Adhesion and material transfer between aluminum and surfaces coated with diamond-like carbon and other coatings.

Adhesion and transfer of aluminum to the surfaces of tool coatings that are potential candidates for dry machining of Al-Si alloys were investigated. First, 319 Al alloy pins were tested against various industrial coatings (CrN, TiB2, TiAlN, TiN, and TiCN) using a pin-on-disc tribometer. The analyzed Scanning Electron Microscope (SEM) images of the wear tracks were used to rank the coatings according to the amount of Al transferred on their surfaces. In general, the TiB2 and TiCN coatings exhibited the least amount of Al transfer on their surfaces compared to the other coatings. Second, the tribological behaviour of the diamond-like carbon (DLC) coatings against Al was investigated since aluminum has much lower tendency to adhere to DLC in ambient air compared to other hard coatings tested. Magnetron sputtered non hydrogenated DLC coatings were tested against 319 Al, tungsten carbide (WC) and sapphire (Al20O3) at 120, 300 and 400°C and under various test atmospheres including air (0-85% RH), vacuum, inert gases (Ar, He and N2) and 40% H2-60% He. Although much softer than WC and Al2O3, 319 Al alloy inflicted the most severe wear of non-hydrogenated DLC especially at elevated temperatures. Non-hydrogenated DLC coatings showed high coefficient of friction, (COF), (0.45-0.75) and high wear rates in inert gases and vacuum compared to ambient air (COF= 0.09-0.16). Very low COF values (0.01-0.02) were observed in 40% H2-60% He mixture. The low COF values in ambient air and in 40% H2-60% He mixture were associated with formation of carbonaceous transfer layers on counterfaces. Formation of easy-to-shear transfer layer together with adsorption and dissociation of the atmospheric water on the sliding surfaces were suggested as the possible mechanisms that minimize COF in ambient air. To elucidate the effect of material properties on adhesion, 1100 Al, Cu, and Ti were tested against CrN, non-hydrogenated DLC, and TiB2 coatings in ambient air and argon. Cu exhibited the least amount of transfer to all three coatings. Chemical affinity towards the counterface, yield strength, and thermal conductivity were found as the most critical properties that determine adhesion and transfer between a given material pair during dry sliding contact.Dept. of Electrical and Computer Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2005 .K66. Source: Dissertation Abstracts International, Volume: 66-11, Section: B, page: 6214. Thesis (Ph.D.)--University of Windsor (Canada), 2005

ANALYSIS OF STUDENT SELECTION FOR SPORT SCIENCES FACULTIES: THE CASE OF SIVAS REPUBLIC UNIVERSITY, TURKEY

The interest in Physical Education and Sports Departments in Turkey is increasing every year and the number of faculties and colleges providing education in this field is increasing day by day. Special aptitude exams are held for student recruitment and the physical abilities of the candidates are tested in these exams. In Sivas Cumhuriyet University, the School of Physical Education and Sports was transformed into the Faculty of Sports Sciences. There are Physical Education and Sports Teaching, Coaching Education, and Sports Management departments within the faculty. Student admission is done by special aptitude exam every year. In recent years, there has not been a unity in the examinations of Physical Education and Sports Schools throughout Turkey, so there is a need for a scientific evaluation of the examination systems. In this study, the accuracy of different exam systems in our country is investigated and the effect of exam parameters on passing the exam is examined.  Article visualizations

Production of 20 mm Thick API PSL 2 X60 and X70 Grade Plates from a Nb-Ti Microalloyed Steel

T his study was undertaken to determine the controlled rolling and cooling conditions for the production of 20 mm thick American Petroleum Institute API X60 and X70 grade steel plates. Nb-Ti microalloyed steel slabs of 200 mm thickness were rolled at four different finish rolling temperatures conventional, 950°C, 850°C and 800°C . In some trials, a water table was employed to provide accelerated cooling just after finish rolling. Mechanical tests tensile, impact and drop weight tear-DWTT and microstructural examinations were performed on the samples taken from the trial production plates. Fine grained and essentially ferritic microstructures with strength values satisfying the minimum yield strength requirement of 415 MPa for the API X60 grade were easily obtained in all rolling conditions. However, the minimum yield strength requirement of 485 MPa for the API X70 grade was reached only when accelerated cooling was applied after finish rolling. The minimum 85% shear fracture required by the DWTT of the API PSL 2 specification could be met when the finish rolling temperature was lowered or when accelerated cooling was applied regardless of the finish rolling temperatur

