Günümüzde, cam ve karbon elyaf takviyeli kompozitler birçok mühendislik alanında geniş bir uygulama alanına sahiptir. Bu çalışmada, cam ve karbon elyaf takviyeli kompozit çubukların kuru kayma koşullarındaki abrasiv aşınmaları gerçekleştirilmiştir. Pin on disk cihazında gerçekleştirilen deneylerde elyaf türünün, uygulanan yükün(5, 10 ve 15 N): kayma hızının(0,4; 0,6 ve 0,8 m/s) ve kayma mesafesinin(250, 500 ve 750 m) kompozitlerin tribolojik davranışlarına etkisi araştırılmıştır. Yapılan çalışmalar neticesinde cam elyaf takviyeli kompozitlerdeki sürtünme katsayısının karbon elyaf takviyeli kompozitlerdeki sürtünme katsayısından daha düşük çıktığı belirlenmiştir. Aşınmaya bağlı kütle kayıplarında, bütün koşullar için cam elyafta kütle kaybının daha az olduğu görülmüştür. Artan yük, kayma hızı ve mesafesinin kütle kaybını arttırdığı tespit edilmiştir. Karbon ve cam elyaf takviyeli kompozitlerde en yüksek kütle kayıpları, 15 N yük, 0.8 m/s kayma hızı ve 750 m kayma mesafesinin uygulandığı durumlarda gerçekleşmiştir.

In this study, adhesive wear of woven E-Glass fabric reinforced composites filled with aramid, B4C and mica particles at 0.5% wt. and 1.5% wt. ratios were carried out under dry sliding conditions. The effects of filler type, applied loads (5, 10 and 15 N) and sliding distances (250, 500 and 750 m) on the tribological behavior of the composites were investigated on the pin-on-disc device. As a result of the studies, it was determined that the friction coefficient in aramid reinforced composites was lower than the other reinforced composites. In wear volume due to wear, it was observed that the aramid wear volume was less. In addition, Wear volume increased with increasing load for all particle reinforcements. But, the highest wear volume occurred in the neat wear sample at 15 N load conditions. For the wear rate and wear volume, the fillers have shown improvement up to 1.5% wt. in the composite. 1.5% wt. aramid-filled glass fiber woven composites showed the lowest wear rate: 2.82 × 10−4 mm3/N-m (at 15 N normal load). In addition, in the scanning electron microscope images taken, it was observed that there were breaks in the size of 15.07 µm in the epoxy and 61.11 µm in the fibers. The use of aramid with particle reinforcement rather than fiber is important for wear. In addition, the lowest wear volume was 65% more resistant at 1.5% wt aramid reinforcement and at 15 N load compared to the unreinforced composite in the abrasion tests.

No abstract

Aluminum and its alloys have become the most popular materials in applications aiming to provide lightness due to their low density. However, the low mechanical properties compared to other competitors are among the disadvantages of aluminum and its alloys. This is an important motivation factor in researching strength increasing mechanisms in aluminum and its alloys. In this study, the effects of reinforcement ratio and type on the microstructure, mechanical properties, and wear behavior of the AA7075/B4C composite produced by squeeze casting method were investigated. Two types of materials were produced and compared—non-reinforced AA7075 alloy and AA7075 allo matrix composite reinforced by 4, 8, 10, and 12 wt% B4C. Microstructures of two materials were analyzed by optical microscope, scanning electron microscope and energy distribution spectrometer. In addition, the mechanical and tribological properties of these materials were investigated. Microstructure and scanning electron microscope analysis reveals that the increasing B4C reinforcement ratio increased the tendency of agglomeration in the matrix. Although B4C reinforcement tends to agglomerate, B4C reinforcement positively affected the AA7075 alloy's hardness, tensile and bending strengths, elasticity modules, and wear resistance.

In this study characterization of a novel Al66Co20Cu13Mg1 alloy produced by the mechanical alloying method was investigated. The effect of milling time on the produced alloy's microstructural evaluations, microhardness, and thermal behaviors was investigated. Scanning electron microscope and X-ray diffractometer results demonstrated that as the milling time was increased, the homogeneity was increased, the particle size was decreased, crystalline cubic Al(Co, Cu) solid solution, α-Co(Cu, Mg) solid solution phase and Al2Cu phase were formed with the mechanical alloying effect after milling of 50 h. When the powder alloy was milled for 100 h, most of the elemental peaks such as Al and Cu disappeared, and Al3.892Cu6.108 phase was formed. The crystallite size of the alloy powders after 100 h of milling was found as 17.42 ± 2 nm. Moreover, as the milling time was increased, both the lattice strain and dislocation density were increased because of fractures, the formation of new intermetallic phases, and excessive deformations. The microhardness of the pressed powder alloys was increased due to the cold welding and intermetallic phases formed in the powder alloy with increasing milling times. The lowest and highest microhardness values are found to be 275 ± 10 and 376 ± 10 HV for the unmilled alloy and the 100 h of milled alloy, respectively.