窒化物セラミックス(AlN,SIALON,Si_3N_4)及びその助剤(Al_2O_3,Y_2O_3,SiO_2,MgO)と銅,酸化銅との反応

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In order to evaluate the feasibility of applying ceramics (AlN, SIALON, Si_3N_4) to casting equipment for copper-based alloys, the reactivity of copper oxides with nitride ceramics and their oxide additives (Al_2O_3, Y_2O_3, SiO_2, MgO) was examined. Ten weight percent Cu, Cu_2 O and CuO were mixed with powders of nitrides and oxides, and kept at temperature between 700° and 1300℃ in air and at 1200℃ in a nitrogen atmosphere having oxygen partial pressure (P_<o_2>) of 〜3×10^<-1> and 〜3×10^<-3> Pa for one hour. In air, CuO accelerated the oxidation of the nitride ceramics, and the three kinds of nitride samples oxidized above 1200℃. Silicon nitride ceramics did not oxidize below 1000℃, and may be used to brass casting. Al_2O_3 and Y_2O_3 reacted with the copper oxides. SiO_2 did not react, but melted above 1050℃. MgO seemed to form a solid solution with CuO. On the other hand, CuO in the mixture was reduced to Cu, and all the seven kinds of ceramics were stable above 1200℃ under nitrogen atmosphere with P_<o_2> below 1 Pa. Therefore, the seven kinds of ceramics may be used for casting of copper-based alloys at P_<o_2> below 1 Pa.
1992-07-01