Effect of Some Lithium Compounds on Sintering of MgO

The addition of 0.25% or more of certain lithium compounds, particularly the halides, facilitates the pressing and sintering of reactive forms of high‐purity magnesium oxide. Densities up to 3.46 gm. per cm. 3 have been obtained at 1400°C. with reagent‐grade magnesium oxide containing 0.5% lithium chloride as an additive. The effectiveness of lithium salts as sintering catalysts for magnesium oxide depends on the original surface area and particle size of the MgO. After autoclaving at 150 lb. per sq. in. gauge for 2 hours, samples of MgO sintered at 1400°C. with 0.5%of LiCl showed a water absorption comparable to that of fused magnesium oxide. Similar samples of lithium‐treated periclase had about the same resistance to attack by a NaOH‐FeO melt as pure MgO fired at 1800° to 1850°C.