Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
  • B22F5/007—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product of moulds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
  • B22F5/10—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product of articles with cavities or holes, not otherwise provided for in the preceding subgroups
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
  • B22F2998/10—Processes characterised by the sequence of their steps

Definitions

• the object of this invention is a method for making inner channels or cavities to a component made of powder using a hot isostatic pressing.
• the hot isostatic pressing can be used to compress powder, usually a metal powder, into a solid component.
• the compression is usually carried out by using a mould made of thin metal plate, that is a so called capsule, which is filled with powder, vacuumed and placed into an autoclave in a high temperature and pressure.
• the capsule can be so formed that it resembles the actual object, then it is a so called near net shape (NNS) manufacturing.
• the gas typically argon
• the pressure of the gas is not necessarily enough to prevent the effects shaping the cross section profile of the material surrounding the channel.
• the risks of the manufacturing are linked to that in the method in question the inner channels must be in connection to the outer side of the capsule and making of welds of the gas tight connection tubes is difficult.
• the aim of this invention is to produce a method for manufacturing a powder made component, where the effects caused by the hot isostatic pressing to the cross section profile of the inner channels are minimized and to minimize the risks relating to the manufacturing of an object, such as the difficult welding joints.
• the inner channels are made so that a) the moulds used to form the inner channels of a component are filled with a first powder, preferably a ceramic powder and placed inside of the actual capsule, or b) a piece is made which is formed like the cavity and made of a solid material, preferably a copper-nickel alloy and placed inside the actual capsule.
• the actual capsule in turn is filled with a second powder, that is a mould powder, which typically is a metal powder.
• it is essential that these materials, the first powder or the solid material and the second powder differ from each other, preferably the difference is either in the different sintrating temperatures of the powder or in the different melting temperatures of the materials.
• the first powder is removed mechanically from the inner channels or b) the solid mould core material is melt from the inner channels. After this, a second hot isostatic pressing is performed, where the mould powder densities further.
• Figure 1 depicts the ceramic filled inner channels which are used for making inner channels and placed inside the actual capsule
• Figure 2 depicts a component to be produced after the hot isostatic pressing, and where there is depicted the openings which are used for removing the ceramic powder after the first hot isostatic pressing.
• a mould 2 of the desired inner channel is placed, which is manufactured preferably from a metal plate.
• These moulds of the inner channels are filled with a powder, preferably a ceramic powder, e.g. aluminium oxide (AL 2 O 3 ) which differs from the actual mould powder.
• the inner channel parts which are filled with ceramic, can be either separately vacuumed and closed or a hole can be left to them, when they get vacuumed during vacuuming of the actual article. In the later case care must be taken that the ceramic powder of the inner channels and the mould powder used to fill the actual capsule, typically a metal powder, do not mix.
• the parameters for the first compression that is the temperature (e.g. 1000-1300 °C), the pressure (e.g. 100-150 Mpa) and the time are so chosen that the mould powder in the capsule compresses almost to a full density (typically >92%, which is a typical bound density of a powder, after which the porosity through the structure is removed) but the ceramic powder used for the inner channels stays loose.
• Fig. 2 is depicted the component to be manufatured after a hot isostatic pressing, and there is also depicted the openings 3 which are used to remove the ceramic powder after a first hot isostatic pressing.
• the capsule is taken again to the hot isostatic pressing, where the used parameters, i.e temperature, pressure and time are so chosen that the desired density in the mould powder is achieved.
• the article which can be e.g. a valve, is ready for follow-up processing that is typically thermal processing and machining.
• the main features of the processing are the same as in the above mentioned example but the parameters of the first hot isostatic pressing are so chosen that the solid mould does not melt during the processing.
• the first hot isostatic pressing holes are made to the capsule and the solid moulds are removed by melting in an oven whose temperature is higher than the melting temperature of the solid moulds but lower than melting temperatures of the second powder and the capsule material.
• a second hot isostatic pressing is performed, whose parameters are so chosen that the second powder achieves a full density.

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• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Mechanical Engineering (AREA)
• Powder Metallurgy (AREA)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (2)

Cited By (6)

Citations (2)

• 2003
  • 2003-11-21 FI FI20031698A patent/FI117085B/sv not_active IP Right Cessation
• 2004
  • 2004-11-22 WO PCT/FI2004/050170 patent/WO2005049251A1/en active Application Filing

Patent Citations (2)

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