Session: 03-04-02: Advanced Machining and Finishing Processes

Paper Number: 145475

145475 - Investigating the Impact of Deposition Pressure on Crn Coating Properties and Machining Performance With Build Up Edge Formation. 

Coating properties such as hardness, elastic modulus, roughness, adhesion to the substrate, and residual stress are crucial determinants of a coating's impact on tool performance and wear patterns in machining. Tool coatings deposited using physical vapor deposition (PVD) offer distinctive property combinations designed for particular applications. These properties can vary considerably based on deposition conditions. By adjusting factors like N2 gas pressure during deposition, it's feasible to customize a PVD coating's properties to resist specific wear modes encountered in machining. This study focuses on investigating how CrN coatings can be customized to enhance machining performance, particularly in scenarios where built-up edge (BUE) formation is prevalent. Three CrN coatings were deposited using PVD, each with variations in N₂ gas pressure during the deposition cycle. To comprehensively assess the coating properties, a range of characterization techniques were employed, including scanning electron microscopy (SEM), X-ray diffraction (XRD), nanoindentation, and scratch testing. These techniques provided insights into the coatings' structural, mechanical, and tribological properties. The SEM analysis revealed the microstructure of the coatings, providing insights into grain size, distribution, and morphology. XRD analysis was employed to identify the crystallographic phases present in the coatings, aiding in understanding their structural properties as well as measuring residual stress. Nanoindentation testing allowed for the determination of hardness and elastic modulus, critical factors influencing a coating's resistance to deformation and wear. Scratch testing provided information on the coatings' adhesion strength and resistance to delamination, crucial for assessing their durability under machining conditions. The wear performance of these coatings was evaluated through a series of machining tests involving the finish turning of TiAl6V4 titanium alloy. Tool life studies were conducted to assess the coatings' performance under machining conditions, while 3D wear volume measurements were executed to quantify the degree of tool wear and observe its progression. The results of the study demonstrated the effectiveness of tailoring CrN coatings to improve machining performance in challenging conditions. Coatings with specific properties, such as a high elastic modulus, low H/E ratio, high plasticity index, moderate residual stress, and low roughness, were found to be particularly effective in minimizing issues related to sticking and BUE formation. In conclusion, this study underscores the importance of considering coating properties in machining applications. By understanding and optimizing these properties, manufacturers can improve tool performance, extend tool life, and enhance overall machining efficiency. The findings of this study provide valuable insights into the development of tailored coatings for enhanced machining performance.

Presenting Author: Abul Fazal Arif King Fahd University of Petroleum and Minerals

Presenting Author Biography: Abul Fazal Arif is a professor of mechanical engineering at KFUPM and has more than 20 years of experience as a faculty member. He is a fellow of ASME. In addition to KFUPM, he has worked at McMaster University and the University of British Columbia in Canada.

Authors:

Mohammad Shariful Islam Chowdhury McMaster University
Bipasha Bose McMaster University
Abul Fazal Arif King Fahd University of Petroleum and Minerals
Stephen Veldhuis McMaster University