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Improving the Surface Properties of Cp-Ti by Pulsed Electro-Spark Deposition

100%

Yılmaz M., Atar E., Şahin O., Kayalı E.

Acta Physica Polonica A

2014

vol. 125

issue 2

593-596

Al-Ti intermetallic compounds were coated by electro-spark deposition. Commercially pure titanium (Cp-Ti) (grade 2) and aluminum rods were used as substrate and electrode materials, respectively. During the electro-spark deposition experiments the following pulse parameters in a group were used: pulse current amplitude, pulse duration and pause between the pulses of a pulse group with 100-300-500 A, 50-100 μs, and 100 μs, respectively. Al-Ti coatings having a thickness range of 15-30 μm were formed on the surface of titanium substrate using electro-spark deposition process. The coating properties such as the roughness and the thickness increased with increasing pulse duration and pulse current amplitude. The mass transfer coefficient decreased with increasing pulse current amplitude and pulse duration. The quality of the adhesion characters of the coatings, determined by Rockwell-C adhesion test, becomes worse from HF-2 to HF-4, due to increase of pulse current amplitude. Depending on the electro-spark deposition process parameters, the coating formed as AlTi or as layered structure consisting of AlTi+AlTi_3 when pulse current amplitude increases. The Al-Ti coatings include some micro cracks lying throughout the coating from surface to interface which is nature of this process. The maximum cross-sectional hardness of the coatings were in the range of 800-1150 HV.

Nano-Bioceramic Synthesis from Tropical Sea Snail Shells (Tiger Cowrie - Cypraea Tigris) with Simple Chemical Treatment

64%

Şahin Y., Gündüz O., Bulut B., Özyeğin L., Gökçe H., Ağaoğulları D., Chou J., Kayalı E., Ben-Nissan B., Oktar F.

Acta Physica Polonica A

2015

vol. 127

issue 4

1055-1058

In this study several bioceramic materials (i.e. hydroxyapatite, whitlockite) were prepared by using chemical synthesis method from sea snail shells (Tiger Cowrie - Cypraea Tigris), originated from Pacific Ocean. Marine shells usually present aragonite-calcite structures and generally, complicated and pressurized equipment is necessary to convert these structures into bioceramics. Instead of using complicated systems, a basic ultrasonic equipment and simple chemical synthesis method was used in the process. DTA analysis was performed to calculate the required amount of H₃PO₄ solution in order to set the appropriate stoichiometric ratio of Ca/P equal to 1.667 for HA bioceramic or to 1.5 for β-TCP bioceramic in the titration. The prepared batches were sintered at 800°C and 400°C for hydroxyapatite (HA) and β-tri calcium phosphate (β-TCP) forms respectively. X-ray diffraction analysis, scanning electron microscopy (SEM) and infrared observations (FTIR) were implemented for both TCP and HA bioceramics. By applying the chemical synthesis with basic ultrasonic equipment, this study proposes a simple way of production for nano-HA /TCP powders from a natural marine sources.

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2 Acta Physica Polonica A

1 2015

1 2014

2 Kayalı E.

1 Atar E.

1 Ağaoğulları D.

1 Ben-Nissan B.

1 Bulut B.

1 Chou J.

1 Gökçe H.

1 Gündüz O.

1 Oktar F.

1 Yılmaz M.

1 Özyeğin L.

1 Şahin O.

1 Şahin Y.

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Improving the Surface Properties of Cp-Ti by Pulsed Electro-Spark Deposition

Nano-Bioceramic Synthesis from Tropical Sea Snail Shells (Tiger Cowrie - Cypraea Tigris) with Simple Chemical Treatment