<p>Mechanical property and thermal stability of Zr-Si-N films of varying silicon contents deposited on Al<sub>2</sub>O<sub>3</sub> (0001) substrates are characterized. All films provided for characterization were deposited by reactive DC magnetron sputter deposition technique from elemental Zr and Si targets in a N<sub>2</sub>/Ar plasma at 800 <sup>o</sup>C. The hardness and microstructures of the as deposited films and post-annealed films up to 1100 <sup>o</sup>C are evaluated by means of nanoindentation, X-ray diffractometry and transmission electron microscopy. The Zr-Si-N films with 9.4 at.% Si exhibit hardness as high as 34 GPa and a strong (002) texture within which vertically elongated ZrN crystallites are embedded in a Si<sub>3</sub>N<sub>4</sub> matrix. The hardness of these two dimensional nanocomposite films remains stable up to 1000 <sup>o</sup>C annealing temperatures which is in contrast to ZrN films where hardness degradation occurs already above 800 <sup>o</sup>C. The enhanced thermal stability is attributed to the presence of Si<sub>3</sub>N<sub>4</sub> grain boundaries which act as efficient barriers to hinder the oxygen diffusion. X-ray amorphous or nanocrystalline structures are observed in Zr-Si-N films with silicon contents > 13.4 at.%. After the annealing treatments, crystalline phases such as ZrSi<sub>2</sub>, ZrO<sub>2</sub> and Zr<sub>2</sub>O are formed above 1000 <sup>o</sup>C in the Si-containing films while only zirconia crystallites are observed at 800 <sup>o</sup>C in pure ZrN films because oxygen acts as artifacts in the vacuum furnace. The structural, compositional and hardness comparison of as-deposited and annealed films reveal that the addition of silicon enhances the thermal stability compared to pure ZrN films and the hardness degradation stems from the formation of oxides at elevated temperatures.</p>
| Identifer | oai:union.ndltd.org:UPSALLA/oai:DiVA.org:liu-58622 |
| Date | January 2010 |
| Creators | Ku, Nai-Yuan |
| Publisher | Linköping University, Linköping University, Department of Physics, Chemistry and Biology |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Student thesis, text |
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