25 Years Of Tialn Hard Coatings In Research And Industry

Hard coating’s thermal stability is essential due to the high temperature environment of high-speed cutting applications, while the phase and microstructure evolution induced by exposing the coating to high temperature affects the mechanical properties. In this thesis, the mechanical stability of arc-evaporated, hard, transition metal nitride coatings annealed at high temperature is analyzed and related to the phase and microstructure evolution. In addition to hardness, fracture toughness is evaluated by surface and cross-sectional investigations by scanning/transmission electron microscopy of damage events following mechanical tests. The crack resistance of Ti1?xAlxN with a range of Al content (x = 0.23-0.82) was studied by contact fatigue tests, where the differences in the microstructure were found to play a major role. Superior mechanical properties were found in Ti0.63Al0.37N; in the as-deposited state as a result of a favorable grain size, and after annealing at 900o C due to the microstructure formed during spinodal decomposition. The mechanical and high-temperature properties of hard coatings can be enhanced by alloying or multi-layering. Within this work, quaternary Ti-Al-X-N (X = Cr, Nb and V) alloys were studied and superior toughness was found for TiAl(Nb)N in both the as-deposited and annealed (1100? C) states. The hexagonal (h)-AlN formation in cubic (c)-TixAl0.37Cr1?0.37?xN (x = 0.03 and 0.16) was analyzed by in-situ x-ray scattering during annealing. The energy for h-AlN formation was found to be dependent on the microstructure evolution during annealing, which varies with the coating composition. High Al content h-ZrAlN/c-TiN and h-ZrAlN/c-ZrN multilayers were investigated through scratch tests followed by focused ion-beam analysis of the crack propagation. A c-Ti(Zr)N phase forms in h-ZrAlN/c-TiN multilayers at high temperatures and that contributes to enhanced hardness and fracture toughness by keeping the semi-coherent sub-interfaces. Finally, an in-situ analysis of coatings by x-ray scattering during a turning process was carried out. It demonstrates the possibility of observation of stress evolution and thermal expansion of the coatings or the work piece material during machining. This experiment provides real-time information on the coating behavior during cutting. Hårda skikts högtemperaturstabilitet är viktig på grund av den höga temperaturskikten utsätts för under skärande bearbetning, och den utveckling av faser och mikrostruktur som då sker påverkar skiktets mekaniska egenskaper. I den här avhandlingen har den mekaniska stabiliteten hos arcförångade, hårda metallnitridskikt som värmebehandlats vid höga temperaturer studerats. Förutom hårdhet har även skiktens seghet utvärderats genom yt- och tvärsnittsstudier av den sprickbildning som uppstår vid mekanisk provning med hjälp av svep- och transmissionselektronmikroskopi. Segheten hos Ti1?xAlxN skikt med varierande Al-halt (x = 0.23-0.82) studerades genom utmattningsprovning och resultaten visar att förändringar i mikrostrukturen spelar en stor roll. Ti0.63Al0.37N skikten hade överlägsna mekaniska egenskaper; på grund av en fördelaktig kornstorlek i de obehandlade skikten och efter värmebehandling som ett resultat av det spinodala sönderfall som skett. De mekaniska egenskaperna och högtemperaturegenskaperna hos hårda skikt kan förbättras genom legering eller genom multilagring. I den här avhandlingen har kvarternära Ti-Al-X-N (X = Cr, Nb eller V) skikt studerats och TiAl(Nb)N skikten hade en överlägsen seghet i både obehandlat och värmebehandlat (1100oC) tillstånd. Bildandet av h-AlN i TixAl0.37Cr1?0.37?xN (x = 0.03 and 0.16) skikt studerades genom in situ röntgenspridning under värmebehandling. Den energi som krävs för att bilda h-AlN beror av mikrostrukturutvecklingen under värmebehandling vilken i sin tur beror av skiktens kemiska sammansättning. h-ZrAlN/c-TiN och h-ZrAlN/c-ZrN multilager med hög Al-halt undersöktes genom reptester följda av tvärsnittsstudier av sprickbildningen genom en analys med en fokuserad jonstråle (FIB). En c-Ti(Zr)N fas bildas vid höga temperaturer i h-ZrAlN/c-TiN multilagren och det bidrar till förhöjd hårdhet och förbättrad seghet på grund av en bibehållen koherens mellan lagren. Slutligen har in situ röntgenspridningsstudier av ytskikt utförts vid svarvning. Studien visar på möjligheten att observera spänning och värmeutvidgning av skikten eller arbetsmaterialet under bearbetning. Experimenten ger information om skiktens beteende under bearbetning i realtid. La estabilidad térmica del recubrimiento es esencial debido a que estos recubrimientos durante su aplicación son utilizados a elevada temperatura y a alta velocidad. Durante dicho proceso, la evolución microestructural afecta a las propiedades mecánicas. En dicha tesis, la estabilidad mecánica de los recubimientos duros base nitruro producidos mediante arco y recocidos a elevada temperatura son analizados y se correlacionado con su transformación de fase. La dureza, la resistencia a la fractura son evaluados mediante la observación tanto superficial como transversal mediante microscopia electrónica de barrido. La resistencia a la propagación de grieta de Ti1?xAlxN con un contenido en Al que fluctúa entre 0.23-0.82 se estudia mediante ensayos de fatiga por contacto, donde la diferencia microstructural juega un papel importante. Las mejores propiedades mecánicas se encentran en las muestras con un 0.63 de Ti donde se ha realizado un proceso de recocido a 900o C debido a la descomposición espinoidal. Las características mecánicas y de alta temperatura de recubrimientos duros pueden ser mejoradas si tenemos un recubrimiento multicapa. Aleaciones cuaternarias de Ti-Al-X-N (X = Cr, Nb y V) son estudiada, y una mejor tenacidad de fractura se encuentra para la muestra TiAl(Nb)N sin tratamiento de recocido como recocida a 1000ºC. La formación del AlN con una estructura hexagonal en la muestra TixAl0.37Cr1?0.37?xN (x = 0.03 y 0.16) son analizadas mediante ensayos in-situ de difracción de rayos X durante el proceso de recocido. Cabe mencionar que la energía cinética para la formación de la AlN con una estructura hexagonal depende del proceso de recocido, la cual hace variar la composición química del recubrimiento. Multicapas de h (hexagonal)-ZrAlN/c (cúbica)-TiN con un elevado contenido de Al son estudiadas mediante ensayos de rayado y la generación de daño es observado mediante la técnica del haz de iones focalizados. Las formas de la fase de c-Ti(Zr)N en las multicapas de (h)-ZrAlN/c-TiN formadas a elevadas temperaturas contribuyen a mejorar la dureza y la tenacidad de fractura manteniendo la semicoherencia en las intercaras entre cada capa. Finalmente, se realiza un análisis in-situ de los diferentes recubrimientos me diante dispersión de rayos X durante un proceso de torneado. En este caso, se demuestra la posibilidad de observar la evolución de las tensiones residuales y de la expansión térmica durante el proceso de conformado. Dicho experimentos proporciona información en tiempo real sobre el comportamiento del recubrimiento en condiciones de servicio.

