Fly ash-enhanced aluminum composites for automotive parts. [Reports for April to June, 1998, and July to September, 1998

Abstract

The objectives of this report are to produce and evaluate the use of aluminum ''ashalloys''--metal matrix composites that incorporate coal fly ash--in the commercial manufacture of cast automotive parts. Some highlights are: (1) Ashalloy ingot with ''C'' type fly ash was synthesized using stir casting techniques similar to the successful castings of ''F'' type fly ash. Agglomeration was noted. Stirring periods were increased up to 45 minutes compared to the normal 5 minutes to determine whether the shear force of stirring would disagglomerate the clusters noted with this type of fly ash. The resulting sample showed clustering. (2) The ashalloy ingots of ''C'' type fly ash were remelted and poured into permanent molds using a cloth filter to screen out clusters. There was no major reduction in clusters of fly ash particles in the composite since the filter with the mesh size larger than 1 x 1 mm was used. The composite melt would not flow through when filters with smaller openings were used. (3) The fly ash sample from Wisconsin Electric Power Company was sent for classification. (4) A 1 lb. sample of JTM-processed fly ash was sent to Wisconsin Electric Power Company for classification and 10 lb. of same fly ash was sent to The Jet Pulverizer Company for jet milling. (5) Experiments on fly ash pretreatment as well as synthesis of ash alloy are continuing. (6) Attempts are being made to apply high speed shear mixing with selected liquids to disperse the clusters noted in ashalloy with the ''C'' type fly ash base. Stir casting processes have been developed to incorporate type ''F'' fly ash of different sizes and measuring tensile data on cast bars. This data enables selection of the optimum size of fly ash to meet specific property requirements. Attempts are underway to develop stir casting techniques to incorporate ''C'' type fly ash in cast aluminum alloys. It is expected that the next milestone for making trial parts will be completed on schedule by June 1999.