Stripping systems for thermal spray coatings tend to use many hazardous acids which require critical safety procedures and produce heavy volumes of environmentally unfriendly waste streams. A new technology, filed under application numbers 2009/0120804A1 and 2009/0229636A1, and additionally covered under U.S. patent numbers 8262870 and 8377324 has been created using a very safe and environmentally friendly percarbonate based chemical system with minimal DC rectified voltage. It was successfully qualified at Tinker Air Force Base and is currently in production use throughout the facility. It has safely stripped WCCo and CrC-NiCr coatings such as WCCo and CrC-NiCr from Ti 6-4 and IN718 substrates showing minimal stock loss in 48 hr exposure testing. Many lessons were learned during this qualification process which will be shared and documented. Both plasma and HVOF coatings can be stripped with this process in the pH 10-12 range. The system can also be combined with a refining system that purifies the waste water and condenses the coating sludge into a condensed volume, eliminating the tremendous volume of waste chemicals. Numerous case studies and actual stripping data will also be presented and discussed.

Tensile testing of thermal spray coatings is currently covered by a variety of internal company specifications and generally by ASTM C-633. It is a highly recognized fact that liquid epoxies, on average, produce higher results in side by side comparisons with their film counterparts. However, the liquid epoxies show a higher standard deviation in those same comparisons. This raises questions about the interaction of liquid epoxies with porous thermal spray coatings. Tensile data from side by side comparisons was analyzed and optical microscopy work performed to determine how the epoxies affected the coatings and if the epoxy infiltration actually occurs. In the case of porous plasma coatings, it is shown that liquid epoxies penetrate into the coatings and, thereby, increase the apparent tensile strength.