US3739445A
Expired / Lapsed
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Powder metal magnetic pole piece
Assignee: Chromalloy American Corp
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Filing: 1970-12-29
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Granted: 1973-06-19
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Expires: 1990-12-29
Abstract
Abstract A powder metallurgy produced wear resistant magnetic pole piece for use as a pickup head with magnetic playback tapes is provided made of a magnetically soft ferrous alloy containing effective amounts of silicon and aluminum. A powder of the alloy is oxidized to provide a thin oxide on the particles thereof. The powder is then hot pressed in vacuum at an elevated temperature into a dense sintered body. The presence of oxide in the grain boundaries confers wear resistant properties to the alloy. An oxygen content of about 3,400 to 4,400 ppm is preferred.
Inventors
- 👤 J Gabriel
- 👤 W Reilly
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 21:14
CPC Classifications
C; C22; C22C; C22C33/00; C22C33/02; C22C33/0257; C22C33/0278; B; B22; B22F; B22F3/00; B22F3/12; B22F3/14; Y; Y10; Y10S; Y10S75/00; Y10S75/95; Y10S75/951
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
77 words
The sintered powder metallurgy alloy of claim 1, wherein the average grain size ranges from about 10 to 20 microns, wherein the composition consists essentially of about 9 to 9.8 percent silicon, about 5.4 to 6 percent aluminum and the balance essentially iron, wherein the oxygen content of said alloy rangest from about 3,300 to 4,400 ppm, and wherein the average grain size of said sintered alloy is within the range of about ASTM 8 to 11.
Claim 2
Dependent Claim
25 words
The sintered powder metallurgy alloy of claim 2, wherein the silicon content is approximately 9.4 percent and wherein the aluminum content is approximately 5.7 percent.
Claim 3
Dependent Claim
118 words
As an article of manufacture, a magnetic pole piece formed from a magnetically soft ferrous alloy characterized by improved wear resistance when employed in rubbing contact with a moving magnetic playback tape of gamma iron oxide, said pole piece being formed of a sintered alloy composition consisting essentially of about 9 to 9.8 percent silicon, about 5.4 to 6 percent aluminum, and the balance essentially iron, the grain size of said sintered alloy being within the range of about ASTM 8 to 11 and being characterized by a thin encapsulated film of thermally produced oxide surrounding the grains thereof which confer improved wear resistance to said alloy, the amount of oxygen ranging from about 3,300 to 4,400 ppm.
Claim 4
Dependent Claim
24 words
The magnetic pole piece of claim 4, wherein the silicon content is approximately 9.4 percent and wherein the aluminum content is approximately 5.7 percent.
References Cited (Backward Citations)
US3661570A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-06-18 | 1976-12-18 | 1977-06-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-18 | 1980-12-18 | 1981-06-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-18 | 1984-12-18 | 1985-06-19 | $7700.00 | Window Closed / Lapsed |