| SiCP/Al composite coatings were prepared on the surface of L1060Al by argon arc surfacing welding, and several phases reinforced Al-MMCs were prepared in the copper mold by TIG smelting experimentally. The microstructures and the distribution of elements were studied by OM, SEM and ED AX. The phases were analyzed by XRD, and the hardnesses of the coatings and the composites were tested.First, SiCP/Al composite coatings were prepared on the surface of L1060Al by argon arc surfacing welding using the experimental wire with6.5%SiC and the preset pressed-block. Using MIG, there were a lot of porosities and fine Al4C3in the coating, and the SiC particles gathered around of the porosities. Using TIG, the porosities in the coating were less and smaller, and SiC particles distributed uniformly and retained the original form. There was no Al4C3in the coating. The hardness of the coating was72.8HV, higher than that of the base metal, L1060Al, which was48.7HV. But, because of the preparation technology of the welding wire, the formation of the porosities couldn’t be controlled by improving the welding technology.Next, the alloy powder containing Al-10%SiC-5%Ti was pressed into blocks, SiCP/Al composite coating was prepared by TIG using preseted block. There was no porosity in the coating, and SiC particles distributed uniformly and retained the original. Due to the addition of titanium, the formation of Al4C3was prevented. The hardnesses of the coating were90.36HV and59.1HB, higher than that of L1060Al, which were48.74HV and27.1HB. But because of the oxide film, it was hard for the block and the base metal to be melted and mixed together.Third, SiCP/Al composites were prepared by TIG smelting. The alloy powders containing Al-10%SiC-5%Ti and Al-10%SiC-5%Ti were pressed into blocks, and then the blocks were melted by TIG in the ordinary copper mold and the special copper mold with the water-cooling device. SiC particles distributed uniformly in the composite blocks and the combination of SiCP and Al was good. Besides, Si diffused quicily to form Al-Si eutectics. On the water-cooling condition, it was beneficial to grain refining. the formation of Al4C3was prevented. A lot of TiC particles and Al3Ti were in-situ formed, with external added SiC particles, to reinforce the composite. Using the composite blocks as filling material to prepare the coatings on the surface of L1060Al, Vickers hardnesses of the coatings were98.52HV and114.9HV, and Brinell hardnesses were63.0HB and75.2HB, which were much higher than before. Besides, the shapes of the coatings were good.At last, several phases, i.e., Al-Fe intermetallic compound, SiC and TiC reinforced aluminium matrix composites were prepared by TIG smelting in the copper mold on the water-cooling condition. Fe powder was added to Al-10%SiC-5%Ti. When the mol ratio of Fe to Al was1to1, most of SiC particles dissolved in the composite, but branched Al-Fe intermetallic compound, short strip of Al3Ti and fine TiC particles were formed. The Vickers hardness of the composite was590.7HV. Because of the addition of Fe powder, the arc was not stable, and the shaping of the composite blocks was worse, and the blocks were hard and brittle. When15%Fe-Si45was added, there was branched Al2FeSi in the composite. The Vickers hardness of the composite was114.9HV, and the Brinell hardness was higher than109HB. When22.5%Fe-Si45was added, there were bulk Al-Fe-Si intermetallic compounds and fine TiC particles distributed uniformly in the composite. The Vickers hardness of the composite was426.OHV, and the Brinell hardness was higher than109HB. However, the block was brittle. The arc was more stable when Fe-Si45was added, and Si diffused quicily to accelerate the generation of Al-Fe-Si intermetallic compound. However, the composite blocks were hard and brittle; it was difficult to surfacing weld directly. |
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