Abstract: Multi-functional hybrid films were developed by doping PTFE into CeO2 by co-sputtering of CeO2 and PTFE targets. The hybrid films formed on borosilicate glass substrate containing from 5 to 15 vol. % PTFE in CeO2 showed UV shielding, high indentation hardness, hydrophobicity, optical transmittance in visible light, and high bending crack resistance. Optical properties of 100 nm thick CeO2 -5 vol. % PTFE film revealed UV light shielding of more than 80 % at 380 nm and visible light transmittance higher than 80 %. Indentation hardness measured under the load of 0.001mN was more than 16,000N/mm2 of 2.7 times higher than the glass substrate. No crack in the film was observed by bending 1.5 cm in diameter. Furthermore, the hydrophobic surface property was evaluated by the water contact angle to be higher than 90 degrees. Preliminary characterization of the CeO2-PTFE film using XPS and XMA revealed that chemical states of F in sputter doped PTFE in CeO2 can be considered to exist as C-F and Ce-F compounds. On the other hand, chemical states of Ce changed partially from Ce+4 (CeO2) to Ce+3 (Ce2O3 or CeF3) with increasing doped PTFEF in the film.

In this rapid communication, we preliminary described the optical, mechanical and chemical properties of newly developed hybrid CeO2-PTFE films prepared by sputtering.

Keywords: Hybrid sputtering films, CeO2-PTFE film, Super-hard, UV shieldinng, Water repellamt, Bending rsistance, Transparent in visible light, PTFE doping, XPS, Nanoindentor.

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Abstract: Ternary zirconia-alumina coatings with different compositional ratios, ranging from pure zirconia to 50% alumina content, were deposited by reactive sputtering from two targets, Zr and Al, in argon-oxygen mixtures. The coating composition was controlled by the Zr/Al target power ratio provided by two pulsed-DC power supplies. The coatings were ~1 µm thick and they were deposited on floating potential substrates at a temperature of 650±3K.

XRD indicated that the pure zirconia coatings possessed a monoclinic structure with a grain size of 35-40 nm. Adding alumina to the zirconia coating stabilized the cubic zirconia phase and decreased the grain size to 10-15 nm. The alumina phase in the coatings remained amorphous. The hardness of the nanocomposite structure increased from 11.6±0.5 GPa to 16.1±0.5 GPa for an alumina content of 17%. At higher alumina concentrations, the zirconia phase became amorphous and the hardness decreased to 10-11 GPa.

Structure stability of the zirconia-alumina coatings was studied by measuring the coating structure and hardness after annealing at temperatures up to 1173 K. Pure zirconia (m-ZrO₂) coatings had low structure stability; the hardness reached a maximum value of 18±1 GPa after annealing at a temperature of 773-873K; however, at higher annealing temperatures the hardness decreased, reaching a minimum value of 12.3±0.6 GPa after annealing at 1173K. The hardness of the nanocomposite ZrO₂/Al₂O₃ coating with various compositions increased with annealing temperature. The hardness of a coating with an alumina content of 17% reached a high value of 19.2±0.5 GPa after annealing at 1073-1173 K. Measurements of post annealing XRD analyses indicated that the stabilization of the coating structure with c-ZrO₂/a-Al₂O₃ phases is the reason for the higher structure stability. From the analyses of phase stability and hardness before and after annealing, we conclude that adding alumina to the zirconia phase promotes the formation of nanocomposite c-ZrO₂/a-Al₂O₃ coatings with a markedly higher stability than single-phase m-ZrO₂.

Highlights:

1. ZrO₂/Al₂O₃ nanocomposite coatings were deposited by co-sputtering from Zr and Al targets.

2. Adding alumina to the zirconia coating stabilized the cubic zirconia phase.

3. ZrO₂-17% Al₂O₃ coatings had a grain size of 10-15 nm and a hardness of 16.1±0.5 GPa.

4. ZrO₂/Al₂O₃ coatings maintained a high hardness after annealing at 1173K with a high value of 19 GPa for alumina content of 17%.

5. The ZrO₂/Al₂O₃ nanocomposite coatings were crack-free after annealing at 1173K.

Keywords: Stabilized Zirconia, Thin coatings, Magnetron sputtering, Hardness, thermal treatments.

Abstract: A novel amorphous CuN/nanocrystal WC (nc-WC/a-CuN) film synthesized by reactive dc magnetron sputtering is reported in this paper. The nc-WC/a-CuN_{42 at.%} film which is composed of many WC dendrite crystals of 5~10 nm with (001) orientation embedded in amorphous CuN possesses ~55 GPa hardness. The high-temperature wear analysis shows that this novel film possesses the comparable excellent friction performance with DLC film which is attributed to self-lubricant function of a-CuN; simultaneously the film was still maintaining the higher hardness at elevated temperature.

Keywords: Nanocomposite film; Reactive magnetron sputtering; CuN; WC; High-temperature wear behavior.

Abstract: : Titanium carbonitride thin films were grown by reactive magnetron sputtering deposition of titanium carbide target in Ar/N₂ gas mixture on p-type silicon (100) substrates. With the increase of sputtering power up to 125W, the deposition rate and films thickness reached a maximum of 14nm/min and 430nm, respectively. A thick film of about 2200nm could be deposited for 120 min at the optimum deposition pressure of 20mTorr. Cathode current decreased from about 290mA to reach a value of about 235mA as the N₂ flow percentage increased from 0 to 100%. X-ray diffraction analyses of the deposited films confirmed the formation of titanium carbide and carbonitride layers as the nitrogen gas concentrations in the process gas were increased. SEM image of the deposited titanium carbonitride thin film for 5 min deposition time showed that the film started to grow as tiny particles of size as low as about 140nm, which in later stage coalesced together to form bigger grains and finally a continuous film. The deposited film shows good thermal stability upon annealing in air and in vacuum at 700^oC for 2 hours.

Keywords: Titanium carbonitride, Nanocomposite thin films, Reactive magnetron sputtering, Thermal stability.

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