STUDENT’S CARDIOVASCULAR HEALTH AWARENESS DURING COVID-19 PANDEMIC PROCESS: THE CASE OF SİVAS, TURKEY

Cardiovascular diseases, one of the important health problems of our day, seriously threaten human health. For this reason, it is very important to raise awareness about cardiovascular health from childhood and to develop behaviors accordingly. The aim of this study is to find out cardiovascular health awareness in students between the ages of 7 and 16 during the pandemic. 216 students continuing their education in the city centre of Sivas, Turkey participated in the study. A survey form on socio-demographic characteristics of the students and Children’s Cardiovascular Health Promotion Attitude Scale (CCHPAS) were used in the study. Demographic characteristics were collected online with a 9-question form. KMO value (0.741) was found to be moderate. Bartlett Sphericity test (p=0.00) was found to be significant. The fact that these two values are significant shows that the survey is suitable for factor analysis. 4 factors were determined as a result of factor analysis. These 4 factors explain 60% of the variance. No statistically significant difference was found in both total scale and 4 factors in terms of gender (p>0.05). While no statistically significant difference was found for the first factor in terms of the state of having social media account (p>0.05), significant difference was found for the other factors and total scale score (p0.05), difference was found in terms of Factor 3 and total scale scores (

ANALYSIS OF PHYSICAL ACTIVITY STATES OF STUDENTS BETWEEN 7-16 AGE GROUP DURING COVID-19 PROCESS

Covid-19 virus, which entered our lives in the last period of 2019, has caused radical changes in our lives. After the pandemic was declared, the threat of the epidemic that affected the whole world caused us to change a large number of our habits. In particular, the periods when people were closed at home, which led to a decrease in physical activity levels. In our study, an international physical activity form was given to 278 students between the ages of 7 and 16. Physical activity levels of the students in the past week and what activities they did were found. 162 male students and 116 female students participated in the study. 28 of these students were in primary education, 154 were in secondary education and 96 were in high school. While 7 of the students who participated in the study had barriers to doing sports, it was found that 271 students did not have any. As a result of the analyses conducted about the prevalence of physical activity, it was found that the students were moderately active. It was found that 8.8% of the students were highly active, 23.8% were very active, 30.74% were moderately active, 19.11% were slightly active and 17.57% were inactive (sedentary). In terms of the ways of doing activity in general, it can be seen that during the pandemic, individuals preferred activities which were easy to do at home and on the street and also which were less risky. It can be said that sports branches performed as a team are generally avoided. Activities that are easy to do and less risky, such as running and walking for exercise, have come to the fore during the pandemic process. Article visualizations

Effects of Alloying Elements (Mo, Ni, and Cu) on the Austemperability of GGG-60 Ductile Cast Iron

The interest in austempered ductile irons (ADI) is continuously increasing due to their various advantageous properties over conventional ductile irons and some steels. This study aimed to determine the roles of alloying elements Ni, Cu, and Mo, on the austemperability of GGG-60 ductile cast iron. Two different sets of GGG-60 (EN-GJS-600-3) samples, one set alloyed with Ni and Cu and the other set alloyed with Mo, Ni, and Cu, were subjected to austempering treatments at 290 °C, 320 °C, and 350 °C. A custom design heat treatment setup, consisting of two units with the top unit (furnace) serving for austenitizing and the 200 L capacity bottom unit (stirred NaNO2-KNO3 salt bath) serving for isothermal treatment, was used for the experiments. It was found that austempering treatment at 290 °C increased the hardness of the Ni-Cu alloyed GGG-60 sample by about 44% without causing a loss in its ductility. In the case of the Mo-Ni-Cu alloyed sample, the increase in hardness due to austempering reached to almost 80% at the same temperature while some ductility was lost. Here, the microstructural investigation and mechanical testing results of the austempered samples are presented and the role of alloying elements (Mo, Ni, and Cu) on the austemperability of GGG-60 is discussed

