Mechanical and wear behaviour of Friction stir processed surface composite through Self-Assembled Monolayer Technique
SURFACE TOPOGRAPHY-METROLOGY AND PROPERTIES
Authors: Butola, Ravi; Singari, Ranganath M.; Murtaza, Qasim
In the present research study, Friction stir processing (FSP) has been utilized to prepare nano surface composites, AA7075 based matrix was reinforced with B4C nanoparticles (size <30 nm). The aim of this study is to form a thin layer of B4C over the surface of AA7075 based matrix material through Self-Assembled Monolayer (SAM) technique followed by Friction stir processing. The major advantage of SAM is to minimize the quantity of B4C nanoparticles used in the preparation of nano surface composites. Additionally, this research also investigates the effect of tool rotation speed of Friction stir processing on mechanical and wear properties of processed nano surface composite. The results observed a uniform dispersion of nanoparticles in the processed nano surface composite and an improved value of microhardness with maximum value was found to be 185 Hv of the sample processed at 1200 rpm, compared to base metal. For the constant load, as FSP tool rotation speed increases, wear resistance increases from 1000 to 1200 rpm and decreases slightly for 1400 rpm. Scanning Electron Microscope (SEM) micrograph, tensile test and Field Emission Scanning-Electron Microscope (FESEM) fractography image used to study microstructure and the mechanical properties of processed nano surface composite. The x-ray Diffraction (XRD) showed the presence of B4C nanoparticles. Processed nano surface composites can be used for aircraft and automobile industry applications.
Degradation of ferritic X10CrAlSi18 stainless steel caused by slurry
ENGINEERING FAILURE ANALYSIS
Authors: Krella, A. K.; Buszko, M. H.; Gajowiec, G.
The slurry erosion tests of ferritic X10CrAlSi18 steel were carried out using a slurry pot device. In order to investigate the erosion process, two series of tests were performed: first one with a constant impact velocity of 5 m/s, 7 m/s and 9 m/s and the second one, during which the impact velocity was changed after every exposure. During each test, an infiuence of test conditions on volume loss, surface hardness and roughness with exposure time was studied. The normalized erosion rate and erosion efficiency parameter increased linearly with velocity in the range between 5 and 9 m/s. Surface hardness increased exponentially with an exponent n = 0.27. The erosive efficiency parameter determined for tests carried out with variable impact velocity was higher than for tests with constant velocity. The erosion performance increased as the difference in consecutive impact velocity increased. At the beginning of slurry tests, surface hardness and roughness increased rapidly. A fiuctuation in erosion rate and surface roughness was noted in the tests performed with variable impact velocity. The amplitudes of these fiuctuations decreased with the test duration. Surface hardness infiuenced damage formed on the specimen's surface. With increasing surface hardness, surface roughness (Ra parameter) decreased. For surface hardness over 280 HV fiakes were formed on the specimen surface.