Research on Powder Forming of Metal Matrix Composite for High Density and High Strength

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(1) A multi-ram hydraulic press was designed and made for investigating the tribo-forming processes of a thin-walled cup and a strip-foil.(2) The forming and cladding of dissimilar metal sheets have been investigated by the tribo-extrusion process of thin-walled cup. The cladding cups for various combinations of dissimilar metal sheets could be formed with the reduction in area Re=90 % and the punch pressure less than about 2.4 GPa.(3) The compacting pressures for the green density d_o=90 % were about 0.3, 0.7, 0.8 and'O.9 GPa for an aluminium, a titanium, a copper and an iron, respectively, The thin-walled cups of aluminium and titanium could be formed with the relative density of 98 %.(4) The tribo-thinning process for producing a strip-foil from aluminium powder was investigated. The very thin aluminium foil of about 0.05 mm in thickness could be formed at the extrusion ratio R=200 with a considerably low punch pressure. The ultimate tensile strength of the foil strips formed at R=10-200 were about 250-300 MPa, which were rather higher than the value of that formed from the solid block by the tribo- thinning process.(5) The aluminium powder mixed with the alumina powder of 10, 20 and 30 wt% were compacted into the relative density of about 90 % into the cylindrical green parts and could be formed into the thin-walled cups by the conventional backward extrusion and the tribo-extrusion. The cylindrical parts which the powder mixtures of aluminium and alumina were compacted and sintered at 600ﾟC could be formed into the thin- walled cups by the both extrusion processes. The relative density of thin-walled cups formed by both the extrusion processes was increased up to about 100 % in the case of pure aluminium powder, but the density for mixture powder of aluminium and alumina could not be increased enough.