This paper analyzes the basic characters ofoptimum open-pit limit.According to them,following gener-al rule for designing pit limit is obtained.The incrementals
YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-δ</sub>-Ag<sub>x</sub> composite superconductorswere prepared by hybrid sintering process using YBa<sub>2</sub>Cu<sub>3</s