D Jianxin et al. International Journal of Machine Tools Manufacture 45(2005)1393-1401 wear resistance of the tool materials when with higher SiCw The flank wear rate at various cutting speeds of AB W20 ceramic tool is shown in Fig. 5. The ceramic tool showed higher flank wear at cutting speed higher than 100 m/min Cutting speeds less than 100 m/min seems to be the best range for AB w20 ceramic tool when turning Inconel718 nickel-based alloys Fig 6 shows the crater wear of abw20 ceramic tool at arious cutting speeds when machining Inconel718 nickel based alloys. It was shown that the abw20 ceramic tool exhibited relative small crater wear at cutting speed lower than 100 m/min, and within further increasing of the cutting peed the crater wear increased greatly Fig. 2. SEM micrograph of the polished surfaces perpendicular to the hot pressing direction of ABW20 ceramic tool material. 3.3. Tool wear surfaces material is shown in Fig. 2. In this structure, the white Different modes of tool failure including rake face wear, needle-like phases with clear contrast are SiC whiskers, and flank wear, and breakage were observed when machining of he grey phases are of Al2O3 and TiB2. It is indicated that Inconel718 nickel-based alloys with Al2O3/TiB ,/SiCw porosity is virtually absent, the Sic whiskers are uniformly ceramic tools in this study. Among these tool wear patterns, distributed within the matrix. and there were few whisker abrasive wear was found to be the main mode of flank wear agglomerates. Fig. 3(a) shows the imprint of Vickers while adhesive and diffusion wear were the main rake face indentation test on the polished surface perpendicular to with ceramic tools such as Al 0,/TiC, Al2O,/TiB2, and the hot pressing direction of AB w20 ceramic tool material Crack path produced by Vickers indentation at higher AlzO3/SiCw Breakage was found to be the main tool failure magnification is shown in Fig 3(b). It is noted that the type during high-speed cutting. It is common that several cracks were deflected considerably tool wear patterns appear simultaneously at the same time and have an effect on each other Abrasive wear is usually a dominant wear mechanism on 3. 2. Flank wear and crater wear rates the flank face, it may also be observed on the rake face Abrasion is characterized by development of grooves and Fig 4 shows the flank wear of Al2O3/TiB,/SiCw ceramic ridges in the direction of tool sliding against a newly tools with different TiB2 and SiCw content when machining machined surface of the work piece or chip sliding against Inconel718 nickel-based alloys. It can be seen that the the rake face. The severity of abrasion can be increased in ceramic tools with higher SiCw content showed more flank cases where the work piece materials contain hard wear resistance under the same test conditions. The higher nclusions. such as Inconel718 nickel-based allo 的 3. Imprint of Vickers indentation test on the polished surfaces perpendicular to the hot pressing direction of ABw20 ceramic tool materialmaterial is shown in Fig. 2. In this structure, the white needle-like phases with clear contrast are SiC whiskers, and the grey phases are of Al2O3 and TiB2. It is indicated that porosity is virtually absent, the SiC whiskers are uniformly distributed within the matrix, and there were few whisker agglomerates. Fig. 3(a) shows the imprint of Vickers indentation test on the polished surface perpendicular to the hot pressing direction of ABW20 ceramic tool material. Crack path produced by Vickers indentation at higher magnification is shown in Fig. 3(b). It is noted that the cracks were deflected considerably. 3.2. Flank wear and crater wear rates Fig. 4 shows the flank wear of Al2O3/TiB2/SiCw ceramic tools with different TiB2 and SiCw content when machining Inconel718 nickel-based alloys. It can be seen that the ceramic tools with higher SiCw content showed more flank wear resistance under the same test conditions. The higher wear resistance of the tool materials when with higher SiCw content corresponds to its higher fracture toughness and hardness. The flank wear rate at various cutting speeds of ABW20 ceramic tool is shown in Fig. 5. The ceramic tool showed higher flank wear at cutting speed higher than 100 m/min. Cutting speeds less than 100 m/min seems to be the best range for ABW20 ceramic tool when turning Inconel718 nickel-based alloys. Fig. 6 shows the crater wear of ABW20 ceramic tool at various cutting speeds when machining Inconel718 nickel￾based alloys. It was shown that the ABW20 ceramic tool exhibited relative small crater wear at cutting speed lower than 100 m/min, and within further increasing of the cutting speed the crater wear increased greatly. 3.3. Tool wear surfaces Different modes of tool failure including rake face wear, flank wear, and breakage were observed when machining of Inconel718 nickel-based alloys with Al2O3/TiB2/SiCw ceramic tools in this study. Among these tool wear patterns, abrasive wear was found to be the main mode of flank wear, while adhesive and diffusion wear were the main rake face wear types, and also reported by researchers [9,11,19–22] with ceramic tools such as Al2O3/TiC, Al2O3/TiB2, and Al2O3/SiCw. Breakage was found to be the main tool failure type during high-speed cutting. It is common that several tool wear patterns appear simultaneously at the same time and have an effect on each other. Abrasive wear is usually a dominant wear mechanism on the flank face, it may also be observed on the rake face. Abrasion is characterized by development of grooves and ridges in the direction of tool sliding against a newly machined surface of the work piece or chip sliding against the rake face. The severity of abrasion can be increased in cases where the work piece materials contain hard inclusions, such as Inconel718 nickel-based alloy. Fig. 2. SEM micrograph of the polished surfaces perpendicular to the hot pressing direction of ABW20 ceramic tool material. Fig. 3. Imprint of Vickers indentation test on the polished surfaces perpendicular to the hot pressing direction of ABW20 ceramic tool material. 1396 D. Jianxin et al. / International Journal of Machine Tools & Manufacture 45 (2005) 1393–1401