Usage of barrier coating for cutting tools for machining parts of titanium alloys

The cutting tools with the durable coatings are widely used in the industry. The tools having coatings made on a base of titanium nitride are most popular. They are used for the structural and tool steels machining. Nevertheless their durability is not too high during machining hard materials. The reason of this fact consists in a high degree of the adhesive interaction due to which the temperature in the cutting zone is increased and the action of water vapors and oxygen the coating softening takes place. A durability of the compound coatings is three times more than for the coating made from titanium nitride during machining of high temperature alloys and stainless steels. While machining titanium alloys, certain coatings do not provide the tools durability increase. This can be explained by the fact that titanium nitride forms the adhesion welding bridges at the cutting temperature above 300degC. By this fact the ionic bombarding of the coating is provided that in the case of the potential low value (absolute) it provides a formation of the finely divided structure of the coating due to interrupting of the crystals growing and generating of the new crystallization centers and in the case of the larger potential value it provides an intensive heating of the treated items and etching of its surface. All this by a direct way is related to the coating applying velocity which specifies the effectiveness of this or another method of the coatings application.