The titanium-palladium alloy is an α-type titanium alloy with titanium as the matrix, containing a small amount of palladium (typically 0.04% - 0.25%). The catalytic effect of the palladium element significantly enhances the corrosion resistance of titanium in reducing media, while retaining the advantages of titanium such as light weight, high strength, and good machinability.
Titanium itself has good corrosion resistance. However, in certain reducing, non-oxidizing or locally oxygen-deficient acidic media (such as dilute hydrochloric acid, dilute sulfuric acid, phosphoric acid, oxalic acid, etc.), the protective oxide film on its surface is not stable enough and is prone to develop crevice corrosion or pitting corrosion.
Cathodic alloying effect: Palladium is a precious metal with a much higher potential than titanium. In corrosive environments, palladium uniformly disperses as a small cathode phase within the titanium matrix. It promotes passivation. When titanium begins to undergo localized corrosion, the cathodic action of palladium can significantly promote the passivation of the titanium anode area, rapidly re-forming a protective oxide film (TiO₂). Reducing the corrosion rate has enabled the titanium-palladium alloy to exhibit a corrosion resistance several orders of magnitude higher than that of industrial pure titanium in reducing media, especially in harsh conditions such as high temperatures, high concentrations, or low pH values.
Outstanding corrosion resistance is demonstrated in both oxidizing and reducing media, and it is particularly superior in terms of anti-seam corrosion ability, far exceeding that of pure titanium. It inherits the advantages of titanium, such as low density, high specific strength, non-magnetism, and good biocompatibility. It also has excellent machinability. Its mechanical properties and processing performance are similar to those of industrial pure titanium, allowing for forging, rolling, welding, etc. The corrosion resistance after welding is also well maintained. The wide application scope has expanded the application range of titanium in the chemical industry. Comparison with titanium-molybdenum-nickel alloy (Gr 12):
Gr 7 (Ti-Pd): Through the cathodic modification with precious metal palladium, the corrosion resistance mechanism is "facilitating passivation", and it performs extremely well even in oxidizing media. Gr 12 (Ti-0.3Mo-0.8Ni): By enhancing the thermodynamic stability of titanium in reducing media through the addition of molybdenum and nickel, it follows the "alloy strengthening" mechanism. Its resistance to reducing acid corrosion is superior to pure titanium but usually slightly inferior to Gr 7. However, the cost is much lower than Gr 7. Selection: When budget is sufficient and the working conditions are extremely harsh, choose Gr 7; when cost is sensitive and the working conditions are moderately harsh, Gr 12 is a more cost-effective choice.
Chemical hydrochloric acid evaporator, dilute sulfuric acid pipeline, phosphoric acid reactor, urea synthesis tower, electrolytic cell resistant to reducing acid corrosion, resistant to high temperature, resistant to chloride ion corrosion. Petrochemical desulfurization device, acidic gas transportation pipeline, hydrogenation reaction equipment resistant to hydrogen sulfide, organic acids, high-temperature and high-pressure environment. Marine engineering seawater desalination equipment, marine platform heat exchanger, seawater treatment system resistant to seawater corrosion, resistant to biological adhesion.
Metallurgical wet metallurgical equipment, electroplating tank, corrosion liquid transportation pipeline resistant to strong acids, strong alkalis, high-salt media. Pharmaceutical and pharmaceutical reaction vessel, sterile fluid transportation system resistant to corrosion, good biocompatibility, no heavy metal pollution.
Heat treatment and processing should be carried out in a vacuum or inert atmosphere to prevent oxidation and hydrogen absorption. During processing, care must be taken to avoid iron contamination, as it can damage the corrosion resistance of the material. Titanium-palladium alloy (such as TA9/Gr 7) is the "king of corrosion resistance" in the titanium material family. By adding a small amount of precious metal palladium, a significant leap in corrosion resistance has been achieved. It is particularly adept at dealing with challenges in reducing acidic media. Its high performance comes with a high cost, and it is one of the ultimate material solutions for extreme corrosion problems.
