The Pennsylvania State University The Graduate School Intercollege Graduate Program in Materials Science and Engineering SYNTHESIS-STRUCTURE-PROPERTY-PERFORMANCE RELATIONSHIPS OF TiN, CrN, AND NANOLAYER (Ti,Cr)N COATINGS DEPOSITED BY CATHODIC ARC EVAPORATION FOR HARD PARTICLE EROSION RESISTANCE A Thesis in Material Science and Engineering by Brian M. Gabriel Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science May 2009 The thesis of Brian M. Gabriel was reviewed and approved* by the following: Douglas E. Wolfe Assistant Professor of Material Science and Engineering Thesis Advisor John R. Hellmann Professor of Materials Science and Engineering Suzanne Mohney Professor of Materials Science and Engineering Joan Redwing Professor of Materials Science and Engineering Chair, Intercollege Materials Science and Engineering Graduate Degree Program *Signatures are on file in the Graduate School iii ABSTRACT Hard particle erosion due to sand particles can cause significant damage to metallic turbine engine components. Hard coating systems such as TiN, CrN, and (Ti,Cr)N offer a potential solution. TiN, CrN, and (Ti,Cr)N coatings were deposited with a multi-source cathodic arc system using high purity Ti and Cr cathode targets in a partial N2 atmosphere. The coatings were characterized using X-ray diffraction, scanning electron microscopy, electron probe microanalysis, scanning transmission electron microscopy, and scratch adhesion testing. Erosion testing was performed using an in- house high-velocity erosion rig with glass beads and alumina media. For the TiN coatings, erosion resistance was strongly dependent on the evaporator current and substrate bias; these parameters influenced crystallite size, preferred crystallographic orientation, and residual stress. CrN coatings were determined to have significantly more macroparticles than the TiN coatings deposited under similar conditions. This was primarily attributed to the lower melting point of the solid phases in the Cr-N system versus the Ti-N system. A nanolayered (Ti,Cr)N coating system comprised of alternating TiN and CrN rich layers was created by co-evaporating Ti and Cr cathode targets with a rotating substrate configuration. Erosion resistance increased along with decreasing density of nanolayer interfaces as well as increasing volume percentage of the CrN rich layers with respect to the TiN rich layers. In all three coating systems, macroparticle defect concentrations were not believed to degrade high impact angle erosion performance. iv TABLE OF CONTENTS LIST OF FIGURES………………………………………………………………. ix LIST OF TABLES………………………………………………………………... xvii ACKNOWLEDGEMENTS………………………………………………………. xiii CHAPTER 1 INTRODUCTION………………………………………………… 1 1.1 Background………………………………………………………............ 1 1.2 Project Objectives……………………………….………………………. 1 CHAPTER 2 LITERATURE REVIEW AND COATING THEORY…………... 3 2.1 Cathodic Arc Deposition………………………………...………………. 3 2.2 Mechanisms of Erosion……………………………..…………………… 9 2.2.1 Solid Particle Erosion through Plastic Deformation…..………. 11 2.2.2 Solid Particle Erosion of Brittle Materials……..……….……... 12 2.2.3 Erosion Resistant Coatings…………...…….………………….. 16 2.3 TiN, CrN, and (Ti,Cr)N Coatings for Erosion Protection……………….. 27 CHAPTER 3 EXPERIMENTAL PROCEDURE………………………………... 35 3.1 Cathodic Arc Deposition Equipment……………………………………. 35 3.2 Substrate Preparation…………………………………………………….. 39 3.3 Cathodic Arc Deposition Processing Procedure………………………… 41 3.4 Design of Experiments for Deposition of TiN, CrN and (Ti,Cr)N Coatings………………………………………………………………….. 43 3.5 Coating Characterization and Evaluation………………………………... 54 3.5.1 X-Ray Diffraction (XRD)……………………………………... 54 3.5.1.1 X-Ray Diffraction for Crystallographic Structure Determination………………………………………... 54 v 3.5.1.2 XRD Crystallite Size……………………………….... 56 3.5.1.3 XRD Residual Stress Analysis………….…………… 57 3.5.2 Cross Sections for Optical Microscopy (OM)……………….… 58 3.5.3 Electron Probe Microanalysis (EPMA)……….……………….. 59 3.5.4 Environmental Scanning Electron Microscopy (ESEM).……... 59 3.5.5 Quantative Microstructural Analysis.…………………………. 60 3.5.6 Annular Dark Field Scanning Transmission Electron Microscope (ADF-STEM)…….………………………………. 62 3.5.7 Vicker’s Micro-Indention Hardness Testing………………….. 62 3.5.8 Scratch Adhesion Testing……………………………………... 63 3.5.9 Surface Roughness Measurements……………………………. 63 3.5.10 Erosion Testing………………………………………............... 65 CHAPTER 4 RESULTS AND DISSCUSSION…………………………………. 70 4.1 XRD Crystallographic Structure Determination from Θ/2Θ and Glancing Angle Scans…………………………………………………… 70 4.1.1 XRD Crystallographic Structure Results for Monolithic TiN… 71 4.1.2 XRD Crystallographic Structure Results for the CrN Coating... 