Effect of polycarbonate film surface morphology and oxygen plasma treatment on mode I and II fracture toughness of interleaved composite laminates

ABSTRACTNanocrystalline diamond (NCD) films are prepared from Ar-rich/N2/CH4 and Ar-rich/H2/CH4 mixtures by microwave plasma-enhanced chemical vapor deposition, and further treated by microwave hydrogen and oxygen plasma exposures separately to enhance the wetting property. The hydrogen plasma treatment has small effect on the surface roughness, while the oxygen plasma treatment forms fine protrusions on the film surface. Results show that the wettability of the hydrogen plasma treated NCD film is nearly constant or little improvement as the polar component of the apparent surface free energy is close to the as-deposit NCD film. In contrast, the wettability of the oxygen plasma treated NCD film is improved dramatically such that the contact angle is reduced from 92º and 4.7º to almost 0º for water and 1-bromonaphthalene, respectively, and the polar component increases significantly to 34 mJ/m2. The low contact angle suggests that the film is considerably a cell adhesive friendly surface, which is essential in maintaining multicellular structure, and thus making it a favorable wetting surface for biological and biomedical applications.

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Effect of Plasma-Treatment of Interleaved Thermoplastic Films on Delamination in Interlayer Fibre Hybrid Composite Laminates

Polymers ◽

10.3390/polym12122834 ◽

2020 ◽

Vol 12 (12) ◽

pp. 2834

Author(s):

Salvatore Giacomo Marino ◽

Florian Mayer ◽

Alexander Bismarck ◽

Gergely Czél

Keyword(s):

Plasma Treatment ◽

Composite Laminates ◽

High Performance ◽

Oxygen Plasma ◽

Mechanical Performance ◽

Hybrid Composites ◽

Acrylonitrile Butadiene Styrene ◽

Tensile Tests ◽

Oxygen Plasma Treatment ◽

Engineering Structures

Safe, light, and high-performance engineering structures may be generated by adopting composite materials with stable damage process (i.e., without catastrophic delamination). Interlayer hybrid composites may fail stably by suppressing catastrophic interlayer delamination. This paper provides a detailed analysis of delamination occurring in poly(acrylonitrile-butadiene-styrene) (ABS) or polystyrene (PS) film interleaved carbon-glass/epoxy hybrid composites. The ABS films toughened the interfaces of the hybrid laminates, generating materials with higher mode II interlaminar fracture toughness (GIIC), delamination stress (σdel), and eliminating the stress drops observed in the reference baseline material, i.e., without interleaf films, during tensile tests. Furthermore, stable behaviour was achieved by treating the ABS films in oxygen plasma. The mechanical performance (GIIC and σdel) of hybrid composites containing PS films, were initially reduced but increased after oxygen plasma treatment. The plasma treatment introduced O-C=O and O-C-O-O functional groups on the PS surfaces, enabling better epoxy/PS interactions. Microscopy analysis provided evidence of the toughening mechanisms, i.e., crack deflection, leading plasma-treated PS to stabilise delamination.

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Shear Bond Strength of Ceramic Veneers to Zirconia–Calcium Silicate Cores

Coatings ◽

10.3390/coatings11111326 ◽

2021 ◽

Vol 11 (11) ◽

pp. 1326

Author(s):

Ting-Yi Chiang ◽

Chun-Chuan Yang ◽

Yi-Hsuan Chen ◽

Min Yan ◽

Shinn-Jyh Ding

Keyword(s):

Contact Angle ◽

Phase Composition ◽

Surface Morphology ◽

Bond Strength ◽

Plasma Treatment ◽

Calcium Silicate ◽

Shear Bond Strength ◽

Oxygen Plasma ◽

Oxygen Plasma Treatment ◽

Water Contact

Improving the bond strength of veneering ceramics to ZrO2-based cores remains a challenge. The purpose of this study was to evaluate the shear bond strength of different ZrO2 cores containing calcium silicate (CaSi) to veneering ceramics. Five types of ZrO2-based cores (n = 230) were divided into two groups: with or without oxygen plasma treatment. These were bound to two veneering ceramics (IPS e.max Ceram or VITA VM9). Shear bond strength of veneering ceramics to various cores was measured (n = 10), in addition to phase composition, surface morphology and contact angle of the cores. The results indicated that the plasma treatment had a significant effect on the water contact angle of the ZrO2-based cores, but had little effect on the bond strength. Regardless of plasma treatment, the highest strength value was recorded in the ZrO2 core specimen containing 20 wt % CaSi, when all cores were adhered to VITA VM 9 veneer. When using IPS e.max Ceram veneer, the shear bond strength of the plasma-treated 20 wt % CaSi-containing ZrO2 core was 16.6 ± 0.9 MPa higher than that of VITA In-Ceram YZ core control (13.4 ± 1.0 MPa) (p < 0.05). We conclude that the presence of 20 wt % CaSi in ZrO2 can improve the shear bond strength of zirconia-based cores to veneering ceramic.

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High Breakdown Voltage GaN HEMT Device Fabricated on Self-Standing GaN Substrate

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.347-350.1535 ◽

2013 ◽

Vol 347-350 ◽

pp. 1535-1539

Author(s):

Jian Jun Zhou ◽

Liang Li ◽

Hai Yan Lu ◽

Ceng Kong ◽

Yue Chan Kong ◽

...

Keyword(s):

Plasma Treatment ◽

Breakdown Voltage ◽

Oxygen Plasma ◽

Cutoff Frequency ◽

Chemical Vapor ◽

Current Gain ◽

Organic Chemical ◽

Oxygen Plasma Treatment ◽

Gan Hemt ◽

High Breakdown Voltage

In this letter, a high breakdown voltage GaN HEMT device fabricated on semi-insulating self-standing GaN substrate is presented. High quality AlGaN/GaN epilayer was grown on self-standing GaN substrate by metal organic chemical vapor deposition. A 0.8μm gate length GaN HEMT device was fabricated with oxygen plasma treatment. By using oxygen plasma treatment, gate forward working voltage is increased, and a breakdown voltage of more than 170V is demonstrated. The measured maximum drain current of the device is larger than 700 mA/mm at 4V gate bias voltage. The maximum transconductance of the device is 162 mS/mm. In addition, high frequency performance of the GaN HEMT device is also obtained. The current gain cutoff frequency and power gain cutoff frequency are 19.7 GHz and 32.8 GHz, respectively. A high fT-LG product of 15.76 GHzμm indicating that homoepitaxy technology is helpful to improve the frequency performance of the device.

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