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Effect of ex situ Al3Zr intermetallic on cold and hot wear behaviors and mechanical properties of FSPed surface hybrid nanocomposite of high-strength aluminum matrix

Jamali Amir, Mirsalehi Seyyed Ehsan, Yaghoubi Ali, Farzadi Ali

Archives of Civil and Mechanical Engineering

2024

Vol. 24, no. 3

art. no. e147, 2024

The extraordinary mechanical properties of AA7075-T6 alloy are comparable to that of steel, but its low hardness, high wear rate at room and high temperature have limited its widespread use, so the main aim of this study is to eliminate these weaknesses by producing a hybrid surface composite with the help of an intermetallic compound (Al3Zr) and other reinforcements (Al2O3 and ZrO2). Friction stir processing was chosen for this purpose, so in addition to obtaining extremely refined grains, the formation of common defects, occurring in the conventional methods, could be avoided. Having produced the composite, surface appearance was evaluated and microstructural characteristics were investigated by stereo, light, and FESEM microscopes. Besides not observing any external and internal critical defect, ultra-fine grains were seen. For a detailed investigation, EDS and XRD analyses were used. To assess mechanical properties, tensile and microhardness tests were conducted. Although yield and UTS experienced a fall, the particles set the stage for remarkable improvements in microhardness, cold, and hot wear. Microhardness was raised uniformly in the whole stir zone, and a ~ 48% rise in this property was obtained. Moreover, hot and cold wear resistances were improved up to about 85% and 65%, respectively. Finally, to study the mechanisms of the fracture and wear, the surfaces were scrutinized under SEM and EDS. It was observed that the fracture had a combination of ductile and brittle behaviors and in worn surfaces, instead of cavities formation, micro-cracks and scratches were produced, which are the signs of enhancement in wear resistance.

Analyzing the dry sliding wear performance on aluminum 6061 alloy reinforced with SiC and B₄C hybrid nanocomposite

Raja D. Elil, Vijayan S., Sonar Tushar, Singh S. Prathap

Advances in Materials Science

2024

Vol. 24, nr 4(82)

42--56

The methodology of enhancing the wear resistance of hybrid Metal Matrix Composites (MMCs) involves reinforcing the metal or alloy with robust materials. This study focuses on the manufacturing of a hybrid nanocomposite, which includes 0.6 vol.% of Silicon Carbide (SiC) and 0.2 vol.% of Boron Carbide (B₄C) nanoparticles with aluminum (Al) 6061 alloy. This is achieved through an ultrasonic assisted stir casting methodology, and a pin-on-disc tribometer is used to investigate the sliding wear rate and Coefficient of Friction (COF). Vicker's microhardness tester evaluated the microhardness of the nanocomposite, revealing it to be 18% harder than the Al 6061 alloy. Further, the metallurgical examination done through Hi-Resolution Scanning Electron Microscope (HRSEM) and X-ray diffraction (XRD) techniques confirmed the existence of SiC and B₄C nanoparticles. The wear experiment was done under diverse input wear experiment variables such as applied load, sliding velocity, and sliding distance, and optimization was done through Taguchi’s technique. Applied load contributed 40.9% to wear rate, and increasing load increased wear rate due to higher pin-counter disc contact pressure. Sliding speed contributed 42.18% to the COF, while increasing it decreased it due to lower pin-disc contact. The worn area inspection revealed an abrasive wear mechanism with substantial surface degradation at higher loads. The study may progress science and develop stronger materials for many purposes.

Modyfikacja nieplastyfikowanego poli(chlorku winylu) nanorurkami węglowymi i grafitem

Skórczewska K., Tomaszewska J., Piszczek K., Lewandowski K.

Przetwórstwo Tworzyw

2015

T. 21, Nr 3 (165)

290--293

Wytworzono hybrydowe nanokompozyty nieplastyfikowanego PVC z nanorurkami węglowymi i grafitem metodą ugniatania w komorze plasfografometru Brabendera, a następnie wytłaczania i prasowania. Udział MWCNT zmieniała się w zakresie od 0,1 do 5% wag. Zawartość grafitu w kompozytach wynosiła 5 % wag. Jednorodność dystrybucji nanocząstek w osnowie PVC zbadano stosując technikę SEM. Na podstawie wyników badań właściwości termicznych i mechanicznych oceniono wpływ nanorurek węglowych na właściwości PVC modyfikowanego grafitem.

Using multistep production procedure which included kneading in Brabender chamber, extrusion and pressing, hybrid nanocomposites of rigid PVC with graphite and nanotubes were manufactured. The MWCNT content in hybrid nanocomposites was in the range 0.1 up to the 5 wt% while the value of graphite was constant 5 wt%. By using scanning electron microscopy technique the distribution of nanofillers in PVC matrix was investigated. Thermal and mechanical properties of produced materials were examined. Basing on results, the influence of carbon nanotubes on properties of PVC matrix was estimated.