Abstract: Vacuum carburizing of ferrous workpieces is performed at low pressure in a vacuum furnace using an unsaturated aromatic such as benzene as the carburizing medium. The unsaturated aromatic is gas phase hydrogenated into naphthenes, such as cyclohexane, which is metered into the furnace chamber proper and functions as the carburizing gas. The furnace is constructed to be generally transparent to the naphthenes so that cracking tends to occur at the workpiece which functions as a catalyst to minimize carbon deposits. The unsaturated aromatic is supplied in liquid form to fuel injectors which inject the liquid aromatic as a vapor at duty cycles and firing orders to produce a uniform dispersion of the hydrocarbon gas about the work resulting in uniform carburizing of the workpieces. An in-situ methane infrared sensor controls the process.

Abstract: Vacuum carburizing of ferrous workpieces is performed at low pressure in a vacuum furnace using a carburizing hydrocarbon as the carburizing medium. The furnace is constructed to be generally transparent to the carburizing hydrocarbon so that cracking tends to occur at the workpiece which functions as a catalyst to minimize carbon deposits. The carburizing hydrocarbon is supplied in liquid form to an injector which injects the liquid carburizing hydrocarbon as a vapor to produce a uniform dispersion of the carburizing hydrocarbon about the workpiece, resulting in uniform carburizing of the workpieces.

Abstract: A method for recovering Tb.sub.4 O.sub.7 from a glass containing terbium oxide is disclosed, the method including the steps of:I. fusing the glass containing terbium oxide with NaOH to provide a solid fusion product;Ii. slurrying the fusion product of Step I to disperse solid particles of Tb.sub.4 O.sub.7 and any Li.sub.2 SiO.sub.3 present and to dissolve any Al.sub.2 O.sub.3, NaOH and Na.sub.2 SiO.sub.3 to thereby separate the same from the solid particles of Tb.sub.4 O.sub.7 ;Iii. reacting the solid particles of Tb.sub.4 O.sub.7 of Step II with HNO.sub.3 to provide Tb(NO.sub.3).sub.3 ;Iv. reacting the Tb(NO.sub.3)3with oxalic acid to form Tb.sub.2 (C.sub.2 O.sub.4).sub.3 ; andV. firing the Tb.sub.2 (C.sub.2 O.sub.4).sub.3 to form CO.sub.2 and solid Tb.sub.4 O.sub.7 to that is recovered from the glass.