ATMOSPHERIC PLASMA EFFECTS ON STRUCTURAL ADHESIVE BONDING

摘要

An atmospheric pressure plasma was used in conjunction with sanding and a Sol-Gel coating forsurface preparation of Ti-6AL-4V titanium alloy. Several plasma chemistries were examined todetermine their ability to clean and activate the sanded titanium surface. Wedge-crack-extensiontests (ASTM D3762) showed that the bonded titanium coupons exhibited 98% or 99% cohesivefailure, provided the metal surface was exposed to nitrogen/helium plasma or hydrogen/heliumplasma. X-ray photoemission spectroscopy indicated that the titanium alloy surface was coveredwith a layer of carbonaceous material after sanding, and that 74% of the atomic oxygen waspresent as (OH)_3~(-3) species. The nitrogen and hydrogen plasmas proved effective at removing thecarbonaceous deposit and the (OH)_3~(-3) species. These results demonstrate the potential ofatmospheric pressure helium-based plasmas to increase titanium bond-line durability withoutincreasing debris generation or using additional wet chemicals.