Ceramic composite cutting tools 321 also be seen in this figure. The nose wear for the Sic whisker composites WG-300 and DX-14 are all low compared to the tin reinforced Si,N4 1,25 materials(SX-5 and RD3905) for all subsequent cutting operations 6. 2 Cutting tests against 4340 steel 是a° One commercially available conventional Tic-alt mina cutting tool and various TiC-alumina lami 2345678 nated designs and one Sic whisker/alumina design Cutting Time, min were tested against 4340 steel. In these tests, each Fig. 2. Notch wear of ceramic composite cutting tools against of the eight corners of the cutting tool were sub- 718 nickel based superalloy jected to increasing cutting times. Figure 4 shows a comparison of nose wear for the conventional and laminated TiC/alumina composite and a lami Figures 1 and 2 compare the nosc and notch nated Sic whisker/alumina cutting tool material wear,respectively, for monolithic materials, wG. The nose wear data for these tests appear to fall 300, SX-5 and RD-3905, with the laminated into three groups. The TiC/alumina composite ceramic design DX-14 during the first cuttin laminate designs GX-06 and GX-08 have the operation. Both tin reinforced Si3N4 composi- highest wear rates, while the design GX-20 has the tions, SX-5 and RD3905, exhibited significantly lowest wear rate. The former two designs use alu greater wear than either the monolithic SiC mina on the outer surface which results in a resid- whisker-reinforced alumina, WG-300, or the lami- ual tensile stress in that layer. The latter nated SiC whisker/alumina hybrid design, DX-14, uses TiCp-alumina as the outer layer and for up to 5.7 minutes of cutting. The DX-14 speci- in a substantial residual compressive stress. The men experienced chipping at 6.7 minutes of cut- conventional TiCp-alumina cutting tool material ting. The notched wear of these materials during has a wear rate between these two design this operation (Fig. 2) did not follow the same The results of these tests indicate that the cut order of wear resistance as did the nosc wcar. In ting performance of ceramic cutting tools is infl- this case, the SX-5 material had the best wear uenced by the state of residual stress in the performance while the wG-300 had the poorest. material. a typical wear surface is shown for lami Both WG-300 and DX-14 chipped after 4.7 min- nate design GX-20 in Fig. 5. Both the wear land utes of cutting in the nose area and in the fank area are similar The chipping in the depth-of-cut notch region is Er rrosive wear is seen to extend from the depth-of clearly seen in Fig 3. The chipping on the rake cut notch to the nose area on the rake face.A face near the nose region of the cutting tool can laminated Sic-alumina design(DX-13)cutting tool was also tested against 4340 steel. The wear surface for this cutting tool is shown in Fig.6 The low flank and nose wear for this tool design is EEz 00LLLL 01234567 Fig. 3. SEM photograph of laminated SiC/alumina(DX-14) Fig. 4. Nose wear of various laminated ceramic composites cutting tool showing large chip near the depth-of-cut region against 4340 steel.Ceramic composite cutting tools 321 c A E 1.25 DX-14 v RD-3905 i I 012345678 Cutting Time, min. Fig. 2. Notch wear of ceramic composite cutting tools against 71X nickel based superalloy. Figures 1 and 2 compare the nose and notch wear, respectively, for monolithic materials, WG- 300, SX-5 and RD-3905, with the laminated ceramic design DX-14 during the first cutting operation. Both TIN reinforced S&N, composi￾tions, SX-5 and RD3905, exhibited significantly greater wear than either the monolithic Sic whisker-reinforced alumina, WG-300, or the lami￾nated SIC whisker/alumina hybrid design, DX-14, for up to 5.7 minutes of cutting. The DX-14 speci￾men experienced chipping at 6.7 minutes of cut￾ting. The notched wear of these materials during this operation (Fig. 2) did not follow the same order of wear resistance as did the nose wear. In this case, the SX-5 material had the best wear performance while the WG-300 had the poorest. Both WG-300 and DX-14 chipped after 4.7 min￾utes of cutting. The chipping in the depth-of-cut notch region is clearly seen in Fig. 3. The chipping on the rake face near the nose region of the cutting tool can Fig. 3. SEM photograph of laminated SKYalumina (DX-14) cutting tool showing large chip near the depth-of-cut region. also be seen in this figure. The nose wear for the Sic whisker composites WG-300 and DX-14 are all low compared to the TiN reinforced S&N, materials (SX-5 and RD3905) for all subsequent cutting operations. 6.2 Cutting tests against 4340 steel One commercially available conventional TiC-alu￾mina cutting tool and various Tic-alumina lami￾nated designs and one SIC whisker/alumina design were tested against 4340 steel. In these tests, each of the eight corners of the cutting tool were sub￾jected to increasing cutting times. Figure 4 shows a comparison of nose wear for the conventional and laminated Tic/alumina composite and a lami￾nated Sic whisker/alumina cutting tool material. The nose wear data for these tests appear to fall into three groups. The Tic/alumina composite laminate designs GX-06 and GX-08 have the highest wear rates, while the design GX-20 has the lowest wear rate. The former two designs use alu￾mina on the outer surface which results in a resid￾ual tensile stress in that layer. The latter design uses TiCp-alumina as the outer layer and results in a substantial residual compressive stress. The conventional TiCp-alumina cutting tool material has a wear rate between these two designs. The results of these tests indicate that the cut￾ting performance of ceramic cutting tools is infl￾uenced by the state of residual stress in the material. A typical wear surface is shown for lami￾nate design GX-20 in Fig. 5. Both the wear land in the nose area and in the flank area are similar. Errosive wear is seen to extend from the depth-of￾cut notch to the nose area on the rake face. A laminated Sic-alumina design (DX-13) cutting tool was also tested against 4340 steel. The wear surface for this cutting tool is shown in Fig. 6. The low flank and nose wear for this tool design is 2 0.2 2 . HC-2 : 0.1 :;I;; v GX-06 + DX-13 0.0 - 01234567 Cutting Time, min. Fig. 4. Nose wear of various laminated ceramic composites against 4340 steel