this process, a thin powder layer previously deposited on the surface of the WC will be irradiated by a laser beam, thereby creating an intermediate coating, dense and strongly bonded to the substrate. This technology is innovative, fast, versatile and low cost, which makes it interesting for a possible transfer to the industry in terms of industrial scheduling.