Surface Morphology Design To Improve The Joining Between TC4 And UHMWPE

The joining between titanium alloy(TC4)and ultra high molecular weight polyethylene(UHMWPE)has a promising future in application especially in the biomedical implantation field.In this thesis,we managed to design and fabricate different TC4 plate with different surface structures via electron beam melting additive manufacturing method.And through the novel hot pressing method,we successfully welded two dissimilar materials with good mechanical performance(max 2446N on 20*10 mm~2).Three major joining mechanism were found between UHMWPE and TC4:1)adhesion through the oxidation of the UHMWPE polymer chain;2)micro interlocking due to the surface roughness 3)macro interlocking via the surface porous layer.UHMWPE went through a variation of the property from the interface to the inside after welding:the crystallinity degree decreased,crystal orientation changed and the interplane distance has increased.The mechanical performance of different surface structures were compared.Diamond type porous layer structure didn't provide stable joint performance.The mechanical performance was improved with better design of the porous layer structure:honeycomb.The new porous layer structure also lowered down the possibility of the defects due to manufacturing and increased the structure strength of the porous layer.