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Metal powder injection molding (MIM) has been a popular technique in production of alloy materials. Through this technique, near-net-shape alloy products can be molded with one-step production. Stainless steel 316 L (SS 316 L) is an important material in aerospace and marine industry for its excellent material strength and resistance to corrosion. As the industry grows with upgraded techniques, the standard for next generation material strength has improved tremendously. Here we present a practical method strengthening SS 316 L via MIM technique, which might provide a pathway for exploration of high strength materials. TiC was introduced into SS 316 matrix with polyoxymethylene (POM) binder. The metallography indicates that the introduction of TiC facilitates the refinement of the 316 L grain. As the TiC content increases from 0 wt% to 3 wt%, the material properties improve significantly, including a rise in hardness from 151 HV to 301 HV, tensile strength from 689 MPa to 792 MPa, and yield strength from 221 MPa to 339 MPa. Additionally, there is a noticeable reduction in the coefficient of friction and the wear cross-section.

The 316L stainless steel powder injection molding feedstock was prepared by melt mixing with polyethylene glycol/epoxy resin (PEG-EP) as the powder surface modifier and polyformaldehyde resin (POM) as the binder system. The sintered 316L samples were obtained by nitric acid catalytic degreasing and sintering. The encapsulation effect of PEG-EP on 316L stainless steel powders and the influence of PEG-EP surface treatment on the properties of 316L stainless steel powder injection molding feedstock and the sintered specimens were studied by Fourier transform infrared spectroscope, scanning electron microscope, contact angle measuring instrument, rotary rheometer, universal material tester, metallographic microscope, carbon-sulfur analyzer, and microhardness meter. The results show that, PEG-EP are successfully coated on the surface of 316L steel powders, which improves the interface compatibility between 316L stainless steel powders and POM and enhances the feedstock fluidity, the mechanical properties of raw billets, and the mechanical properties and hardness of the sintered samples. When the PEG-EP mass fraction is 0.662% and the powder loading (volume fraction) is 63%, the tensile strength, fracture elongation, and bending strength of the 316L injection raw billets are 10.57 MPa, 8.38 %, and 21.24 N·(mm2)−1, respectively. The grain size, the maximum tensile strength, and the Vickers hardness of the sintered sample are 50.8 μm, 688 MPa, and 151 HV, respectively, leading to the best comprehensive performance.

The goal of this research was to better understand the spatial characteristics and hot areas of heavy metal concentrations in the soil-rice system, which was critical for implementing heavy metal pollution prevention and control strategies. The amounts of heavy metals in soil-rice were determined using high-precision testing methods such as XRF, ICP-MS, and AFS based on the systematic collection of 285 pairs of soil-rice samples from Wanjiang Economic Zone, China. The Getis-Ord index, Kriging method, and geostatistical method were used to reveal the spatial distribution of heavy metal contamination hot spots in the soil-rice system. The results revealed that the average concentration of heavy metals in soil was Zn>Cr>Cu>Pb>Ni>As>Cd>Hg, whereas it was Zn>Cu>Ni>Cr>Cd>As>Pb>Hg in rice. The average concentrations of heavy metals in the soil were all well below the maximum allowable limit, except for Cd, which was slightly above the allowable limit. Only Cd and Ni concentrations in rice exceeded the maximum permitted limits. In soil, Cd, Hg, Pb, and Zn pollution hotspots were mostly found in the southeast, while Cr and Ni were mostly found in the northeast. An intriguing discovery was that there was a weak relationship between heavy metal concentrations in soil and rice and the spatial pattern of their distribution. The study's findings offer a scientific foundation for establishing a long-term agricultural development strategy for the soil-rice system in the Wanjiang Economic Zone. [ABSTRACT FROM AUTHOR]