Effect of Electrodeposition Parameters on the Current Density of Hydrogen Evolution Reaction in Ni and Ni-MoS2 Composite Coatings

Nickel composites with co-deposited insoluble, solid lubricant particles such as MoS2 have been reported to reduce friction. It is known that hydrogen evolution reaction (HER), competes with nickel deposition. The influence of the parameters and their interaction effects on the peak current density of HER during the electrodeposition of Ni and Ni-MoS2 composite coatings were studied by fractional factorial design. The parameters and their ranges studied were; MoS2 particle concentration (0-30 g/l), temperature (30-50 degrees C), pH (2-4) and two surfactants, namely; ammoniumlignosulfonate (ALS) and depramin-C (DC) (0-1 g/l). Electrodeposition processes were carried out from a typical Watts bath containing leveler, wetting agent and brightener by using a potentiostat. The peak current densities (i(p)) were extended to higher values and the peaks on linear sweep voltammograms became noticeable by increasing the scan rate from 20 mV/s to 100 mV/s over the range of 0 to 2.5 V. The peak current densities (i(p)) of HER for each experimental route were determined by fractional factorial design for two mineral processing surfactants; ammoniumlignosulfonate (ALS) and depramin-C (DC) using a statistical analysis software named Minitab [1]. Adding MoS2, decreasing temperature and increasing pH had decreasing effects on the peak current density of HER regardless of the surfactant used. On the other hand, the surfactants increased the peak current density

Effects of current density, coating thickness, temperature, pH and particle concentration on internal stress during Ni-MoS2 electrocodeposition

Internal stress in plated deposits has been a common problem that may affect the functionality of coatings. Electrodeposition parameters and insoluble particles modify the characteristics and the level of internal stress of coatings. The influence of the electrocodeposition parameters and their interaction effects on the internal stress during the electrodeposition of Ni and Ni-MoS2 composite coatings were studied by fractional factorial design. The parameters studied and their ranges were: MoS2 particle concentration (0-10 g L-1), temperature (30-50 degrees C), pH (2-4), current density (1.2-4.8 A dm(-2)), and coating thickness (25-50 mu m). MoS2 addition into Watts bath resulted in the decrease in the tensile internal stress values or even changed the stress character from tensile to compressive. Moreover, low stress values were obtained when pH was 2 and coating thickness was 50 mu m

EFFECT OF ELECTROPLATING PARAMETERS ON "HER" CURRENT DENSITY IN Ni-MoS2 COMPOSITE PLATING

Nickel composites with co-deposited insoluble, solid lubricant particles such as MoS2 have been reported to reduce friction. It is known that hydrogen evolution reaction (HER), competes with nickel deposition. The influence of the electroplating parameters and their interaction effects on the peak current density for HER were studied by fractional factorial design. The parameters and their ranges were; MoS2 concentration (0-30 g/l), temperature (30-50 degrees C), pH (2-4) and surfactants (0-1 g/l). Electrodeposition processes were carried out from a typical Watts bath containing leveler, wetting agent and brightener by using a potentiostat. The peak currents (I-p) were extended to higher values and the peaks on linear sweep voltammograms became noticeable by increasing the scan rate from 20 mV/s to 100 mV/s over the range 0 to 2.5 V. The peak current densities (i(p)) for each experimental route were determined by fractional factorial design for three types of mineral processing surfactants; sodiumlignosulfonate (SLS), depramin-C (DC) and ammoniumlignosulfonate (ALS) using Minitab program [1]. Adding MoS2, decreasing temperature and increasing pH has decreasing effect on peak current density for all surfactants. ALS and DC have increasing effect whereas SLS has descending effect on peak current