Characterization of microstructure of H13 tool steel using ultrasonic measurements

This study presents nondestructive characterization of microstructure of AISI H13 hot work tool steel. Heat treatments were carried out in order to obtain different microstructural phases in the tool steel specimens. The microstructural phases were characterized by metallographic examinations and hardness measurements. Velocities of ultrasonic longitudinal and transverse waves were measured by means of pulse-echo method using contact type normal beam probes. Ultrasonic apparent attenuation also determined in the steel specimens having different microstructural phases. A lower value of ultrasonic velocity was observed for the martensite compared to the other microstructures, while the opposite was observed in ultrasonic attenuation. Results show that the use of ultrasonic measurements in order to correlate them with the microstructures is fast and reliable, permitting nondestructive characterization of microstructure in steels.     

Major flavan-3-ol composition and antioxidant activity of seeds from different grape cultivars grown in Turkey

The major flavan-3-ols composition and antioxidant activity of the seeds of 12 different common grape varieties that grow in Turkey were investigated. The quantities of gallic acid, catechin, epicatechin and total flavan-3-ol were determined with high performance liquid chromatography (HPLC) and spectrophotometric method in grape seeds extracts. Gallic acid, catechin, epicatechin and total flavan-3-ol varied from 18 to 101, 121–845, 85–893 and 4 507–13 360 mg/100 g in grape seeds, respectively. The seeds of Papaz Karası, Alicante Boushet and Kalecik Karası cultivars were good sources for these compounds among the cultivars examined. In most cultivars, the amount of epicatechin was greater than that of catechin. The cultivars that have high total flavan-3-ol content had the strongest free radical scavenging activities and results were shown that there is a highly significant correlation between the total flavan-3-ol content and antiradical efficiency (AE) (r=0.9168, P<0001).     

Nondestructive Characterization of Corrosion Properties of Stainless Steel and Titanium Alloys

Russian Journal of Nondestructive Testing - In this study, non-destructive characterisation of the corrosion properties of titanium and stainless steels was carried out. Stainless steel and...     

Effect of sonication time on the synthesis of the CdS nanoparticle based multiwall carbon nanotube – maleic anhydride – 1-octene nanocomposites

Effect of sonication time on the synthesis of the CdS nanoparticles within the matrix obtained through the covalent functionalization of multiwall carbon nanotube (MWCNT) with maleic anhydride (MA) – 1-octene copolymer was investigated. Cadmium chloride and thiourea were used as the raw materials. MWCNTs used for the matrix were synthesized by Catalytic Chemical Vapor Deposition using Fe-Co/Al₂O₃ as the catalyst. The obtained nanostructures were characterized by FTIR, XRD, Raman spectroscopy, TEM, SEM, TG and UV-Vis spectroscopy. Electrophysical properties of the polymer nanocomposites obtained using different periods of time for sonication were comparably investigated. The average CdS particle diameter was between 3.9–7.9 nm as confirmed independently by TEM and XRD. UV-Vis spectroscopy revealed that the obtained nanostructures are appropriate base materials for making optical devices.     

Olive Cake as a Biomass Fuel for Energy Production

Olive cake (OC) is a by-product of olive oil production and is a solid material consisting of seed particles and the fleshy parts of olive. The Mediterranean region represents 98% of the world's olive tree population, and Turkey is among the top five main olive oil producer countries around the world. The main objective of the present study is to investigate the potential and utilization of olive cake (OC) in the country. It is estimated that over 360,000 tons of OC, corresponding to an average of 150,000 tons of oil equivalent (toe), were produced in the season of 2000–2001 in Turkey. From the combustion experiments performed in the conventional OC-fired boilers in the country, the values for CO-emissions were found to vary from 1,800 to 10,000 mg/m ³ . Suitable combustion systems, such as fluidized bed systems, stoker fed from the bottom with secondary air supply, etc., should be used for efficient energy production from the OC. Determination of values of the flue gas can be used in calculating for heating surfaces.