Abstract: Dental titanium alloy castings have physical properties equal to physical characteristics incidental to a Ti-6Al-4 V alloy can be obtained by casting titanium alloys containing aluminium at a ratio of 1.5 to 4.0% by weight and vanadium at a ratio of 1.0 to 3.0% by weight.

Abstract: The present invention relates to a mold material for casting pure titanium or a titanium alloy which comprises one or more chief materials selected from among silica-alumina mixtures, mullite and spinel and a hardening agent comprising a phosphate and a basic metal oxide and a process for casting pure titanium or a titanium alloy by the use of said mold material. This mold material forms a refractory structure having a melting point higher than that of pure titanium or a titanium alloy therein to enable pure titanium which is unstable in a molten state to be cast stably.

Abstract: A nitride layer is formed on the surface of a shaped article of titanium by a method which comprises bringing nitrogen gas into contact with the shaped article of titanium in a heated state. The nitrogen gas, en route to the site of contact with the shaped article of titanium, is preparatorily caused to come into contact and react with small particles of titanium so as to be deprived of such extraneous components as hydrogen and oxygen and consequently converted into pure nitrogen gas. This pure nitrogen gas is introduced into contact with the shaped article of titanium in a heated state to effect the nitriding of the surface of the shaped article. An apparatus to be used in effecting the nitriding treatment by the method of this invention is also disclosed.

Abstract: The present invention relates to a mold material for casting pure titanium or a titanium alloy which comprises one or more chief materials selected from among silica-alumina mixtures, mullite and spinel and a hardening agent comprising a phosphate and a basic metal oxide and a process for casting pure titanium or a titanium alloy by the use of said mold material. This mold material forms a refractory structure having a melting point higher than that of pure titanium or a titanium alloy therein to enable pure titanium which is unstable in a molten state to be cast stably.

Abstract: Improved casting of titanum or alloy of titanium is obtained by using a crucible and a mold made of high-purity magnesium oxide and/or zirconium oxide. It is also possible for only the interior portion of the crucible to be made of such high-purity material, or for the mold to be made of copper or an alloy of copper. The mold and crucible can be used in a centrifugal-type casting machine or a compression-type casting machine. In either machine, discharge vents must be provided in the mold to connect the casting chamber with the outer atmosphere. An argon electric arc generated between a pivotable, tiltable cathode and an anode may be used for melting the titanium in the crucible. A high-frequency electric current can also be used to melt the titanium. By using the above apparatus, it is possible to obtain castings which are dimensionally accurate and do not have an external layer of fragile metal oxide or rough cavities.