A new manufacturing process of Fe-Cr-Al powder porous metal was attempted. First, ultra-fine fecralloy powders were produced by using the submerged electric wire explosion process. Evenly distributed colloid (0.05~0.5% powders) was dispersed on PU (Polyurethane) foam through the electrospray process. And then degreasing and sintering processes were conduced. In order to examine the effect of sintering temperature in process, pre-samples were sintered for two hours at temperatures of , , , and , respectively, in atmospheres. A 24-hour TGA (thermo gravimetric analysis) test was conducted at in a 79% +21% to investigate the high temperature oxidation behavior of powder porous metal. The results of the high temperature oxidation tests showed that oxidation resistance increased with increasing sintering temperature (2.57% oxidation weight gain at sintered specimen). The high temperature oxidation mechanism of newly manufactured Fe-Cr-Al powder porous metal was also discussed.
A connection between pulse-periodical laser radiation power and stability of liquid-metal contacts between powder particles during selective laser sintering (SLS) is determined based on analysis solving the problem of stability of liquid column in the gravity and capillary forces field. On the grounds of obtained relationships the optimization of pulse-periodical laser radiation power and SLS-process duration is realized, that allows to produce voluminous powder porous materials with pre-determined physical and mechanical properties and surface geometry. Results of metallographic investigations of powder porous materials of titanium powder produced with technological regimes calculated by means of obtained relationships are given in the work
We present a systematic study of the heating and pre-sintering behavior of porous copper powder metal compacts. We employ a TE102 single mode microwave system to position the samples in the separated electric field (E) or magnetic field (H) anti-node of the cavity. We observe significant differences in the heating, pre-sintering, and microstructure evolution of the samples due to the individual fields. We note that sample history (whether heated first in the E-field or H-field) greatly effects a difference in heating trends and subsequent heating behavior and does not appear to be solely a thermal process.
The behaviour of steel powder compacts during sintering has been investigated by dilatometry and X-ray computed microtomography. Dilatometry measurements showed that the anisotropic deformation results from various phenomena arising at different moments of the cycle including the delubrication stage. Microtomography provided 3D images of the microstructure induced by prior die pressing and its changes throughout sintering. Finally a schematic description of the main phenomena responsible for the deformation of metal powder compacts during sintering is proposed.
The effect ofgas sintering atmosphere on the carbon content and mechanical properties during the metal injection molding process of carbonyl iron-nickel powder was studied. The carbon content of the specimen after debinding in the pureatmosphere appeared 0.78 wt%. After showing the maximum value of 1.48 wt.% in the debinding atmosphere of 10%gas mixture, the carbon content of the debinded specimen decreased gradually with increasing thecontent in thegas mixture. The carbon contents of the sintered specimen were 0.46~0.63wt% in Na gas atmosphere, while they appeared extremely low above 40%gas atmosphere. The relative sintered density increased abruptly from 88~90% to 93~96% with the addition of Ni, while the density nearly unchanged above 2% Ni addition. The sintered density increased with increasing the fraction ofgas mixture. Tensile strength and hardness increased, and elongation decreased with increasing carbon and Ni content. In spite of high carbon content of 0.63 wt%, the superior elongation value of 10% was shown.