Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C14/00—Alloys based on titanium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
  • C22F1/16—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of other metals or alloys based thereon
  • C22F1/18—High-melting or refractory metals or alloys based thereon
  • C22F1/183—High-melting or refractory metals or alloys based thereon of titanium or alloys based thereon

Definitions

• the present invention relates to a titanium alloy for corrosion-resistant materials.
• Titanium forms thereon an oxidized film and therefore is not easily corroded as compared with general metals, so that it is widely used in a place requiring corrosion resistance.
• titanium has more excellent corrosion resistance, and in order to deal with it, corrosion resistance is improved hitherto by adding another element to titanium.
• Ti—Pd alloys which are also prescribed in JIS 11 type, 12 type and 13type, are known. These are alloys containing 0.12-0.25% by mass of Pd in pure titanium. Also, it is conventional to contain therein Co, Ni or the like other than Pd (cf. Patent Documents 1 and 2).
• titanium has excellent characteristics as compared with general metals, and specifically it has not only excellent corrosion resistance but also a light weight and a high strength, and therefore various alloys are used in various applications, such as sports goods such as golf clubs and bicycles.
• titanium alloys are expensive compared with general metals, and in these days, utilization of low cost, recycled titanium alloys, which are obtained by recycling not only sponge titanium produced from titanium ores, but also titanium alloys, which were once introduced into markets and had become out of use, are now being studied.
• titanium alloys for corrosion-resistant materials have been very expensive in the past.
• conventional titanium alloys for corrosion-resistant materials have a problem in that they cannot be produced at low cost while maintaining the capability to suppress the deterioration of corrosion resistance.
• Patent Document 1 Japanese Patent No. 2132925
• Patent Document 2 Japanese Patent Application Publication No. Hei-4-57735
• the present inventors intensively studied in order to solve the above problems, consequently found that it is possible to suppress the deterioration of corrosion resistance when a certain amount or less of at least one of Al, Cr, Zr, Nb, Si, Sn and Mn is contained in a titanium alloy, and thus achieved the present invention.
• a titanium alloy for corrosion-resistant materials which is characterized in that it contains 0.01-0.12% by mass in total of at least one of platinum group elements, at least one of Al, Cr, Zr, Nb, Si, Sn and Mn, in which at least one of Sn and Mn is included, and the residue comprising Ti and impurities, in which the total content of Al, Cr, Zr, Nb, Si, Sn and Mn is 5% by mass or less.
• containing Al, Cr, Zr, Nb, Si, Sn and Mn in a titanium alloy is meant that Al, Cr, Zr, Nb, Si, Sn and Mn each are present in the titanium alloy in an amount exceeding the unavoidable level.
• the content of each of these elements can be measured by using a conventionally used analytic instrument.
• the contents, as the unavoidable levels, of these elements present in a titanium alloy are, at maximum, Al: 0.007% by mass, Cr: 0.007% by mass, Zr: 0.001% by mass, Nb: 0.001% by mass, Si: 0.004% by mass, Sn: 0.001% by mass and Mn: 0.001% by mass, respectively.
• Al, Cr, Zr, Nb, Si, Sn and Mn in a titanium alloy is meant in the specification of this application that these elements each are present in the titanium alloy in an amount exceeding the corresponding amount.
• Al, Cr, Zr, Nb, Si, Sn or Mn is contained in a titanium alloy for corrosion-resistant materials, so that it is possible to reuse recycled titanium alloys coming from products in which at least one of Al, Cr, Zr, Nb, Si, Sn and Mn is used.
• 0.01-0.12% by mass in total of at least one of platinum group elements is contained in the titanium alloy for corrosion-resistant materials, and the total content of Al, Cr, Zr, Nb, Si, Sn and Mn is 5% by mass or less. Whereby, it is possible to suppress the deterioration of corrosion resistance.
• a titanium alloy for corrosion-resistant materials of this embodiment usually contains a platinum group element, any one or both of Co and Ni, at least one of Al, Cr, Zr, Nb, Si, Sn and Mn, in which at least one of Sn and Mn is included, and the residue comprising Ti and impurities.
• the platinum group element is an essential component of a titanium alloy for corrosion-resistant materials, and the content thereof is 0.01-0.12% by mass.
• the content of the platinum group element is 0.01-0.12% for the reason that when the platinum group element is less than 0.01% by mass, the corrosion resistance of the titanium alloy for corrosion-resistant materials does not reach a satisfactory level, which may cause corrosion, and on the other hand, even when the content thereof exceeds 0.12% by mass, it cannot be expected to have the corrosion resistance improved as the increase of the content thereof, and in addition, there is a possibility of increasing the cost of a titanium alloy for corrosion-resistant materials.
