Tham khảo tài liệu 'metal machining - theory and applications episode 2 part 11', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Ceramics and superhard materials 393 Table Cermet tool materials data from a range of other manufacturers Wt. Grain ISO code Ti C N WC Other carbide Ni Co size m p kg m3 HV GPa TRS GPa K W mK P01-10 50 16 20 6 8 2 6900 20 P05-25 49 16 15 8 12 2 7000 20 P01-15 48 16 20 5 11 - 7000 - 20 P05 Total carbide 94 Total metal 6 - 6100 - P10 Total carbide 86 Total metal 14 - 7000 11 P20 Total carbide 82 Total metal 18 - 7000 16 P01-20 Total carbide 87 Total metal 13 2 6600 25 P10-30 Total carbide 83 Total metal 17 2 7000 27 P10-30 Not given - 7400 29 data not provided. Ceramics and superhard materials Even less systematically detailed information than for cermet tools is available for the composition and properties of ceramic and superhard materials. Data for tools based on alumina extracted from Brookes 1992 are gathered in Table . There are three sub-groups of material. The first called white alumina because of its colour is pure alumina together with minor additions headed other in the table to promote sintering. These sintering aids can be either magnesium oxide MgO or zirconia ZrO2 for tool grade aluminas ZrO2 is predominantly used. The second group is the black aluminas alumina to which is added TiC. The third group is SiC whisker reinforced alumina. The data demonstrate that the black aluminas are harder but no tougher than the white aluminas. Silicon carbide whisker reinforcement increases toughness without improving hardness relative to the black aluminas. All the materials are developed according to their ISO classification for finishing duties. The data in Table were all collected before 1992. Recently a new handbook has appeared which uprates the maximum toughness of whisker reinforced aluminas to GPa Japanese Carbide Manufacturers Handbook 1998 . Manufacturers data in the authors possession also show maximum hardness of the black aluminas has been enhanced up to .
