ASSESSMENT OF A PRE-BOND SURFACE TREATMENT ON A ROTORBLADE TITANIUM LEADING EDGE NOSECAP: STRUCTURAL VALIDATION AND PROCESS IMPROVEMENT

摘要

A phosphate-fluoride process has been used to treat titanium rotorblade leading edge nosecaps prior to adhesive bonding at Boeing Rotorcraft Systems in Ridley Park, PA for several years. In 2009, there was a high amount of rejections of a quality control bond verification test that was linked to improper processing during the phosphate-fluoride treatment. Several mechanical and physical tests were performed in order to understand the source and extent of the problem, as well as to correlate the effect of improper processing on the performance and durability of the part. Structural testing showed that there was a significant knockdown in the mechanical properties of the part when improperly processed, while simple surface energy tests were used as a method to detect a potential problem prior to bonding. SEM imaging of the processed titanium surfaces was able to indicate if a part had been properly or improperly processed based on the surface morphology. Measures were implemented within the processing lines and packaging procedure in order to prevent future issues with this sensitive operation.