Tim-
I believe the Certanium info you are seeking is from Certanium Alloys and Research Co. Cleveland, OH. They specialize in "maintenance alloys" for welding and brazing as do Cronatron, Nassau and Eutectic. I have a 1991 catalog and cannot find 703SP. There is a 701,702,705, etc. listed. The catalog indicates Certanium Alloys is owned by Premier Industrial Corp. I found their web site: www.premierind.com/industrial.php. As I have found with the other "maintenance alloys" manufacturers, the request of chemistries and other proprietary specifics can be a challenge. They are hesitant about releasing info. The telephone number in the catalog I have is 216-391-8300. Good luck