Hi Dialists, Awhile back, researching machining on vitreous ceramics, I came upon the statement that most rock/ceramic surfaces have a much lowered surface strength when the surface was alkaline and a much greater strength when acidic. (It was in a NASA report, but I don't remember the number ) Experiments showed that indeed drilling speed was up to 7 times faster on alumina ceramics while in a solution of a mild base such as borax than on a neutral surface. A mild acidic solution such as boric acid doubled the time of drilling. Shear testing and microcrack examination showed that the acid surface actually was both stronger and healed many microcracks. Even mild acetic acid made a great degree of difference. Shaping with sand-blasting obeyed a simular effect. i.e. The surface chemistry of the etched lines and their surrounds may be acidic enough to hold up to erosion longer.
Just a thought. Edley McKnight -
