TY - THES

T1 - Synthesis and characterization of B1-AlN containing superlattice structures

AU - Becker, Maria-Theresia

N1 - no embargo

PY - 2022

Y1 - 2022

N2 - Due to their excellent mechanical properties, nitride superlattices (SLs) are used industrially as hard protective coatings, e.g., to protect and enhance the performance of cutting tools in the machining industry. This master´s thesis deals with the synthesis and characterization of chromium nitride (CrN) / aluminum nitride (AlN) SL coatings with AlN stabilized in its metastable B1 structure. The films were synthesized in an unbalanced reactive magnetron sputtering system equipped with computer-controlled mechanical shutters. Polycrystalline SLs were obtained by using Si (100) as substrate material, while single-crystal SLs develop when depositing on MgO (100). The films’ structural and mechanical properties were determined by X-ray diffraction and nanoindentation, respectively. Polycrystalline SLs with 4 nm CrN / 2 nm AlN architecture had a hardness of 28.2 ±0.7 GPa, while an even higher hardness of 33.3 ±1.3 GPa was measured for single-crystal SLs with the same architecture. The SLs were about 6.5 GPa harder than monolithic CrN on the same type of substrate. The hardness of B3-AlN containing 4 nm CrN / 5 nm AlN SL films was with 24.8 ±1.0 and 27.8 ±1.0 GPa for films on Si (100) and MgO (100), respectively, lower compared to the exclusively B1-structured SLs. Explanations for the SL hardness effect and the influence of interfaces between the nanolayers and columnar grain boundaries on the mechanical behavior of SLs are discussed.

AB - Due to their excellent mechanical properties, nitride superlattices (SLs) are used industrially as hard protective coatings, e.g., to protect and enhance the performance of cutting tools in the machining industry. This master´s thesis deals with the synthesis and characterization of chromium nitride (CrN) / aluminum nitride (AlN) SL coatings with AlN stabilized in its metastable B1 structure. The films were synthesized in an unbalanced reactive magnetron sputtering system equipped with computer-controlled mechanical shutters. Polycrystalline SLs were obtained by using Si (100) as substrate material, while single-crystal SLs develop when depositing on MgO (100). The films’ structural and mechanical properties were determined by X-ray diffraction and nanoindentation, respectively. Polycrystalline SLs with 4 nm CrN / 2 nm AlN architecture had a hardness of 28.2 ±0.7 GPa, while an even higher hardness of 33.3 ±1.3 GPa was measured for single-crystal SLs with the same architecture. The SLs were about 6.5 GPa harder than monolithic CrN on the same type of substrate. The hardness of B3-AlN containing 4 nm CrN / 5 nm AlN SL films was with 24.8 ±1.0 and 27.8 ±1.0 GPa for films on Si (100) and MgO (100), respectively, lower compared to the exclusively B1-structured SLs. Explanations for the SL hardness effect and the influence of interfaces between the nanolayers and columnar grain boundaries on the mechanical behavior of SLs are discussed.

KW - PVD

KW - Sputtern

KW - Hard Coatings

KW - Multilagenschichten

KW - Superlattice

KW - Nitride

KW - CrN

KW - AlN

KW - Stabilisierung von B1-AlN

KW - strukturelle Eigenschaften

KW - mechanische Eigenschaften

KW - PVD

KW - sputtering

KW - hard coatings

KW - multilayer films

KW - superlattice films

KW - nitrides

KW - CrN

KW - AlN

KW - stabilization of B1-AlN

KW - structural properties

KW - mechanical properties

M3 - Master's Thesis

ER -