Effect of Sintering Parameters and Powder Characteristics on the Performance of Metal-Injection-Molded SKD 11 Parts
—Metal-injection-molded parts were fabricated using three kinds of SKD11 powder under different sintering parameters and with different binders and additives. An analysis of the microstructures and mechanical properties of these metal-injection-molded parts revealed that the porosity decreased and the grain size increased when the sintering isothermal holding increased. The average grain size was smaller for the part made of gas-atomized powder than for that made of water-atomized powder under the same sintering condition. The microstructures consisted of (Fe,Cr) solid solution substrates and Cr 7 C 3 carbide precipitates for the sintered part. For the specimen containing 10 wt % Fe, the mechanical property decreased due to less chromium carbide precipitates. The wear resistance and hardness of the sintered part made of gas-atomized powder were superior to those of the part made of water-atomized powder. In the pin-on-disk wear test, adhesive wear and a lower friction force were observed on the specimen with a lower hardness value. On the other hand, abrasive wear and a higher friction force were found for the specimen with a higher hardness value.
Microstructure and Mechanical Performance Analysis of Metal‐injection‐molded Fe‐2Ni Sintered Components
The influence of iron powders and heat treating processes on the microstructure, mechanical properties, wear properties and fracture modes of the metal injection molded Fe‐2Ni (wt.%) components were investigated in this work. Experimental results indicated that the components using BASF‐OS grade carbonyl iron powder showed a finer grains and lower residual carbon content than that using BASF‐OM grade carbonyl iron powder. It was observed that the hardness and wear‐resistance of the carburized and quenched OS‐grade components decreased as the tempering temperature was higher. On the other hand, BASF‐OM grade carbonyl iron powder sintered components maintained original carbon contents and lower hardness than that of BASF OS‐grade specimen. Dramatic fluctuations of friction forces were observed on the BASF‐OS grade and BASF‐OM grade components, which were tempered between 100–150° C and 300° C, respectively. It was believed that such phenomena were caused by the difference of wear modes and had detrimental e...
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.