Nanostructured Multilayer Composite Coatings for Cutting Tools

The chapter deals with the specific features concerning the application of wear-resistant coatings to improve the performance properties of ceramic cutting tools. The paper discusses the theoretical background associated with the specific operation conditions and wear of ceramic cutting tools and influencing the choice of the compositions and structures of wear-resistant coatings. The studies were focused on the application of the Ti-(Ti,Al)N-(Zr,Nb,Ti,Al)N multilayer composite coating with a nanostructured wear-resistant layer, as well as the (Cr,Al,Si)N–(DLC–Si)–DLC–(DLC–Si) and (Cr,Al,Si)N–DLC composite coatings in order to improve the cutting properties of ceramic tools. The chapter presents the results of the comparative cutting tests for the tools with the coatings under study, uncoated tools, and tools with the Ti-(Ti,Al)N commercial coating. The wear mechanisms typical for ceramic cutting tools with coatings of various compositions have been investigated.

Study of Properties of Nanostructured Multilayer Composite Coatings of Ti-TiN-(TiCrAl)N and Zr-ZrN-(ZrNbCrAl)N

The structures of surface layers of the tool material, adapted to the conditions of the thermomechanical loading during the cutting process, can be formed with the use of different processing methods, the most effective of which is to deposit functional coatings on working surfaces of the cutting tool. During the studies, two nanostructured multilayer composite coatings (NMCCs) were considered: Ti-TiN-(TiCrAl)N and Zr-ZrN-(ZrNbCrAl)N. Metallographic studies were conducted, and the phase compositions of the coatings were determined by X-ray crystal analysis. The efficiency of tools made of carbide T14K8 with developed coatings was determined by comparative evaluation of tool life of a tool without coating, a tool with standard coating (TiN), and a tool with elaborated coatings (Ti-TiN-(TiCrAl)N and Zr-ZrN-(ZrNbCrAl)N) in turning structural steel 45. These tests allow noting the increase in tool life of a tool with elaborated NMCCs by up to 4 times as compared with tool life of an uncoated tool and by up to 2 times as compared with tool life of standard coating TiN. Meanwhile, NMCC of Ti-TiN-(TiCrAl) showed lifetime about 10% longer than NMCC of Zr-ZrN-(ZrNbCrAl)N). The longer lifetime of NMCC of Ti-TiN-(TiCrAl) conforms to its better adhesion characteristics and thinner nanosublayers of its wear-resistant layer.

Improving Efficiency of End Mills by Deposition of Modifying Nano-Scale Multilayer Composite Coatings

The study considers the challenge of improving the efficiency of end mills made of carbides through modification of physical and mechanical properties of tools by forming nanostructured multilayer composite coatings on its working surfaces with the use of filtered cathodic vacuum-arc deposition (FCVAD). The system and structure of three-component nanostructured multilayer composite modifying coatings for deposition on the working surfaces of the end mills are developed. The study presents the results of laboratory and industrial tests of end mills with coatings designed for conditions for rough and finish machining.

Improving operational characteristics of tool from tungsten-free carbides (cermets) by nanostructured multilayer composite coatings.

This paper discusses the issues of improving the efficiency of cutting tool made of tungsten-free carbides (cermets) by using nano-dispersed multi-layered composite coatings formed by use of innovative processes of filtered cathodic vacuum arc deposition (FCVAD). Developed composi-tions of nano-structured multi-layered composite coatings contributes to significant improvement of properties of cutting tool made of cermets in cutting constructional steel and expansion of their application area for machining of heat-resistant alloys.