Search Results

The recycling and reclamation of metal-matrix composites (MMC's) are critical aspects of the commercialization process. By recycling, we mean the economic processing of MMC scrap for reuse as composite. Reclamation refers to the separation and recovery of the individual components of the composite, i.e., the various aluminum alloys and ceramic particles. Three forms of MMC wrought alloy scrap have been considered; i.e., D. C. (direct chill) cast log ends, extrusion butts, and cut extrusion scrap. Recycling each of these forms of scrap back into D. C. cast extrusion billet has been demonstrated. This has been accomplished by recycling the scrap back through the basic mixing process. Various ratios of scrap to virgin composite have been explored and optimum blends are being studied. Similarly, for MMC foundry alloy (high silicon) gates and risers produced in shape-casting, fluxing and degassing techniques have been developed so these may be recycled back into useful castings.

The need to reduce the weight of automobiles has favored the widespread use of aluminum in automotive ventilation and cooling systems. Space, weight restrictions, the need for increased thermal efficiency, and recycling legislation have all contributed to new designs for heat exchangers. In many cases there has been a move to using extruded tube rather than seam-welded tube, leading to a reliance on the relatively more expensive clad fin. A new process, NOCOLOK™ Sil flux brazing, offers the potential for materials cost savings through the use of “in-situ” filler metal generation. This eliminates the need for using clad brazing materials. It can be applied to a number of alloy systems and product forms. This new technology is firmly rooted in the well established NOCOLOK™ non-corrosive aluminum brazing flux system.

The paper summarises work which has been carried out to establish the sensitivity of the Alcan AVT weld-bonding system to manufacturing process variability. The robustness of the joint-line to factors such as panel fit-up, bondline thickness, adhesive fillet size and missing adhesive is discussed and their effects demonstrated. Manufacturing factors, such as pretreatment damage during part forming and the cure-cycle window for the adhesive, are considered and their effects on performance are indicated. Finally the effect of a series of manufacturing shortfalls and environmental factors have been put together in one experiment and the resulting strength and fatigue performance of bonded joints has been established.