[en] Glass ceramics (A-W) were implanted with 200 keV Zr ions at doses of 1 x 10¹⁵ to 2.5 x 10¹⁵ ions/cm². The mechanical strength of Zr implanted ceramics was measured for the case of one-faced and four-faced implantation, and it was 140 - 200 MPa depending on the loading rate. Although the tensile strength has much influence on the critical value of the fracture strength, the A-W ceramics implanted on four faces showed higher fracture strength due to the prevention of the crack from proceeding than that on one faced implantation. (author)