Yazar "Sagiroglu, Selami" seçeneğine göre listele

Listeleniyor 1 - 5 / 5
  • Küçük Resim Yok
    Öğe
    Braking performance and noise in excessive worn brake discs coated with HVOF thermal spray process
    (Korean Soc Mechanical Engineers, 2017) Oz, Ali; Gurbuz, Habib; Yakut, Ali Kemal; Sagiroglu, Selami
    In this paper, two excessive worn brake discs of a light commercial vehicle were coated with High velocity oxygen fuel (HVOF) thermal spray process for reuse. The coated discs were compared with uncoated Original equipment manufacturer (OEM) D1 disc in terms of braking performance and noise. The D2 disc was coated with tungsten-carbide-cobalt (88 %WC-12 %Co) powder and NiCr (80/20) binder, and 500 Gm thick coating was obtained. The D3 disc was coated with Colmonoy-88 (Ni-W-Cr-B-Si) powder and NiCr (80/20) binder and 600 Gm thick coating was obtained. Several test procedures (e.g. bedding, vibration, and structural-strength tests) was applied to three discs using inertia brake dynamometer. Results showed that coated D2 disc with tungsten carbide cobalt provided lower brake noise and higher brake performance compared with OEM disc. Considering the coefficient of friction and temperature, coated D3 disc has approximately equal braking performance with OEM D1 disc despite the high braking noise value.
  • Küçük Resim Yok
    Öğe
    Effect of 0.20% Beryllium (Be)-Added CuAl₁₀Ni₅Fe₄ Alloy on Tribological Behavior and Microstructural Properties After Post-Casting Heat Treatment and Forging Process
    (MDPI AG, 2024-11-25) Khaled A. A. Babay; Esen, Ismail; Sagiroglu, Selami; Ahlatci, Hayrettin; Keskin, Esma
    This study explored how post-casting heat treatment and forging affected the tribological and microstructural characteristics of 0.20% beryllium (Be)-added CuAl₁₀Ni₅Fe₄ alloys. The heat-treated CuAl₁₀Ni₅Fe₄ microstructure exhibits a copper-rich α (alpha)-solid-solution phase, a martensitic β (beta)-phase, and diverse intermetallic κ (kappa)-phases, such as leaf-shaped κI, thin κIII, and black globs. Adding 0.20% beryllium to CuAl₁₀Ni₅Fe₄ alloys enhanced the dendritic arm thickness, needle-like shape, and κ-phase quantities. Significant κIV- and κII-phase precipitation was observed in the tempered β-phase. Beryllium improves the aluminum matrix’s microstructure. Forging greatly reduced the microstructural thickness of CuAl₁₀Ni₅Fe₄ and CuAl₁₀Ni₅Fe₄-0.20% Be alloys. The forging process also developed new κIV-phases. Wear resistance and hardness improved with beryllium. The CuAl₁₀Ni₅Fe₄-0.20% Be alloy had the highest hardness values (235.29 and 255.08 HB) after solution treatment (ST) and tempering (T) after casting and forging (F). The CuAl10Ni5Fe4-0.20% alloy with Be added had the best wear after solution treatment, tempering, and forging. The CuAl₁₀Ni₅Fe₄-0.20% Be alloy demonstrated a 0.00272 g weight loss, a 1.36 × 10−8 g/N*m wear rate, and a 0.059 friction coefficient at 10,000 m after forging (F).
  • Küçük Resim Yok
    Öğe
    The effect of the addition of blast furnace slag on the wear behavior of heavy transport polymer-based brake pads
    (Elsevier Sci Ltd, 2023) Sagiroglu, Selami; Akdogan, Kamil
    This study developed a new asbestos-free brake lining by including blast furnace slag. In addition to phenolic resin as the main binder, brass shavings, copper powder, alumina, and iron oxide powders as reinforcement material, graphite powder to increase friction stability, and calcium carbonate as filler were used. First, by applying a hot press and heat treatment, five samples were created in which these materials were used in various proportions. All samples were tested for tribological behavior and wear parameters, and wear surfaces were evaluated. According to the experimental results, the model containing 50% slag had the lowest wear rate (4.05 gcm3/Nm-6) and the highest friction coefficient (0.4552); yet it also had the most frictional irregularity. The sample containing 7.5% slag, 15% bronze chips, 15% copper powder, 20% phenolic resin, 15% graphite powder, 5% Alumina, 2.5% iron oxide and 20% calcium carbonate gave the best results. The average coefficient of friction for this sample was 0.4511 and the specific wear rate was 6.77 cm3/Nm-6. It has been proven that up to 7.5% slag in brake pads can be beneficial; however, it is not beneficial to use more than this ratio.
  • Küçük Resim Yok
    Öğe
    The Effects of a Pneumatic-Driven Variable Valve Timing Mechanism on the Performance of an Otto Engine
    (Assoc Mechanical Engineers Technicians Slovenia, 2015) Uysal, Fatih; Sagiroglu, Selami
    In this study, the classic cam mechanism of a single cylinder, four-stroke, 6 hp spark-ignited engine was replaced by an electro-pneumatic rocker mechanism, which is designed and manufactured to open the intake valve at low (3.7 mm), normal (5.7 mm) and high (7.7 mm) lifts between engine speeds of 1600 rpm to 2200 rpm. An air compressor was used to feed 6 bar air pressure in order to have the plungers drive the cams in an orderly manner. A control panel was used to control plungers in order to modulate the valve lifts gradually. The volumetric efficiency, torque, power and specific fuel consumption with this operation were measured at full load and compared to the values with a classic cam mechanism. The results of the study showed that decreasing the valve lift at low engine speeds and increasing the lift at high speeds improve the engine performance. Moreover, it was concluded that the idle speed can be lowered by decreasing the valve lift at low engine speeds.
  • Küçük Resim Yok
    Öğe
    Estimating Seebeck Coefficient of a p-Type High Temperature Thermoelectric Material Using Bee Algorithm Multi-layer Perception
    (Springer, 2017) Uysal, Fatih; Kilinc, Enes; Kurt, Huseyin; Celik, Erdal; Dugenci, Muharrem; Sagiroglu, Selami
    Thermoelectric generators (TEGs) convert heat into electrical energy. These energy-conversion systems do not involve any moving parts and are made of thermoelectric (TE) elements connected electrically in a series and thermally in parallel; however, they are currently not suitable for use in regular operations due to their low efficiency levels. In order to produce high-efficiency TEGs, there is a need for highly heat-resistant thermoelectric materials (TEMs) with an improved figure of merit (ZT). Production and test methods used for TEMs today are highly expensive. This study attempts to estimate the Seebeck coefficient of TEMs by using the values of existing materials in the literature. The estimation is made within an artificial neural network (ANN) based on the amount of doping and production methods. Results of the estimations show that the Seebeck coefficient can approximate the real values with an average accuracy of 94.4%. In addition, ANN has detected that any change in production methods is followed by a change in the Seebeck coefficient.