Search

Friction stir welding between AA7075-T6 aluminum alloy and 304 L stainless steel sheet metal was performed with the addition of Al-Ni powder between the joining interfaces to increase the joining performance. The welding tool was rotated at 200 min 1 to 800 min-1 with the constant traverse speed of 25 mm/min. The resulting joint interfaces were analyzed using a field emission-scanning electron microscope and energy-dispersive x-ray spectroscopy analysis. The tensile strength was greater for the Al-Ni powder added specimens at the lower tool rotational speeds. The tensile strength of 360 MPa was obtained for the 'with-powder' specimen as compared to 220 MPa for the 'without-powder' specimen at the 200 min-1 tool speed. Electron microscope images of the stir zone showed a significant mixing of the Al-Ni powder with the base materials, increased contact at the interface, which resulted in increased joining strength at the lower tool rotational speeds. However, based on the images, intermetallic compound that may contribute to the joining strength in the vicinity of the interfacial region was not detected. [ABSTRACT FROM AUTHOR]

Friction and wear of polymeric composites formed by blending polyethylene (PE) and polymethylmethacrylate (PMMA) filled with different metallic powders is discussed in the present work. The scratch test was carried out to investigate wear resistance and friction coefficient of the tested composites prepared by molding of polymeric blends. Wear was measured by the net area of the cross section of the groove caused by the scratch and friction coefficient was measured as the ratio between the tangential and normal force exerted during scratch process. The test results showed that the best blend was 25 % polyethylene and 75 % polymethylmethacrylate with addition of bronze caused significant decrease in friction and wear. Increasing cooling rate of polymeric composites increased plasticization and consequently wear decreased. The strong adhesion of silicon carbide and bronze in the polymeric matrix caused significant wear decrease. [ABSTRACT FROM AUTHOR]