Active carbon barrier for x-ray tube targets

An x-ray tube comprising:

• an envelope having an evacuated interior region;
• a cathode disposed within the envelope vacuum interior;
• and
• an anode target disposed within the envelope vacuum region, the anode target having a target track which is impacted by electrons emanating from the cathode to generate x-rays, the anode target including;
• body portion,
• an oxide layer for dissipating thermal energy from the target,
• a layer which is at least 50 atom percent of a stable carbide forming material that includes at least one of titanium, zirconium, hafnium, vanadium, uranium, tantalum, niobium, chromium, and alloys thereof between the body portion and the oxide coating, the layer being sufficiently dense and pore-free that carbon migrating through the body portion form carbides with the dense pore-free layer, which carbides have sufficient stability that carbon is not released from the carbide to form carbon monoxide gas at temperatures below about 1200.degree. C.

A method of forming an anode target for an x-ray tube, the method comprising:

• forming a target body portion with a target track extending therearound;
• applying a porous layer of the carbide forming material that forms carbides with a free-energy of carbide formation at least 100 KJ/mole at 1200.degree. C. to the body portion;
• heating the carbide forming material sufficiently near to the carbide forming material melting point that the carbide forming material flows into a dense and pore-free layer;
• coating the carbide forming layer with an oxide, such that the dense, pore-free layer prevents carbon from the body portion from reaching the oxide to form carbon monoxide.

An x-ray tube comprising:

• an envelope having an evacuated interior region;
• a cathode disposed within the vacuum envelope;
• and
• an anode target disposed within the vacuum envelope, the anode target including:
• a body portion;
• a hydrogen-free barrier layer of a material that forms carbides with migrating free carbon at temperatures above 1100.degree. C.,
• a heat emissive layer for dissipating thermal energy.