2195.     MATSUBARA, A.  Chemical Equilibrium Between Iron, Carbon, and Oxygen.  Trans. Am. Inst. Min. and Met. Eng., vol. 67, 1922, pp. 3-55; Chem. Abs., vol. 15, 1921, p. 1683.

        Detailed report on an extended research on (1) the equilibrium composition of the gas phase in the system CO, CO₂, and Fe (containing 2-30% O) at the temperatures 873°, 1,070° and 1,175°; (2) the equilibrium composition of the gas phase in the systems (a) CO, CO₂, FeO (saturated with Fe), and Fe (saturated with FeO) and (b) CO, CO₂, Fe₃O₄ (saturated with FeO), and FeO (saturated with Fe₃O₄) at several temperatures above 700°; (3) the equilibrium composition of the gas phase of the systems (a) FeO, Fe₃C, CO, and CO₃ and (b) Fe, Fe₃C, CO, and CO₂ in the range 700°-1,100°.  The specific reactions considered are (A) 3 Fe₂O₃+CO=2 Fe₃O₄+CO; (B) Fe₃O₄+CO=3 FeO+CO₂; (C) FeO+CO=Fe+CO₂; (D) 2 CO=C+CO₂; (E) 3 FE+2CO=Fe₃C+CO₂; (F) 3 FeO+5CO=Fe₃C+4CO₂.  Pure CO was admitted to a porcelain tube containing a sample of Fe₂O₃ heated to a definite temperature.  After equilibrium was attained the gas phase was withdrawn and analyzed, and the boat containing the partly reduced Fe₂O₃ was weighed to check the amount of O remaining in the solid phase.  This procedure was repeated until the O in the solid phase was reduced to about 2%.  To make sure of the reversibility of the reactions concerned, an already reduced solid phase (Fe-FeO) was oxidized by successive charges of CO₂.  These values agreed with those obtained by reduction with CO.  The equilibrium pressures within the range 561°-1,175° for reactions (B) and (C) when each system contains amorphous C are calculated from the experimental values for the composition of the gas phase. The dissociation pressures for FeO and Fe₃O₄ are also calculated.  When, by successive reductions with CO, the O in the solid phase of the systems considered above is decreased to a small quantity a new reaction begins, and the solid phase contains, besides O, some combined C.  The reaction of carburization takes place according to (E) or (F).  From determinations of the equilibrium constants for (E) or (F) it is concluded that the 1^st period of carburizing reaction coincides with (F) and at a later period with (E); that there exist transient equilibria between the above 2, between the 1^st and reaction (C) and between the 2d and (D); equilibria at lower temperature occur with a more oxidized form of the solid phase than at higher temperature even in the same carburizing reaction.  The limits of temperature and pressure for carburization are determined from the experimental data.  Above 1,300° the carburizing action of CO does not occur; carburized Fe is oxidized to FeO-Fe solid solution by pure CO at 1 atm. pressure.  Under 1 atm. pressure, at 1,200° neither carburization nor decarburization occurs in pure CO; between 1,200° and 1,300°, C-bearing Fe is decarburized by pure CO, but O-bearing Fe may be carburized by the same gas, both reactions ending in the formation of O-bearing carboniferous Fe proper to that temperature; between 695°-1,200° a gas rich enough tin CO will carburize Fe; below 695° no carburization in the ordinary sense can occur.  The carburization theory is applied to the practice of casehardening, the making of malleable castings, and to the explanation of a blast-furnace diagram and the problem of quick smelting.

        MATSUBARA, I.  See abs. 1119, 1120.

        MATSUMOTO, E.  See abs. 1906a.

        MATSUMURA, A.  See abs. 1930.

        MATSUMURA, S.  See abs. 2197, 2198, 2199, 2200, 2201, 2202, 2203, 2204, 2205.