Method for preparation of sintered parts from an aluminum sinter mixture

• US 6,468,468 B1
• Filed: 10/20/2000
• Issued: 10/22/2002
• Est. Priority Date: 10/21/1999
• Status: Expired due to Term

• Current Assignee: ECKA Granulate GmbH & Co. KG (Kymera International)
• Original Assignee: ECKA Granulate GmbH & Co. KG (Kymera International)
• Inventors: Müller, Armin, Gradl, Johann, Neubing, Hans-Claus
• Primary Examiner(s): MAI, NGOCLAN THI
• Application Number:
  US09/692,314
• Time in Patent Office: 732 Days
• Field of Search: 419/38, 419/57, 752/49
• US Class Current: 419/38
• CPC Class Codes: B22F 1/09 Mixtures of metallic powders
• CPC Class Codes: B22F 2201/02 Nitrogen
• CPC Class Codes: B22F 2998/10 Processes characterised by the sequence of their steps
• CPC Class Codes: B22F 2999/00 Aspects linked to processes or compositions used in powder metallurgy
• CPC Class Codes: B22F 3/1007 Atmosphere B22F3/1021 takes precedence
• CPC Class Codes: B22F 3/1021 Removal of binder or filler removal of binder from ceramics C04B35/638
• CPC Class Codes: B22F 9/082 atomising using a fluid using centrifugal force B22F9/10
• CPC Class Codes: C22C 1/0416 Aluminium-based alloys

Abstract

Described is a process for producing sintered parts from an aluminum sintering mixture, wherein between 10 and 70% by weight of pure aluminum powder and between 30 and 90% by weight of an aluminum alloy powder are mixed to form an aluminum sintering mixture. The aluminum alloy powder is of the following composition:

between 14 and 35% by weight of Si;

between 1 and 7% by weight of Cu;

between 0.3 and 2.5% by weight of Mg;

between 0.3 and 6% by weight of a transition metal, the balance aluminum.

The pure alloy powder and the aluminum alloy powder are each of a grain size of a maximum of 315 μm. The aluminum sintering mixture is mixed with between 0.5 and 2% by weight of compacting additive. The mix of alloy sintering mixture and compacting additive is compacted to form a green compact. The green compact is then sintered. As no low-melting phases occur in the invention, sintered bodies which are stable in respect of shape are reproducibly obtained in the sintering operation.

Claims

1. A process for producing sintered parts from an aluminum sintering mixture comprising the following steps:

mixing between 10 and 70% by weight of a pure aluminum power and between 30 and 90% by weight of an aluminum alloy powder to form an aluminum sintering mixture;

mixing the aluminum sintering mixture with between 0.5% and 2% by weight of a compacting additive to form a mix;

compacting the mix to form a green preform; and

sintering the green preform;

wherein the aluminum alloy powder comprises;

aluminum,

between 14 and 35% by weight of Si,

between 1.0 and 7% by weight of Cu,

between 0.3 and 2.5% by weight of Mg,

between 0.03 and 6% by weight of one or more elements selected from the group consisting of Ti, Fe, V, Zr, Ni, and Cr; and

wherein the pure aluminum powder and the aluminum alloy powder have a maximum grain size of 350 μ

m.

2. A process as set forth in claim 1, further comprising the step of:

atomizing an aluminum alloy powder melt and a pure aluminum powder melt in a protective gas environment or in air to respectively produce the aluminum alloy powder and the pure aluminum powder.

3. A process as set forth in claim 1, further comprising the step of:

atomizing a pure aluminum powder melt in air to produce the pure aluminum powder.

4. A process as set forth in claim 2, further comprising the step of:

quenching the aluminum alloy powder melt such that Si-primary crystallites are present in a fine distribution of a maximum of 25 μ

m, with the Si-content being above the eutectic composition.

5. A process as set forth in claim 1, wherein the mix is compacted to 95% of a theoretical density for the green preform.

6. A process as set forth in claim 1, wherein the sintering of the green preform is effected in a protective gas atmosphere.

7. A process as set forth in claim 6, wherein the sintering of the green preform is effected in a pure nitrogen atmosphere with a low dew point.

8. A process as set forth in one of the preceding claims, further comprising the step of:

dewaxing the green preform prior to the sintering.

9. The process according to claim 1, wherein the pure aluminum powder and the aluminum alloy powder have a maximum grain size of 200 μ

m.