Magnesium (Mg) and its alloys have received widespread acceptance in automobile industries and biomedical applications with substantial recent advancements made in their development, however a significant limitation remains their poor aqueous and galvanic corrosion resistance. This book covers both the fundamentals and recent advancements in two major corrosion protection strategies of magnesium and its alloys, namely, metal-matrix composites and protective coatings. Key features: Covers all aspects of metal-matrix composites and protective coatings for magnesium alloys to improve their corrosion resistance, wear resistance, mechanical properties and biocompatibility Provides the most recent research advancements in the corrosion mitigation strategies of magnesium and its alloys Complete with case studies specific to practical applications, this book serves as a ready reference for graduate students, researchers, engineers and industry professionals in the fields of materials, corrosion science, biofouling and protective coatings.

TiAlN/VN multilayers, with a layer periodicity of ~3nm, have exhibited superior sliding wear resistance (1.26xlO-17m3N-lm-l) and lower friction coefficient (~=0.4, pin-on-disc test, Ah03 ball counterpart) when compared to other commonly used wear protective coatings, e.g. TiN, TiAlN and TiAlN/CrN. They require excellent oxidation and wear resistance for dry high speed machining operations. This project investigates the microstructure of the as-deposited coatings, their oxidation degradation mechanism and their wear and friction properties at room and elevated temperatures. The microstructure of the starting films was studied in terms of intermixing between the TiAlN and VN individual layers caused by the absence of shutters during the industrial PVD deposition. A FEGTEM coupled with EELS revealed chemical distribution of individual layers at nanometre resolution. Cs corrected STEM allowed the composition of individual atomic columns to be imaged. It was also used to probe across the interface of TiAlN/VN with angstrom beam (1 A) using EELS which showed a 1±0.1 nm thick intermixing between TiAlN and VN. Film growth and elemental distributions were therefore theoretically predicted in association with substrate rotation. The experimental compositional profiles and the prediction showed good agreement. The coatings deposited with -75 V and -85 V substrate bias voltage were multilayer TiAlNNN, 37at%:::;V:::;55at%, 0.81:::;(Ti+Al)/V:::;1.73, which were used for subsequent oxidation and wear studies. The oxidation behaviour of these coatings in air was investigated using thermal gravimetric analysis up to 1000°C and compared to TiN and TiAlN. Static oxidation of TiAlN/VN films was studied in the range 550-700°C, and characterised by high temperature in-situ X-ray diffraction and STEM/EDXlEELS of selected surface cross-sections. The oxidation resistance of TiAlN/VN was found to be controlled by the VN layers and consequently oxidation was initiated at a lower temperature than TiN and TiAlN coatings. The onset for rapid oxidation of the TiAlN/VN coating was found to be 2550°C. At temperatures >600°C, a duplex oxide structure was formed; the inner layer comprised a porous region of Ti-rich and V-rich nanocrystallites, while several phases were observed in the outer region, including V20 5, Ti02 and AlV04. V20 5 was the dominant oxide at the outer layer at 2638°C. An Au marker study suggested roughly equal diffusivity of cations outward and oxygen inward diffusion occurred during oxidation. Further to the oxidation study, dry sliding ball-on-disc wear tests of TiAlN/VN (V 55.2at%, Ti 28.5at% and Al 16.3at%) coatings on flat stainless steel substrates were undertaken against Ah03 at 25°C, 300°C and 635°C in air to investigate the relation between the presence of V 205 and low friction. The friction coefficient was 0.53 at 25°C which increased to 1.03 at 300°C and decreased to 0.46 at 635°C. Detailed investigation of the worn surfaces was undertaken using site-specific TEM via FIB, along with FTIR and Raman spectroscopy. Microstructure and tribo-induced chemical reactions at these temperatures were correlated with the coating's wear and friction behaviour. The friction behaviour at room temperature is attributed to the presence of a thin hydrated tribofilm and the presence of V 205 at high temperature.

