TY - THES

T1 - Characterisation of novel metallic films on silicon using nanoindentation

AU - Kampichler, Juliane

N1 - embargoed until 20-06-2022

PY - 2017

Y1 - 2017

N2 - Increasing interest in the field of open and closed porous materials led to this study. The focus was set on material characterisation through nanoindentation. The experiments have been performed on an open porous copper material on silicon. The state of the art method for porous material is the Ashby-Gibson model, though especially for sintered material the model reveals huge discrepancies. Therefore, the correlation of young´s modulus to the model as well as boundaries and possible improvements of those nanoindentation measurements should be investigated. In the first stage the nanoindentation behaviour of the porous material was tested to find the optimal depth. Notably for pure copper is the influence of the surface roughness, which affects the indenter depth. Therefore, the further investigation was settled on the surface and material preparation to improve the measurements. To minimise the roughness different preparation techniques, like fine mechanical treatment, polishing with suspension, ion milling and etching, have been tested. The most promising results have been developed with OP-S polish, but the limits for sufficient indentation values could only partly be reached. Thus, the next stage was to infiltrate the material, to create a two-phase-composite. The original material couldn’t be infiltrated because of the silicon layer. As a consequence additional material batches without silicon with different porosities have been produced and infiltrated. On these composites successful indentation measurements could be accomplished with deviations below 10%. In additional to the model of Hashin-Shtikman for coated spheres a correlation between porosity and the shear modulus could be made, which was extremely exact for the more homogenous samples. As a result of the infiltration reproducible nanoindentation values and a sufficient model for correlation of porosity and moduli could be attained. Based on the achieved results additional work respecting the 3D material structure and behaviour through X-ray computed- and FIB-tomography as well as EBSD will be carried out comprehensively in the future.

AB - Increasing interest in the field of open and closed porous materials led to this study. The focus was set on material characterisation through nanoindentation. The experiments have been performed on an open porous copper material on silicon. The state of the art method for porous material is the Ashby-Gibson model, though especially for sintered material the model reveals huge discrepancies. Therefore, the correlation of young´s modulus to the model as well as boundaries and possible improvements of those nanoindentation measurements should be investigated. In the first stage the nanoindentation behaviour of the porous material was tested to find the optimal depth. Notably for pure copper is the influence of the surface roughness, which affects the indenter depth. Therefore, the further investigation was settled on the surface and material preparation to improve the measurements. To minimise the roughness different preparation techniques, like fine mechanical treatment, polishing with suspension, ion milling and etching, have been tested. The most promising results have been developed with OP-S polish, but the limits for sufficient indentation values could only partly be reached. Thus, the next stage was to infiltrate the material, to create a two-phase-composite. The original material couldn’t be infiltrated because of the silicon layer. As a consequence additional material batches without silicon with different porosities have been produced and infiltrated. On these composites successful indentation measurements could be accomplished with deviations below 10%. In additional to the model of Hashin-Shtikman for coated spheres a correlation between porosity and the shear modulus could be made, which was extremely exact for the more homogenous samples. As a result of the infiltration reproducible nanoindentation values and a sufficient model for correlation of porosity and moduli could be attained. Based on the achieved results additional work respecting the 3D material structure and behaviour through X-ray computed- and FIB-tomography as well as EBSD will be carried out comprehensively in the future.

KW - Poröses Kupfer

KW - Rauheit

KW - Nanoindentierung

KW - Oberflöchenpräparation

KW - Materialpräparation

KW - Infiltration

KW - Kompositmodell

KW - porous copper films

KW - roughness

KW - nanoindentation

KW - surface preparation

KW - material preparation

KW - infiltration

KW - composite model

M3 - Diploma Thesis

ER -