Electron probe microanalysis of ball-bearing steel powder obtained using the method of electroerosion dispersion in kerosene
The results of electron probe microanalysis of powder obtained using the method of electroerosion dispersion of ball-bearing steel scrap have been provided. It has been determined that the main elements of powder obtained using the method of electroerosion dispersion of ball-bearing steel scrap in water are ferrum, oxygen, carbon, silicon, molybdenum, and chrome.
Deuterium penetration into the bulk of a steel ball of a ball bearing due to its rotation in vacuum
Abstract The experiments were performed to study a phenomenon of mechanically stimulated solution of adatoms into the bulk under friction. A ball bearing with carbon chromium steel balls of 3.97 mm diameter was used for testing. An axial load of L =34 N was applied per ball. After degassing the ball bearing performed a total of 23.8×10 3 revolutions at n =196 rpm at deuterium pressure p =5×10 −2 Torr. The same ball bearing was kept in the chamber without motion as a reference. The SIMS depth profiling of the contact surface areas of the ball shows that deuterium concentration has the highest value of C 0 =1.3×10 18 atoms cm −3 at a depth of 0.1 μm from the surface. Then, it decreases to a background value of C 1 =6.5×10 16 atoms cm −3 at a depth less than 0.55 μm. For the reference ball, a considerable deuterium concentration was observed only on the surface. These results are in a good agreement with recent computer simulation of the phenomenon.
Failure analysis for poor solderability of Au surface of PCB
Nonwetting is one of the common problems and is always rejected in electronic assemblies. ENIG pads of a PCBA exhibited nonwetting after lead-free reflow soldering. With the aid of stereomicroscope, SEM&EDS and XRF, a series of analysis was performed. And after visual inspection, surface and cross section analysis, thickness measurement and solderability test, it can be inferred that oxidation of plating surface was the main reason for nonwetting, and corrosion in Ni plating caused an adverse impact on solderalibity.