الفهرس | Only 14 pages are availabe for public view |
Abstract Aluminum alloy AA7075 is considered one of the commercial aluminum alloys which is characterized by its light weight and the specific strength (high strength to weight ratio), it is used widely in aerospace and transportation applications. In the present work, green, novel, and energy saving processing technique called Friction stir processing; (FSP) is used to produce surface composite layer using the base material Al-7075 and reinforcement particle of boron carbide (B4C). In the present investigation a discussion is demonstrated to produce surface composite using combination of different tool rotation speeds (400 and 600 RPM) and different number of passes (one, two, three and four passes) for each rotational speed with a constant travel speed (50 mm/min) and tilt angle of 3o . The processed samples were investigated through the microstructural analysis as optical microscopy (OM), and scanning electron microscopy (SEM) equipped with EDS analysis. Mechanical properties were conducted by using hardness test (Vickers) and wear and friction tests using block on ring dry sliding test to study the wear scar depth and the coefficient of friction (COF). This study displayed an improvement of the hardness, wear and friction properties with increasing in number of passes that is attributed to B4C particles dispersed in aluminum matrix. The hardness increase from 67 HV1 (base material AA7075) to maximum value 150 HV1 in the processed samples, higher coefficient of friction in the friction stir processed samples as compared to the base material from average value COF 0.6 (BM) to 1 (processed samples). The presence of surface composite layer enhanced the hardness and wear resistance of Al7075. |