For your Passivate requirements, ProPlate® has facilities for passivation of both small and large parts using both citric and nitric passivation methods.
Passivation refers to a material becoming "passive," which means, being less influenced by environmental factors. Passivation incorporates a protective outer-layer of base material, that can be utilized as a microcoating, or oxidation which develops extemporaneously in nature. Passivation is the use of a thin coating of a shielding material, such as metal oxide, to build a protection against corrosion. The process of passivation is used to preserve and strengthen the appearance and properties of metals.
ASTM-A967, AMS-2700, ASTM-F86, QQ-P-35
Properties and Process
Passivation improves the surface characteristics of stainless steel through dissolving iron that has been attached to the surface during manufacturing. Without removal, the iron will corrode and present rust spots on the surface.
Passivation also improves the surface of titanium and nitinol by dissolving iron that has been attached to the surface during manufacturing, and by inhibiting the Nitinol or titanium to grow a thicker protective oxide layer, providing optimum corrosion resistance. Passivation is not actually removing any rust, and it is not a coating process, rather it is a deep cleaning process that maximizes corrosion resistance.
Nitric and Citric Passivate
Citric Acid passivation is employed at varied temperatures & pH levels. The particular citric acid passivation process is a function of its respective stainless steel material grade, or other material type.
Nitric acid passivation is employed either with or without sodium dichromate at varied temperatures, chemical concentrations and times immersed. The particular nitric acid passivation process is a function of its respective stainless steel material grade, or other material type.
Medical and Dental Passivation Services
ProPlate® provides precision medical passivation of titanium, nitinol, stainless steel and other medical grade alloys. ProPlate® is a ISO 9001 certified surface finisher and is currently seeking its ISO 13485 certification to support its demanding applications within the medical and dental industries. ProPlate® provides passivation services to various industries including the medical, dental, amd aerospace markets.
Passivation of Nitinol Wire for Medical Devices
Some medical applications call for the passivation of polished nitinol wires and vascular stent components, after conducting a shape setting heat treatment. Surface analysis of passivated nitinol parts reveals that passivation reduces Ni and NiO content in the oxide and increases TiO2 content. Chemical analysis of passivated nitinol commends that the increase in corrosion resistance is relative to the amount of nickel removed. Long term immersion tests suggested that nickel release from the material reduces with time and the amount of nickel released is lower for passivated nitinol. The enhanced corrosion resistance is preserved after extended periods in a saline solution.