74 4.1.3 XRD Crystallographic Structure Results for Nanolayer (Ti,Cr)N Deposited as a Function of Evaporator Current (Constant Ti Evaporator Current)……………………………... 75 4.1.4 XRD Crystallographic Structure Results for Nanolayer (Ti,Cr)N Deposited as a Function of Substrate Bias (Ti at 65 A and Cr at 45 A Evaporator Current)…………………………… 78 4.1.5 XRD Crystallographic Structure Results for Multilayer (Ti,Cr)N Coatings with Ti and Nb Interlayers………………… 80 4.2 Crystallite Size…………………………………………………………... 82 4.2.1 Trends in XRD Crystallite Size of Monolithic TiN Coatings vi Deposited as a Function of Evaporator Current (Constant -150 V Substrate Bias)………………………………………………. 83 4.2.2 Trends in XRD Crystallite Size of Monolithic TiN Coatings Deposited as a Function of Substrate Bias…………………….. 84 4.2.3 Trends in XRD Crystallite Size of Nanolayer (Ti,Cr)N Coatings Deposited as a Function Substrate Bias (Ti Evaporator of 65 A, Cr Evaporator of 45 A)…………………... 85 4.3 Preferred Crystallographic Orientation……………………….................. 87 4.3.1 Preferred Crystallographic Orientation of the Monolithic TiN Coatings Deposited as a Function of Evaporator Current (Constant Substrate Bias)……………………………………… 88 4.3.2 Preferred Crystallographic Orientation of the Monolithic TiN Coatings Deposited as a Function of Substrate bias (Constant Ti Evaporator Current)………………………………………… 92 4.3.3 Crystallographic Orientation of the CrN Coating……………... 93 4.3.4 Preferred Crystallographic Orientation of Nanolayered (Ti, Cr)N Coatings Deposited as a Function of Cr Evaporator Current (65 A Ti Evaporator, Constant Substrate Bias)……….. 96 4.3.5 Preferred Crystallographic Orientation of Nanolayered (Ti,Cr)N Coatings Deposited as a Function of Substrate Bias (65 A Ti Evaporator Current, 45 A Cr Evaporator Current)...… 98 4.3.6 Crystallographic Orientation of the (Ti,Cr)N Multilayer Coatings with Ti Interlayers (-150 V Substrate Bias, Ti Evaporator Current of 65 A, Cr Evaporator Current of 45 A)… 100 4.4 Residual Stress Analysis………………………………………………… 101 4.4.1 Trends in XRD Residual Stress Analysis of the Monolithic TiN Coatings Deposited with Different Evaporator Currents (Constant Substrate Bias)……………………………………… 103 4.4.2 Trends in XRD Residual Stress Analysis of the Monolithic TiN Coatings Deposited with Different Substrate Biases (Constant Ti Evaporator Current)……………………………... 105 4.5 Deposition Rate of Nitride Coatings…………………………...………... 107 vii 4.5.1 Deposition Rate of Monolithic TiN Coatings Deposited at Different Evaporator Currents (-150 V Substrate Bias)……….. 108 4.5.2 Deposition Rate of TiN Coatings Deposited at Different Substrate Biases (65 A Evaporator Current)…………………... 110 4.5.3 Deposition Rate of Nanolayer (Ti,Cr)N Coatings as a Function of Cr Evaporator Current (Ti Evaporator of 65 A, Substrate Bias of -150 V)………………………………………………… 111 4.5.4 Deposition Rate of Nanolayer (Ti,Cr)N Coatings Deposited at Different Substrate Biases (65 A Ti Evaporator Current, 45 A Cr Evaporator Current)……………………...…………………. 112 4.6 Electron Probe Micro Analysis of the Nanolayer (Ti,Cr)N Coatings…… 113 4.7 Quantative Analysis of Large Scale Defects of Nanolayer (Ti,Cr)N Coatings………………………………………………………………….. 115 4.8 ESEM Fracture Surfaces………………………………………………… 118 4.9 STEM of Nanolayer (Ti,Cr)N Coatings Deposited at Different Cr Evaporator Currents (65 A Ti Evaporator Current, -150 V Substrate Bias)……………………………………………………………………... 120 4.10 Vicker’s Micro-Hardness…………………………………. 122 4.11 Scratch Adhesion Testing of Nanolayer (Ti,Cr)N Coatings………...…... 123 4.12 Surface Roughness………………………………………………………. 124 4.12.1 Surface Roughness of the Monolithic TiN and CrN Coatings… 125 4.12.2 Surface Roughness of Nanolayer (Ti,Cr)N Coatings………….. 126 4.13 Erosion Performance…………………………………………………….. 129 4.13.1 Erosion Performance of Monolithic TiN Coatings Deposited with Different Evaporator Currents (Constant Substrate Bias)... 130 4.13.2 Erosion Performance of Monolithic TiN Coatings Deposited with Different Substrate Biases (Constant Ti Evaporator Current)………………………………………………………... 134 4.13.3 Erosion Performance of the Monolithic CrN Coating………… 137 viii 4.13.4 Erosion Performance of Nanolayer (Ti,Cr)N Coatings Deposited at Different Cr Evaporator Currents (65 A Ti Evaporator Current, -150 V Substrate Bias)…………………... 140 4.13.5 Erosion Performance of Nanolayer (Ti,Cr)N Coatings Deposited at Different Substrate Biases (65 A Ti Evaporator Current, 45 A Cr Evaporator Current)………………………… 144 4.13.6 Erosion Performance of Multilayer(Ti,Cr)N Coatings Deposited at (65 A Ti Evaporator Current, 45 A Cr Evaporator Current, -150 V Substrate Bias)……………………………….. 147 4.14 Proposed Coating Design……...………………………………………… 152 CHAPTER 5 CONCLUSION……………………………………………………. 154 5.1 Monolithic TiN Coatings Deposited as a Function of Evaporator Current (-150 V Substrate Bias)………………………………………………….