The field of coatings and thin-film technologies is rapidly advancing to keep up with new uses for semiconductor, optical, tribological, thermoelectric, solar, security, and smart sensing applications, among others. In this sense, thin-film coatings and structures are increasingly sophisticated with more specific properties, new geometries, large areas, the use of heterogeneous materials and flexible and rigid coating substrates to produce thin-film structures with improved performance and properties in response to new challenges that the industry presents. This book aims to provide the reader with a complete overview of the current state of applications and developments in thin-film technology, discussing applications, health and safety in thin films, and presenting reviews and experimental results of recognized experts in the area of coatings and thin-film technologies.

In the industrial manufacturing of metals, the achievement of products featuring desired characteristics always requires the control of process parameters in order to obtain a suitable microstructure. The strict relationship among process parameters, microstructure, and mechanical properties is a matter of interest in different areas, such as foundry, plastic forming, sintering, welding, etc., and regards both well-established and innovative processes. Nowadays, circular economy and sustainable technological development are dominant paradigms and impose an optimized use of resources, a lower energetic impact of industrial processes and new tasks for materials and products. In this frame, this Special Issue covers a broad range of research works and contains research and review papers.

High Power Impulse Magnetron Sputtering: Fundamentals, Technologies, Challenges and Applications is an in-depth introduction to HiPIMS that emphasizes how this novel sputtering technique differs from conventional magnetron processes in terms of both discharge physics and the resulting thin film characteristics. Ionization of sputtered atoms is discussed in detail for various target materials. In addition, the role of self-sputtering, secondary electron emission and the importance of controlling the process gas dynamics, both inert and reactive gases, are examined in detail with an aim to generate stable HiPIMS processes. Lastly, the book also looks at how to characterize the HiPIMS discharge, including essential diagnostic equipment. Experimental results and simulations based on industrially relevant material systems are used to illustrate mechanisms controlling nucleation kinetics, column formation and microstructure evolution. Includes a comprehensive description of the HiPIMS process from fundamental physics to applications Provides a distinctive link between the process plasma and thin film communities Discusses the industrialization of HiPIMS and its real world applications

This book comprises select proceedings of the International Conference on Innovations in Mechanical Engineering (ICIME 2021). It presents innovative ideas and new findings in the field of mechanical engineering. Various topics covered in this book are aerospace engineering, automobile engineering, thermal engineering, renewable energy sources, bio-mechanics, fluid mechanics, MEMS, mechatronics, robotics, CAD/CAM, CAE, CFD, design andoptimization, tribology, materials engineering and metallurgy, mimics, surface engineering, nanotechnology, polymer science, manufacturing, production management, industrial engineering and rapid prototyping. This book will be useful for the students, researchers and professionals working in the various areas of mechanical engineering.

The current status of the science and technology related to coatings, thin films and surface modifications produced by directed energy techniques is assessed in Materials Surface Processing by Directed Energy Techniques. The subject matter is divided into 20 chapters - each presented at a tutorial level – rich with fundamental science and experimental results. New trends and new results are also evoked to give an overview of future developments and applications. Provides a broad overview on modern coating and thin film deposition techniques, and their applications Presents and discusses various problems of physics and chemistry involved in the production, characterization and applications of coatings and thin films Each chapter includes experimental results illustrating various models, mechanisms or theories

This book is a compilation of research work in the interdisciplinary areas of electronics, communication, and computing. This book is specifically targeted at students, research scholars and academicians. The book covers the different approaches and techniques for specific applications, such as particle-swarm optimization, Otsu’s function and harmony search optimization algorithm, triple gate silicon on insulator (SOI)MOSFET, micro-Raman and Fourier Transform Infrared Spectroscopy (FTIR) analysis, high-k dielectric gate oxide, spectrum sensing in cognitive radio, microstrip antenna, Ground-penetrating radar (GPR) with conducting surfaces, and digital image forgery detection. The contents of the book will be useful to academic and professional researchers alike.