تأثير افزودن اكسيد سريم بر رفتار سايشي و خوردگي نانو كامپوزيت سطحي Al5083/CeO2 ساخته شده به روش فرآيند اصطكاكي اغتشاشي

Effect of Cerium Oxide on Wear and Corrosion Behavior of Al5083/CeO2 Surface Composite Fabricated by Friction Stir Processing

در تحقيق حاضر، نانو كامپوزيت سطحيAl5083/CeO2 با افزودن نانو ذرات اكسيد سريم(CeO2) به سطح آلياژ آلومينيم 5083 توسط فرآيند اصطكاكي اغتشاشي ايجاد گرديد. ريزساختار، رفتار سايشي و خوردگي فلز پايه، نمونه­ تحت فرآيند بدون ذرات تقويت­كننده و كامپوزيت سطحي Al5083/CeO2 مورد بررسي قرار گرفت. بررسي­هاي ريزساختاري توزيع يكنواخت ذرات تقويت­كننده را در ناحيه­ اغتشاشي نشان داد. در مقايسه­ با فلز پايه، نمونه­ كامپوزيتي سختي بيشتر و خواص سايشي بهتري را در آزمون سايش از خود نشان داد. حضور نانو ذرات اكسيد سريم در ناحيه­ تحت اغتشاش، سبب بهبود قابل ملاحظه­ خواص خوردگي، يعني ايجاد ناحيه­ پسيو بزرگ و كاهش 95 درصدي چگالي جريان خوردگي(icorr) كامپوزيت حاصل نسبت به فلز پايه شد. نتايج بررسي­ها نشان داد كه افزودن ذرات اكسيد سريم موجب بهبود قابل ملاحظه رفتار سايشي و خوردگي آلياژ 5083 بطور همزمان مي­گردد.

In the present study, friction stir processing (FSP) was utilized to fabricate an Al5083/CeO2 surface composite by incorporating the nanosized cerium oxide particles into the matrix of Al5083 base alloy. Microstructural features, hardness and dry sliding wear were examined. In addition, the corrosion behavior of the base alloy, FSPed base alloy and the FSPed surface composite were studied and compared with each other. Optical and scanning electron microscopes were used for microstructural examinations. The corrosion resistance of the samples was examined by potentiodynamic polarization tests and was assessed in term of pitting potential and passivation range. The dry wear tests were conducted with a pin-on-disk tribometer at room temperature. Microstructural examinations revealed a uniform distribution of the reinforcement particles inside the stirred zone (SZ). The FSPed surface composite showed higher hardness and wear resistance in comparison to the base alloy. The dominant wear mechanisms for the FSPed and the FSPed composite specimens were adhesive and abrasive wear, respectively. The presence of CeO2 nano-particles in the SZ was caused a significant improvement in the pitting resistance, i.e. long passivation range and 95 percent reduction in the corrosion current density compared with the base alloy. The results indicated that incorporation of the cerium oxide into the surface of the Al5083 alloy enhanced the dry sliding wear as well as the pitting resistance of the alloy simultaneously.