• platinum group element it is possible to use Ru, Rh, Pd, Os, Ir and Pt, and preferably use Pd.
• Co and Ni are optional components, and the content thereof is 0.05-2.00% by mass. These may be contained in the titanium alloy for corrosion-resistant materials, in place of Ti contained in the titanium alloy as a residue of the essential components, such as the platinum group element and at least one of hereinafter described Al, Cr, Zr, Nb, Si, Sn and Mn. They are contained in the amount of 0.05-2.00% by mass, thereby producing an advantage of further improving the corrosion resistance while increasing the strength of the titanium alloy for corrosion-resistant materials. When the total amount of Co and Ni is less than 0.05% by mass, it is difficult to produce the advantage of further improving the corrosion resistance while increasing the strength of the titanium alloy.
• the at least one of Al, Cr, Zr, Nb, Si, Sn and Mn, in which at least one of Sn and Mn is included, is an essential component of a titanium alloy for corrosion-resistant materials, and the total content of Al, Cr, Zr, Nb, Si, Sn and Mn is 5% by mass or less.
• These elements are contained in such a range for the reason that when the total content of Al, Cr, Zr, Nb, Si, Sn and Mn exceeds 5%, the corrosion resistance of the titanium alloy for corrosion-resistant materials is deteriorated, which causes corrosion. From these points of view, the total content of them is preferably 3% or less, and more preferably 2% or less.
• impurities include unavoidable impurities such as C, O, H and Fe, and a small amount of another element may be contained in the titanium alloy for corrosion-resistant materials to such an extent as not to deteriorate the advantages of the present invention.
• V, Mo and W are known as the elements causing less influences on the corrosion resistance, and can be contained in a titanium alloy for corrosion-resistant materials as long as the total content thereof is about 5% by mass or less.
• the titanium alloy for corrosion-resistant materials mentioned above is preferably used for conduits, heat exchangers, electrolysis vessels and the like of such as a nickel refining plant, which are used in environments, in which they are exposed to concentrated sulfuric acid, nickel sulfate or nickel chloride at about 250° C.
• Titanium alloys for corrosion-resistant materials are prepared by adjusting samples for evaluation on corrosion resistance of the respective Examples, Comparative Examples and Reference Examples, using pure titanium and the respective components so as to have the components of Tables 1 and 2 contained in the amounts of Tables 1 and 2.
• pure titanium is used for Comparative Example 1.
• the titanium alloy of each composition is produced with a size having a thickness of 20 mm, a width of 70 mm and a length of 90 mm by melting through button arc melting.
• the thus produced pieces each are hot rolled into 3 mm thickness, and then acid-washed, thereby removing scale from the surface, and cut into a test piece having a width of 50 mm and a length of 100 mm. Then, one side of this test piece is polished with a #200 polishing sheet, while the lateral and rear sides thereof were sealed with a sealing agent, thereby allowing only the polished surface to be exposed to the surface.
• each sample for evaluation of corrosion resistance is prepared.
• the weight of each sample for evaluation of corrosion resistance is measured before and after the immersion in the nickel chloride solution by using an electronic balance that is capable of measuring the weight with the unit of 0.1 mg, and the difference thereof is calculated as a weight reduction ( ⁇ M).
• the reduced amount is calculated by the following expression based on the surface area (S) of each sample for evaluation of corrosion resistance before the immersion.
• the titanium alloy for corrosion-resistant materials of the present invention is capable of suppressing deterioration of corrosion resistance even though it uses recycled titanium alloys or the like, and thus being produced at low cost while maintaining the capability to suppress the deterioration of corrosion resistance.

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• Preventing Corrosion Or Incrustation Of Metals (AREA)
• Prevention Of Electric Corrosion (AREA)
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• Investigating And Analyzing Materials By Characteristic Methods (AREA)

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• 2005
  • 2005-12-28 JP JP2005377163A patent/JP3916088B2/ja not_active Expired - Fee Related
• 2006
  • 2006-07-31 WO PCT/JP2006/315132 patent/WO2007077645A1/fr not_active Ceased
  • 2006-07-31 EP EP06782010.0A patent/EP1978119B1/fr active Active
  • 2006-07-31 US US12/087,066 patent/US20090004042A1/en not_active Abandoned
  • 2006-07-31 PL PL06782010T patent/PL1978119T3/pl unknown
  • 2006-07-31 RU RU2008130858/02A patent/RU2405850C2/ru active
  • 2006-07-31 CN CNA2006800444487A patent/CN101316939A/zh active Pending

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