Hayrettin Düzcükoğlu

Enhancement of Wear and Friction Characteristics of Epoxy Resin by Multiwalled Carbon Nanotube and Boron Nitride Nanoparticles

Epoxy resins are widely used in engineering applications. However, their low thermal stability limits their usage at high sliding velocities and loads. The mechanical properties and thermal stability of a machine element subjected to friction and wear are very important. In this study, friction and tribology behaviors of multiwalled carbon nanotubes (MWCNTs) and boron nitride (BN)-modified epoxy resin have been investigated. Epoxy resin modified by three different nanoparticle configurations, 0.3% MWCNT, 0.5% BN, and 0.5% MWCNT/0.3% BN, was investigated. The tribological characteristics of nanoparticle-modified epoxy resin were compared with properties of neat resin. The friction and tribological behavior of modified epoxy resin were tested using a ball-on-disc test stand at 1.2 and 1.5 ms−1 sliding velocities under 10 N applied load. The tests were done under dry condition and 1,800 m distance. The friction coefficient, wear loss, and temperature increase during testing were recorded and compared with that obtained for neat epoxy. It is observed that nanoparticle modification resulted in enhanced wear resistance and a reduction in friction coefficient and working temperatures.

The Investigation of Lubrication Properties Performance of Euro-Diesel and Biodiesel

All diesel engines work with a specially designed injection system. The lubrication of these moving inner parts is achieved with fuel. The inadequacy of lubrication properties of the fuel either causes low pressure or wear. Applications carried out to decrease the sulfur level to lower than 10 ppm have also been effective in decreasing particulate emissions. However, this process decreases the lubrication properties of the fuel. As a solution to this problem, instead of diesel, biodiesel, which has comparatively better lubrication properties, is suggested. In this study, the physical and chemical properties of biodiesels produced from safflower oil, cottonseed oil, soybean oil, and sunflower oil are investigated and then their lubrication performances were investigated with a pin-on-disc test device under constant load with different sliding velocities. The results obtained were compared with euro-diesel. The coefficient of friction was the lowest in safflower oil biodiesel, which was followed by cottonseed oil biodiesel, soybean oil biodiesel, sunflower oil biodiesel; the highest coefficient of friction was for euro-diesel.

Investigation of Wear Performance of Canola Oil Containing Boric Acid under Boundary Friction Condition

The aim of this study is to investigate the tribological behaviors of pure canola oil and 5% boric acid–added canola oil after unexpected oil drainage. Tests were performed under 0.6 m/s sliding velocity and 80 N contact force using a pin-on-disc test stand. Tests were started with full lubrication and continued for 800 m. After that the oil was drained from the oil tank and the system was run for 10,000 m without lubrication. The variation of friction coefficient, contact temperature, and wear was compared for pure and boric acid–added oil. It was observed that boric acid–added oil can continue lubricating even after oil was drained from the tank.

Examination of Pitting and Wear in Borided, Carburized, and Borocarburized AISI 8620 Gears

The most important characteristic feature of boronizing is that the boron layer obtained at the surface has a very high hardness, improved wear resistance, and low coefficient of friction. Due to the sudden transition from a very hard surface to a relatively soft core, cracks are likely to occur at the interface. These cracks may lead to spalling, and therefore the advantageous effects of boronizing are limited under heavy loads. In this study, the pitting and wear behavior of spur gear surfaces of AISI 8620 steel treated by carburizing, boronizing, and borocarburizing have been examined.

Investigation of impact force on aluminium honeycomb structures by finite element analysis

In this study, the behaviour of aluminium honeycomb structures under low-speed impact has been investigated by experimental and finite element analysis method. The production of aluminium honeycomb composite structures was carried out using different adhesives of different widths and heights. The low-velocity impact experiments of the honeycomb structures produced were performed according to ASTM D7766 standard. As a result of the experiment, the force values which caused damage to the structure were measured according to the time, and the maximum force values were taken. Findings have shown that the decrease in cell width, the increase in cell height, and depletion of multiwall carbon nanotubes increase the maximum impact force values in honeycomb composite structures. It is seen that the results obtained by the finite element method and the experimental results are approximately 85% in agreement. There was no statistically significant difference between the results as a result of conducted t-test.

Examining the Abrasion Behaviour of PA 66 Gears in Different Cycles

Gears made of plastic-based materials are anticorrosive, resistant to magnetic environments, and light and have pulse decay, low noise, and self-lubrication properties, and therefore their usage areas are widening every single day. In this experiment, the working conditions of 30% fibreglass PA 66 (PA 66 GFR 30) plastic material with PA 66 (PA 66 GFR 30) plastic material and AISI 8620 couple gear are observed. Usage of PA 66 GFR 30 material as gear material at 56.75 Nm constant load and 750 rpm, 1000 rpm, and 1500 rpm was analysed. The load capacity damage formation of the material was also analysed. The tooth surface temperature, corrosion depth of the tooth profile, tooth damage, and the tooth surface were examined with an scanning electron microscopy (SEM) and the corrosive behaviour of gears was analysed.

Pitting Formation in Concave-Convex Gears Manufactured from AISI 8620 Steel

In this study, the pitting formation of the tooth flank of concave-convex involute gears was investigated. The gears were manufactured from AISI 8620 steel with computer numerical control (CNC) machining and subjected to a cementation hardening process because they could not be produced using traditional methods. The results of the experimental studies with these gears were compared to those obtained with spur gears. As a result of this comparison, and because the pitch line of spur gears is less than the pitch line of concave-convex gears with exactly the same dimensions, the maximum Hertz stress formed in the pitch point of concave-convex gears is found to be less than that formed in the pitch point of spur gears. Therefore, the formation of pitting in concave-convex gears is quite delayed.