TiN[BCN/BN] n /c-BN system improves the surface properties of machining tools used in industrial applications

Abstract

Tribological and mechanical properties essential for applications in machine tools using multilayers TiN[boron carbon nitride (BCN)/boron nitride (BN)]n/cubic boron nitride (c-BN) were extensively studied in this research. Therefore, improvement of both hardness and elastic modulus up to 30 and 220 GPa, respectively, was observed as the bilayer periods (Λ) in the coatings were decreased. So, the sample with higher bilayer number n = 25 showed the lowest friction coefficient (∼0.32) and the highest critical load (61 N), corresponding to 1.7 and 3.05 times better than those values for the coating deposited with n = 1, respectively. Taking into account the last result, tungsten carbide (WC) inserts and high-speed steel (HSS) drill bits were used as substrates to improve the mechanical and tribological properties of TiN[BCN/BN]n/c-BN/WC coatings as a function of increased of interface number and to manage greater efficiency of these coatings in different industrial applications, such as machining and extrusion processes. Their physical, mechanical, and tribological characteristics were investigated, the bilayer period and the number of bilayers. A comparison of the tribological properties in relation to bilayer period (Λ) revealed a decrease of flank wear for coated WC inserts (around 60 %) and 82 % in HSS drill bits for TiN[BCN/BN]n/c-BN with n = 25 when compared with multilayers deposited with n = 1. They also showed better machining properties onto hardened AISI 4340 steel pieces, when compared to uncoated WC inserts and HSS drill bits. These results open the possibility of using TiN[BCN/BN]n/c-BN multilayers as coatings for tool machining with excellent industrial performance.