Microstructural investigation of CVD TiAlN, TiN and WN coatings
Doctoral thesis, 2021
This thesis focuses on examining topics of relevance to increase the understanding of hard nitride coatings synthesized by CVD. The main research methods are analytical transmission and scanning electron microscopy (TEM and SEM), with complementary X-ray diffraction (XRD), atom probe tomography (APT) and simulations. Three types of CVD coatings were studied in this work: TiAlN coatings, TiN coatings and WN coatings.
The work on TiAlN coatings: (i) First, the growth facets and texture were revealed. (ii) Second, an effect of precursor gas flow on the growth of the coating was studied, including the correlation between the formation of a nanolamella structure and the rotating precursor gas supply, and a microstructural inhomogeneity relevant to the varying gas environment. (iii) In addition, the full chemical composition of the TiAlN coating was studied via APT and electron microscopy. (iv) Finally, an intra-grain misorientation that forms in TiAlN during the CVD growth, and the formation of relevant dislocations, was studied. The work on TiN coatings: (i) The microstructure of the CVD TiN coatings deposited on a CoCrFeNi multi-principal elemental alloy (MPEA) substrate was studied, and (ii) the etching effect of the corrosive gas environment on the MPEA substrate was evaluated. The work on WN coatings: The microstructure and grain morphology of WN deposited on a (0001) sapphire substrate, especially the influence of deposition temperature on the microstructures, were studied.
In conclusion, the results presented in this thesis provide insights into the detailed microstructures of TiAlN, TiN and WN coatings, which will increase the understanding of the growth mechanisms for these CVD coatings.
Chalmers, Physics, Microstructure Physics
CVD TiAlN coatings with tunable nanolamella architectures
Surface and Coatings Technology,; Vol. 413(2021)
Effects of gas flow on detailed microstructure inhomogeneities in LPCVD TiAlN nanolamella coatings
Materialia,; Vol. 9(2020)
Ren Qiu, Hisham Aboulfadl, Olof Bäcke, Dirk Stiens, Hans-Olof Andrén, Mats Halvarsson, Atom probe tomography investigation of 3D nanoscale compositional variations in CVD TiAlN nanolamella coatings
Ren Qiu, Olof Bäcke, Dirk Stiens, Hans-Olof Andrén, Mats Halvarsson, Grain rotation during growth of CVD TiAlN
Chemical vapor deposition of TiN on a CoCrFeNi multi-principal element alloy substrate
Surface and Coatings Technology,; Vol. 393(2020)
Johan G. Hulkko, Katalin Böőr, Ren Qiu, Olof Bäcke, Mats Boman, Mats Halvarsson, Erik Lindahl, Kinetics of the low-pressure chemical vapour deposited tungsten nitride process using tungsten hexafluoride and ammonia precursors
The aim of this work is to generate new knowledge about growth of hard, wear-resistant CVD coatings through systematic microstructural studies, using various state-of-the-art materials analysis method, such as X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM), and electron backscattered diffraction (EBSD). This work studies microstructures of different CVD coatings, including titanium nitride (TiN), titanium aluminium nitride (TiAlN) and tungsten nitride (WN). For the TiN coating, which was deposited on a CoCrFeNi multi-principle elemental alloy (MPEA) substrate, the etching effect of the corrosive CVD gas environment on the substrate was studied. For the WN coatings, the variation of microstructures at different deposition conditions was studied. For the TiAlN coatings, the influence of precursors gas flow on an internal microscopic nanolamella structure and microstructural inhomogeneities was revealed. The 3D nanoscale compositional variation in the CVD TiAlN was also studied. In addition, a grain rotation phenomenon during the growth of CVD TiAlN, associated to internal dislocation structures, was revealed. It is hoped that the results presented in this thesis could help the design and synthesis of new and better CVD coatings in the future.
Gothenburg, Sweden, August 2021
CVD 2.0 - En ny generation av hårda beläggningar
Swedish Foundation for Strategic Research (SSF) (RMA15-0048), 2016-05-01 -- 2021-06-30.
Chalmers Materials Analysis Laboratory
Areas of Advance
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 5009
Chalmers University of Technology
PJ lecture hall at the Department of Physics, Chalmers University of technology
Opponent: Prof. Magnus Odén from Linköping University, Sweden