Abstract
This paper presents the results of a study of the mechanisms of delamination and the formation of longitudinal cracks in the structure of multi-layered nano-structured coatings to predict the mechanisms for further improvement of tool life and the reliability of metal-cutting tools. Various mechanisms of formation of longitudinal cracks and delaminations in coatings on rake and flank tool surfaces, which vary based on the compositions and architectures of the coatings, are addressed. In addition, the influence of internal defects, including embedded microdrops and pores, on the formation of cracks and delaminations and the failure of coatings is discussed. The importance of ensuring a balance of the basic properties of coatings to achieve high wear resistance and maximum tool life of coated metal cutting tools is shown. The properties of coatings and the natures of their failures, as investigated during scratch testing and dry turning of steel C45, are provided.
Highlights
IntroductionOne way to improve the performance characteristics of tool materials is to enhance their surface properties by applying modified coatings [1]
The obtained curves were used to determine two parameters: the first critical load LC1, at which first cracks appeared in nano-scale multi-layered composite coatings (NMCC), and the second critical load LC2, which caused the total failure of NMCC
This test enables a study of the nature of the coating failure, from the point of view of delaminations that occur in its structure
Summary
One way to improve the performance characteristics of tool materials is to enhance their surface properties by applying modified coatings [1]. The properties of modified coatings continue to be improved, and their architecture and elemental composition become more complicated. Multi-layered composite coatings, nano-structured and gradient coatings, and coatings with multi-component elemental composition have been used extensively in recent years [2,3,4,5,6,7,8]. The use of a multi-layered architecture of coatings and the use of nano-structured technology can significantly improve the performance characteristics of a new generation of coatings. Along with the use of such coatings comes new problems that did not occur with monolithic coatings of the first generation. Problems arose concerning interlayer delamination and formation of specific longitudinal cracks in the structure of coating
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