Silicon sputtering as a surface treatment to titanium alloy for bonding with PEKEKK

Thermoplastics, having strong polar or hydrogen bonding groups, are potenti al candidates for thin film bonding. In this investigation, a thermoplastic polymer poly(ether ketone ether ketone ketone) (PEKEKK) is used as an adhe sive to bond the titanium alloy (Ti-6Al-4V). The titanium alloy is silicon- sputtered to improve the bond strength to PEKEKK. The bond strengths of but t-joined specimens prepared using silicon-sputtered, silane-coated, sodium hydroxide-anodized round bars of titanium alloy as adherends are determined and compared with that of untreated titanium alloy round bars. Of the vari ous thicknesses of silicon layers studied, layers that are 200 Angstrom thi ck proved to have a more durable bond, as demonstrated by soak test results in Ringer's solution. It is observed that silicon sputtering enhances the bond strength of titanium alloy/PEKEKK butt joints and provides a more resi stant interface to intruding water. The combination of anodization followed by silicon sputtering further improves the durability of the bond. It is c onfirmed by XPS analysis that fracture does not take place between the sili con and the titanium substrate. Wetting studies by contact angle method usi ng water as test liquid, indicate significantly better wetting after silico n sputtering for Ti-6AL-4V adherends. (C) 1998 Elsevier Science Ltd. All ri ghts reserved.