Papers by Keyword: Coated Powder

Abstract: The heterogeneous conglomeration method, chemical precipitation method and Hydroxy combination theory are adopted in the paper through detailed theoretical analysis and contrast experiments. Tourmaline powder surface is completely covered with ZnO by 1.2:1 mass ratio of ZnO to tourmaline powder. Submicron-nanometer powder is achieved due to 78.71 mean particle diameter, the electrical resistivity of composite powder is decreased to 7.45Ω.cm. Improvement of conductive performance extends the application of tourmaline in the field of environmental purification.

Abstract: Using reduced iron powder as raw material, Copper coated iron powder(CCIP) is prepared by electroless alkaline-based plating. We discuss the impacts of reductant concentration, plating solution temperature and main salt concentration on the properties of CCIP. Surface morphology and composition are studied by using scanning electron microscopy and X-ray diffraction. The results show that after coating, the iron powder surface is rougher and the copper layer is uniform in its simple metallic form without any oxide states.

Abstract: Core-shell nano-Al2O3-coated ZrO2 materials were prepared via a liquid co-deposition method using ZrO2 as cores. Surface of ZrO2 was modified by silane coupling agent. The mechanism of A-151[CH2=CH-Si-(OC2H5)3] was studied under the condition of HAc. The composite powders were characterized by FT-IR, TEM, EDS and SEM. TEM observation confirmed that amorphous Al2O3 layer deposited on the surface of ZrO2 and the thickness of the Al2O3 coating ranged from 5 to 10 nm. After sintered at 1650°C for 10 h, the size distribution narrowed down and the compactness of composite sintered body was better in comparison with pure zirconia.

Abstract: The present study aims to prepare feedstocks for MIM (Metal Injection Molding) where the metal powders are 316L stainless steel powders (SS). The master objective is to compare the performance of a biodegradable binder with a commercial one based on polyolefins. Different challenges must be overcome in SS injection molding, as follows: to decrease binder/carbon content in feedstocks; to decrease carbon contamination during debinding and sintering; to avoid the formation of chromium carbide and presence of precipitation-free zones; to avoid the grain growth during sintering and to reduce the feedstock price. The optimization of the feedstocks was performed using a torque rheometry technique. Feedstocks of coated and uncoated SS powders mixed with an agar-based binder were used to produce sound parts. A feedstock constituted by SS powders mixed with a high quality commercial binder was the standard. SS with agar-based on feedstocks can admit solids content similar to those based on the commercial binder (62 vol.%). For similar powder content, the sinters resulting from feedstocks with the agar-based binder shows a lower quantity of solid solution of carbon and chromium carbides, absence of precipitation-free zones than commercial feedstocks and good sinter soundness. Coating powders with nanocrystalline stainless steel contribute to control grain growth during debinding and sintering.